Acute Onset of Scrotal Pain Without Trauma Without Antecedent Mass. US findings in patients with epididymitis include an enlarged and hypoechoic epididymis due to edema. Reactive hydroceles and scrotal wall thickening can also be seen. Color Doppler imaging shows increased blood flow corresponding to hyperemia, which is an important diagnostic feature of epididymitis. The sensitivity of color Doppler in detecting scrotal inflammation is nearly 100% [76,91]. The epididymis is the organ primarily involved in epididymoorchitis, with orchitis developing in 20% to 40% due to direct retrograde spread of infection [76]. Reperfusion after early ischemia, seen with torsion/detorsion, can induce a reactive hyperemia on color Doppler imaging, which is not sonographically distinguishable from the hyperemia seen with acute epididymoorchitis. Correlation with clinical data including presence of fever, waxing, and waning pain, as well as laboratory markers for infection must be integrated in the clinical assessment to distinguish both entities [54].


Acute Onset of Scrotal Pain Without Trauma Without Antecedent Mass. Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.


Acute Onset of Scrotal Pain Without Trauma Without Antecedent Mass. For additional information on the Appropriateness Criteria methodology and other supporting documents go to www.acr.org/ac.


Acute Onset of Scrotal Pain

Acute Onset of Scrotal Pain Without Trauma Without Antecedent Mass. Acute Onset of Scrotal Pain


Tracheobronchial Disease

Tracheobronchial Disease. Bronchiectasis is defined as irreversible abnormal bronchial dilatation, with patients most commonly presenting with chronic productive cough. Although a wide range of congenital and acquired conditions can be associated with bronchiectasis, a common etiologic pathway is thought to be impairment of normal bronchial clearance and airway immune mechanisms, resulting in recurrent infections and chronic bronchial inflammation that cause bronchial injury and dilatation [9,10]. The prevalence of bronchiectasis has increased worldwide over the last few decades; in the United States, prevalence has been estimated as approximately 139 per 100,000 individuals [9]. Treatment includes preventive airway clearance therapies, anti-inflammatory agents, prophylactic or therapeutic antibiotics, and, in severe cases, surgical resection or lung transplantation.


Tracheobronchial Disease

Tracheobronchial Disease. Special Imaging Considerations In cases of tracheal stenosis and central airway lesions in general, special CT reformatting techniques such as 2-D multiplanar, 3-D volume-rendered, and virtual bronchoscopic images may be helpful for illustration of findings and preprocedural planning [11-13]. For example, coronal and sagittal 2-D reformatted images and 3-D volume reformatted images can depict the craniocaudal extent of lesions and distance from landmarks such as the vocal cords and carina, and virtual bronchoscopic images can illustrate the expected endoluminal appearance of lesions and provide guidance for bronchoscopy and procedures by demonstrating local airway anatomy. Minimum intensity projection reformatted images can also display central airway abnormalities and bronchiectasis [10].


Tracheobronchial Disease

Tracheobronchial Disease. Modern multidetector CT can be used to image the entire trachea at end expiration or during forced expiration (dynamic expiratory imaging). More recently, 320-row multidetector CT scanners have enabled cinematic 4-D volumetric images of the trachea, allowing time-resolved coverage of the entire trachea throughout an inspiratory/expiratory cycle [14,15]. Low-dose volumetric CT using 40 to 80 mA is comparable to standard higher-


Tracheobronchial Disease

Tracheobronchial Disease. Reprint requests to: publications@acr.org


Tracheobronchial Disease

Tracheobronchial Disease

Tracheobronchial Disease. Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. dose techniques in demonstrating degree of trachea collapse [16], and low-dose techniques have been widely adopted for dynamic expiratory imaging assessment of ECAC [17,18].


Tracheobronchial Disease

Tracheobronchial Disease. Optimal evaluation of the airways requires thin-section imaging with a slice thickness of 1.5 mm or thinner. Larger slice thicknesses cause partial volume averaging that can obscure airway anatomy and airway lesions. Adequate breath holding at inspiration is also important, because respiratory motion can also obscure airway lesions and can also cause an erroneous impression of bronchiectasis caused by volume averaging and image blurring.


Tracheobronchial Disease

Tracheobronchial Disease. OR Discussion of Procedures by Variant Variant 1: Adult. Clinically suspected tracheal or bronchial stenosis. Initial imaging. CT Chest With IV Contrast Chest CT is widely used for first-line imaging evaluation of central airway pathology such as masses, thickening, and stenosis. CT with intravenous (IV) contrast provides the advantage of evaluation of enhancement characteristics and optimal evaluation of hilar and mediastinal adenopathy [19], however, relevant studies comparing contrast- enhanced CT with unenhanced CT are lacking. CT has shown a high correlation with findings at bronchoscopy and offers additional advantages by depicting degree of stenosis, extraluminal involvement of lesions, and extension to adjacent structures [19-21]. CT allows assessment of the location, shape, dimensions, mural extent, and attenuation characteristics of tumors of the large airways and detection of intrathoracic disease in cases of malignancy [19,20].


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without and With IV Contrast There is no relevant literature to support the use of chest CT without and with IV contrast in the initial evaluation of suspected tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without IV Contrast Chest CT is widely used for first-line imaging evaluation of central airway pathology such as masses, thickening, and stenosis. CT without IV contrast readily depicts central airway lesions, thickening, and stenosis. CT has shown high correlation with findings at bronchoscopy and offers additional advantages by depicting degree of stenosis, extraluminal involvement of lesions, and extension to adjacent structures [20,21]. CT allows assessment of the location, shape, dimensions, mural extent, and attenuation characteristics of tumors of the large airways and detection of intrathoracic disease in cases of malignancy [19,20].


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest With IV Contrast There is no relevant literature to support the use of neck and chest CT with IV contrast in the initial evaluation of suspected tracheal stenosis. However, combined neck and chest CT with IV contrast can be performed for


Tracheobronchial Disease

Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. assessment of suspected tracheal lesions and stenosis, especially for diseases that can involve the subglottic trachea, such as diffuse tracheal diseases and suspected or known malignancies of the neck. Chest CT protocols to evaluate tracheal stenosis often prescribe z-axis coverage through the lower neck.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without and With IV Contrast There is no relevant literature to support the use of neck and chest CT without and with IV contrast in the initial evaluation of suspected tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without IV Contrast There is no relevant literature to support the use of neck and chest CT without IV contrast in the initial evaluation of suspected tracheal stenosis. However, combined neck and chest CT without IV contrast may be performed for assessment of suspected tracheal lesions and stenosis, especially for diseases that can involve the subglottic trachea, such as diffuse tracheal diseases and suspected or known malignancies of the neck. Chest CT protocols to evaluate tracheal stenosis often prescribe z-axis coverage through the lower neck.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck With IV Contrast Neck CT with IV contrast may occasionally be performed as a targeted assessment of known lesions within the superior trachea, including primary neck malignancies with tracheal involvement. However, the limited z-axis coverage of neck CT risks exclusion of the full extent of tracheal disease. More commonly, neck CT may be performed as part of a combined neck and chest CT for assessment of suspected tracheal lesions and stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without and With IV Contrast There is no relevant literature to support the use of neck CT without and with IV contrast in the initial evaluation of suspected tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without IV Contrast Neck CT without IV contrast may occasionally be performed as a targeted assessment of known lesions within the superior trachea, including primary neck malignancies with tracheal involvement. However, the limited z-axis coverage of neck CT risks exclusion of the full extent of tracheal disease. More commonly, neck CT may be performed as part of a combined neck and chest CT for assessment of suspected tracheal lesions and stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CTA Chest With IV Contrast Chest CT angiography (CTA) with IV contrast may be used in evaluation of suspected tracheal stenosis in the setting of extrinsic compression due to a vascular cause, such as aberrant vessel or aneurysm. However, there is no relevant evidence comparing chest CTA and standard chest CT with or without IV contrast in initial evaluation of suspected tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. FDG-PET/CT Skull Base To Mid-Thigh Fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT is often used in the initial staging and follow-up of known thoracic malignancies, including tracheal tumors. However, FDG-PET/CT is not usually obtained as the initial imaging assessment of suspected tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without and With IV Contrast Although tracheal imaging can be performed with MRI, including dynamic imaging, this tool has been used mainly as a research tool.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without IV Contrast Although tracheal imaging can be performed with MRI, including dynamic imaging, this tool has been used mainly as a research tool.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Chest Radiography is often performed as initial imaging in patients with respiratory symptoms. Although tracheal stenosis and masses are occasionally incidental findings at chest radiography, the modality is much less sensitive for detection of central airway pathology than cross-sectional imaging. In a study of 41 patients with tumors and nonneoplastic stenosis of the central airways, radiography performed poorly compared to CT in depicting and characterizing lesions [22]. Radiography may be useful as an evaluation of possible complications of central airway disease, such as postobstructive atelectasis or pneumonia.


Tracheobronchial Disease

Tracheobronchial Disease

Tracheobronchial Disease. Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Neck There is no relevant literature to support the use of neck radiography in the initial evaluation of suspected tracheal stenosis. Radiography of the neck may be obtained in patients with suspected upper airway obstruction due to certain infections or foreign bodies. However, it is not routinely used for evaluation of tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. Variant 2: Adult. Tracheal or bronchial stenosis. Pre- or posttreatment assessment. CT Chest With IV Contrast CT of the chest with IV contrast can be used for pretreatment assessment of lesions and stenosis of the large airways and can help determine suitability and type of surgical or nonsurgical treatment approach [24]. However, studies comparing performance of chest CT with IV contrast to chest CT without IV contrast for evaluation of tracheal stenosis and associated lesions are lacking. A few small studies have documented additional incremental benefits of review of 2-D multiplanar, 3-D reformatted, and VB images, including changes in surgical approach or identification of associated findings such as small fistulae [11]. Chest CT is also used for evaluation of suspected posttreatment complications of tracheal interventions.


