Hematospermia

Hematospermia. Introduction/Background Hematospermia (HS), or hemospermia, the presence of blood in the ejaculate or semen, has been recognized for centuries. Although it is not uncommon to encounter HS in clinical practice, the exact prevalence and incidence are not known. Most men with HS are young (<40 years of age), and HS may occur either as a single episode or repeatedly over time. It is typically a cause of great anxiety to men, mainly because of the imagined possibility of underlying malignancy or venereal disease. HS may be associated with pathology in the prostate gland, seminal tract (seminal vesicles, vasa deferentia, and ejaculatory ducts), verumontanum, urethra, urinary bladder, epididymis, or testes, with cited causes reported to include prior prostatic biopsy, prostatic calculi, inflammatory or infectious conditions such as prostatitis or seminal vesiculitis, ductal obstruction, prostatic cyst formation, and rarely vascular malformations. The majority of cases of HS were thought to be idiopathic in nature; however, as a result of improved imaging techniques, the number of cases labeled as idiopathic has decreased significantly, with one of the main sites of bleeding occurring in the seminal vesicles [1-13]. Of specific etiologies, infectious or inflammatory conditions are the most common, accounting for approximately 40% of HS cases overall. An infectious or inflammatory condition of the urogenital tract is the most common etiology in men <40 years of age [1,6,9,14].


Hematospermia

Hematospermia. Overview of Imaging Modalities Transrectal ultrasound (ultrasound pelvis [prostate] transrectal) Transrectal ultrasound (TRUS) is a safe, inexpensive, effective, noninvasive, radiation-free imaging technique often used as the primary screening or diagnostic modality in men with HS to evaluate the prostate gland and seminal tract. Patients are typically placed in the left lateral decubitus position, and grayscale images are obtained with a 5.0- to 10-MHz TRUS transducer in axial and sagittal planes [12,13,19,20]. Color and power Doppler images can also be acquired, particularly when prostate cancer is suspected and prostatic biopsy is contemplated [2,8]. TRUS-guided aspiration or biopsy of the seminal vesicles or prostate gland can be performed to further elucidate the site of bleeding, to provide a definitive diagnosis if a lesion is detected, or to confirm the presence of ejaculatory duct obstruction [4,15].


Hematospermia

Hematospermia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document.


Hematospermia

Hematospermia. Reprint requests to: publications@acr.org


Hematospermia

Hematospermia. Hematospermia Magnetic resonance imaging Magnetic resonance imaging (MRI), with its excellent soft-tissue contrast, provides radiation-free, multiplanar, high-spatial-resolution anatomic evaluation of the prostate gland and seminal tract. Imaging should be performed at either 1.5T or 3T, although there is no consensus at this time on the appropriate coil selection or field strength. The fundamental advantage of 3T over 1.5T is increased signal-to-noise ratio, which improves the spatial, temporal, and spectral resolution. Comparable performance between multichannel phased array coil MRI of the prostate at 3T and endorectal phased array coil MRI at 1.5T has been reported [20]. As opposed to TRUS, MRI is operator independent and can be performed when TRUS is unsatisfactory or nondiagnostic. Subsequently, small field-of-view axial T1-weighted images and axial, sagittal, and coronal T2-weighted images are obtained for high- resolution evaluation of the prostate gland, seminal vesicles, ejaculatory ducts, and ampullary portions of the vasa deferentia, followed by large field-of-view images to evaluate for pelvic lymphadenopathy [3,7,10,21]. The increasing availability of 3T MRI, which offers a higher signal-to-noise ratio and improved spatial resolution, may preclude the use of an endorectal coil for evaluating the seminal tract [22].


Hematospermia

Hematospermia. Computed tomography Computed tomography (CT) is a noninvasive imaging modality that uses ionizing radiation to identify calcifications, gross soft-tissue masses, or cystic lesions of the prostate gland and seminal vesicles. However, it has limited value in the etiologic determination of HS given its lack of soft-tissue contrast and limitation in differentiating structural changes of the prostate and seminal tract [11,21].


Hematospermia

Hematospermia. Pelvic angiography Pelvic angiography can be useful to evaluate for vascular causes of HS and is mainly reserved for men with intractable HS with or without hematuria when clinical, laboratory, and noninvasive imaging evaluations have not revealed an etiology. If an arterial source of hemorrhage is identified, such as from the internal pudendal artery, transcatheter arterial embolization can be performed in the same session for therapeutic purposes [23].


Hematospermia

Hematospermia. Discussion of Imaging Modalities by Variant Factors that determine the extent of investigation are patient age, duration of HS, and associated symptoms and signs. However, a confounding issue is that currently there are no consensus or society guidelines on the distinction between transient or episodic HS and persistent HS. The distinction has been based on either the number of ejaculates or a specific time period, with differing opinions. Ultimately the decision to pursue further investigation will be made by the referring physician, typically a urologist.


Hematospermia

Hematospermia. TRUS Many investigators have reported that TRUS should be used as the first-line imaging tool in this patient population. TRUS is very sensitive for detecting a variety of abnormalities that may involve the prostate gland and seminal tract in the setting of HS, reportedly demonstrating abnormalities in 82% to 95% of men with HS [4,12,13,19,21]. Abnormalities may include calcifications or calculi in the prostate, ejaculatory ducts, or seminal


Hematospermia

Hematospermia. Hematospermia vesicles; seminal vesicle, ejaculatory duct, or prostatic cysts; benign prostatic hypertrophy; prostatitis; and Cowper gland masses. However, it is important to consider that some of these abnormalities can be found in asymptomatic patients, such as benign prostatic hyperplasia and prostatic calcifications, which are age-related changes, and nonobstructing prostatic cysts [10,13,28,29]. TRUS has shown utility in guiding transperineal aspiration of the seminal vesicles [4]. A recent prospective trial enrolled 106 patients with persistent HS and found the diagnostic accuracy of TRUS and transurethral seminal vesiculoscopy was 45.3% and 74.5%, respectively, although the diagnostic accuracy was higher when both modalities were combined. Vesiculoscopy was most useful in the detection of calculi and obstruction/stricture at the level of the verumontanum orifice or ejaculatory duct [19].


Hematospermia

Hematospermia. Computed tomography CT has very limited value in the etiologic determination of HS for the reasons described above.


Hematospermia

Hematospermia. Pelvic angiography Angiography has been reported sparsely in the literature to be useful for vascular masses when evaluating men with intractable HS with or without hematuria when clinical, laboratory, and noninvasive imaging evaluations have not revealed the etiology. If an arterial source of hemorrhage is identified, transcatheter arterial embolization can be performed during the same session as well [23].


Hematospermia

Hematospermia. Although there are references that report on studies with design limitations, 3 good-quality studies provide good evidence.


Hematospermia

Hematospermia. Relative Radiation Level Information Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with


Hematospermia

Hematospermia. Supporting Documents For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Dizziness and Ataxia

Dizziness and Ataxia. aUniversity of Cincinnati Medical Center, Cincinnati, Ohio. bResearch Author, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio. cPanel Chair, Uniformed Services University, Bethesda, Maryland. dOhio State University, Columbus, Ohio. eUCONN Health, University of Connecticut, Farmington, Connecticut; Neurosurgery expert. fMontefiore Medical Center, Bronx, New York. gYale University School of Medicine, New Haven, Connecticut; Committee on Emergency Radiology-GSER. hWeill Cornell Medical College, New York, New York. iUniversity of Chicago, Chicago, Illinois. jUniversity of Arizona, Tucson, Arizona; Commission on Nuclear Medicine and Molecular Imaging. kUniversity of California Los Angeles, Los Angeles, California. lUniversity of California San Diego, San Diego, California. mOregon Health & Science University, Portland, Oregon. nUT Southwestern Medical Center, Dallas, Texas; American Academy of Neurology. oSchmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida; American College of Emergency Physicians. pThe University of Vermont Medical Center, Burlington, Vermont. qNaval Medical Center Portsmouth, Portsmouth, Virginia. rColumbia University Medical Center, New York, New York. sAssociation for Utah Community Health, Salt Lake City, Utah; American Academy of Family Physicians. tSpecialty Chair, University of Iowa Hospitals and Clinics, Iowa City, Iowa.


