Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Special Imaging Considerations In many stroke-related clinical scenarios, both parenchymal and vascular imaging procedures are commonly used, particularly in the initial imaging of acute clinical presentations. Noncontrast head CT can be performed rapidly, either alone or included in the performance of CT angiography (CTA) of the head. For the purposes of this document, both procedures are discussed separately for each variant, highlighting the individual usefulness of both the noncontrast examination and contrast-enhanced vascular imaging phase.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA of the head and neck are often acquired together, using a single contrast bolus for optimal arterial vascular opacification. Although the diagnostic usefulness and/or acuity of intracranial and extracranial vascular assessment may differ within a particular clinical context, the benefit of combined neck and head vascular imaging may have added clinical benefit in circumstances in which transcatheter arterial intervention is a potential consideration.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI perfusion imaging is most commonly performed using intravenous (IV) contrast; however, newer scanners may also have the ability to perform noncontrast perfusion imaging without IV contrast using arterial spin-labeled (ASL) techniques. Future Appropriateness Criteria documents may consider this technique as it achieves greater adoption in routine clinical practice.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. aUniversity of California San Diego, San Diego, California. bPanel Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. cPanel Vice-Chair, Uniformed Services University, Bethesda, Maryland. dUniversity of Virginia Health System, Charlottesville, Virginia. eUniversity of Washington, Seattle, Washington and University of British Columbia, Vancouver, British Columbia, Canada. fYale University School of Medicine, New Haven, Connecticut; Committee on Emergency Radiology-GSER. gBarrow Neurological Institute, Phoenix, Arizona; Neurosurgery expert. hMayo Clinic, Rochester, Minnesota; Commission on Nuclear Medicine and Molecular Imaging. iWeill Cornell Medical College, New York, New York. jUniversity of Chicago, Chicago, Illinois. kWashington State University, Spokane, Washington; American College of Physicians. lSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. mAlbany ENT & Allergy Services, PC, Albany, New York; American Academy of Otolaryngology-Head and Neck Surgery. nAlbert Einstein College of Medicine Montefiore Medical Center, Bronx, New York, Primary care physician. oStanford University School of Medicine, Stanford, California. pUniformed Services University of the Health Sciences, Bethesda, Maryland, Naval Medical Center Portsmouth, Portsmouth, Virginia. qUniversity of Colorado School of Medicine, Aurora, Colorado. rUniversity of Cincinnati Medical Center, Cincinnati, Ohio. sSpecialty Chair, Montefiore Medical Center, Bronx, New York.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. 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.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Reprint requests to: publications@acr.org


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. OR Discussion of Procedures by Variant Variant 1: Adult. Clinical transient ischemic attack (TIA). Symptoms resolved. Initial imaging. Transient ischemic attacks (TIA) are self-limited focal neurologic deficits resulting from a temporary interruption in blood supply to the brain, with no permanent clinical deficit or demonstrated infarct on subsequent imaging. In the United States, the incidence of TIA is approximately 1.2 per 1,000 [7]. The traditional time-based definition of TIA set the maximum duration at 24 hours. A newer imaging-based definition restricts the term TIA to those without neuroimaging evidence of tissue damage. Practically, those with and without tissue damage are considered together for diagnosis and management proposes [8,9]. Although symptoms may resolve within a short period of time, typically <1 hour, the risk for subsequent stroke is high: 8.8% at 7 days and 11.6% at 90 days [10]. In the setting of symptomatic carotid disease, the 90-day risk of ipsilateral stroke is 20.1% [11]. Given the high risk for stroke following TIA, expeditious initial imaging is important. There is a direct correlation between the risk of stroke following a carotid territory TIA or minor stroke and degree of carotid stenosis, and this drives the decision for carotid endarterectomy (CEA) or stenting [12,13]. Therefore, evaluation of patients with clinical carotid TIA or minor stroke requires rapid vascular imaging of the cervical carotid arteries [12,13] in addition to brain parenchymal imaging.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Although the spatial resolution of catheter-directed cerebral angiography is higher than any noninvasive technique, cerebral angiography is not preferred as an initial test due to the invasive nature and the diversity of etiologies for TIA. Cerebral angiography may be indicated later in the diagnostic pathway as a secondary examination in the workup of TIA, depending on the suspected underlying etiology and potential indications for endovascular therapy (EVT).


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast CT perfusion (CTP) can identify abnormalities in the setting of TIA in up to one-third of cases. The detection of an underlying perfusion abnormality may be helpful for risk stratification [14-16]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Therefore, CTP is not typically used for the initial assessment of TIA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of TIA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of TIA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast Noncontrast CT of the head is useful in the initial evaluation of TIA to exclude alternative etiologies and to evaluate for early ischemic changes. Many other lesions may mimic the symptoms of a TIA including intracranial hemorrhage (ICH), infection, and intracranial masses [14,19,20]. Most importantly, ICH must be excluded because it is a contraindication to administration of tissue thrombolytic agents, anticoagulants, and antiplatelet agents used to treat and prevent both TIA and stroke [13]. Moreover, the extent of ischemic changes seen on noncontrast CT, regardless of chronicity, is correlated with the risk of subsequent strokes [21].


Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and other intracranial steno-occlusive diseases, which may be useful in the secondary workup and triage of patients presenting with TIA. The identification of atherosclerotic intracranial vascular lesions in the setting of TIA may be useful in determining the most appropriate treatment options, although this is controversial [22,23].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature and is useful in the initial workup and triage of patients presenting with carotid territory TIA. Current American Heart Association (AHA) guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. Heavy calcifications or calcified plaque on both sides of the lumen can lead to overestimation of the stenosis [24].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast There is no relevant literature to support the use of CT venography (CTV) head in the evaluation of TIA in the absence of suspicion for cerebral venous thrombosis (CVT). Please see Variant 7 for further details.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MR angiography (MRA) of the head in the evaluation of TIA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast MRA of the head is an alternative means of evaluating intracranial steno-occlusive disease and may be useful in the initial workup and triage of patients presenting with TIA. Owing to the relatively rapid and noninvasive nature of the examination obviating the need for IV contrast, MRA may be preferable to CTA in patients with renal impairment, x-ray contrast allergy, or repeat presentations. Typically, noncontrast time-of-flight (TOF) MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [25].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional abnormalities not identified on initial vascular imaging or diffusion-weighted imaging (DWI) in some patients presenting with TIA. Either technique may be useful in the secondary workup and triage of patients presenting with TIA depending on the suspected underlying etiology, particularly if no abnormalities are identified on direct vascular or parenchymal imaging studies [28-30]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast Noncontrast MRI head is typically sufficient for the routine assessment of uncomplicated TIA. Conditions rarely mimicking TIA include tumors and cerebral convexity subarachnoid hemorrhage due to amyloid angiopathy. MRI


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke without and with IV contrast may be helpful in the secondary workup of patients presenting with transient focal neurological symptoms [34].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast Owing to the relatively rapid noninvasive nature of MRI and the high sensitivity of DWI for ischemic change, MRI is the most sensitive test for acute infarct. MRI of the head may be useful in the initial or secondary evaluation of TIA to evaluate for ischemic changes on DWI or for other alternative etiologies [34,35]. MRI is particularly useful prognostically as an initial test in the setting of complete resolution of associated symptoms before presentation or shortly after presentation [29]. Additionally, MRI may be useful as an initial test on repeat clinical presentation [36].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MR venography (MRV) of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery Ultrasound (US) duplex carotid Doppler is a useful test in the initial evaluation of the extracranial vasculature in the workup of TIA. Carotid Doppler US is noninvasive and is accurate in evaluating the degree of carotid stenosis [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler can be used for the detection of microembolic events and in the detection of intracranial vascular pathology in the secondary workup of TIA. However, this is not typically used as an initial imaging test in the setting of TIA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke. However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54]. More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55].


Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast Within the initial 6-hour window of presentation of an acute stroke, CTP of the head is usually not necessary as an initial examination; conversely, delay, created by obtaining and analyzing CTP in the setting of a known LVO patient who is a clear EVT candidate, may be harmful [13,56]. In contrast, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA presenting in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke. CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Stroke, possibly due to LVO, is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. The use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast Although sensitive and specific in the detection of LVO, TOF MRA of the head may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast


Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49]. However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and fluid-attenuated inversion recovery (FLAIR) sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. In patients with renal insufficiency or x-ray contrast allergy, the combination TOF MRA to identify arterial occlusions and DWI-MRI head without IV contrast can identify patients eligible for EVT 6 to 24 hours without putting the patient at risk and inform subsequent therapeutic decisions [46,47,52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI is a reasonable complementary examination used in the initial workup of a focal neurological deficit if LVO is excluded by CTA, when there are confounding imaging and clinical variables.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT.


Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery Although sensitive and specific in the detection of extracranial vascular disease, duplex carotid Doppler does not provide the information necessary to determine eligibility for thrombolytics or thrombolysis or EVT. US duplex carotid Doppler, which is noninvasive and is accurate in evaluating the degree of carotid stenosis, is a useful test for the evaluation of the extracranial vasculature to determine eligibility for CEA or stenting if this information has not already been obtained from other vascular imaging [63,64]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke due to the poor anatomical delineation of US and potential consequences of delayed treatment in the setting of LVO [39].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 3: Adult. Recent ischemic infarct; less than 24 hours. Initial imaging. This variant is focused on new clinical presentation of stroke in the acute phase, <24 hours from onset of symptoms, but beyond hyperacute clinical presentation. Because stroke due to LVO is a significant source of death and disability, rapid stroke diagnosis and triage remain essential, particularly in the setting of possible LVO [39]. Recent studies have shown the benefit of extending the thrombolytic window up to 9 hours using perfusion imaging [40- 43]. However, a number of positive RCTs have demonstrated the benefit of EVT in the treatment of stroke due to LVO up to 24 hours underscoring the urgency of LVO detection and resulting in a paradigmatic shift in the urgency of obtaining vascular imaging [44-49]. In the context of nonemergent suspected stroke, parenchymal and vascular imaging are still needed, although the determination of eligibility for EVT in cases of delayed or unknown presentation may require additional MRI sequences or perfusion imaging with CT or MRI depending on the time since last known normal and the severity of the neurological deficit [52]. In the absence of LVO, the workup of a new stroke focuses on treatment of complications, rehabilitation, and secondary prevention.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke. However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54]. More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast Beyond the early 6-hour time window, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head with and without contrast in the evaluation of ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke irreversible tissue damage. Because many RCTs of acute ischemic stroke treatments used the ASPECTS or pc- ASPECTS based on noncontrast CT or DWI-MRI to exclude subjects with large, completed infarcts, an initial noncontrast CT or DWI-MRI is essential for making therapeutic decisions [44,46-49,57-59].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke. CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Acute stroke possibly due to LVO is a true medical emergency requiring rapid diagnosis, and the use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast TOF MRA of the head is sensitive and specific in the detection of LVO and characterization of intracranial atherosclerosis. In the acute setting, CTA is generally acquired more rapidly than MRI and delay due to MRI should be avoided, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing a benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49]. However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and FLAIR sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. In patients with renal insufficiency or x-ray contrast allergy, the combination TOF MRA to identify arterial occlusions and DWI-MRI head without IV contrast can identify patients eligible for EVT 6 to 24 hours without putting the patient at risk and inform subsequent therapeutic decisions [46,47,52].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI is a reasonable complementary examination used in the initial workup of a focal neurological deficit if LVO is excluded by CTA, when there are confounding imaging and clinical variables.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery Although sensitive and specific in the detection of extracranial vascular disease, duplex carotid Doppler does not provide the information necessary to determine eligibility for thrombolytics or EVT. US duplex carotid Doppler, which is noninvasive and is accurate in evaluating the degree of carotid stenosis, is a useful test for the evaluation of the extracranial vasculature to determine eligibility for CEA or stenting if this information has not already been obtained from other vascular imaging. [63,64]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke due to the poor anatomical delineation of US and potential consequences of delayed treatment in the setting of LVO [39].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 4: Adult. Recent ischemic infarct; greater than 24 hours. Initial imaging. This variant addresses cases of clinically suspected recent ischemic infarct, although beyond the established and extended stroke windows, that is, >24 hours after symptom onset. Whereas some observational studies suggest benefit [65], no large RCTs have demonstrated the benefit of EVT for LVO strokes after the 24 hour mark. Given the lack of supporting evidence for the usefulness for EVT beyond 24 hours, the urgency of exclusion of stroke due to LVO is largely abated and the workup of a new stroke becomes less urgent. At this stage, imaging is more focused on stroke follow-up and treatment of complications, rehabilitation planning, and secondary prevention [13].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke Arteriography Cervicocerebral Cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study and may detect underlying etiologies in patients presenting with stroke in a delayed fashion beyond 24 hours, which may not be detectable by other modalities, and can potentially help guide management. The usefulness of revascularization for intracranial LVO beyond 24 hours has not been demonstrated by RCT, which reduces the urgency of diagnosis [65]. Moreover, the urgency of diagnosis of many other stroke etiologies detected only by arteriography in the setting of delayed presentation is less well defined beyond 24 hours. Cerebral angiography is typically reserved for diagnoses not excluded by less invasive modalities and even then is of uncertain specificity and sensitivity [66].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast CT head perfusion imaging may detect an underlying lesion not identified by other imaging modalities in some cases of late presenting with strokes and may identify additional at-risk regions of the brain. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. CTP may be a reasonable examination in the secondary workup of late presenting strokes, but it is not generally a first-line test in this clinical context.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke; in fact, contrast may obscure early complications such as hemorrhage.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke; in fact, contrast may obscure early complications such as hemorrhage.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast Noncontrast CT of the head is essential in the initial evaluation of delayed presenting strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation. Moreover, noncontrast CT is more sensitive for the evaluation of early ischemic changes in late presenting strokes than in the hyperacute setting [67]. Dual-energy CT may play a role in the setting of prior contrast administration for other studies or for prior EVT in evaluating for underlying hemorrhage [68].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head is a rapid and highly sensitive means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis, LVO, and other intracranial steno-occlusive diseases, which may be useful in the management of late presenting strokes, although this is controversial [22,23,69]. However, the urgency of diagnosis of the underlying etiology is less well defined. Moreover, similar information can be obtained from MRA of the head, when there is no need for rapid triage and vascular diagnosis.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is a rapid and highly sensitive means of evaluating the extracranial vasculature underlying carotid stenosis and other steno-occlusive disease of the cervical vasculature, which is useful in the management of late presenting strokes. However, the urgency of diagnosis of the underlying etiology is less well defined. Moreover, similar information can be obtained from MRA of the head, when there is no need for rapid triage and vascular diagnosis. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast MRA of the head is a rapid, noninvasive tool, which is useful in the initial workup of late presenting stroke to evaluate for intracranial steno-occlusive disease when there is no indication for urgent EVT, although the clinical value of this information is controversial [22,23,69].


Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease. However, MRA of the neck tends to overestimate the degree of carotid stenosis in the absence of contrast administration [70] and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts [71].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease. However, MRA of the neck tends to overestimate the degree of carotid stenosis in the absence of contrast administration [70] and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts [71].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional at-risk regions not demonstrated by DWI and aid in identifying the underlying etiology in some patients presenting with stroke beyond the 24-hour period. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Perfusion imaging is not generally considered a first-line test in this clinical context [72,73].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast DWI-MRI and T2-weighted sequences are highly sensitive for ischemic changes in the patient with acute ischemic stroke. Although often performed as part of the initial evaluation of late presenting strokes to delineate the extent of completed ischemic infarct, evaluate potential underlying etiology, and identify any complications, the value of the information provided by MRI over initial CT for improving patient outcome is unclear, as are the circumstances in which it is useful [74-79]. Current AHA guidelines only specify MRI in 2 circumstances: evaluation for wake- up strokes and evaluation for patent foramen ovale closure [12,13].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head without and with IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head without IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. US duplex carotid Doppler is useful for assessing the degree of carotid stenosis in anterior circulation infarcts due to the noninvasive nature of the examination, the high degree of accuracy, and the absence of time pressure of EVT candidacy associated with delayed presenting strokes [38,80]. Carotid Doppler is a highly accurate tool for evaluating for and assessing the degree of carotid stenosis in anterior circulation infarcts, which CTA may overestimate, particularly in the setting of significant carotid calcification [24,38].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 5: Adult. Prior ischemic infarct. Surveillance imaging. After the initial ischemic injury is defined, identifying the presence of any complications such as hemorrhagic conversion or associated mass effect become the focus of evaluation of recent ischemic infarcts, which are both less emergent than identifying EVT candidates. The extent of the initial ischemic injury plays a key role in defining the risk for delayed complications and the need for and expected duration of ongoing surveillance. Ongoing ischemia or hemorrhagic complication may impact the timeline for initiation of anticoagulant and/or antiplatelet therapy. For large hemispheric or cerebellar infarcts, prolonged observation or early craniectomy may be indicated, which would


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke argue for delaying any preventative measures and/or treatments that pose a risk of operative bleeding [13]. If not previously performed during initial triage, cardiocerebrovascular assessment has a secondary but important clinical role.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study and may detect early progression of known steno-occlusive intracranial or cervical atherosclerotic disease before detection on other studies. As such, cerebral angiography may be useful in follow-up imaging in select ischemic strokes, particularly those in which the findings on noninvasive imaging are indeterminate. Cerebral angiography is typically reserved for diagnoses not excluded by less invasive modalities and even then is of uncertain specificity and sensitivity [66].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion CT head perfusion imaging may identify the progression of known underlying intracranial or extracranial atherosclerotic disease, which could predict recurrent or new ischemic events in the future. CTP may be used for surveillance examination in the cases in which known vascular lesions are present. In the absence of a known steno- occlusive lesion, there is no literature to support the use of CTP in surveillance imaging of prior ischemic strokes. In patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast There is no role for IV contrast in the CT evaluation of evolving or subacute infarct. In fact, contrast enhancement within previously undocumented subacute infarcts can paradoxically cause confusion with other more aggressive brain lesions or hemorrhagic conversion of prior infarcts.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no role for IV contrast in the CT evaluation of evolving or subacute infarct. In fact, contrast enhancement within previously undocumented subacute infarcts can paradoxically cause confusion with other more aggressive brain lesions or hemorrhagic conversion of prior infarcts.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast Noncontrast CT of the head can be useful in the early surveillance of ischemic strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation when clinically indicated. Moreover, noncontrast CT is more sensitive for the evaluation of the extent of ischemic changes on follow-up imaging of strokes than in the hyperacute setting [67]. In circumstances in which ongoing surveillance is warranted, CT is usually preferred due to its quick repeatability and ease of comparison to prior examinations. Dual-energy CT may play a role in the setting of prior contrast administration for other studies or for prior EVT in evaluating for underlying hemorrhage [68].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and steno-occlusive diseases, although the clinical value of this information is controversial [22,23,69]. Identification of the underlying etiology in the absence of progressive symptoms is less time sensitive than with patients undergoing EVT evaluation. Moreover, similar information can be obtained from MRA of the head without the need for rapid triage and vascular diagnosis. CTA of the head may be indicated in unstable patients presenting with uncertainty or concern for progression of prior ischemic infarcts.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature underlying carotid stenosis and other steno-occlusive disease of the cervical vasculature, which is useful in the management of late presenting strokes. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. In the absence of bilateral disease, carotid Doppler is more accurate in evaluating the degree of carotid stenosis; CTA typically overestimates stenosis, particularly in the setting of dense carotid calcification [24]. In the setting of cryptogenic stroke, CTA may be helpful to diagnose unsuspected carotid webs or other features of unstable plaque [81,82].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the evaluation of ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of ischemic stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast MRA of the head is a useful initial screening tests for intracranial steno-occlusive disease in the setting of late presenting stroke, owing to the lack of indication for emergent EVT in delayed presenting strokes and relatively rapid noninvasive nature of the examination without the need for IV contrast, although the clinical value of this information is controversial [22,23,69].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease given the lack of urgency in evaluation of delayed presenting strokes. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis. In the setting of cryptogenic stroke, MRA can be useful to identify unstable plaque or other culprit lesions [83-85].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease given the lack of urgency in the evaluation of delayed presenting strokes. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts. Contrast- enhanced MRA may more accurately quantify stenosis and identify ostial stenoses. In the setting of cryptogenic stroke, MRA can be useful to identify unstable plaque or other culprit lesions [83-85].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional at-risk regions not demonstrated by DWI in some patients presenting with stroke beyond the 24-hour period. In patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. However, this procedure is more useful as a problem-solving tool and is not considered standard as surveillance imaging in the setting of prior infarct.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast MRI of the head may be a useful initial test in evaluation of the extent of completed ischemic infarct in the setting of late presenting strokes owing to the relatively rapid noninvasive nature of the examination, the lack of need for IV contrast, and the high sensitivity of DWI for concurrent acute ischemic change. Although often performed as part of the initial evaluation of late presenting strokes to delineate the extent of completed ischemic infarct, evaluate potential underlying etiology, and identify any complications, the value of the information provided by MRI over initial CT for improving patient outcome is unclear, as are the circumstances in which it is useful [74-79]. Current AHA guidelines only specify MRI in 2 circumstances: evaluation for wake-up strokes and evaluation for patent foramen ovale closure [12,13].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head without and with IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head without IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT.


Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very useful screening test in the evaluation of the extracranial vasculature for carotid stenosis in delayed presenting strokes, due to the high degree of accuracy in evaluating the degree of carotid stenosis in the absence of multifocal disease and the absence of time pressure of EVT candidacy associated with delayed presenting strokes [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 6: Adult. Known intraparenchymal hemorrhage. No history of trauma. Follow-up imaging study. IPH may complicate many cerebrovascular and systemic conditions including hypertension, cerebral amyloid angiopathy, coagulopathy, arteriovenous malformation, dural arteriovenous fistula, CVT, cortical venous thrombosis, aneurysm, certain primary central nervous system neoplasms, cerebral hyperperfusion syndromes in the setting of carotid revascularization, metastatic disease, cavernous malformations, prior ischemic infarct, and Moyamoya disease [86]. Hypertensive hemorrhage is the most common etiology for atraumatic IPH and is often supported by clinical history of hypertension and associated imaging findings of a single deep IPH in the basal ganglia, thalamus, pons, or cerebellum. Cerebral amyloid angiopathy is the second most common cause of IPH. Without pathological conformation, it can be diagnosed with acceptable accuracy based on MRI [87]. Diagnostic evaluation of IPH is directed at determining causes for IPH that may require specific interventions beyond supportive care for the IPH itself. These include arteriovenous malformation, dural arteriovenous fistula, CVT, cortical venous thrombosis, aneurysm, central nervous system neoplasms, cerebral hyperperfusion syndromes in the setting of carotid revascularization, metastatic disease, cavernous malformations, and Moyamoya disease. In cases of typical hypertensive hemorrhage or cerebral amyloid angiopathy, additional imaging may not even be warranted [87,88].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. This variant focuses on imaging follow-up of patients previously diagnosed with IPH. Patients with IPH may require advanced monitoring or undergo emergent neurosurgical intervention depending on the degree of associated mass effect, edema, and the rate of expansion associated with the hemorrhage. Many potential etiologies for IPH may require both vascular imaging and advanced parenchymal imaging for full evaluation, if not previously performed during initial imaging triage.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Catheter-directed arteriography is the reference standard for identifying vascular lesions in patients with IPH. However, catheter angiography is an invasive procedure, and noninvasive vascular imaging studies are typically preferable as first-line vascular imaging once hemorrhage is identified. Catheter angiography is useful to further characterize vascular malformations, particularly if suggested by noninvasive testing. Although CTA and MRI/MRA have a high sensitivity and specificity compared with catheter arteriography (see below), they may miss important lesions. In one series of 89 patients with IPH not in the typical hypertensive locations who had negative CTA and MRI/MRA, catheter arteriography identified 7 arteriovenous malformations and 3 dural arteriovenous fistulas [89]. In the acute period, catheter arteriography may miss vascular lesions that are detected by repeat arteriography several weeks later [90]. In addition, catheter arteriography is usually performed in patients with pure intraventricular hemorrhage, due to the high prevalence of vascular lesions [88].


Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast Contrast-enhanced CT is typically not helpful in the setting of typical hypertensive hemorrhage or in serial follow- up, except in cases in which underlying metastatic disease is suspected and MRI is not feasible for a specific patient.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast Contrast-enhanced CT is typically not helpful in the setting of typical hypertensive hemorrhage or in serial follow- up, except in cases in which underlying metastatic disease is suspected and MRI is not feasible for a specific patient.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast In the setting of IPH, noncontrast CT examinations of the head is essential, both for the initial diagnosis and, if clinically indicated, for follow-up examinations to evaluate for expansion and worsening mass effect. Additional noncontrast CT imaging may not be warranted when the patient is stable.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast In the setting of IPH, CTA of the neck is not supported by the literature. CTA of the neck may be useful for treatment planning when endovascular management is expected.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support CTV of the head. However, CTV of the head may be useful to exclude CVT as a potential etiology. Imaging features on noncontrast CT suggesting venous infarction with hemorrhage may include atypical distributions not matching arterial vascular territories, infarcts with cortical sparing, typical parasagittal or temporoparietal location, or dural venous/cortical venous hyperdensity suggestive of thrombus. For further discussion of the evaluation of CVT, see Variant 7.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is a limited role for MRA of the head with IV contrast except when dynamic imaging is performed, such as in the setting of known arteriovenous malformations.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRA of the head. However, MRA of the head may be useful in advanced workups to exclude underlying vascular malformations if the etiology is uncertain. In a 2014 review, MRA had a reported sensitivity and specificity exceeding 90% compared with catheter arteriography for detecting intracranial vascular malformations [93]. More recently, MRA was shown to be useful in identifying macrovascular causes such of IPH as aneurysms or arteriovenous malformations [95].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast In the setting of IPH, MRA of the neck is not supported by the literature. MRA of the neck may be useful for treatment planning when endovascular management is expected.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast In the setting of IPH, MRA of the neck is not supported by the literature. MRA of the neck may be useful for treatment planning when endovascular management is expected.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRI perfusion of the head as a follow-up imaging study. MRI perfusion of the head may be useful in evaluating for secondary etiologies such as hyperperfusion associated with carotid revascularization, tumors, prior ischemic strokes, arteriovenous shunt lesions, or other cerebrovascular malformations, particularly if clinically suspected or suggested on prior imaging. Recommendations for imaging in the setting of suspected aneurysm, arteriovenous shunt lesion, or


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast MRI of the head is a useful test for evaluating alternative etiologies in patients <55 years of age who do not have typical hypertensive hemorrhage [96]. MRI without and with IV contrast can be useful in evaluating for cerebral amyloid angiopathy, tumor, vasculitis, dural venous sinus thrombosis, vascular shunt lesions, and in further characterizing other etiologies seen on noncontrast imaging [97,98].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast MRI of the head is a useful test for evaluating alternative etiologies when the diagnosis of hypertensive hemorrhage is in doubt. Noncontrast MRI can exclude stroke and may suggest certain etiologies including cerebral amyloid angiopathy and cavernous malformations [97,98].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRV of the head. However, MRV of the head may be useful to exclude CVT as an etiology, particularly if suggested by features of hemorrhage on initial CT imaging or the diagnosis is in doubt based on contrast-enhanced MRI.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRV of the head. However, MRV of the head may be useful to exclude CVT as an etiology, particularly if suggested by features of hemorrhage on initial CT imaging or the diagnosis is in doubt based on contrast-enhanced MRI.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery In the setting of IPH, US duplex Doppler carotid of the neck is not supported by the literature.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial In the setting of suspected hypertensive hemorrhage, there is no relevant literature to support transcranial Doppler.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 7: Adult. Suspected venous sinus thrombosis. Initial imaging. CVT is an uncommon cause for stroke, accounting for approximately 1% to 2% of all strokes [99]. The patients often have hypercoagulable risk factors (cancer, recent oral contraceptive use, and pregnancy) and may present with headaches, seizures, or decreased level of consciousness due to either venous ischemic or hemorrhagic complications. Unlike other stroke etiologies, the presence of ICH is often not a contraindication to anticoagulation but necessitates serial assessment for hematoma expansion in this patient population. Venous infarction and hemorrhage may complicate venous thrombosis, particularly cortical venous thrombosis. Imaging features suggesting venous infarction with hemorrhage may include atypical distributions not matching arterial vascular territories, infarcts with cortical sparing, typical parasagittal or temporoparietal location, or dural venous/cortical venous hyperdensity on noncontrast CT suggestive of thrombus.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Catheter-directed cerebral angiography and runoff venography are infrequently necessary in the setting of dural venous sinus thrombosis due to the sensitivity and specificity of CTV and MRV. In the setting of progressive infarct despite adequate medical therapy, catheter-directed angiography and venography may be useful to assess potential endovascular treatment targets.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. However, perfusion imaging is typically a follow-up imaging study after the diagnosis of CVT. Moreover, the requirement for iodinated contrast may limit use of CTP in patients with acute or severe chronic renal insufficiency.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke head without and with IV contrast specifically for the evaluation of venous sinus thrombosis unless noncontrast CT is otherwise indicated for parenchymal assessment.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast Noncontrast CT of the head is essential in the initial evaluation of CVT. The primary usefulness of noncontrast CT of the head in the initial evaluation of CVT is to evaluate for hemorrhagic complication and alternative etiologies. Noncontrast CT may show sinus hyperdensity. However, only 30% of noncontrast head CT examinations are abnormal in the setting of CVT [99].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast There is no relevant literature to support the use of CTA of the neck in the initial evaluation of CVT. CTA of the neck may be useful for endovascular surgical planning for venous sinus thrombectomy, if clinically relevant.