Tracheobronchial Disease

Tracheobronchial Disease. CT is commonly used for planning for tracheal stent implantation; a study of 69 patients with stenosis due to malignancy used CT to select stent diameter by measuring proximal and distal landing zone diameters and to determine desired stent length by measuring length of the involved segment [25]. A small study of 17 stenoses in 14 patients with postintubation stenosis confirmed at surgery found a detection rate of stenosis of 94% (16 of 17 lesions) of CT with VB and 88% (15 of 17) by rigid bronchoscopy; assessment of length was accurate for 87% of stenotic segments by CT and VB and 73% of segments by rigid bronchoscopy [13].


Tracheobronchial Disease

Tracheobronchial Disease. In a study of contrast-enhanced CT of 46 adenoid cystic carcinomas of the trachea and 36 other tracheal tumors, several imaging characteristics were predictive of poor disease-free survival, including longitudinal length >34 mm, transmural growth, and transverse length >20 mm, although only the latter remained significant in multivariate analysis [19].


Tracheobronchial Disease

Tracheobronchial Disease. A retrospective study of 31 tumors of the trachea or main bronchi compared a combination of pre- and postcontrast CT axial images, volume-rendered, and VB postprocessing techniques with surgical and pathology findings, finding good correlations for tumor locations, morphologies, longitudinal involvement, extent and morphology of stenosis, extramural invasion, and distance from the carina [12]. In a study of 52 patients comparing VB with bronchoscopy, VB had a high sensitivity and accuracy (both 93%) for detection of central airway tumors and had a high sensitivity (90%) and accuracy (96%) for characterization of airway stenosis [26].


Tracheobronchial Disease

Tracheobronchial Disease. However, there is no relevant literature specifically comparing chest CT with IV contrast to chest CT without IV contrast.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without and With IV Contrast There is no relevant literature to support the use of chest CT without and with IV contrast for pre- or posttreatment evaluation of tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without IV Contrast CT of the chest without IV contrast is widely used for pretreatment assessment of lesions and stenosis of the large airways and can help determine suitability and type of surgical or nonsurgical treatment approach [24]. A few small studies have documented additional incremental benefits of review of 2-D multiplanar, 3-D reformatted, and VB images, including changes in surgical approach or identification of associated findings such as small fistulae [11]. Chest CT is also used for evaluation of suspected posttreatment complications of tracheal interventions.


Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. A retrospective study of 31 tumors of the trachea or main bronchi compared a combination of pre- and postcontrast CT axial images, volume-rendered, and VB postprocessing techniques with surgical and pathology findings, finding good correlations for tumor locations, morphologies, longitudinal involvement, extent and morphology of stenosis, extramural invasion, and distance from the carina [12]. In a study of 52 patients comparing VB with bronchoscopy,


Tracheobronchial Disease

Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. VB had a high sensitivity and accuracy (both 93%) for detection of central airway tumors and had a high sensitivity (90%) and accuracy (96%) for characterization of airway stenosis [26].


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest With IV Contrast Combined neck and chest CT with IV contrast can be performed for pre- or posttreatment evaluation of tracheal stenosis, especially for diseases that can involve the subglottic trachea, such as diffuse tracheal diseases and suspected or known malignancies of the neck. Chest CT protocols to evaluate tracheal stenosis often prescribe z- axis coverage through the lower neck.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without and With IV Contrast There is no relevant literature to support the use of neck and chest CT without and with IV contrast for pre- or posttreatment evaluation of tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without IV Contrast Combined neck and chest CT without IV contrast can be performed for pre- or posttreatment evaluation of tracheal stenosis, especially for diseases that can involve the subglottic trachea, such as diffuse tracheal diseases and suspected or known malignancies of the neck. Chest CT protocols to evaluate tracheal stenosis often prescribe z- axis coverage through the lower neck.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck With IV Contrast Neck CT with IV contrast may occasionally be performed as a targeted assessment of known lesions within the superior trachea, including primary neck malignancies with tracheal involvement. However, the limited z-axis coverage of neck CT risks exclusion of the full extent of tracheal disease. More commonly, neck CT may be performed as part of a combined neck and chest CT for pre- or posttreatment assessment of tracheal lesions and stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without and With IV Contrast There is no relevant literature to support the use of neck CT without and with IV contrast for pre- or posttreatment evaluation of tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without IV Contrast Neck CT without IV contrast may occasionally be performed as a targeted assessment of known lesions within the superior trachea, including primary neck malignancies with tracheal involvement. However, the limited z-axis coverage of neck CT risks exclusion of the full extent of tracheal disease. More commonly, neck CT may be performed as part of a combined neck and chest CT for pre- or posttreatment assessment of tracheal lesions and stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. CTA Chest With IV Contrast Chest CTA with IV contrast may be used in preoperative evaluation of tracheal stenosis in the setting of extrinsic compression due to a vascular cause, such as aberrant vessel or aneurysm. Chest CTA with aortic contrast phase timing may be used in selected cases to evaluate suspected bleeding as a complication of tracheal interventions.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without and With IV Contrast Although tracheal imaging can be performed with MRI, including dynamic imaging, this tool has been used mainly as a research tool.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without IV Contrast Although tracheal imaging can be performed with MRI, including dynamic imaging, this tool has been used mainly as a research tool.


Tracheobronchial Disease

Tracheobronchial Disease

Tracheobronchial Disease. Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Chest There is no relevant literature to support the use of chest radiography for pretreatment evaluation of tracheal stenosis. Although there is no relevant literature to support the routine use of chest radiographs after procedures designed to treat tracheal stenosis, in practice chest radiographs may be obtained to evaluate possible complications such as pneumothorax, excessive pneumomediastinum, or aspiration.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Neck There is no relevant literature to support the use of neck radiography for pre- or posttreatment evaluation of tracheal stenosis.


Tracheobronchial Disease

Tracheobronchial Disease. Variant 3: Adult. Clinically suspected tracheomalacia or bronchomalacia. Initial imaging. CT Chest With IV Contrast There is no relevant literature to support the use of chest CT with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without and With IV Contrast There is no relevant literature to support the use of chest CT without and with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without IV Contrast Chest CT without IV contrast is useful for noninvasive imaging of ECAC, including tracheobronchomalacia and excessive dynamic airway collapse. Chest CT during forced expiration has been widely adopted as the primary imaging protocol because it is more sensitive for detection of ECAC, eliciting greater degrees of expiratory collapse than CT obtained at end expiration [29-31]. In a study of 29 patients with suspected ECAC, forced expiratory dynamic cine imaging showed tracheal collapse >50% at 38% of assessed levels compared to 13% at end-expiratory CT [32]; a study of 67 patients with chronic obstructive pulmonary disease (COPD) showed a mean tracheal collapse of 62% at forced expiratory CT and only 17% at end expiratory CT [31]. Fifty percent area narrowing of the lumen of the trachea on CT at expiration had originally been considered suggestive of ECAC, but a threshold of 70% collapse is now proposed following a study by Boiselle et al [17], finding >50% collapse in 40 of 51 (78%) healthy volunteers.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest With IV Contrast There is no relevant literature to support the use of neck and chest CT with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without and With IV Contrast There is no relevant literature to support the use of neck and chest CT without and with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without IV Contrast There is no relevant literature to support performing a full neck CT in this setting, however, z-axis coverage through the lower neck is often prescribed as part of a standard chest CT without IV contrast for evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck With IV Contrast There is no relevant literature to support the use of neck CT with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without and With IV Contrast There is no relevant literature to support the use of neck CT without and with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without IV Contrast There is no relevant literature to support the use of neck CT without IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CTA Chest With IV Contrast There is no relevant literature to support the use of chest CTA for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. FDG-PET/CT Skull Base To Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of MRI chest without and with IV contrast for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Chest Dynamic chest radiography has been proposed for evaluating ECAC but use has been limited to small preliminary research investigations [34]. Chest radiography may be used in the initial evaluation of other pulmonary diseases that may manifest with respiratory symptoms also seen in ECAC.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Neck There is no relevant literature to support the use of neck radiography for initial evaluation of suspected tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. Variant 4: Adult. Tracheomalacia or bronchomalacia. Pre- or posttreatment assessment. CT Chest With IV Contrast There is no relevant literature to support the use of chest CT with IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia. In practice, chest CT may be performed with IV contrast in evaluation of postsurgical complications of procedures used to treat tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without and With IV Contrast There is no relevant literature to support the use of chest CT without and with IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without IV Contrast Evaluation of ECAC with dynamic expiratory CT can change treatment approach in some patients compared with evaluation with bronchoscopy alone and is standardly performed without IV contrast. In one study, a change in planned treatment was performed in 12 of 29 patients with tracheomalacia or bronchomalacia who had previously undergone bronchoscopy, including changes in surgical approach [30].