Dizziness and Ataxia

Dizziness and Ataxia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization.


Dizziness and Ataxia

Dizziness and Ataxia. Reprint requests to: publications@acr.org


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. Special Imaging Considerations Conventional diagnostic angiography (DA) may be used in a specific subset of patients presenting with episodic vertigo if there is clinical concern for positional insufficiency of the posterior circulation. DA allows for real-time dynamic evaluation of vessel patency in various neck positions, which is difficult to accomplish via conventional CT angiography (CTA) or MR angiography (MRA) imaging. This information may inform subsequent surgical management in these patients [12]. DA also remains the reference standard for confirmation of clinically suspected VBI as well as vertebral artery dissection, both of which can present with vertigo [13,14]. In cases of vertebral artery dissection documented by DA, however, CTA demonstrated a similar sensitivity approaching 100% [14]. The risks of DA include the potential for rare, severe, or life-threatening allergic-like reactions to contrast media, renal injury related to iodinated contrast administration, potential vascular injury, or infarct due to catheter manipulation in the vessels, as well as local complications at the vascular access site to include infection, hematoma, pseudoaneurysm, or arterial occlusion.


Dizziness and Ataxia

Dizziness and Ataxia. Transcranial Doppler ultrasound (US) has demonstrated differences in vascular flow parameters between patients with vertigo related to VBI, patients with vertigo unrelated to VBI, and asymptomatic controls, making this a potential diagnostic tool in the characterization of vertigo [13,15].


Dizziness and Ataxia

Dizziness and Ataxia. Brain PET using various radiotracers has shown promise in detecting presymptomatic neuronal dysfunction in patients with certain types of spinocerebellar ataxia (SCA) and in asymptomatic mutation carriers. Changes on PET were detectable sooner than alterations in morphology and signal intensity on conventional MRI. As such, PET may be a valuable adjunct to conventional brain imaging in this patient population [16,17].


Dizziness and Ataxia

Dizziness and Ataxia. OR Discussion of Procedures by Variant Variant 1: Adult. Brief episodic vertigo. Triggered by specific head movements (eg, Dix-Hallpike maneuver). Initial imaging. Brief episodic vertigo triggered by specific head movements (eg, Dix-Hallpike maneuver) is referred to as triggered episodic vestibular syndrome (t-EVS) and is most commonly due to BPPV; however, more ominous central causes may clinically mimic BPPV and are collectively referred to as CPPV [1]. BPPV results from mobile debris (canaliths) in the vestibular labyrinth. The diagnostic criteria for BPPV are clinical and well established [18-20]. Imaging evaluation in BPPV with typical nystagmus on Dix-Hallpike testing is unnecessary. In contrast, patients with CPPV present with symptoms of t-EVS but negative or atypical Dix-Hallpike testing are at an increased risk of having an acute central cause of vertigo identified on imaging [6]. Potential causes of CPPV include mass lesions, hemorrhage, infarct, and demyelinating disease, among others [1]. Other specific t-EVS subgroups may also be at increased risk of incidental but potentially actionable findings on neuroimaging, including those with subjective symptoms but no objective signs, younger patients with post-traumatic onset of symptoms, elderly patients, those unresponsive to repositioning maneuvers, and those with short-term recurrence of symptoms [21]. Vestibular migraine may mimic a variety of causes of dizziness and vertigo, including t-EVS, but often has associated headache and other migrainous features (ie, photophobia, phonophobia, visual aura) [20,22]. Imaging is not required to


Dizziness and Ataxia

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Dizziness and Ataxia

Dizziness and Ataxia. diagnose vestibular migraine. To summarize, most patients with t-EVS will not require imaging unless there are atypical features such as lack of nystagmus on provoking maneuvers (eg, Dix-Hallpike) or lack of response to treatment maneuvers (eg, Epley).


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast Imaging evaluation in BPPV with typical nystagmus on Dix-Hallpike testing is unnecessary. Head CT allows for the evaluation of the intracranial structures; however, soft tissue contrast is inferior to MRI. In a single-center retrospective study of patients with episodic vertigo triggered by specific head movements but negative or atypical Dix-Hallpike testing (CPPV), CT detected acute brain lesions in 6% of cases compared with 11% with MRI [6].


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of t- EVS.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast There is no relevant literature regarding the use of CTA head and neck with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast There is no relevant literature regarding the use of MRA head and neck with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast There is no relevant literature regarding the use of MRA head and neck without and with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without IV Contrast Imaging evaluation in BPPV with typical nystagmus on Dix-Hallpike testing is unnecessary. MRA allows for evaluation of the course and luminal caliber of the arteries. MRA can also detect luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web. MRA of the head and neck can be performed either without intravenous (IV) contrast, with IV contrast, or as a combination of without and with IV contrast. Although imaging is not required in the setting of typical BPPV, MRA of the head and neck has been used to detect abnormalities of the carotid or vertebrobasilar arteries, which may be associated with symptoms of BPPV. The prevalence of vascular changes is higher in the elderly population with underlying comorbidities such as diabetes, hypertension, and hyperlipidemia in a small prospective study of 126 patients [23].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and internal auditory canal (IAC) with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

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Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast Imaging evaluation in BPPV with typical nystagmus on Dix-Hallpike testing is unnecessary. MRI of the head and IACs provides evaluation of the entire brain with the addition of specific sequences tailored toward assessment of the skull base and associated cranial nerves. The addition of these sequences allows improved detection of small masses and compressive vascular lesions (ie, aneurysm, vessel tortuosity) in and around the IACs. The addition of gadolinium-based IV contrast agents also improves the detection and characterization of masses as well as inflammatory, infectious, or demyelinating processes, which have been described in the setting of CPPV in a retrospective study of 500 patients [21].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of t- EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head With IV Contrast There is no relevant literature regarding the use of MRI head with IV contrast in the evaluation of t-EVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast Imaging evaluation in BPPV with typical nystagmus on Dix-Hallpike testing is unnecessary. MRI allows detailed evaluation of the intracranial structures with improved soft tissue resolution when compared with CT. The addition of MRI of the brain following the IV administration of gadolinium-based contrast allows further characterization of any detected lesions and improves the detection and characterization of masses as well as inflammatory, infectious, or demyelinating processes, which have been described in the setting of CPPV [20]. Acute brain lesions have been reported in 6% of patients undergoing head CT and 11% of those undergoing MRI for CPPV [6].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast Imaging evaluation in BPPV with typical nystagmus on Dix-Hallpike testing is unnecessary. MRI allows detailed evaluation of the intracranial structures with improved soft tissue resolution when compared with CT. MRI of the head is not indicated for the initial diagnosis of typical BPPV. The presence of coexisting brain atrophy on MRI, however, is associated with a higher risk of prolonged dizziness following a diagnosis of BPPV and so may be of prognostic value in these patients in a retrospective study of 120 patients [24].


Dizziness and Ataxia

Dizziness and Ataxia. Variant 2: Adult. Acute persistent vertigo. Normal neurologic examination and HINTS examination is consistent with peripheral vertigo. Initial imaging. The acute onset of persistent vertigo with associated nausea/vomiting, gait instability, nystagmus, and head-motion intolerance defines AVS. These patients may or may not have associated deficits on neurologic examination [1]. This variant will address the imaging approach to those presenting with AVS but a normal neurologic examination (isolated AVS). The approach to those with associated neurologic deficits will be discussed as a separate variant (Variant 3). Patients with vertigo of any cause are often initially evaluated in the emergency department. Although the use of CT imaging performed for this indication has dramatically increased over the past several decades, the detection rate of contributory central nervous system pathology in those with a normal neurologic examination remains very low (<1% in an emergency department in a single center, which included 3,165 patients); see Variant 8 [25]. This is not surprising because many patients with acute vertigo and a normal neurologic examination will have a benign peripheral etiology. In patients with AVS and a normal neurologic examination, the most common causes of symptoms are vestibular neuritis and labyrinthitis, neither of which has associated findings on CT imaging.