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast CTV of the head is a useful, rapid initial evaluation with a high sensitivity and specificity for detection of CVT. CT is particularly useful when MRI is contraindicated or when MRI artifacts are suspected that could obscure the diagnosis. Specifically, CTV is as accurate in diagnosis of CVT as MRV [101].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of MRA of the head in the initial evaluation of CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast There is no relevant literature to support the use of MRA of the head in the initial evaluation of CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast There is no relevant literature to support the use of MRA of the neck in the initial evaluation of CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast There is no relevant literature to support the use of MRA of the neck in the initial evaluation of CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. Although perfusion imaging is not the most appropriate initial imaging study, ASL perfusion is often acquired with conventional brain MRI as part of the diagnostic workup.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast MRI of the head is a useful initial examination in the workup of CVT. MRI of the head is useful not only for evaluation of the extent of cytotoxic and vasogenic edema but also in the initial detection of petechial hemorrhage and the actual thrombus in many cases. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast MRI of the head is a useful initial examination in the workup of CVT. MRI of the head is useful not only for evaluation of the extent of cytotoxic and vasogenic edema but also in the initial detection of petechial hemorrhage and the actual thrombus in many cases. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke MRV Head Without and With IV Contrast MRV of the head along with MRI of the head is an essential component of the workup of CVT in most cases. The MRV of the head is useful for confirming the presence of thrombus and ideally consists of both noncontrast TOF and contrast-enhanced MRV. Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], contrast-enhanced and TOF MRV imaging techniques are complementary in that a contrast- enhanced MRV may provide a better assessment of a hypoplastic dural venous sinus with slow flow and TOF MRV mitigates against T1 isointense thrombus, which may mimic normal opacification of the sinus on contrast-enhanced MRV. Additionally, T1 hyperintense thrombus can mimic normal flow and enhancement patterns, which necessitates evaluation with noncontrast MRI. Volumetric MRI sequences are essential for contrast-enhanced MRV. Delayed postcontrast imaging can further increase the sensitivity for detection of T1 isointense thrombus.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast MRV of the head along with MRI of the head is an essential component of the workup of CVT in most cases. Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], TOF and phase- contrast MRV are noncontrast alternatives for the diagnosis of CVT. If the findings on noncontrast MRV are unclear, then further imaging with contrast-enhanced CTV or MRV should be considered.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid Doppler in the setting of CVT. However, US assessment of the adjacent venous structures could yield useful information about the extent of the thrombus if extending into the neck.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial There is no relevant literature to support the use of transcranial Doppler in the setting of CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 8: Adult. Known venous sinus thrombosis. Surveillance imaging. CVT is an uncommon cause for stroke, accounting for approximately 1% to 2% of all strokes [99]. The patients often have hypercoagulable risk factors (cancer, recent oral contraceptive use, and pregnancy) and may present with headaches, seizures, or decreased level of consciousness due to either venous ischemic or hemorrhagic complications. Unlike other stroke etiologies, the presence of ICH is often not a contraindication to anticoagulation but necessitates serial assessment for hematoma development and/or expansion in the acute and early subacute phases in this patient population. An early follow-up is recommended in patients with CVT with persistent or evolving symptoms despite medical treatment or with symptoms suggestive of propagation of thrombus. In patients with previous CVT who present with recurrent symptoms suggestive of CVT, repeat imaging is also recommended. Serial follow-up at 3 to 6 months after diagnosis is used to assess for recanalization of the occluded cortical vein/sinuses in stable patients. However, recommendations for duration of anticoagulation are not based on the presence or absence of recanalization [99,105]. In the delayed setting, CVT may be complicated by dural arteriovenous fistula, which may necessitate delayed arterial imaging.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Catheter-directed cerebral angiography and venography are infrequently necessary in the setting of dural venous sinus thrombosis due to the sensitivity and specificity of CTV and MRV. In the setting of progressive infarct despite adequate medical therapy, catheter-directed angiography and venography may be useful for the identification of endovascular treatment targets or definitive evaluation for dural arteriovenous fistula development, which may complicate CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. In ongoing surveillance, however, the role for perfusion imaging is limited.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast Serial follow-up noncontrast CT of the head is useful in the patient with persistent or evolving symptoms despite medical treatment or with symptoms suggestive of propagation of thrombus. This is particularly useful in the late acute and subacute phases following initial presentation. Noncontrast CT may show sinus hyperdensity, which may be useful in early evaluation of thrombus extent; however, only 30% of noncontrast head CT examinations are abnormal in the setting of CVT [99].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast There is no relevant literature to support the use of CTA of the neck in the setting of known CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast In the setting of known CVT, CTV of the head may be useful in assessing thrombus burden; however, there are no data to support its use in determining the duration of anticoagulation. CTV is as accurate in evaluation of CVT as MRV [101,106]. CTV has high spatial resolution and is not affected by typical MRI artifacts that may complicate thrombus imaging. CTV may be useful when MRV is degraded and accurate measurement of thrombus extent is desired or when thrombus involves hypoplastic dural sinuses or cortical branches.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the setting of known CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast There is no relevant literature to support the use of MRA of the neck in the setting of known CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck With IV Contrast There is no relevant literature to support the use of MRA of the neck in the setting of known CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of known CVT [100]. CTP is not typically performed, however, in ongoing surveillance imaging in the absence of changes in clinical status.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast MRI of the head is useful in the ongoing evaluation of CVT in evaluating for progressive ischemic and hemorrhagic venous infarct. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Delayed postcontrast imaging can further improve assessment of T1 hyperintense thrombus burden. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast MRI of the head is useful in the ongoing evaluation of CVT in evaluating for progressive ischemic and hemorrhagic venous infarct. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Delayed postcontrast imaging can further improve assessment of T1 hyperintense thrombus burden. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast Although contrast-enhanced venography is the most accurate means of assessment for CVT, contrast-enhanced and TOF MRV imaging techniques are complementary, in that a contrast-enhanced MRV may provide a better assessment of a hypoplastic dural venous sinus with slow flow and TOF MRV mitigates against T1 isointense thrombus, which may mimic a normal opacification of the sinus on contrast-enhanced MRV [104]. Additionally, T1 hyperintense thrombus can mimic normal flow and enhancement patterns, which necessitates evaluation with noncontrast MRI imaging. Volumetric MRI sequences are essential for contrast-enhanced MRV. Delayed postcontrast imaging can further increase the sensitivity for detection of T1 isointense thrombus.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without IV Contrast Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], TOF and phase- contrast MRV are noncontrast alternatives for the diagnosis of CVT. If the findings on noncontrast MRV are unclear, then further imaging with contrast-enhanced CTV or MRV should be considered.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid Doppler in the setting of CVT. However, US assessment of the adjacent venous structures could yield useful information about the extent of the thrombus if extending into the neck.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial There is no relevant literature to support the use of transcranial Doppler in the setting of CVT.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Variant 9: Adult. Asymptomatic cervical bruit. Initial imaging. Cervical carotid bruit is an important diagnostic sign of potential underlying carotid stenosis because patients with carotid bruit are >50% more likely to harbor hemodynamically significant internal carotid stenosis. Although the advent of electronic auscultation has driven the negative predictive value to an all-time high, the positive predictive value is now at an all-time low, in the 30% range, which increases the importance of radiographic evaluation following detection of carotid bruit [107]. In the patient with recent TIA or minor stroke who is a candidate for CEA or stenting, the presence or absence of carotid bruit does not alter the necessity or urgency of evaluating the degree of carotid stenosis (see Variants 1-5). For asymptomatic patients, advances in medical therapy have rendered data from older clinical trials on the benefit of endarterectomy out of date, and thus the value of determining the degree of stenosis in these patients is less clear and currently the subject of a large randomized clinical trial [108- 110]. Currently, guidelines from professional societies continue to recommend CEA for certain selected patients with asymptomatic stenosis in which the degree of stenosis is an important deciding factor [111,112].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography is the most accurate means of delineating the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for screening is obviated by the invasive nature of the examination. Moreover, there is no literature supporting cerebral angiography as the initial imaging test in evaluation of a carotid bruit. Nonetheless, cerebral angiography may be necessary in some cases after the initial diagnosis of hemodynamically significant carotid stenosis is made on noninvasive imaging.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast CT head perfusion imaging may help delineate the hemodynamic significance of a known carotid lesion and the collateral support in each distribution. However, there is no literature to support the use of CTP for the initial detection of hemodynamically significant carotid disease in the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast There is no literature to support noncontrast CT of the head in the initial workup of the asymptomatic patient with a carotid bruit. Noncontrast CT of the head is useful in evaluating for the sequela of known asymptomatic carotid stenosis such as clinically silent strokes or microvascular ischemic changes. However, MRI is much more sensitive in evaluating microvascular ischemic changes or recent strokes. Symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head may be useful in treatment planning for patients with an established diagnosis of asymptomatic carotid stenosis. However, there is no literature to support CTA of the head in the initial workup for the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis as well as status of the other cervical vessels. Specifically, CTA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. CTA of the neck is also useful for treatment planning [114]. However, CTA of the neck may also underestimate the degree of stenosis in the setting of tortuosity or calcifications similar in density to contrast media [24]. Conversely, CTA may overestimate stenosis in the setting of very severe near occlusive stenosis [115]. Dual-energy CT may help limit overestimation of stenosis in some instances [116]. However, the requirement for iodinated contrast detracts from this examination in comparison to Doppler and MRA.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the evaluation of the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast There is no literature to support MRA of the head in the initial workup of the asymptomatic patient with a carotid bruit. MRA of the head may be useful in treatment planning for patients with an established diagnosis of carotid stenosis. Intracranial collateral characterization may be important when considering proximal embolic protection strategies.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast MRA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis, which will limit both false-positives and false-negatives. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over- or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast- enhanced MRA of the neck has a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, composition of carotid plaque including intraplaque hemorrhage on magnetization-prepared rapid acquisition gradient echo images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [118,119].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without IV Contrast MRA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis, which will limit both false-positives and false-negatives. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular Diseases-Stroke in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast- enhanced MRA of the neck has a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, composition of carotid plaque including intraplaque hemorrhage on magnetization-prepared rapid acquisition gradient echo images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [118,119].


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. However, there is no literature to support the use of MRI perfusion in the initial evaluation of the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the evaluation of the asymptomatic patient with a carotid bruit.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast There is no literature to support MRI of the head in the initial workup for the asymptomatic patient with a carotid bruit. MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of asymptomatic carotid stenosis.


Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of the asymptomatic patient with a carotid bruit.