Tracheobronchial Disease

Tracheobronchial Disease. A small study using inspiratory and dynamic expiratory CT to evaluate 5 patients with tracheomalacia before and after tracheobronchoplasty found a decrease in degree of tracheal collapse after surgery in all participants [35]. Other studies of 18 patients [8] and 16 patients [36] with tracheobronchomalacia using end inspiratory and dynamic expiratory CT showed significant average decreases trachea after tracheobronchoplasty. However, there are no guidelines for performing routine follow up of patients after treatment for ECAC.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest With IV Contrast Z-axis coverage through the lower neck is often prescribed as part of a standard chest CT with IV contrast for evaluation of suspected tracheomalacia or bronchomalacia, but there is no relevant evidence to support performing a full neck CT in this setting. In clinical practice, neck CT may be performed in conjunction with chest CT to evaluate suspected complications of tracheal interventions.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without and With IV Contrast There is no relevant literature to support the use of neck and chest CT without and with IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease

Tracheobronchial Disease. Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without IV Contrast Z-axis coverage through the lower neck is often prescribed as part of a standard chest CT without IV contrast for evaluation of suspected tracheomalacia or bronchomalacia, but there is no relevant evidence to support performing a full neck CT in this setting. In clinical practice, neck CT may be performed in conjunction with chest CT to evaluate suspected complications of tracheal interventions.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck With IV Contrast There is no relevant literature to support the use of neck CT with IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without and With IV Contrast There is no relevant literature to support the use of neck CT without and with IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without IV Contrast There is no relevant literature to support the use of neck CT without IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. CTA Chest With IV Contrast There is no relevant literature to support the use of chest CTA for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia. However, chest CTA timed for an aortic phase of contrast may be used in selected cases to evaluate suspected bleeding as a complication of tracheal interventions.


Tracheobronchial Disease

Tracheobronchial Disease. FDG-PET/CT Skull Base To Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of MRI chest without and with IV contrast for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Chest Although there is no relevant literature to support the routine use of chest radiographs after procedures designed to treat tracheomalacia or bronchomalacia, in practice, chest radiographs may be obtained to evaluate possible complications such as pneumothorax, excessive pneumomediastinum, or aspiration.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Neck There is no relevant literature to support the use of neck radiography for pre- or posttreatment evaluation of tracheomalacia or bronchomalacia.


Tracheobronchial Disease

Tracheobronchial Disease. Variant 5: Adult. Clinically suspected bronchiectasis. Initial imaging. CT Chest With IV Contrast There is no relevant literature to support the use of chest CT with IV contrast for initial evaluation of suspected bronchiectasis. However, bronchiectasis can be detected incidentally on chest CT with IV contrast performed for other indications.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without and With IV Contrast There is no relevant literature to support the use of chest CT without and with IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. The 2010 British Thoracic Society guidelines for non-cystic fibrosis (non-CF) bronchiectasis recommend thin- section CT, either conventional high-resolution CT or volumetric thin-slice CT, as the preferred examination for evaluation of suspected bronchiectasis. The guidelines acknowledge that, although certain CT distributions and appearances of bronchiectasis may suggest a particular etiology, in many cases, findings are not pathognomonic, as confirmed by the relatively low reader diagnostic performance in several retrospective CT studies [38-41]. However, CT can play a role in suggesting further clinical evaluation of causes of bronchiectasis and associated findings, such as in prompting testing for nontuberculous mycobacterial infection (NTMB) in the appropriate clinical setting [42].


Tracheobronchial Disease

Tracheobronchial Disease. CT can be used to quantify the extent and severity of bronchiectasis using a variety of techniques and software. A systematic review of 122 studies found 42 quantitative CT scoring methods in the research literature, including calculation of bronchial-arterial ratios, bronchial diameters, or bronchial surface area [43]. Severity of bronchiectasis at CT correlates with measures of airflow obstruction [40]. A relatively large prospective cohort study of 608 patients with bronchiectasis examined the association between a variety of clinical, laboratory, and CT findings and clinical outcomes; a CT finding of bronchiectasis in at least 3 lobes was associated with poorer outcomes and was incorporated along with several clinical variables into a bronchiectasis severity score with relatively high predictive value for exacerbations, hospitalizations, and mortality in patients with bronchiectasis [44]. A prospective multicenter study of 261 patients with non-CF bronchiectasis found weak but statistically significant correlations between severity and extent of bronchiectasis at CT and forced expiratory volume in one second and forced vital capacity [45]. A study of 277 patients with NTMB found correlations between bronchiectasis (as assessed by semiquantitative scores) and clinical variables such as more frequent exacerbations and lower blood oxygenation [46].


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest With IV Contrast There is no relevant literature to support the use of neck and chest CT with IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without and With IV Contrast There is no relevant literature to support the use of neck and chest CT without and with IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without IV Contrast There is no relevant literature to support the use of neck and chest CT without IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck With IV Contrast There is no relevant literature to support the use of neck CT with IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without and With IV Contrast There is no relevant literature to support the use of neck CT without and with IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without IV Contrast There is no relevant literature to support the use of neck CT without IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. CTA Chest With IV Contrast There is no relevant literature to support the use of chest CTA for initial evaluation of suspected bronchiectasis. However, bronchiectasis can be detected incidentally on chest CTA with IV contrast performed for other indications.


Tracheobronchial Disease

Tracheobronchial Disease

Tracheobronchial Disease. Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. FDG-PET/CT Skull Base To Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of MRI chest without and with IV contrast for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without IV Contrast Limited data exist on the use of MRI without IV contrast in characterization of bronchiectasis. A small study of 23 adults with primary immunodeficiency found MRI inferior to CT in characterizing extent of bronchiectasis but found similar performance of MRI and CT in assessing severity of bronchiectasis, mucous plugging, bronchial wall thickening, and other associated parenchymal findings [47]. An exploratory study of 25 patients showed moderate agreement between MRI and CT scores for imaging findings in mycobacterium avium complex pneumonia, including for bronchiectasis [48]. However, the use of MRI for assessment of bronchiectasis is currently limited mainly to research settings or use in young patients such as those with cystic fibrosis.


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Chest Chest radiography is relatively insensitive for detection of bronchiectasis but is often performed as initial imaging in patients with respiratory symptoms that are common in patients with bronchiectasis [9,10]. Chest radiography may be useful for the initial evaluation of the lung parenchyma in conditions associated with bronchiectasis, but it provides limited characterization of severity and morphology of bronchiectasis. The 2010 British Thoracic Society guidelines for non-CF bronchiectasis recommend a baseline chest radiograph in all patients with suspected bronchiectasis but recommend repeat radiographs only if clinically warranted [40].


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Neck There is no relevant literature to support the use of neck radiography for initial evaluation of suspected bronchiectasis.


Tracheobronchial Disease

Tracheobronchial Disease. Variant 6: Adult. Bronchiectasis. Assessment of complications or treatment response. CT Chest With IV Contrast There is no relevant literature to support the use of chest CT with IV contrast in the evaluation of bronchiectasis complications or treatment response. CT chest with IV contrast may also be appropriate in the setting of suspected acute infection and associated complications such as abscess or necrosis.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without and With IV Contrast There is no relevant literature to support the use of chest CT without and with IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CT Chest Without IV Contrast Chest CT without IV contrast may be used to evaluate complications associated with bronchiectasis, including pneumonia and hemoptysis, and is often used in follow-up of conditions associated with bronchiectasis, such as chronic infections or interstitial lung diseases. Chest CT without IV contrast may be appropriate for assessing patients with known bronchiectasis and a change in clinical status to exclude pulmonary causes [40].


Tracheobronchial Disease

Tracheobronchial Disease. Chest CT without IV contrast can be used to quantify extent and severity of bronchiectasis with special software. A systematic review of 122 studies found 42 quantitative CT scoring methods in the research literature, including calculation of bronchial-arterial ratios, bronchial diameters, or bronchial surface area [43]. Severity of bronchiectasis at CT correlates with measures of airflow obstruction [40].


Tracheobronchial Disease

Tracheobronchial Disease. Although well-established guidelines on imaging follow-up of bronchiectasis are lacking, in practice, patients with diseases associated with bronchiectasis may be assessed with CT to help guide therapy and to provide prognostic information. Patients with NTMB may be followed with chest CT to assess response to therapy or worsening of disease. A study of 210 patients with NTMB found that higher CT severity scores (a combined assessment of nodules, bronchiectasis, cavities, and consolidation) were associated with higher organism sputum counts and worse prognosis [49]; higher sputum organism count was also associated with CT findings of small nodules, consolidation, bronchiectasis, and pleural thickening in another study of 50 patients with NTMB [50]. In a study of 488 patients with NTMB, patients with predominantly fibrocavitary disease were more likely to experience clinical deterioration than those with primarily noncavitary manifestations [51]. In a study of 40 patients with NTMB lung disease not undergoing antimycobacterial treatment, 39 (98%) showed worsening on chest CT findings over the course of


Tracheobronchial Disease

Tracheobronchial Disease


Tracheobronchial Disease

Tracheobronchial Disease. several years [52], although another study of 475 patients with NTMB pulmonary disease showed improvement in CT scores with antibiotic treatment [53]. In a study of 67 patients with NTMB, more extensive total lung involvement and higher cavitary volume were independently associated with worse pulmonary function [54].


Tracheobronchial Disease

Tracheobronchial Disease. CT may be useful for follow-up of patients with bronchiectasis who may be at risk of developing NTMB. A study of 221 patients with bronchiectasis found new-onset NTMB pulmonary disease in 31 (14%) patients, which was associated with worsening of bronchiectasis, bronchiolitis, and other nodules on CT [55], and another study of 84 patients showed that more severe bronchiectasis and presence of cavities were more likely in NTMB pulmonary disease than in asymptomatic colonization [42]. Some studies have also found an association of CT severity scores and likelihood of NTMB treatment failure [56].