Dizziness and Ataxia

Dizziness and Ataxia. The most worrisome cause of AVS to be excluded is a posterior circulation infarct involving the brainstem or cerebellum; see Variant 3. Although the prevalence of cerebrovascular disease in all patients presenting to the emergency department with dizziness or vertigo is approximately 4%, the prevalence of cerebrovascular disease in those presenting with AVS is closer to 25% and may be as high as 75% in the highest vascular risk cohorts [26]. Depending on the skill and training of the examiner, focal neurologic symptoms/signs are reportedly lacking in between one-third and two-thirds of these patients [27]. In one study, 11% of patients presenting with acute persistent vertigo but no focal neurologic symptoms/signs were found to have an acute infarct on CT or MRI of the brain [28]. Other studies estimate that 75% to 80% of patients presenting with AVS related to infarct have no associated focal neurologic deficits [29].


Dizziness and Ataxia

Dizziness and Ataxia. Isolated AVS is most commonly due to a benign peripheral cause; however, a lack of associated neurologic deficits does not exclude a central cause such as infarct. To address this, various bedside tests like the HINTS examination


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. have been developed to distinguish AVS of benign cause from posterior circulation infarct. When performed by specially trained practitioners, these tests have been shown to be even more sensitive than early MRI for the detection of infarct (100% versus 46%) [30]. Similar testing performed by nonexperts has shown more mixed results [6,31]. In another retrospective study involving 610 patients in an emergency department, not a single patient with an AVS, in whom the complete HINTS triad was consistent with peripheral vertigo, had abnormalities on CT/MRI [6]. Multiple sclerosis involving the brainstem or cerebellar peduncles is an additional but rare cause of AVS, accounting for approximately 4% of cases. Of note, nearly all of these patients also have additional abnormal neurologic findings suggesting a central lesion [32]. Even rarer causes of isolated AVS include cerebellar hemorrhage and a variety of autoimmune, infectious, and metabolic conditions [25]. Vestibular migraine may mimic a variety of causes of dizziness/vertigo, including AVS, but often has associated headache and other migrainous features (ie, photophobia, phonophobia, visual aura) [22,33]. Imaging is not required to diagnose vestibular migraine. To summarize, patients with isolated AVS may not require imaging if HINTS examination by specially trained providers is available and negative; otherwise, imaging may be required to rule out stroke.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast Imaging evaluation in isolated AVS without features of central vertigo is unnecessary. Patients with features of central vertigo or high baseline risk for stroke may be candidates for neuroimaging. Head CT allows for rapid evaluation of the intracranial structures. In isolated AVS, the detection rate of acute infarct may be as high at 11% at a single-center study involving 221 patients; therefore, noncontrast head CT may be of benefit in select patients [28]. Brain MRI may be useful for follow up evaluation if initial head CT is negative.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast There is no relevant literature regarding the use of CTA head and neck with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast There is no relevant literature regarding the use of MRA head and neck with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast There is no relevant literature regarding the use of MRA head and neck without and with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without IV Contrast There is no relevant literature regarding the use of MRA head and neck without IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

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Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and IAC with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast Imaging evaluation in isolated AVS without features of central vertigo is unnecessary. Routine MRI of the head in the setting of vestibular neuritis, the most common cause of isolated AVS, is characteristically normal. Dedicated imaging of the IACs allows for improved evaluation of the vestibular nerve and may show a decreased caliber of the nerve following vestibular neuritis; however, this is not always present and is not required to establish the diagnosis [34,35]. Detection of vestibular nerve enhancement following the IV administration of gadolinium- containing contrast would also support the clinical diagnosis of vestibular neuritis [36]. Labyrinthitis, another common cause of AVS, may also have findings on contrast-enhanced MRI of the IACs; however, this is often diagnosed clinically due to the presence of associated hearing loss or tinnitus and will be discussed separately (Variant 4) [1].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head With IV Contrast There is no relevant literature regarding the use of MRI head with IV contrast in the evaluation of isolated AVS.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast Imaging evaluation in isolated AVS without features of central vertigo is unnecessary. MRI of the head without and with IV contrast would be the imaging modality of choice to evaluate demyelinating, autoimmune, inflammatory, or metabolic conditions involving the brainstem or cerebellum, which would all be rare causes of isolated AVS [25]. Although brain parenchymal signal alterations would be demonstrable on precontrast imaging, the addition of gadolinium-containing IV contrast allows for the differentiation of acute and chronic demyelinating lesions as well as detection of other acute inflammation.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast Imaging evaluation in isolated AVS without features of central vertigo is unnecessary. Because routine MRI of the head is characteristically normal in vestibular neuritis, MRI is not required for diagnosis. Patients with features of central vertigo or high baseline risk for stroke may be candidates for neuroimaging. In patients with isolated dizziness symptoms without associated neurological symptoms, the incidence of acute central lesions was 2.3% on MRI in a single center of 645 patients presented to the emergency department [37]. The presence of white matter abnormalities identified on MRI of the head, however, has been shown to positively correlate with the risk of developing subsequent chronic vestibular insufficiency and so may be prognostically useful especially in the elderly population [38]. Approximately 3% to 4% of patients presenting with isolated dizziness had acute stroke on MRI DWI [39]. MRI also has a better sensitivity than CT for the detection of parenchymal infarcts. Studies of patients presenting with AVS related to infarct have shown an overall sensitivity of approximately 80% for MRI performed within 24 hours of symptom onset. Early MRI, however, may be negative in half of cases when the area of infarct is small (<10 mm in size) and located in the brainstem/cerebellum. Patients with these small areas of infarct are also those more likely to present with isolated AVS. In these cases, delaying MRI until at least 48 hours from symptom onset or repeating an initially negative MRI will improve lesion detection [29].


Dizziness and Ataxia

Dizziness and Ataxia. Variant 3: Adult. Acute persistent vertigo. Abnormal neurologic examination or HINTS examination is consistent with central vertigo. Initial imaging. Posterior circulation strokes involving the brainstem and cerebellum account for a smaller proportion of acute stroke presentations but may have severe devastating and debilitating consequences. It is estimated that 25% of AVS are caused by stroke. Approximately 20% of these patients have focal neurologic signs whereas the remainder have


Dizziness and Ataxia

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Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of postcontrast head CT in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of postcontrast head CT in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast CT is usually performed first in the emergency setting for workup of acute stroke. Hemorrhage can be excluded rapidly to select patients for thrombolysis. Posterior fossa ischemic strokes are difficult to detect on CT with a low sensitivity (~10% at a single academic emergency department in 610 patients in a 2-year period) [6]. Overall, the diagnostic yield for head CT ordered in the emergency department for acute dizziness is low (2.2%; 1.6% for emergent findings in an academic emergency department in 448 patients), but MRI changes the diagnosis up to 16% of the time, acutely in 8% of cases [2].


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast CTA head and neck may be performed for evaluation of suspected acute posterior fossa stroke, particularly those who are eligible for mechanical thrombectomy.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast MRA head and neck may be performed for the evaluation of acute ischemic strokes and may assist in the management of patients, particularly those who are eligible for mechanical thrombectomy. The decision between CTA and MRA for initial vascular evaluation may depend on institutional preferences.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast MRA head and neck may be performed for the evaluation of acute ischemic strokes and may assist in the management of patients, particularly those who are eligible for mechanical thrombectomy. The decision between CTA and MRA for initial vascular evaluation may depend on institutional preferences.


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and IAC with IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast There is no relevant literature regarding the use of MRI head and IAC without and with IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head With IV Contrast There is no relevant literature regarding the use of postcontrast brain MRI in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast There is no relevant literature regarding the use of postcontrast brain MRI in the evaluation of suspected acute posterior fossa stroke.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast The ability to detect an acute stroke on DWI is dependent on size [29]. False-negative MRIs with small strokes occurred 6 to 48 hours after the onset of vestibular symptoms. In this retrospective study, central oculomotor signs (odds ratio [OR] 2.8, 95% confidence interval [CI], 1.5-5.2) and focal abnormalities on clinical examination (OR 3.3, 95% CI, 1.8-6.2) are statistically significantly positive predictors for abnormal brain lesions on CT/MRI, whereas the transient nature of symptoms was associated with a reduced risk (OR 0.3, 95% CI, 0.1-0.6).


Dizziness and Ataxia

Dizziness and Ataxia. In a study of emergency department patients with dizziness, combined neurological symptoms with an OR of 16.72, P < .01, was found to be the strongest predictor of a lesion positive on MRI [37]. In a cross-sectional study of 190 high-risk patients with dizziness, HINTS examination outperforms ABCD2 risk scores [30]. The diagnostic yield for head CT ordered in the emergency department for acute dizziness is low (2.2%; 1.6% for emergent findings), but MRI changes the diagnosis up to 16% of the time, acutely in 8% of cases [2].


Dizziness and Ataxia

Dizziness and Ataxia. Earlier MRI studies in posterior fossa stroke showed a high false-negative rate on DWI when performed within the first 24 hours of symptom onset [44,45]. This has improved with better imaging techniques over time. MRI has a higher sensitivity for acute ischemic strokes than CT, although within the first 48 hours DWI still can be falsely negative in approximately 50% of small ischemic strokes in the posterior fossa [6,46]. Some have advocated for delayed MRI (3-7 days) if initial imaging was negative [1,29]. One single-center study of 36 patients with basilar artery occlusion found DWI MRI helps predict outcome in basilar artery occlusion patients treated with intra-arterial thrombolysis [47].


Dizziness and Ataxia

Dizziness and Ataxia. Variant 4: Adult. Chronic recurrent vertigo. Associated with unilateral hearing loss or tinnitus. Initial imaging. In contrast to an isolated episode of acute vertigo, chronic recurrent vertigo suggests an intermittently symptomatic long-standing condition. When associated unilateral hearing loss or tinnitus is present, the diagnosis of MD should be considered. MD is of unknown etiology. Patients have intermittent episodes of vertigo, fluctuating sensorineural hearing loss, tinnitus, and aural fullness. Previously a purely clinical diagnosis, imaging in MD has increased in the past decade. It is associated with endolymphatic hydrops (distension of labyrinthine structures). Imaging may also


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. be used to exclude other causes of such symptoms, such as vestibular schwannoma, superior semicircular dehiscence, and other IAC masses. Most imaging facilities are unable to perform the specific type of MRI required for evaluation of endolymphatic hydrops. Outside of academic medical centers with specialized imaging protocols, IAC MRI is usually performed to negatively exclude other causes of vertigo with unilateral hearing loss or tinnitus, rather than to make a positive imaging-based diagnosis of MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast There is no relevant literature regarding the use of CT head without IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast Superior semicircular canal dehiscence, which can present with similar symptoms to MD, can be readily diagnosed on a CT temporal bone without IV contrast.


Dizziness and Ataxia

Dizziness and Ataxia. Three-dimensional CT temporal bone may be used for the evaluation of stenosis of the vestibular aqueduct [48,49] and high jugular bulb in patients with suspected MD [50].


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast There is no relevant literature regarding the use of CTA head and neck with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast There is no relevant literature regarding the use of MRA head and neck with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast There is no relevant literature regarding the use of MRA head and neck without and with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without IV Contrast There is no relevant literature regarding the use of MRA head and neck without IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. Highly specialized techniques with high resolution such as delayed 3-D fluid-attenuated inversion recovery (FLAIR), inversion recovery turbo spin-echo with real reconstruction (3-D real-inversion recovery), and imaged after gadolinium administration demonstrates accumulation of gadolinium in the endolymphatic sac [53-57]. Intratympanic gadolinium may also be performed but is more invasive [58,59]. Some studies used double dose contrast. Volumetric assessment with ratio of endolymph to perilymph volume in the cochlea and vestibule are performed. Endolymphatic hydrops and grading on MRI in patients with MD has shown correlation with clinical symptoms in multiple studies [52,60-64] and histopathologic specimens [65].


Dizziness and Ataxia

Dizziness and Ataxia. The vestibular endolymphatic space contacting the oval window has a high specificity and positive predictive value in differentiating MD ears from other ears in a small study [66].


Dizziness and Ataxia

Dizziness and Ataxia. Although most of the recent studies have been focused on the postgadolinium enhancement, the noncontrast portion of the MR studies can be helpful in diagnosing alternative causes such as stroke, superior semicircular dehiscence, and other IAC masses. Volumetric measure of inner ear structures has been shown to be useful [67]. Although often not specifically mentioned, a sequence (typically heavily T2-weighted) that shows both perilymph and endolymph to help determine the area of the entire labyrinth is needed, and this is performed without IV contrast.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head With IV Contrast There is no relevant literature regarding the use of MRI head with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast There is no relevant literature regarding the use of MRI head without and with IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast There is no relevant literature regarding the use of MRI head without IV contrast in the evaluation of suspected MD.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast CT head without IV contrast may be useful in the evaluation of suspected VBI, although brain MRI is expected to be more sensitive for the detection of posterior fossa infarcts.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast CTA allows for the evaluation of the course and luminal caliber of the studied arteries. CTA can also detect luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web. In cases of vertebral artery dissection confirmed by conventional angiography, CTA has the highest reported sensitivity (100%), followed by MRA (77%) and Doppler US (71%), in a systematic review of 75 observational studies. Because symptomatic dissection may involve any portion of the vertebral artery, from the origin at the aortic arch branch vessels to the basilar artery, the entirety of the vessel should be included for evaluation [14].


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast MRA allows for evaluation of the course and luminal caliber of the arteries. MRA can also detect luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web. MRA of the head and neck can be performed without IV contrast, with IV contrast, or as a combination of without and with IV contrast. Although 3-D time-of-flight MRA of the head is typically diagnostic without the use of IV gadolinium- based contrast agents, MRA of the neck is often best performed with contrast for better evaluation of the vessels with increased spatial resolution and decreased flow-related artifacts.


Dizziness and Ataxia

Dizziness and Ataxia. In a study comparing the diagnostic performance of contrast-enhanced MRA of the neck to digital subtraction angiography in evaluation of vertebral artery origin stenosis, the sensitivity, specificity, and accuracy of MRA were shown to be as high as 97%, 98%, and 93%, respectively, in 49 patients [69]. However, MRA has not demonstrated significant differences in the degree of arterial stenosis between symptomatic patients with VBI and asymptomatic controls [13]. In cases of vertebral artery dissection confirmed by conventional angiography, CTA has the highest reported sensitivity (100%), followed by MRA (77%) and Doppler US (71%). The addition of nonluminal vessel wall imaging sequences likely improves the detection of nonstenotic arterial dissection, but it is unclear whether these types of lesions would result in VBI. Because symptomatic dissection may involve any portion of the vertebral artery, from the origin at the aortic arch branch vessels to the basilar artery, the entirety of the vessel should be included for evaluation [14].


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast MRA allows for the evaluation of the course and luminal caliber of the arteries. MRA can also detect luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web. MRA of the head and neck can be performed without IV contrast, with IV contrast, or as a combination of without and with IV contrast. Although 3-D time-of-flight MRA of the head is typically diagnostic without the use of IV gadolinium- based contrast agents, MRA of the neck is often best performed with contrast for better evaluation of the vessels with increased spatial resolution and decreased flow-related artifacts.