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest With IV Contrast There is no relevant literature to support the use of neck and chest CT with IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without and With IV Contrast There is no relevant literature to support the use of neck and chest CT without and with IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck and Chest Without IV Contrast There is no relevant literature to support the use of neck and chest CT without IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck With IV Contrast There is no relevant literature to support the use of neck CT with IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without and With IV Contrast There is no relevant literature to support the use of neck CT without and with IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CT Neck Without IV Contrast There is no relevant literature to support the use of neck CT without IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. CTA Chest With IV Contrast There is no relevant literature to support the use of chest CTA for assessment of other bronchiectasis complications or treatment response. However, chest CTA with IV contrast with aortic contrast phase timing may be used to evaluate possible sources of hemoptysis in patients with bronchiectasis, such as in cystic fibrosis.


Tracheobronchial Disease

Tracheobronchial Disease. FDG-PET/CT Skull Base To Mid-Thigh There is no relevant literature to support the use of FDG-PET/CT in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without and With IV Contrast There is no relevant literature to support the use of chest MRI without and with IV contrast in the evaluation of bronchiectasis complications or treatment response.


Tracheobronchial Disease

Tracheobronchial Disease. MRI Chest Without IV Contrast Chest MRI is not routinely used in the assessment of bronchiectasis complications or treatment response. A small prospective study used MRI with inhaled hyperpolarized 3He to assess ventilation in 15 patients with non-CF bronchiectasis and 15 age-matched controls, finding a greater percentage of ventilation defects in lobes with bronchiectasis than in healthy controls; ventilation defects improved in 8 of 14 patients who underwent respiratory therapy [57].


Tracheobronchial Disease

Tracheobronchial Disease. Radiography Chest Radiography is often the initial chest imaging examination to evaluate acute conditions that may occur in patients with bronchiectasis, such as pneumonia and hemoptysis. Radiographs may also be used in follow-up of chronic lung conditions associated with bronchiectasis. The 2010 British Thoracic Society guidelines for non-CF bronchiectasis recommend a baseline chest radiograph in all patients with suspected bronchiectasis but recommend repeat radiographs only as clinically warranted [40].


Tracheobronchial Disease

Tracheobronchial Disease

Tracheobronchial Disease. Tracheobronchial Disease


Tracheobronchial Disease

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


Tracheobronchial Disease

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


Tracheobronchial Disease

Tracheobronchial Disease


Thyroid Disease

Thyroid Disease. Introduction/Background There are a wide variety of diseases that affect the thyroid gland and range from hyperplastic to neoplastic, autoimmune, or inflammatory. They can present with functional abnormality or a palpable structural change. Imaging has a key role in diagnosing and characterizing the thyroid finding for management. Imaging is also essential in the management of thyroid cancer.


Thyroid Disease

Thyroid Disease. When biopsy reveals the diagnosis of thyroid cancer, imaging has several roles, depending on the type of cancer. Papillary and follicular carcinomas arise from the follicular epithelial cells are known as differentiated thyroid carcinomas (DTC), representing 84% and 11% of all thyroid malignancies, respectively [2]. DTC have an excellent prognosis, with a 10-year survival rate of 99% for papillary carcinoma and 95% for follicular type [2]. DTCs are treated primarily with surgery and may have radioiodine ablation depending on the stage of disease. Medullary thyroid carcinoma (MTC) arises from parafollicular cells and is more aggressive, with a survival rate of 82% at 10 years [2]. MTC is also treated with surgery. Anaplastic carcinoma is an aggressive undifferentiated tumor typically occurring in the elderly with a 10-year survival of 8% [9]. Treatment of anaplastic carcinoma does not significantly impact survival. Other malignancies, such as thyroid lymphoma, sarcoma, and metastases, are rare. Imaging is used in operative planning, routine tumor surveillance, and further evaluation of suspected recurrence.


Thyroid Disease

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


Thyroid Disease

Thyroid Disease. *The views expressed in this manuscript are those of the author and do not reflect the official policy of the Department of Army/Navy/Air Force,


Thyroid Disease

Thyroid Disease. Department of Defense, or United States Government. Reprint requests to: publications@acr.org


Thyroid Disease

Thyroid Disease. Thyroid Disease Special Imaging Considerations Use of iodinated intravenous (IV) contrast for CT helps to delineate invasive tumor and morphological abnormalities in small nodal metastases. In the past, there were concerns about iodinated contrast agents delaying subsequent whole-body scans or radioiodine ablation; however, this has now been shown to be unfounded. Recent studies show that water-soluble iodinated contrast agents are generally cleared within 4 to 8 weeks in most patients; therefore, post-thyroidectomy patients requiring radioiodine therapy can be scanned with radioactive iodine (RAI) within 1 month of the contrast-enhanced CT [11,12].


Thyroid Disease

Thyroid Disease. Discussion of Procedures by Variant Variant 1: Palpable thyroid nodule. Not goiter. Euthyroid. Initial imaging. Screening for thyroid cancer by palpation is not recommended by the U.S. Preventive Task Force [15]. However, if a patient presents with a palpable neck nodule, the goal of imaging is to determine if the palpable abnormality corresponds to a thyroid nodule and to characterize the nodule for malignancy risk. Thyroid function tests should be performed first. If the serum thyroid-stimulating hormone (TSH) is subnormal, then the patient has thyrotoxicosis (Variant 3). This variant refers to a palpable thyroid nodule in the setting of a euthyroid patient.


Thyroid Disease

Thyroid Disease. US Thyroid US provides high-resolution imaging to show that the palpable abnormality is within the thyroid and is the best study to characterize the nodule for the risk of malignancy. Certain sonographic features are more prevalent in malignancies. The combination of these features and the nodule size guide the decision to biopsy under the ACR TI-RADS and other risk stratification criteria [8,16].


Thyroid Disease

Thyroid Disease. CT Neck There is no evidence that CT can differentiate between malignant and benign nodules unless there is gross invasion or metastatic disease [7]. There may be a role for this cross-sectional imaging modality if the nodule is part of a goiter that is suspected to extend substernally or there is a suspicion of invasive thyroid cancer. Dual- phase CT imaging with and without IV contrast does not provide any additional information.


Thyroid Disease

Thyroid Disease. MRI Neck There is no evidence that MRI can differentiate between malignant and benign nodules unless there is gross invasion or metastatic disease. There may be a role for this cross-sectional imaging modality if the nodule is part of a goiter that is suspected to extend substernally or there is a suspicion of invasive thyroid cancer. CT is preferred since there is less respiratory motion artifact.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body There is no evidence to support the use of PET using the tracer fluorine-18-2-fluoro-2-deoxy-D-glucose (FDG)/CT in the setting of palpable thyroid nodule.


Thyroid Disease

Thyroid Disease. Radionuclide Uptake and Scan In euthyroid patients, radioisotope scanning is not helpful in determining malignancy and decision to biopsy. Although cold nodules are more likely to be malignant, the majority of nodules are cold, and the majority of cold nodules are benign, resulting in a low positive predictive value.


Thyroid Disease

Thyroid Disease. Variant 2: Suspected goiter. Initial imaging. A goiter is suspected based on a diffuse palpable abnormality or obstructive symptoms, such as dyspnea, orthopnea, obstructive sleep apnea, dysphagia, and dysphonia. These symptoms are related to mass effect on the trachea or esophagus.


Thyroid Disease

Thyroid Disease. Thyroid Disease The role of imaging is to confirm the diagnosis of goiter and document the size and extent of the goiter. If obstructive symptoms are present, imaging can quantify the degree of compression on the trachea. This information is valuable in deciding if surgery will improve obstructive symptoms and planning operative approach.


Thyroid Disease

Thyroid Disease. US Thyroid US is the preferred first-line imaging modality for suspected goiter. It confirms that the neck mass is arising from the thyroid and characterizes the size and morphology of the goiter. If the goiter is nodular, US can also evaluate for suspicious features in nodules (see Variant 1).


Thyroid Disease

Thyroid Disease. CT Neck CT is superior to US for evaluating substernal extension and deep extension to the retropharyngeal space [17]. CT can also define the degree of tracheal compression more effectively than US. Performing a CT with iodinated contrast is not necessary for goiter evaluation unless there is concern for an infiltrative neoplasm. Dual-phase CT imaging with and without IV contrast does not provide any additional information.


Thyroid Disease

Thyroid Disease. MRI Neck MRI is an alternative to CT for characterizing the goiter, but CT is preferred because there is less respiratory motion artifact. Performing an MRI with IV contrast is not necessary for goiter evaluation unless there is concern for an infiltrative neoplasm.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body FDG-PET/CT imaging is not recommended as the initial imaging for the evaluation of suspected goiter.


Thyroid Disease

Thyroid Disease. Radionuclide Uptake and Scan Radionuclide uptake may have a role if the goiter is associated with thyrotoxicosis. The radionuclide uptake and scan confirms that the entire goiter consists of thyroid tissue. Iodine-123 (I-123) is preferred over iodine-131 (I- 131) because of its superior imaging quality [18]. In addition to confirming the entire goiter is made of thyroid tissue, in a multinodular goiter the scan should be compared to an US to identify hypofunctioning or isofunctioning nodules to be targeted for biopsy [16].


Thyroid Disease

Thyroid Disease. Variant 3: Thyrotoxicosis. Initial imaging. Thyrotoxicosis may present with symptoms of hyperthyroidism, such as heat intolerance, tachycardia, anxiety, and weight loss, or be subclinical and found as an incidental laboratory abnormality (low TSH). The most common causes of thyrotoxicosis are Graves disease, toxic adenoma, toxic multinodular goiter, and subacute thyroiditis. Rare causes include trophoblastic disease, thyroid hormone resistance, amiodarone-induced thyroiditis, iatrogenic thyrotoxicosis, factitious ingestion of thyroid hormone, and struma ovarii [19].