Dizziness and Ataxia

Dizziness and Ataxia. In a study comparing the diagnostic performance of contrast-enhanced MRA of the neck to digital subtraction angiography in evaluation of vertebral artery origin stenosis, the sensitivity, specificity, and accuracy of MRA were shown to be as high as 97%, 98%, and 93%, respectively in 49 patients [69]. However, MRA has not demonstrated significant differences in the degree of arterial stenosis between symptomatic patients with VBI and asymptomatic controls [13]. In cases of vertebral artery dissection confirmed by conventional angiography, CTA has the highest


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. reported sensitivity (100%), followed by MRA (77%) and Doppler US (71%). The addition of nonluminal vessel wall imaging sequences likely improves the detection of nonstenotic arterial dissection, but it is unclear whether these types of lesions would result in VBI. Because symptomatic dissection may involve any portion of the vertebral artery, from the origin at the aortic arch branch vessels to the basilar artery, the entirety of the vessel should be included for evaluation [14].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and IAC with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast There is no relevant literature regarding the use of MRI head and IAC without and with IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of suspected VBI.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast MRI allows for detailed evaluation of the intracranial structures with improved soft tissue resolution when compared with CT. MRI before and after the administration of gadolinium-containing IV contrast allows for the additional characterization of these tissues and improved detection of intracranial pathology. In the setting of VBI, high- resolution vessel wall imaging of the posterior circulation using IV contrast may be of use as both a diagnostic and prognostic tool, but it is not used as initial imaging in the evaluation of suspected VBI. In a single-center study of 219 patients, when compared with MRA, atherosclerotic plaque in the basilar artery and associated luminal stenosis of >50% was more often identified on vessel wall imaging; however, the degree of narrowing was felt to be likely overestimated. Although atherosclerotic vessel narrowing can certainly result in VBI, the clinical applicability of these findings on vessel wall imaging has yet to be fully elucidated [70]. Interestingly, the degree of vessel wall enhancement in basilar artery stenosis on vessel wall imaging has been shown to correlate with the risk of subsequent infarct and may serve as a noninvasive prognostic marker in patients with VBI [71]. Additionally, alterations of perfusion parameters using arterial-spin labelling in the brain has been shown to correlate with the presence and severity of vertebrobasilar stenosis and serves as an adjunct to contrast-enhanced imaging of the vessel wall as well as luminal imaging via MRA/CTA [68].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast MRI head without IV contrast is useful in the evaluation of VBI and for the detection of posterior fossa infarcts. A negative MRI does not exclude the possibility of chronic ischemia without completed infarction and therefore does not replace the need for vascular imaging.


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. Variant 6: Adult. Chronic disequilibrium with signs of cerebellar ataxia. Initial imaging. Disequilibrium refers to a sensation of imbalance, unsteadiness, or instability. Disequilibrium in addition to loss of muscle coordination is a common finding in cerebellar ataxia, which indicates loss of coordination due to loss of normal motor control by the cerebellum. Cerebellar ataxia includes a variety of clinical conditions characterized by neurodegeneration of the cerebellum and/or brainstem and may result from inherited or sporadic etiologies. The current classification system for the inherited cerebellar ataxias includes autosomal dominant spinocerebellar, autosomal recessive, congenital, mitochondrial, X-linked, and sporadic types. Autosomal ataxias have complex genetic heterogeneity and variable phenotypic expression, which makes diagnosis difficult [72]. Adult-onset sporadic ataxia encompasses a more heterogeneous group of etiologies, which includes toxic/nutritional, immune- mediated, infectious, degenerative, and reclassification as having a genetic basis [73]. Some patients with cerebellar ataxia may also have coexisting symptoms of central or peripheral vestibulopathy, which can further confound the clinic picture [74]. Imaging in cerebellar ataxia is aimed at primarily detecting parenchymal injury in the form of volume loss or alternations in attenuation (CT) or signal intensity (MRI). Patterns of parenchymal injury may suggest a certain ataxia subtype; however, there is a significant overlap of imaging features among various etiologies, and conventional neuroimaging may be unremarkable in early disease. As such, diagnosis relies on the combination of history, a thorough clinical neurologic examination, and imaging with confirmatory laboratory and/or genetic testing based on these findings [73]. In some forms of ataxia, detection of abnormal iron deposition or calcification may also be helpful [75,76]. Finally, imaging is also important to exclude nondegenerative central etiologies of ataxia such as mass lesion or infarct [77].


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast Head CT allows for evaluation of the intracranial structures; however, soft tissue contrast is inferior to MRI. Certain materials, however, are more conspicuous on CT imaging including calcification. Rare subtypes of SCA may show calcification within the brain parenchyma; however, other more common brain parenchymal changes in patients with cerebellar ataxia are best evaluated with MRI [76]. Additionally, parenchymal calcification can often be adequately detected and characterized on MRI.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast There is no relevant literature regarding the use of CTA head and neck with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast There is no relevant literature regarding the use of MRA head and neck with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast There is no relevant literature regarding the use of MRA head and neck without and with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without IV Contrast There is no relevant literature regarding the use of MRA head and neck without IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast MRI of the spine allows for evaluation of the spinal column as well as the soft tissues within and surrounding the spinal column including the spinal cord. Atrophy of the cervical spinal cord on MRI has been described in SCA type 1 (SCA1) and shown to be correlated with symptom severity, disease duration, and the number of pathologic cytosine, adenine, and guanine repeats, which serves at the genetic cause of SCA1 [78]. Similar atrophy has been reported in SCA type 7, Friedreich ataxia, and ataxia with vitamin E deficiency [79,80]. Spinal findings were associated with abnormalities of the brain parenchyma and generally not reported in isolation. Imaging of the spinal cord in other forms of cerebellar ataxia has either been reported as normal or, more often, not specifically described in the literature [81]. Spine MRI may be considered in patients with cerebellar ataxia and additional signs of spinal cord involvement, such as motor spasticity or sensory ataxia (see Variant 7).


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and IAC with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast There is no relevant literature regarding the use of MRI head and IAC without and with IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of cerebellar ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast MRI of the head is the preferred initial imaging modality for the evaluation of patients with cerebellar ataxia. In cerebellar ataxia, morphologic changes (atrophy) and signal alterations primarily involve the cerebellum and brainstem. These findings are typically adequately evaluated on MRI without IV contrast; however, if there is concern for an inflammatory or neoplastic cause of cerebellar ataxia, contrast-enhanced imaging should be included. Advanced MRI techniques such as DWI/diffusion-tensor imaging and spectroscopy do not require contrast administration and have shown promise in detecting early changes in ataxia and may also be useful in distinguishing between some ataxia subtypes in some studies [82-84].


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast MRI of the head is the preferred initial imaging modality for the evaluation of patients with cerebellar ataxia. In cerebellar ataxia, morphologic changes (atrophy) and signal alterations primarily involve the cerebellum and brainstem. These findings are typically adequately evaluated on MRI without IV contrast. Lack of contrast, however, may impair the ability to distinguish between degenerative and inflammatory/infectious causes of cerebellar ataxia. Advanced MRI techniques such as DWI/diffusion-tensor imaging and spectroscopy do not require contrast administration and have shown promise in detecting early changes in ataxia and may also be useful in distinguishing between some ataxia subtypes in some studies [82-84].


Dizziness and Ataxia

Dizziness and Ataxia. Variant 7: Adult. Chronic disequilibrium with signs of sensory or proprioceptive ataxia. Initial imaging. Disequilibrium refers to a sensation of imbalance, unsteadiness, or instability. Symptoms of disequilibrium may result from neurodegeneration or inflammation involving the spinocerebellar tracts, dorsal columns of the spinal


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. cord, dorsal root ganglia, or more peripheral sensory nerves. In contrast to cerebellar ataxia (see Variant 6), sensory or proprioceptive ataxia indicates loss of coordination due to loss of normal position sense and is characterized by worsening with closed eyes (eg, Romberg test). SCAs may manifest with these symptoms if there is involvement of the described spinal structures. Peripheral neuropathy (ataxic neuropathy) can also be seen in various forms of SCA; however, cerebellar symptoms should be present [81]. The combination of cerebellar ataxia and sensory neuropathy, both of which can contribute to symptoms of disequilibrium, has also been described in cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome [85]. In these cases, neuroimaging is primarily directed at evaluating the coexisting central abnormalities of the cerebellum and brainstem (see Variant 6). There are also several known autoimmune sensory ataxic neuropathies, which result in symptoms of disequilibrium without cerebellar or brainstem involvement. Diagnostic confirmation of these neuropathies is generally via clinical evaluation and electrodiagnostic testing; however, targeted US has also been used to detect changes in size of the affected nerve in a small study [86]. Most of the studies in patients with SCA involve a small number of patients due to the rarity of the disease and particular mutations.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast There is no relevant literature regarding the use of CT head without IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast There is no relevant literature regarding the use of CTA head and neck with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast There is no relevant literature regarding the use of MRA head and neck with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast There is no relevant literature regarding the use of MRA head and neck without and with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without IV Contrast There is no relevant literature regarding the use of MRA head and neck without IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast MRI of the spine allows for evaluation of the spinal column as well as the soft tissues within and surrounding the spinal column including the spinal cord. Atrophy of the cervical spinal cord has been reported in several forms of degenerative ataxia, which may be a helpful diagnostic finding in patients presenting with disequilibrium [78-80]. In patients with chronic disequilibrium due to sensory ataxia and loss of proprioception that is out of proportion to


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. other sensory modalities and motor function, spine MRI is useful to evaluate the dorsal columns of the spinal cord (eg, compressive myelopathy, B12/copper deficiency, or tabes dorsalis neurosyphilis). These findings are typically adequately evaluated on MRI without IV contrast; however, if there is concern for an inflammatory or infectious neoplastic cause of sensory ataxia, contrast-enhanced imaging should be included.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast MRI of the spine allows for evaluation of the spinal column as well as the soft tissues within and surrounding the spinal column including the spinal cord. Atrophy of the cervical spinal cord has been reported in several forms of degenerative ataxia, which may be a helpful diagnostic finding in patients presenting with disequilibrium [78-80]. In patients with chronic disequilibrium due to sensory ataxia and loss of proprioception that is out of proportion to other sensory modalities and motor function, spine MRI is useful to evaluate the dorsal columns of the spinal cord (eg, compressive myelopathy, B12/copper deficiency, or tabes dorsalis neurosyphilis).


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and IAC with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast There is no relevant literature regarding the use of MRI head and IAC without and with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head With IV Contrast There is no relevant literature regarding the use of MRI head with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast There is no relevant literature regarding the use of MRI head without and with IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast There is no relevant literature regarding the use of MRI head without IV contrast in the evaluation of sensory ataxia.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head With IV Contrast There is no relevant literature regarding the use of CT head with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without and With IV Contrast There is no relevant literature regarding the use of CT head without and with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. CT Head Without IV Contrast Head CT allows for evaluation of the intracranial structures; however, soft tissue contrast is inferior to MRI. This is especially true of lesions in the posterior cranial fossa, which are more likely to cause dizziness [2]. In 29,510 patients with isolated dizziness presenting to a large academic emergency department, the overall diagnostic yield of CT is very low (<1%) [4]. In multiple studies, CT has demonstrated a high negative predictive value of approximately 90% but a low sensitivity (20%-40%) for detecting a causative etiology [2,3].


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone With IV Contrast There is no relevant literature regarding the use of CT temporal bone with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without and With IV Contrast There is no relevant literature regarding the use of CT temporal bone without and with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. CT Temporal Bone Without IV Contrast There is no relevant literature regarding the use of CT temporal bone without IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. CTA Head and Neck With IV Contrast CTA allows for evaluation of the course and luminal caliber of the studied arteries. CTA can also detect luminal filling defects, which may include thrombus, embolus, atherosclerotic plaque, dissection flap, or vascular web. CTA of the head and neck has been shown to have a low overall diagnostic yield of approximately 3% in the setting of isolated dizziness. CTA also did not contribute any additional information over noncontrast head CT in this clinical setting. Overall, CTA in isolated dizziness was shown to have a sensitivity of 14%, specificity of 98%, positive predicative value of 40% and negative predicative value of 92% [3].


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck With IV Contrast There is no relevant literature regarding the use of MRA head and neck with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without and With IV Contrast There is no relevant literature regarding the use of MRA head and neck without and with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRA Head and Neck Without IV Contrast There is no relevant literature regarding the use of MRA head and neck without IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without and With IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without and with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Cervical and Thoracic Spine Without IV Contrast There is no relevant literature regarding the use of MRI cervical and thoracic spine without IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal With IV Contrast There is no relevant literature regarding the use of MRI head and IAC with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without and With IV Contrast There is no relevant literature regarding the use of MRI head and IAC without and with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head and Internal Auditory Canal Without IV Contrast There is no relevant literature regarding the use of MRI head and IAC without IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia

Dizziness and Ataxia. Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head With IV Contrast There is no relevant literature regarding the use of MRI head with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without and With IV Contrast There is no relevant literature regarding the use of MRI head without and with IV contrast in the evaluation of isolated dizziness.


Dizziness and Ataxia

Dizziness and Ataxia. MRI Head Without IV Contrast MRI allows for detailed evaluation of the intracranial structures with improved soft tissue resolution when compared with CT. Despite this, the diagnostic yield of noncontrast MRI head in patients presenting to the emergency department with isolated dizziness is low (~4%). Of those with positive findings on MRI, ischemic stroke was the most common abnormality seen in nearly 70% of cases. Approximately two-thirds of these were located in the posterior circulation [4]. In another study with patients presenting with dizziness, 3.6% had acute lesions. Risk factors include older age, hypertension, atrial fibrillation, nonwhirling type of dizziness symptoms, and combined neurological symptoms (see Variant 3) [37].


Dizziness and Ataxia

Dizziness and Ataxia. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Dizziness and Ataxia

Dizziness and Ataxia


Dizziness and Ataxia

Dizziness and Ataxia. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Dizziness and Ataxia

Dizziness and Ataxia. Relative Radiation Level Designations 30-100 mSv


Dizziness and Ataxia

10-30 mSv

Dizziness and Ataxia. 10-30 mSv


Acute Respiratory Illness in Immunocompetent Patients. Introduction/Background Acute respiratory illness (ARI) is defined as one or more of the following symptoms: cough, sputum production, chest pain, or dyspnea (with or without fever), usually in the setting of suspected respiratory infection. ARI is a major public health issue, being one of the most common reasons for doctor office or emergency department (ED) visits. Cough, chest pain, and dyspnea account for 3 of the top 10 presenting symptoms during ED visits [1]. Most cases of ARI are attributable to infection, and the major diagnostic dilemma for patients with ARI is distinguishing patients with self-limited viral infection from those with a bacterial pneumonia (PNA), such as community-acquired PNA. In 2014, PNA (combined with influenza) accounted for the eighth most common cause of death in the United States [2].


Acute Respiratory Illness in Immunocompetent Patients. The primary role of imaging in patients with ARI is to aid in the diagnosis or exclusion of PNA. By helping to identify the subset of ARI patients with PNA, imaging helps separate patients who would benefit from antibiotic therapy from those who would not. This increases the chance that patients with PNA receive appropriate therapy and reduces the risks associated with inappropriate use of antibiotics in patients with viral causes of ARI. The need for imaging in the ARI patient may depend on a number of factors, which can include severity of illness; presence of fever, leukocytosis, or hypoxemia; clinical history; physical examination findings; patient age; and the presence of other risk factors. Not all studies concur as to which patients with ARI should have an initial imaging study.