Thyroid Disease

Thyroid Disease. Graves disease is diagnosed by laboratory tests, including measurement of TSH receptor antibodies [20], but in ambiguous cases or where toxic adenoma or multinodular goiter is suspected [19], imaging with an iodine uptake and scan can help confirm the cause for thyrotoxicosis. Imaging also has a role in planning therapy with RAI.


Thyroid Disease

Thyroid Disease. US Thyroid US is the best imaging study to evaluate thyroid morphology and can be a helpful adjunct study to a radioiodine uptake. When a radioactive uptake scan shows nodules from toxic multinodular goiter or toxic adenoma, US can confirm presence of nodules and also evaluate for suspicious features of malignancy (see Variant 1). US also provides thyroid dimensions for planning RAI treatment [19].


Thyroid Disease

Thyroid Disease. Doppler US may be an alternative to nuclear medicine for separating thyrotoxicosis that is due to an overactive thyroid, such as Graves disease and toxic adenoma, from thyrotoxicosis, which is due to destructive causes such as subacute or lymphocytic thyroiditis. On Doppler US, these two causes of thyrotoxicosis have increased and decreased thyroid blood flow, respectively [21,22]. Although one study found similar sensitivity and specificity for Doppler US (95% and 90%) and radionuclide uptake studies (90% and 100%) [23], a radionuclide uptake study is still preferred because it directly measures thyroid activity rather than inferring it based on blood flow [24].


Thyroid Disease

Thyroid Disease. Among rarer causes of thyrotoxicosis, US can also distinguish between the two types of amiodarone-induced thyrotoxicosis. Type I (iodine-induced hyperthyroidism) has an enlarged or nodular thyroid gland, whereas type II (destructive) has a normal or small diffuse goiter with decreased blood flow [24]. Other causes also have characteristic features. Postpartum destructive thyroiditis has decreased blood flow. Findings of acute thyroiditis


Thyroid Disease

Thyroid Disease

Thyroid Disease. Thyroid Disease


Thyroid Disease

Thyroid Disease. on US are hypoechoic lesions in and near the thyroid, tissue destruction, and abscesses. Painless thyroiditis has inhomogeneous hypoechogenic texture with decreased blood flow [19].


Thyroid Disease

Thyroid Disease. CT Neck CT is usually not used in the workup of thyrotoxicosis.


Thyroid Disease

Thyroid Disease. MRI Neck MRI is usually not used in the workup of thyrotoxicosis.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body FDG-PET/CT imaging is not recommended as the initial imaging for the evaluation of a palpable thyroid nodule.


Thyroid Disease

Thyroid Disease. Radionuclide Uptake and Scan Radioiodine uptake and scan can distinguish between high-uptake causes of thyrotoxicosis, such as Graves disease, toxic adenoma, and toxic multinodular goiter, and low-uptake causes, such as subacute thyroiditis and exogenous thyroid hormone [19,25]. The scan component is also helpful in differentiating between high-uptake causes, such as toxic adenoma, toxic multinodular goiter, and Graves disease (diffuse uptake) [19], as well as rarer causes, such as Marine-Lenhart syndrome (toxic nodule plus Graves) [26]. If radioiodine therapy is planned, the uptake component of the scan can then help determine the dose. Either I-123 or I-131 plus pertechnetate can be used [19]. If nodularity is present, I-123 is preferred so as to identify any hypofunctioning or isofunctioning nodules to target for biopsy [16]. In postpartum thyrotoxicosis, I-131 should be avoided [19].


Thyroid Disease

Thyroid Disease. Variant 4: Primary hypothyroidism. Initial imaging. Hypothyroidism is a condition of low thyroid hormone that is due to an underactive gland. Hypothyroidism can present with symptoms such as weight gain, cold intolerance, constipation, weakness, and fatigue, or be diagnosed as a laboratory abnormality. The treatment of hypothyroidism is thyroid hormone replacement. The most common etiology in the developed world (where dietary iodine supply is adequate) is Hashimoto thyroiditis, also known as chronic lymphocytic thyroiditis. Other etiologies include thyroidectomy, radioiodine therapy, external neck irradiation, iodine deficiency or excess, and drugs.


Thyroid Disease

Thyroid Disease. There is no role for imaging in the workup of hypothyroidism in adults. Imaging for thyroid morphology does not help differentiate among causes of hypothyroidism, and all causes of hypothyroidism will have decreased radioiodine uptake.


Thyroid Disease

Thyroid Disease. US Thyroid There is no role for US imaging in the workup of hypothyroidism in adults. Imaging for thyroid morphology does not help differentiate among causes of hypothyroidism.


Thyroid Disease

Thyroid Disease. CT Neck There is no role for CT imaging in the workup of hypothyroidism in adults. Imaging for thyroid morphology does not help differentiate among causes of hypothyroidism.


Thyroid Disease

Thyroid Disease. MRI Neck There is no role for MRI in the workup of hypothyroidism in adults. Imaging for thyroid morphology does not help differentiate among causes of hypothyroidism.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body There is no role for FDG-PET/CT imaging in the workup of hypothyroidism in adults.


Thyroid Disease

Thyroid Disease. Radionuclide Uptake and Scan There is no role for radioiodine uptake and scan in the workup of hypothyroidism in adults. Imaging for thyroid morphology does not help differentiate among causes of hypothyroidism, and all causes of hypothyroidism will have decreased radioiodine uptake.


Thyroid Disease

Thyroid Disease. Variant 5: Preoperative evaluation of differentiated thyroid cancer. Surgery for DTC involves resection of the primary tumor and clinically significant lymph nodes. The goals of preoperative imaging are to evaluate for extrathyroidal invasion into surrounding structures (airway, esophagus, muscles) and for vascular encasement, and to identify lymph nodes in the lateral compartment >8 to 10 mm. Of note, the resection of larger nodal metastases, not micrometastases, is associated with improved survival, especially in patients <45 years of age [27].


Thyroid Disease

Thyroid Disease. In addition to the American Joint Committee on Cancer staging, which provides prognosis for survival, thyroid cancers are categorized by the American Thyroid Association into low, intermediate, and high risk, which provides risk for recurrence [16]. Preoperative staging and risk of recurrence both determine the need for RAI therapy after surgery and the protocol for tumor surveillance (Variant 6).


Thyroid Disease

Thyroid Disease. US Thyroid US is a routine preoperative study in all patients with thyroid cancer. The role of US is to stage the primary tumor and cervical lymph nodes. In a retrospective study of patients who had primary surgery for thyroid cancer, US detected additional sites of metastatic disease not appreciated on physical examination in 20% of patients [28]. Compared to CT, US is more accurate in predicting early extrathyroidal tumor extension and multifocal bilobar disease [29]. US has excellent resolution for lymph node morphology. Most studies find US has higher diagnostic accuracy compared to CT for preoperative evaluation of nodal disease, especially for lateral compartment nodes [29-33]. Some centers use US for routine preoperative lymph node mapping and fine-needle aspiration of suspicious lymph nodes >8 to 10 mm [31].


Thyroid Disease

Thyroid Disease. CT Neck Preoperative CT with IV contrast is recommended as an adjunct to US for patients with clinical suspicion for advanced disease, including invasive primary tumor or clinically apparent multiple or bulky lymph node involvement [16]. CT is a better modality than US for delineating the extent of laryngeal, tracheal, esophageal, or vascular involvement [30,33]. CT is useful in defining the inferior border of disease and in determining the extent to which mediastinal structures are involved in cases with significant caudal spread. These inferior sites cannot be visualized on US.


Thyroid Disease

Thyroid Disease. CT can also delineate bulky nodal disease and extranodal extension that involves muscle and blood vessels [34]. In particular, CT has higher sensitivity than US in detecting lymph node metastases in the central compartment and retropharyngeal space [32].


Thyroid Disease

Thyroid Disease. CT should be performed with iodinated contrast in order to better assess for tumor vascular encasement and small nodal metastases with hyperenhancement and necrosis. Contrast is not contraindicated for DTC based on new studies on iodine retention [11,12] (see Special Imaging Considerations section above). Dual-phase CT imaging with and without IV contrast does not provide any additional information.


Thyroid Disease

Thyroid Disease. MRI Neck MRI of the neck and mediastinum has the same role as CT in evaluating sites that are limited on US. The performance of MRI for imaging the neck and mediastinum has not been directly compared with CT on large numbers of thyroid cancer patients. Contrast is valuable for local staging and assessing suspicious lymph nodes. MRI has disadvantages of motion artifact in the lower neck from respiration and swallowing and is less sensitive than CT scan for the detection of small pulmonary nodules.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body A small prospective study compared diagnostic accuracy of FDG-PET/CT with US and contrast-enhanced CT. The sensitivity of PET for the detection of cervical lymph node metastases at all nodal levels is lowest for PET (30% versus 41% for US and 35% for CT) [35]. In general, because of the low avidity of well-differentiated thyroid cancers, FDG-PET/CT is not useful. Sensitivity of FDG-PET/CT scanning for malignancy may be slightly increased with TSH stimulation with recombinant human TSH but not enough to change management in most patients [36].


Thyroid Disease

Thyroid Disease. Whole-Body Scintigraphy Whole-body scintigraphy (WBS) has no role in the preoperative staging for DTC since the normal thyroid has very high iodine uptake and will take up most of the tracer.


Thyroid Disease

Thyroid Disease. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no role for indium-111 (In-111) somatostatin receptor scintigraphy at any stage of evaluation of DTC.


Thyroid Disease

Thyroid Disease. Variant 6: Early imaging after treatment of thyroid cancer. After surgery, an early postoperative US within 6 to 12 months should be performed on all patients. Additional imaging depends on the extent of disease and surgery. In patients with total thyroidectomy, extent of residual disease cannot be determined at surgery or on US, so WBS helps to decide if and how much RAI the patient should receive. WBS is also performed after RAI therapy.


Thyroid Disease

Thyroid Disease

Thyroid Disease. Thyroid Disease


Thyroid Disease

Thyroid Disease. Imaging combined with serum thyroglobulin and thyroglobulin antibodies helps to categorize patients into risk groups according to response to therapy. Thyroglobulin testing with different cutoffs can be used to define response to therapy in patients after thyroidectomy with or without RAI and in those with lobectomy alone [37]. The choice of further imaging depends on the response to therapy based upon results from serum thyroglobulin testing and US performed in the first year after definitive treatment [15]. An excellent response to therapy is associated with a low recurrence risk (<5%) in patients with low- or intermediate-risk tumors. For these patients, if the serum thyroglobulin remains low, additional imaging is not indicated. For patients with thyroidectomy and ng/mL on thyroid hormone therapy in a RAI ablation, a low serum thyroglobulin is defined as a level of <0.2 sensitive assay or <1 ng/mL after TSH stimulation in patients who have undergone thyroidectomy and radioiodine ablation [16]. For patients with thyroidectomy or lobectomy but no RAI therapy, a low serum thyroglobulin is defined as a level of <0.2 ng/mL or <30 ng/mL, respectively [37]. However, if the serum thyroglobulin is elevated above the appropriate cutoff or if thyroglobulin antibodies are present and especially if they are rising, additional surveillance imaging is performed (see Variant 7 if there is concern for residual/recurrent disease on this basis).


Thyroid Disease

Thyroid Disease. CT Neck CT is not recommended as the initial imaging study after treatment. See Variant 7 if there is concern for residual/recurrent disease.


Thyroid Disease

Thyroid Disease. MRI Neck MRI is not recommended as the initial imaging study after treatment. See Variant 7 if there is concern for residual/recurrent disease.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body FDG-PET/CT scanning is not recommended for routine surveillance if there is no residual disease.


Thyroid Disease

Thyroid Disease. Whole-Body Scintigraphy If the patient receives RAI therapy, a post-therapy WBS should be performed to evaluate for residual disease. WBS is not utilized in low-risk patients without suspicion for recurrence and normal thyroid US [16]. It has no role in low-risk patients who have had a lobectomy.


Thyroid Disease

Thyroid Disease. In intermediate- and high-risk patients, WBS has a role in evaluating initial response to radioiodine ablation. If there has been excellent response to therapy, WBS is usually not performed for ongoing surveillance. An uptake in the thyroid bed is sometimes performed to aid in detection of local recurrence and guide therapy. Either I-123 or I-131 can be used if a pretherapy scan is desired [16], as rates of successful remnant ablation are similar after I- 123 and I-131 [38,39]. If the choice exists, I-123 has better image quality [40,41]. Note that a post-therapy scan after radioiodine ablation using the radioactivity from the radioiodine ablation is recommended, as it upstages disease in 6% to 13% of cases [42-44].


Thyroid Disease

Thyroid Disease. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen There is no role for Octreotide scan with SPECT or SPECT/CT chest and abdomen at any stage of evaluation of DTC.


Thyroid Disease

Thyroid Disease. Variant 7: Suspected recurrence of differentiated thyroid cancer. Suspected recurrence of DTC may present with a palpable neck abnormality or symptoms related to the organ of distant metastasis. More commonly, there may be no symptoms, but the patient may have a persistently elevated or rising thyroglobulin or rising thyroglobulin antibodies. After imaging, these patients can be categorized as elevated thyroglobulin with structural disease or elevated thyroglobulin with no detectable abnormality on imaging. The latter is thought to be due to small nodal metastases and can remain untreated for years.


Thyroid Disease

Thyroid Disease. The 3 American Thyroid Association risk categories of recurrence help to guide imaging. After initial excellent response, the risk for recurrence is 1% to 2% in low-risk patients, 2% to 4% in intermediate-risk patients, and 14% in high-risk patients [45-47]. In general, more imaging modalities are used to pursue recurrence in high-risk


Thyroid Disease

Thyroid Disease. patients because distant metastases are more likely in these patients and negatively impacts on survival. Recurrence with a structural abnormality can be treated with neck dissection, repeat RAI therapy, external beam radiotherapy, and systemic therapy [16].


Thyroid Disease

Thyroid Disease. US Thyroid US of the neck is the first imaging investigation for suspected DTC recurrence and includes evaluation of the thyroid bed and cervical nodes. It can characterize palpable abnormalities in the neck and detect deeper neck masses that are not palpable [28].


Thyroid Disease

Thyroid Disease. CT Neck CT of the neck complements US of the neck for detection of additional metastases in the central compartment, in the mediastinum, and behind the trachea [29,33,48] or for assessment for invasive recurrent disease into the aerodigestive tract.


Thyroid Disease

Thyroid Disease. CT should be performed with iodinated contrast in order to better assess for tumor vascular encasement and small nodal metastases with hyperenhancement and necrosis. Contrast is not contraindicated for DTC based on new studies on iodine retention [11,12] (see Special Imaging Considerations section above). Dual-phase CT imaging with and without IV contrast does not provide any additional information.


Thyroid Disease

Thyroid Disease. CT Chest CT imaging of the chest should be considered in high-risk DTC patients with elevated serum thyroglobulin (>10 ng/mL) or rising thyroglobulin antibodies with negative imaging studies in the neck. CT chest is favored over MRI chest because it is able to detect small pulmonary metastases [16]. Contrast CT is not necessary for pulmonary metastases but adds to evaluation of metastatic nodes and the thyroid bed.


Thyroid Disease

Thyroid Disease. MRI Neck MRI of the neck and mediastinum has the same role as CT. The performance of MRI for imaging the neck and mediastinum has not been directly compared with CT on large numbers of thyroid cancer patients. MRI has disadvantages of motion artifact in the lower neck from respiration and swallowing and is less sensitive than CT scan for the detection of small pulmonary nodules. Using IV contrast is valuable for detecting recurrence in the surgical bed and assessing suspicious lymph nodes.


Thyroid Disease


Thyroid Disease

Thyroid Disease. Whole-Body Scintigraphy If the US is negative, radioiodine WBS can be performed for suspected recurrence of DTC. WBS may be performed as a first-line investigation in high-risk DTC patients, such as those who initially had macroscopic invasion, gross residual disease, or iodine avid distant metastases. An uptake is sometimes performed to aid in detection of local recurrence and guide dosage of local therapy. I-123 is preferred over I-131 if possible [16], as image quality is higher [40,41].


Thyroid Disease

Thyroid Disease. Variant 8: Suspected recurrence of medullary thyroid cancers. Surveillance for MTC involves monitoring tumor markers, calcitonin, and carcinoembryonic antigen. Imaging of the neck is the preferred initial study. If there is suspicion of recurrence in a body site because of localizing signs or symptoms and elevated tumor markers, the specific body site is imaged. If the patient is asymptomatic, imaging depends on the calcitonin level.


Thyroid Disease

Thyroid Disease

Thyroid Disease. Thyroid Disease


Thyroid Disease

Thyroid Disease. US Thyroid US of the neck is the first imaging investigation for suspected MTC recurrence and includes evaluation of the thyroid bed and cervical nodes. It can characterize palpable abnormalities in the neck and detect deeper neck masses that are not palpable. Imaging with US of the neck alone is generally adequate with calcitonin levels <150 pg/mL, as disease is usually limited to the neck [51]. Overall, per-person sensitivity is similar to CT with much greater specificity for cervical nodes (sensitivity 75% and specificity 92% for US versus sensitivity 80% and specificity 25% for CT) [52], and detection rate is greater than PET (US finds nodes in 56% of patients versus 32% for PET) [53].


Thyroid Disease

Thyroid Disease. CT Neck CT has greater specificity than US for evaluation of cervical nodes (sensitivity 75% and specificity 92% for US versus sensitivity 80% and specificity 25% for CT) [52]. For calcitonin levels >150 pg/mL, the risk of metastases outside the neck is higher. In these patients, imaging is appropriate, starting with neck and chest CT [54]. Dual- phase CT imaging with and without IV contrast does not provide any additional information.


Thyroid Disease

Thyroid Disease. CT Chest For calcitonin levels >150 pg/mL, the risk of metastases outside the neck is higher. CT chest is more sensitive than PET alone for lung nodules (detection rate, 35% for CT versus 20% for PET) and mediastinal nodes (detection rate, 31% for CT versus 20% for PET) [53]. CT should be performed with iodinated contrast in order to better assess for tumor in the surgical bed, vascular encasement, and morphology of small nodal metastases.


Thyroid Disease

Thyroid Disease. CT Abdomen For calcitonin levels >150 pg/mL, the risk of metastases outside the neck is higher. Three-phase contrast CT of the liver is an alternative to MRI [54].


Thyroid Disease

Thyroid Disease. MRI Neck MRI has the same role as CT in evaluating sites that are limited on US. The performance of MRI for imaging the neck and mediastinum has not been directly compared with CT on large numbers of thyroid cancer patients. MRI has disadvantages of motion artifact in the lower neck from respiration and swallowing and is less sensitive than CT scan for the detection of small pulmonary nodules. Using IV contrast is valuable for detecting recurrence in the surgical bed and assessing suspicious lymph nodes.