Acute Respiratory Illness in Immunocompetent Patients. While chest radiographs have a long track record, they do have lower sensitivity for PNA relative to other imaging modalities such as CT. Self et al [5] performed an observational cross-sectional multicenter study that enrolled 3,423 ED patients presenting with ARI. This is one of the largest studies comparing chest radiographs and CT in the ED setting. Using CT as a gold standard, chest radiograph test characteristics for detection of pulmonary opacities included: sensitivity of 43.5%, specificity of 93.0%, positive predictive value of 26.9%, and negative predictive value of 96.5%. Conversely, other studies, such as Haga et al [6], demonstrate sensitivities as high as 91% for chest radiographs relative to CT for diagnosing PNA. Despite inconsistent data regarding the


Acute Respiratory Illness in Immunocompetent Patients. aMayo Clinic, Phoenix, Arizona. bPanel Chair, National Jewish Health, Denver, Colorado. cMassachusetts General Hospital and Harvard Medical School, Boston, Massachusetts. dThe University of Texas MD Anderson Cancer Center, Houston, Texas. eUniversity of Southern California, Los Angeles, California. fSouthern Illinois University School of Medicine, Springfield, Illinois; The Society of Thoracic Surgeons. gThe University of Texas MD Anderson Cancer Center, Houston, Texas. hUniversity of Iowa, Iowa City, Iowa; The Society of Thoracic Surgeons. iVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. jMayo Clinic, Jacksonville, Florida. kColumbia University Medical Center New York and Temple University Health System, Philadelphia, Pennsylvania. lSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.


Acute Respiratory Illness in Immunocompetent Patients. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document.


Acute Respiratory Illness in Immunocompetent Patients. Reprint requests to: publications@acr.org


Acute Respiratory Illness in Immunocompetent Patients. sensitivity of chest radiographs for PNA, it still plays a role as the primary modality for making or excluding the diagnosis of PNA in patients presenting with ARI.


Acute Respiratory Illness in Immunocompetent Patients. CT Chest The major advantage of CT in the setting of ARI is its increased sensitivity relative to chest radiographs for the diagnosis of PNA. In comparative studies in which patients with PNA received both CT and chest radiograph, the rate of PNA missed by chest radiographs but detected by CT has been highly variable, ranging from 9.4% [6] to 56.5% [5]. CT has also been shown to be more specific than chest radiographs for the diagnosis of PNA [5,7].


Acute Respiratory Illness in Immunocompetent Patients. US Chest There is a growing body of literature suggesting that bedside lung ultrasound (US) can be a useful tool in the diagnosis and management of PNA [8-12]. Nazerian et al [10] evaluated the accuracy of US relative to CT on 285 patients who had at least one respiratory complaint for which the ED physician ordered a CT. CT was considered positive if at least one typical consolidation was detected. US identified at least one consolidation in 81 patients versus 87 for CT. Relative to CT; US had a sensitivity of 82.8% and a specificity of 95.5%. While this study demonstrates impressive performance of US for detecting pulmonary consolidation, the study was limited by the fact that patients were enrolled based on whether or not they had a CT ordered rather than clinical suspicion of PNA.


Acute Respiratory Illness in Immunocompetent Patients. US is of limited value in patients with subcutaneous emphysema, in the setting of obesity/thick chest wall, and in patients with limited chest wall access related to bandages, prosthetic material, and skin disorders [13]. In addition, US has difficulty identifying PNAs that are not adjacent to the pleura. This limits its effectiveness for detecting more central infections, especially when there is aerated lung intervening between the transducer and the PNA [8,10,11].


Acute Respiratory Illness in Immunocompetent Patients. MRI Chest Our literature search identified one recently published article evaluating the use of MRI in the setting of ARI in immunocompetent adult patients [14]. The study suggests a sensitivity for PNA that approaches that of CT. Over the past 10 years, the utility of MRI for detecting PNA has been studied more extensively in pediatric and immunocompromised patient populations; these studies demonstrated a similar favorable sensitivity of MRI for detecting PNA [15-20].


Acute Respiratory Illness in Immunocompetent Patients. PET/CT Our literature search failed to identify any articles published within the past 10 years that justify the use of PET/CT in the initial workup of ARI in the immunocompetent patient. The usefulness of this imaging modality is not discussed in any of the clinical variants because of lack of evidence.


Acute Respiratory Illness in Immunocompetent Patients. CT Chest Our literature search failed to identify any data that suggest that CT serves any significant role in the initial imaging of immunocompetent patients with a low pretest probability of PNA.


Acute Respiratory Illness in Immunocompetent Patients. US Chest Many of the studies evaluating the potential of US to diagnose PNA in the ED are aimed at assessing the diagnostic accuracy of US for PNA using either CT or discharge diagnosis as the gold standard [8-11]. Many of these patients were sick enough to warrant CT or admission, representing a subset of patients with a relatively high pretest probability of PNA. The current literature does not suggest a routine role for initial imaging with US in a clinical variant with a low pretest probability of PNA.


Acute Respiratory Illness in Immunocompetent Patients. MRI Chest Our literature search failed to identify any data that suggest that MRI serves any significant role in the initial imaging of immunocompetent patients with a low pretest probability of PNA.


Acute Respiratory Illness in Immunocompetent Patients. Variant 2: Acute respiratory illnesses in immunocompetent patients with positive physical examination, abnormal vital signs, organic brain disease, or other risk factors. Initial imaging. Radiography Chest In a series of 300 patients with acute cough illness, Aagaard et al [29] found that a chest radiograph was not always obtained for patients with a high pretest probability of PNA; they infer that when the clinical probability of PNA exceeds a certain level, a negative radiograph would not alter treatment decisions. A series by Basi et al [30] that included 2,706 patients hospitalized with community-acquired PNA similarly showed that about one- third had radiographs initially interpreted as negative for PNA, with minimal change in this interpretation on retrospective review of a random subgroup. These two studies call into question the usefulness of radiographs in patients with a high pretest probability of PNA. That being said, data from many of the studies that suggested the low utility of chest radiographs in Variant 1 also demonstrate a relatively high incidence of PNA on chest radiographs in patients with physical examination findings, abnormal vital signs, leukocytosis, or other risk factors, such as advanced age [21-25].


Acute Respiratory Illness in Immunocompetent Patients. For example, Benacerraf et al [21] reported that a subgroup of patients <40 years of age with an abnormal physical examination were about six times more likely to have an acute finding on their chest radiograph. Speets et al [31] evaluated 192 patients with a clinical suspicion of PNA by general practitioners and found that the post- test probability of PNA was changed by chest radiographic results in 53% of patients, with a 47% decrease in probability and a 6% increase in probability. Patient management changed following a chest radiograph in 69% of patients. These data would seem to support the routine use of chest radiographs to confirm the diagnosis of PNA in this clinical variant. Current IDSA/ATS guidelines also support this approach [4].


Acute Respiratory Illness in Immunocompetent Patients. In a population of ED patients who received a chest radiograph for respiratory complaints, Heckerling [22] found that over 75% of the patients with dementia had PNA on their chest radiograph regardless of physical examination findings. The authors postulate that aspiration related to altered level of consciousness and compromised epiglottic closure could account for the high prevalence of PNA amongst these patients. Although there is a paucity of data to support this, it would be logical to include other patients with organic brain disease, such as


Acute Respiratory Illness in Immunocompetent Patients. Acute Respiratory Illness in Immunocompetent Patients stroke and delirium, in addition to dementia, as also having a high pretest probability of PNA despite otherwise negative physical examination findings and normal vital signs.


Acute Respiratory Illness in Immunocompetent Patients. CT Chest Our literature search failed to identify any data that suggest that CT serves any significant role in the initial imaging of immunocompetent patients with a high pretest probability of PNA. The role of CT for patients with a negative or equivocal initial chest radiograph is discussed in Variant 3.


Acute Respiratory Illness in Immunocompetent Patients. US Chest One prospective multicenter study performed by Reissig et al [11] enrolled 362 patients with abnormal vital signs or physical examination findings in addition to ARI symptoms. Patients received a two-view chest radiograph and a US. In cases in which the chest radiograph was negative or inconclusive and the US was positive, a chest CT was performed. This study demonstrated US sensitivity and specificity of 93.4% and 97.7%, respectively; however, these values are almost certainly overestimated because of the fact that a chest radiograph, rather than CT, was used as the reference standard in all cases except those in which there was discordance between an inconclusive or negative chest radiograph and a positive US. Bourcier et al [8] studied US and chest radiographs in a similar patient population. The final diagnosis was based on a chart review made by an independent expert and included clinical findings, labs, chest radiographs, and CT, if available. US in this study again demonstrated superior sensitivity for PNA relative to chest radiographs. Like Reissig et al, this study was limited by the lack of a consistent end point. Even with these limitations, the results of these studies suggest bedside US can be a useful tool for evaluating certain patients with a high pretest probability of PNA.


Acute Respiratory Illness in Immunocompetent Patients. MRI Chest Our literature search failed to identify any data that suggest that MRI serves any significant role in the initial imaging of immunocompetent patients with a high pretest probability of PNA. The role of MRI for patients with a negative or equivocal initial chest radiograph is discussed in Variant 3.


Acute Respiratory Illness in Immunocompetent Patients. Variant 3: Acute respiratory illness in immunocompetent patients with positive physical examination, abnormal vital signs, organic brain disease, or other risk factors and negative or equivocal initial chest radiograph. Next imaging study. Radiography Chest There is no indication in the literature to suggest that repeat chest radiograph serves any significant role in imaging patients with a high pretest probability of PNA and a negative or equivocal initial chest radiograph.


Acute Respiratory Illness in Immunocompetent Patients. CT Chest There are several studies that assess the use of CT as a subsequent study in patients who have already had a chest radiograph. One of the larger reviews by Hayden et al [32] identified 97 of 1,057 ED patients with a diagnosis of PNA who had both a chest radiograph and CT. Within this selected group, 26 patients (27%) had PNA that was not detected with chest radiograph but was subsequently detected with CT. Maughan et al [33], in a retrospective review designed to evaluate the false-negative rate of chest radiographs in ED patients with PNA, identified 49 cases (11.4%) where PNA was diagnosed with CT, despite a normal chest radiograph. Haga et al [6] also demonstrated the improved ability of CT to assess the severity of PNA relative to chest radiographs. Bilateral PNA, as detected by CT, was associated with a higher degree of mortality. The presence of multilobar opacities, which is a minor criterion in the IDSA/ATS guidelines for intensive care unit admission, is best assessed with CT [4].


Acute Respiratory Illness in Immunocompetent Patients. One of the more recent studies assessing the use of CT for ED patients with suspected PNA is Claessens et al [7], a prospective multicenter study that enrolled 319 patients. The inclusion criteria included a mix of ARI symptoms and abnormal vital signs or physical examination findings. All patients received a chest radiograph and a CT within 4 hours of presentation. Chest radiographs identified opacities consistent with PNA in 188 of 319 (59%) patients. CT revealed PNA in 40 (33%) of the 131 patients without opacity on chest radiographs and excluded PNA in 56 (29.8%) of the 188 patients with opacities on chest radiographs. Because of CT, antibiotics were initiated in 51 (16%) patients and discontinued in 29 (9%) patients. CT findings also resulted in 22 additional hospitalizations and 23 discharges.


Acute Respiratory Illness in Immunocompetent Patients. The available data clearly show that CT is more accurate than chest radiographs for the diagnosis of PNA. In most cases a combination of vital signs and physical examination findings, along with judicious use of chest radiographs, is deemed sufficient for diagnosing or excluding PNA. However, in certain patients, such as those


Acute Respiratory Illness in Immunocompetent Patients. who cannot reliably follow-up or for whom any delay in diagnosis of PNA could be life-threatening (such as patients with advanced age, unreliable follow-up, or significant comorbidities), chest CT may be warranted when initial chest radiograph is negative or equivocal [24,32,34]. The IDSA/ATS consensus guidelines consider CT a reasonable alternative to empiric antibiotic therapy with follow-up chest radiographs when there is a high clinical suspicion of PNA [4].


Acute Respiratory Illness in Immunocompetent Patients. Given the difficulty of obtaining an accurate history and physical examination and the high incidence of PNA in patients with organic brain disease, CT is a reasonable alternative to empiric treatment antibiotics in the setting of a negative or equivocal initial chest radiograph.


Acute Respiratory Illness in Immunocompetent Patients. US Chest Studies performed by Reissig et al [11] and Bourcier et al [8] suggest that US has a higher sensitivity than radiographs for PNA, implying that US may add value in cases in which PNA is suspected but initial chest radiographs are negative or equivocal. Nazerian et al [10] evaluated the accuracy of US relative to CT on 285 patients who had at least one respiratory complaint for which the ED physician ordered a CT. In the subgroup of patients who also had a chest radiograph, US demonstrated sensitivity and specificity of 81.4% and 94.2%, respectively, versus 64.3% and 90% for chest radiographs. The increased sensitivity of US implies additional value of US in cases in which the initial chest radiograph is discordant with clinical suspicion; however, the study was limited by the fact that patients were enrolled based on whether or not they had a CT ordered, rather than clinical suspicion of PNA.


Acute Respiratory Illness in Immunocompetent Patients. Given the difficulty of obtaining an accurate history and physical examination as well as the high incidence of PNA in patients with organic brain disease, US is a reasonable alternative to empiric treatment with antibiotics in the setting of a negative or equivocal initial chest radiograph. The ability of the patient to tolerate an US examination, presence of an adequate acoustic window, and the limited ability of US to detect all but peripheral PNAs would be additional considerations.


Acute Respiratory Illness in Immunocompetent Patients. MRI Chest Syrjala et al [14] compared the sensitivity and specificity of noncontrast MRI (respiratory-triggered T2 fast spin- echo) to chest radiographs using CT as a gold standard. The patient population consisted of immunocompetent adult ambulatory outpatients with ARI who were febrile and symptomatic for <7 days. CT detected 32 cases of PNA out of 77 prospectively enrolled patients. MRI detected 30/32 cases (sensitivity 94%) with no false-positives (specificity 98%), whereas chest radiographs only detected 23 cases (sensitivity 72%) and gave 4 false-positive results (specificity 91%). These data suggest a potential role for MRI in detecting PNA in situations where initial chest radiographs findings are negative or equivocal; however, the sensitivity of CT appears to be slightly superior to that of MRI.


Acute Respiratory Illness in Immunocompetent Patients. Variant 4: Acute respiratory illnesses in immunocompetent patients with pneumonia complicated by suspected parapneumonic effusion or abscess on initial chest radiograph. Next imaging study. Radiography Chest Chest radiographs are a useful initial imaging modality for complicated PNA, but they are inferior to other modalities for evaluating the pleura, for guiding interventions, or for assessing an opacity that has been refractory to therapy.


Acute Respiratory Illness in Immunocompetent Patients. CT Chest In severe cases of PNA, CT can demonstrate the overall extent of disease, which may provide important prognostic information [6]. CT can also demonstrate necrotizing PNA and abscess formation long before the findings become visible on a chest radiograph. The use of intravenous contrast can increase the conspicuity of empyemas and other pleural complications. CT can also serve as a guide for pleural drainage or localization of an appropriate site for biopsy [35]. CT is the modality of choice for evaluating a persistent opacity. Its superior contrast resolution allows it to detect obstructing masses, delineate lesions, such as sequestrations, and even characterize patterns of parenchymal disease, such that a particular etiology, such as organizing PNA or mycobacterial infection, can sometimes be suggested.


Acute Respiratory Illness in Immunocompetent Patients. US Chest US may be a useful adjunct for the evaluation of parapneumonic effusions as it is superior to chest radiographs for demonstrating pleural thickening and adhesions. US is superior to noncontrast CT for detecting septations in


Acute Respiratory Illness in Immunocompetent Patients. Acute Respiratory Illness in Immunocompetent Patients complex effusions. US can also be used to guide PNA-related interventions, such as biopsy, thoracentesis, and thoracostomy tube placement [36].