Thyroid Disease

Thyroid Disease. MRI Abdomen MRI of the abdomen is performed for evaluation of liver metastases, and one study reports that it is more sensitive than CT, US, or PET (with a detection rate of 49% versus 44% for CT, 41% for US, and 27% for PET) [53]. A meta-analysis of CT versus MRI for liver metastases of various origins (not MTC) suggests MRI with liver-specific agents is more sensitive than CT [55]. If MRI is used, diffusion-weighted imaging sequences should be included [56].


Thyroid Disease

Thyroid Disease. MRI Complete Spine MRI of the complete spine may be more sensitive than bone scan for bone metastases (100% versus 72% in one study of patients on immunotherapy) [57]. However, another study concluded they were complementary, with equal overall detection rates but bone scintigraphy having the advantage of detecting additional lesions in the extremities (and MRI in the axial skeleton) [53]. Using IV contrast is valuable for detecting bone lesions in this case.


Thyroid Disease

Thyroid Disease. FDG-PET/CT Whole Body Medullary cancer is challenging to image with nuclear medicine because it lacks the iodine avidity of DTC while still not being aggressive enough to take up FDG in many cases. FDG-PET/CT has suboptimal detection for MTC in most patients, with 59% sensitivity according to a meta-analysis of 25 studies [58]. However, the sensitivity increases to 75% in patients with more aggressive disease, as indicated by calcitonin levels >1,000 pg/mL and with a calcitonin doubling time <12 months [58-60]. In these patients, FDG-PET/CT may be a first-line study or performed after other imaging studies are negative [61,62]. In countries where the tracer FDOPA (3,4-dihydroxy- 6-18F-fluoro-L-phenylalanine) is available, it should be used in place of FDG as it is more sensitive for MTC [63- 65].


Thyroid Disease

Thyroid Disease. Bone Scan Whole Body Bone scan has a role in imaging for patients with symptoms of bone pain with elevated tumor markers and in asymptomatic patients with calcitonin levels >150 pg/mL [16]. There is no conclusive evidence that bone scan performs better than MRI, but it does survey the entire skeleton rather than body regions on MRI.


Thyroid Disease

Thyroid Disease. Octreotide Scan with SPECT or SPECT/CT Chest and Abdomen Octreotide scan with SPECT or SPECT/CT chest and abdomen, radioiodine uptake and WBS, and DOTATATE have no role for imaging of MTC; pentetreotide is insensitive, and MTC cells do not take up iodine [61,62,66].


Thyroid Disease

Thyroid Disease. Whole-Body Scintigraphy WBS has no role in the imaging of MTC, and MTC cells do not uptake iodine [61,62,66].


Thyroid Disease

Thyroid Disease. DOTATATE Skull Base to Mid-Thigh There is some early evidence gallium-68 (Ga-68) DOTATATE is more sensitive than FDG-PET/CT [67], although results are mixed, and the studies may be complementary [68]. In any event, it is more sensitive than pentetreotide [69]. It would not be recommended until further work is done.


Thyroid Disease

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


Thyroid Disease

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


Suspected Appendicitis Child

Suspected Appendicitis Child. Introduction/Background Acute abdominal pain is one of the most common presenting complaints to the emergency department for the pediatric population. While the differential diagnosis for acute abdominal pain in children is broad and includes infectious, inflammatory, musculoskeletal, traumatic, gynecologic, and other etiologies, acute appendicitis is an important differential diagnostic consideration because of the potential need for surgical intervention. Acute appendicitis represents in children [1,2]. Approximately 70,000 children per year in the United States are diagnosed with acute appendicitis, accounting for close to 30% of the total cost of all pediatric general surgical conditions combined [1]. The incidence of appendicitis peaks during adolescence and is uncommon in infants and preschool children and rare in newborns [3].


Suspected Appendicitis Child

Suspected Appendicitis Child. In spite of its high incidence, the diagnosis of acute appendicitis often presents a challenge, as the classic presenting symptoms of periumbilical pain, anorexia, nausea, vomiting, guarding, and migration of pain to the right lower quadrant (RLQ) are not always elicited and are only moderately reproducible between clinicians [4]. Furthermore, these symptoms are less reliable in the pediatric population, particularly those <5 years of age, who more frequently present with atypical symptoms [1]. As a result, presentation and diagnosis may be delayed, which may contribute to a higher rate of perforated appendicitis in the youngest children [5]. While perforated appendicitis tends to be more common in children than adults [6], morbidity is similar to or lower in children than in adults.


Suspected Appendicitis Child

Suspected Appendicitis Child. The most common treatment of appendicitis is appendectomy. In complicated cases of perforated appendicitis with abscess formation, surgery may follow percutaneous abscess drainage and treatment with broad-spectrum antibiotics [2]. Nonoperative treatment of early, uncomplicated appendicitis is increasingly being explored, and imaging plays a role in identifying candidates for nonoperative management [2]. Imaging has been shown to facilitate management and decrease the rate of negative appendectomies in children with suspected acute appendicitis [7-10] and remains a central tool in the diagnosis of pediatric acute appendicitis.


Suspected Appendicitis Child

Suspected Appendicitis Child. Special Imaging Considerations This document aims to provide guidance related to the imaging technique(s) best suited for the diagnosis of acute appendicitis. Importantly, this document does not encompass the appropriate imaging of all potential causes of RLQ quadrant pain. While this guideline emphasizes the role of imaging in the diagnosis of acute appendicitis in children, the initial consideration for imaging is based on clinical assessment. Clinical scoring systems and clinical pathways based upon history, symptoms, physical examination, and laboratory findings have been developed to risk stratify regarding the diagnosis of acute appendicitis and to guide imaging, clinical management, and surgery [11-14]. Two of the more widely used scoring systems are the Alvarado Score and Pediatric Appendicitis Score [13,15]. As primary diagnostic tools, clinical scoring systems have been shown to


Suspected Appendicitis Child

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


Suspected Appendicitis Child

Suspected Appendicitis Child. Reprint requests to: publications@acr.org


Suspected Appendicitis Child

Suspected Appendicitis Child. perform variably well depending on the population and often perform less well than imaging or a combination of scoring and imaging [13,15].


Suspected Appendicitis Child

Suspected Appendicitis Child. The greatest benefit of clinical scoring systems has been to differentiate low-risk patients who do not need surgery and generally do not require imaging from high-risk patients who can be triaged to surgical management, potentially without imaging [16-18]. Imaging should still be considered in cases where clinical judgement is at odds with the high or low risk stratification based on a scoring system. The major role for imaging in the context of clinical scoring systems is in the further evaluation of patients considered to have an intermediate risk of appendicitis [11]. While the specific cut-off values for intermediate risk vary based on the clinical score being used and the desired sensitivity and specificity, the intermediate-risk population is the subgroup that has historical, physical examination, or laboratory findings that do not qualify for either the low- or high-risk groups [13].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Appendix ultrasound (US) is performed in all potential locations of the appendix with gradual increasing pressure to displace overlying bowel gas and content, which is known as the graded compression technique. Graded compression also serves to bring the appendix closer to the transducer. Appendiceal US can be performed as either a focused examination of the RLQ or as a complete abdominal US. For the purpose of this topic, US abdomen includes dedicated appendiceal study. Accuracy of appendix US varies widely, is operator dependent [19], and may be dependent on patient-specific factors, including obesity [20,21]. The sensitivity and specificity of US for the diagnosis of pediatric acute appendicitis and percentage of equivocal cases varies. US accuracy is optimized in experienced hands and can approach that of CT [22-25]. For this document, it is assumed all procedures are performed and interpreted by an expert. In a large series of 3,799 patients with suspected acute appendicitis, Cundy et al [26] showed 92% visualization of the appendix with 95.5% accuracy, 97% sensitivity, and 95% specificity for the diagnosis of acute appendicitis. As an initial imaging modality for suspected acute appendicitis, US has been shown to have high diagnostic accuracy and to reduce or obviate the need for further imaging without increased complications or unacceptable increases in length of stay [22,26-28].


Suspected Appendicitis Child

Suspected Appendicitis Child. An important limitation of US is its low sensitivity in the diagnosis of perforated appendicitis [2]. This should be taken in consideration if nonoperative management is considered.


Suspected Appendicitis Child

Suspected Appendicitis Child. CT CT has high sensitivity (~94%) and specificity (~95%) for the diagnosis of acute appendicitis [29]. If the appendix is not visualized, the negative predictive value is similar to a CT with normal visualized appendix [51]. Studies in both children and adults have allowed optimization of CT technique for the diagnosis of acute appendicitis. There is debate about the usefulness of oral contrast because some studies showed no significant increased accuracy, longer time to examination completion, and increased rates of patient emesis [30-32]. Rectal contrast does not increase accuracy compared to CT with intravenous (IV) contrast only [33].


Suspected Appendicitis Child

Suspected Appendicitis Child. Most CT examinations for appendicitis are performed with standard technique and coverage for imaging the abdomen and pelvis. Some centers have had success decreasing CT exposure parameters without compromising diagnostic performance [34,35] for acute appendicitis. Other retrospective studies in both adult and pediatric populations have shown that a focused CT from L2 or L3 or based on height-adjusted distance from the umbilicus through the pubis symphysis is sufficient to diagnose acute appendicitis and identify most alternative diagnoses [36,37].


Suspected Appendicitis Child

Suspected Appendicitis Child. There are no studies that compare unenhanced and contrast-enhanced CT for diagnosis of acute appendicitis. A limited number of retrospective studies of pediatric cohorts imaged without IV contrast have shown rates of visualization of the appendix similar to CT performed with IV contrast as well as high sensitivity and specificity for the diagnosis of appendicitis [1,2]. Potential limitations of unenhanced CT include decreased sensitivity and incomplete characterization of complicated appendicitis (eg, perforation and abscess formation) and possibly lower sensitivity for alternative diagnoses [38,39].


Suspected Appendicitis Child

Suspected Appendicitis Child. There are no data to suggest that CT with and without IV contrast has better diagnostic performance for acute appendicitis or alternative diagnoses than a single phase (CT with or CT without IV contrast) examination. Furthermore, CT with and without IV contrast approximately doubles radiation exposure to the patient.


Suspected Appendicitis Child

Suspected Appendicitis Child. Radiography Abdomen Most studies have shown that in patients stratified as low risk (which varies per study and is based on the system used), imaging for acute appendicitis is not required, and other causes of abdominopelvic pain should be sought [13,16,17,48-50]. Radiographs may identify alternative causes of pain, such as constipation or lower lobe pneumonia [51].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen RLQ Most studies have shown that in patients stratified as low risk (which varies per study and is based on the system used), imaging for acute appendicitis is not required, and other causes of abdominopelvic pain should be sought [13,16,17,48-50].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen Most studies have shown that in patients stratified as low risk (which varies per study and is based on the system used), imaging for acute appendicitis is not required, and other causes of abdominopelvic pain should be sought [13,16,17,48-50].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Pelvis Most studies have shown that in patients stratified as low risk (which varies per study and is based on the system used), imaging for acute appendicitis is not required, and other causes of abdominopelvic pain should be sought [13,16,17,48-50]. Pelvic US may identify other causes of pain in girls but there are no data regarding its performance as a first-line imaging modality for acute appendicitis [52].


Suspected Appendicitis Child

Suspected Appendicitis Child. CT Abdomen and Pelvis In a retrospective study of children who underwent CT of the abdomen and pelvis for suspected acute appendicitis, Kim et al [50] found that no patient categorized as low risk by the Pediatric Appendicitis Score had a positive CT. Similarly, based on retrospective study of a mixed population of children and adults who underwent CT, McKay and Shepard [53] showed that the Alvarado score could rule out appendicitis in low-risk patients with 96% sensitivity. Alternative causes of abdominopelvic pain, which have been described to occur at rates between 7% and 25%, may be identified by CT [54,55].


Suspected Appendicitis Child

Suspected Appendicitis Child. There are no studies that compare unenhanced and contrast-enhanced CT for diagnosis of acute appendicitis [38,39].


Suspected Appendicitis Child

Suspected Appendicitis Child. MRI Abdomen and Pelvis Most studies have shown that in patients stratified as low risk (which varies per study and is based on the system used), imaging for acute appendicitis is not required, and other causes of abdominopelvic pain should be sought [13,16,17,48-50]. Alternative causes of abdominopelvic pain, which occurred at a rate of 20% in a study of MRI as the primary imaging modality for suspected acute appendicitis, may be identified by MRI [55].


Suspected Appendicitis Child

Suspected Appendicitis Child. Radiography Abdomen Radiographs are neither sensitive nor specific for the diagnosis of acute appendicitis but may identify alternative causes of pain [51].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen There are no specific data regarding the relative performance of a focused RLQ US versus a complete abdominal US in intermediate-risk patients.


Suspected Appendicitis Child

Suspected Appendicitis Child. US Pelvis There are no data specific to the use of pelvic US only in children with intermediate clinical risk for acute appendicitis. Pelvic US may be part of a complete evaluation for abdominopelvic pain in peri- or postmenarchal girls [52].


Suspected Appendicitis Child

Suspected Appendicitis Child. CT Abdomen and Pelvis CT of the abdomen and pelvis has been shown to provide diagnostic benefit in a mixed population of children and adults with intermediate clinical risk for acute appendicitis where the examination had 90% sensitivity and 95% specificity for acute appendicitis [53]. Because CT covers more anatomic territory than a limited RLQ US, it may identify alternative causes of abdominopelvic pain [54,55].


Suspected Appendicitis Child


Suspected Appendicitis Child

Suspected Appendicitis Child. MRI Abdomen and Pelvis Given its high sensitivity and specificity for acute appendicitis, MRI may be indicated in children with an intermediate clinical risk for acute appendicitis [40,41,43]. Similar to CT, the greater anatomic coverage of MRI (versus US) may identify alternative causes of abdominopelvic pain [54,55].


Suspected Appendicitis Child

Suspected Appendicitis Child. Variant 3: Child. Suspected acute appendicitis, high clinical risk. Initial imaging. Risk stratification for acute appendicitis can be achieved based on overall subjective assessment or use of published scoring systems. The patient-specific likelihood of acute appendicitis among patients classified as high risk varies across the range of high-risk scores and varies between published studies [56]. Approaches to high-risk patients vary in the literature, with some studies using imaging to confirm the diagnosis of appendicitis [49] and other studies advocating surgical intervention without imaging based on a demonstrated high accuracy of the scoring system in their practice [13,17,18,48,57].


Suspected Appendicitis Child

Suspected Appendicitis Child. Radiography Abdomen Radiographs are neither sensitive nor specific for a diagnosis of acute appendicitis but may aid in terms of excluding complications of acute appendicitis, such as bowel obstruction or gross perforation [51].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen RLQ There is no evidence to support routine US in all patients considered high risk for acute appendicitis. However, US could be used to confirm the diagnosis of acute appendicitis in this population and to exclude other processes


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen US may be performed in selected high-risk patients to confirm the diagnosis of appendicitis, but US is likely not needed in all high-risk patients, and false-negative results are more common in this population [58].


Suspected Appendicitis Child

Suspected Appendicitis Child. US Pelvis There are no data regarding the performance of pelvic US as a first-line imaging modality for acute appendicitis. In peri- or postmenarchal girls, a pelvic US may identify alternative causes of pelvic pain [52].


Suspected Appendicitis Child

Suspected Appendicitis Child. CT Abdomen and Pelvis There is no evidence to support routine use of CT of the abdomen and pelvis or of focused CT in high-risk patients. Based on high sensitivity and specificity, CT could be used to confirm the diagnosis of acute appendicitis in these patients and to exclude other processes that clinically mimic appendicitis. Tan et al [14] showed that in a population of adult and adolescent patients, the positive likelihood ratio for CT was no different from clinical scoring in patients with a high-risk clinical score, suggesting no diagnostic benefit of CT in this context.


Suspected Appendicitis Child

Suspected Appendicitis Child. MRI Abdomen and Pelvis There is no evidence to support routine use of MRI in high-risk patients. Based on high sensitivity and specificity that is similar to CT, MRI could be used to confirm the diagnosis of acute appendicitis in high-risk patients and to exclude other processes that clinically mimic appendicitis. However, the diagnostic benefit of MRI in this context has not been demonstrated.


Suspected Appendicitis Child

Suspected Appendicitis Child. Variant 4: Child. Suspected acute appendicitis, equivocal or nondiagnostic right lower quadrant ultrasound. Next imaging study. The definition of an equivocal or nondiagnostic US for acute appendicitis varies widely in the literature, and careful definition of this category has major implications on imaging utilization [22,59,60]. Some consider nonvisualization of the appendix as an equivocal result [40,61]. However, in several retrospective studies, an appendiceal US in which the appendix is not visualized and no inflammatory findings are present in the RLQ has high negative predictive value [3,62-64]. In this context, further imaging is unlikely to be contributory unless there is discordance between the clinical picture and the negative US result [65]. Further imaging, however, is contributory after equivocal US examinations in which the appendix is either visualized or not visualized, and there are findings that could reflect appendicitis. In one study, appendicitis was present in 26% of patients who met this criteria [3].


Suspected Appendicitis Child

Suspected Appendicitis Child. While there is good evidence regarding secondary imaging modalities following an equivocal US, there is also evidence of the benefit of repeat clinical assessment in these cases, which can obviate further imaging at the expense of delay in diagnosis and the risk associated with extending the hospital visit [10,66]. Schuh et al [67] in a prospective study found that of 123 patients with an initially equivocal US, acute appendicitis could be correctly ruled out clinically in 59% based on reassessment without further imaging.


Suspected Appendicitis Child

Suspected Appendicitis Child. Radiography Abdomen Given the limited sensitivity and specificity, a radiograph is unlikely to diagnose acute appendicitis in patients with an initial equivocal or nondiagnostic appendiceal US [51]. Radiographs may identify an alternative cause of pain.


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen RLQ Repeating a US examination after an initially equivocal result increases sensitivity for acute appendicitis. Schuh et al [67] showed that repeat US could make a diagnosis in 55% of cases with persistent clinical concern for acute appendicitis after an initially equivocal US. This final diagnosis rate, however, is lower than what has been reported with both CT and MRI.


Suspected Appendicitis Child

Suspected Appendicitis Child. US Abdomen There are no specific data related to whether a repeat focused RLQ US or a completed abdominal US is more effective in the setting of an initial equivocal US.


Suspected Appendicitis Child

Suspected Appendicitis Child. There are no studies that compare unenhanced and contrast-enhanced CT for diagnosis of acute appendicitis [38,39].


Suspected Appendicitis Child

Suspected Appendicitis Child. MRI Abdomen and Pelvis MRI performed following equivocal or nondiagnostic appendix US has similar sensitivity and specificity to CT with 100% sensitivity and 96% specificity demonstrated by Herliczek et al [41,71]. In a clinical pathway with US as the initial modality and MRI for problem solving, Epifanio et al [48] demonstrated MRI to add diagnostic benefit in the small subset of cases that remained indeterminate after US. The overall sensitivity and specificity of the described pathway were 96% and 100%, respectively. Importantly, Aspelund et al [72] showed no difference in clinical outcomes following a shift from CT as the primary imaging modality for acute appendicitis to US with MRI for equivocal cases.