Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . nWisconsin Heart Hospital, Milwaukee, Wisconsin; Nuclear cardiology expert. oJohns Hopkins Medical Institute, Baltimore, Maryland. pSpecialty Chair, UT Southwestern Medical Center, Dallas, Texas. Reprint requests to: publications@acr.org Nonischemic Myocardial Disease treated with chelation therapy; cardiac sarcoidosis is treated with high-dose corticosteroids; cardiac amyloidosis is treated with chemotherapy for light-chain amyloidosis (AL type) and novel therapies for transthyretin type; Fabry disease is treated with enzyme replacement therapy; and severe HCM or endomyocardial fibrosis is treated with surgery [2]. An endomyocardial biopsy may be required for definitive diagnosis in some cases; however, it is an invasive procedure and the yield may be low because of the patchy nature of disease processes. In unexplained cardiomyopathy, the final diagnosis based on biopsy differed from initial diagnosis in 31% of patients, and endomyocardial biopsy made the final diagnosis in 75% of these cases [9]. Imaging is also helpful for quantification of the disease process, risk stratification, prognosis, and monitoring response to therapy. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. Chest Radiography Chest radiography can provide information on HF and vascular abnormalities; however, there is no specific role for radiography in characterizing the different types of NICM. Echocardiography Echocardiography provides information on ventricular function (global/regional, systolic/diastolic), volumes, mass, thickness, as well as valvular function.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . The morphology can be assessed, although it is limited in the evaluation of the right ventricle (RV). With the use of advanced techniques such as 3-D echocardiography, further subtyping of NICM is possible. Myocardial deformation can be evaluated using tissue Doppler imaging and speckle-tracking (2-D or 3-D). Abnormal global longitudinal strain enables detection of subclinical left ventricle (LV) dysfunction in several disease entities [11]. Doppler metrics are useful in evaluation of diastolic dysfunction, especially in restrictive cardiomyopathies and HCM [12]. However, routine echocardiography does not have tissue characterization capabilities. Contrast echocardiography can be used in the quantification of ventricular volumes and EF as well as regional wall motion when the routine images are suboptimal. It is also used in the evaluation of noncompaction, thrombus aneurysm, and apical lesions such as apical variant HCM, stress-induced cardiomyopathy, and endocardial fibroelastosis [13]. Cardiac CT Coronary CTA has a limited role in the evaluation of NICM, predominantly for excluding coronary artery disease (CAD) as the etiology of HF [15]. Cardiac CT can be used in the evaluation of morphology, characterization, and quantification of function in patients when echocardiography is suboptimal because of poor acoustic windows and MRI is suboptimal because of artifacts. The function and volumes obtained from CT correlate with other Nonischemic Myocardial Disease modalities including MRI [16,17]. With retrospective ECG-gated acquisition, dynamic and functional information can be obtained. First-pass myocardial perfusion can be used to evaluate for ischemia. Delayed iodine- enhancement imaging can show variable patterns of enhancement in NICM, albeit at a lower contrast-to-noise ratio compared with MRI.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Similar to MRI, extracellular volume (ECV) can be quantified with CT either using a single- or dual-energy CT technique [18]. CT strain imaging to quantify regional function [19] and CT evaluation of diastolic function are not routinely used in clinical practice [20]. Coronary calcium score is used for risk stratification of CAD in asymptomatic patients and does not have a specific role in evaluation of NICM. Coronary Arteriography Coronary arteriography is used to evaluate CAD as a cause of HF, especially in high-risk patients. Right and left heart catheterizations are useful in pulmonary hypertension, providing cardiac hemodynamics and prognostic value. Right heart and simultaneous right and left heart catheterization is useful in distinguishing restrictive cardiomyopathies from constrictive pericarditis [31]. A ventriculogram can be used to evaluate associated regional wall motion abnormalities (RWMA). Endomyocardial biopsy is used to establish etiology in cases that are indeterminate after imaging. Discussion of Procedures by Variant Variant 1: Suspected hypertrophic cardiomyopathy. Ischemic cardiomyopathy already excluded. Initial imaging. HCM is an inherited myocardial hypertrophy with heterogeneous phenotypic expression (asymmetric septal, apical, mid ventricular, lateral wall, mass-like, and concentric types) [32]. Patients with HCM can present with diastolic dysfunction, LV outflow tract (LVOT) obstruction, ischemic chest pain, arrhythmias, or sudden cardiac death [33]. Occasionally, clinical symptoms are produced by papillary muscle abnormalities (anomalous chordal attachment to the base of anterior leaflet, double bifid muscles, apical displacement, hypermobility, elongated anterior mitral leaflet) without significant myocardial hypertrophy [34]. Asymptomatic family members of HCM often undergo imaging as a screening test.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Arteriography Coronary There is no relevant literature to support the use of coronary arteriography for the evaluation of HCM. Arteriography Coronary with Ventriculography There is no relevant literature to support the use of coronary arteriography with ventriculography for the evaluation of HCM. CT Chest There is no relevant literature to support the use of CT chest for the evaluation of HCM. CT Coronary Calcium There is no relevant literature to support the use of CT coronary calcium for the evaluation of HCM. CT Heart Function and Morphology Cardiac CT can be used in the evaluation of morphology and function in patients with suboptimal echocardiography. CT can provide accurate measurements of myocardial thickness. Myocardial fibrosis can be demonstrated and quantified in delayed-enhancement images with substantial agreement with MRI [36-38]. CTA Coronary There is no relevant literature to support the use of CTA in the evaluation of HCM when ischemic cardiomyopathy has already been excluded. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart for the evaluation of HCM. MRI Chest There is no relevant literature to support the use of MRI chest for the evaluation of HCM. MRI Heart Function and Morphology MRI provides comprehensive information for the evaluation of HCM, including the morphology, location, distribution, and extent of hypertrophy and fibrosis [39]. MRI is superior to echocardiography in recognizing areas of segmental hypertrophy, which may be missed or underestimated with echocardiography, particularly the LV apex, the RV anterior free wall, and the LV inferoseptum [39,40]. RV hypertrophy is seen in a third of Nonischemic Myocardial Disease patients [40]. MRI is more accurate than echocardiography in quantifying the myocardial thickness, which is an important prognostic indicator for myectomy [39].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . LVOT obstruction (seen in one-third of patients with HCM and provocable in another third), systolic anterior motion of the mitral valve and mitral regurgitation may be seen in asymmetric basal septal type of HCM [33], although the quantification of flow acceleration due to LVOT obstruction is inferior when using MRI compared with echocardiography. MRI also helps in risk stratification and identification of patients who will benefit from primary prevention with ICD, primarily by the use of LGE. LGE is seen in up to 50% to 80% of HCM patients, with the extent of LGE correlating directly with adverse prognosis [39]. HCM patients with LGE have a 7-fold risk for nonsustained ventricular tachycardia, and extensive LGE >15% of LV mass is a marker for sudden death [39]. Apical aneurysm and massive hypertrophy >30 mm are also high-risk factors for sudden cardiac death [39]. Elevated native T1 and ECV measurements may be seen in HCM. One study showed that native T1 has 100% sensitivity, 96% specificity, and 98% accuracy in distinguishing healthy from diseased myocardium, including HCM [41,42]. Another advantage of MRI is its ability to evaluate papillary muscle abnormalities, which require different surgical management [34,43]. MRI is also useful in follow-up after treatment such as myectomy or septal ablation. MRI is used to screen family members with myocardial crypts, elongated mitral leaflets, delayed relaxation, high EF, and LGE seen in gene-positive, phenotype-negative patients [40]. Anderson-Fabry disease presents with concentric LV thickening but may occasionally be asymmetric. Mid myocardial or subepicardial LGE is seen in the basal inferolateral segment of the LV, unlike HCM, wherein LGE is seen anywhere. There is no systolic anterior motion of the mitral valve or LVOT obstruction in Anderson-Fabry disease [35].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Low native T1 values are seen in Fabry disease because of sphingolipid deposition, often prior to the onset of structural and functional abnormalities [44]. With development of fibrosis, long native T1 and elevated ECV values can be seen. High T2 values, RV involvement, valve thickening, and lower global longitudinal strain can also be seen [45]. Danon disease also shows concentric LV thickening with edema and stress perfusion defect. LGE is usually in a mid myocardial distribution, less often in a subendocardial and transmural pattern in anterolateral and inferior segments of the LV, often with sparing of septum [46,47]. MRI Heart Inotropic Stress There is no relevant literature to support the use of MRI heart inotropic stress for the evaluation of HCM. MRI Heart Vasodilator Stress Reduced myocardial perfusion due to microvascular dysfunction is a poor prognostic factor in HCM. This may be seen even in areas without LGE, both in adults and children [48,49]. There is no evidence to support the use of MRI heart vasodilator stress for the evaluation of HCM when ischemic cardiomyopathy has already been excluded. Echocardiography Transesophageal There is no relevant literature to support the use of transesophageal echocardiography for the evaluation of HCM. Echocardiography Transthoracic Resting Echocardiography is usually the initial imaging test in most patients with HCM. It is used in the evaluation of morphology, distribution, and quantification of HCM. Contrast echocardiography improves characterization of apical type of HCM [50]. Echocardiography is the preferred technique for the quantification of LVOT pressure gradient, which is a factor in selecting patients for myomectomy, as well as the assessment of systolic anterior motion, mitral regurgitation, and papillary muscle abnormalities. It can quantify LV systolic function, diastolic function, and left atrial volume.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Decreased myocardial strain can be identified using speckle-tracking echocardiography [50]. Stress maneuvers, including a Valsalva maneuver in sitting, semisupine, and standing Nonischemic Myocardial Disease positions can be used to provoke LVOT gradients that may not be seen in resting states [51]. It is also the first- line test for screening, such as in the risk assessment of sudden cardiac death in competitive athletes [50]. Echocardiography Transthoracic Stress Exercise stress echo is used to assess provocable LVOT gradient if resting gradient is not severe. It is also useful in the assessment of worsening mitral regurgitation [51]. Variant 2: Suspected restrictive cardiomyopathy or infiltrative disease. Ischemic cardiomyopathy already excluded. Initial imaging. Infiltrative disease is characterized by deposition of abnormal substances in the myocardium, resulting in myocardial thickening or dilation and restricted ventricular filling. Amyloidosis, Anderson-Fabry disease, acute sarcoidosis, Danon disease, endomyocardial fibrosis, oxalosis, mucopolysaccharidoses, and Friedrich ataxia result in myocardial thickening, whereas chronic sarcoidosis, scleroderma, and iron overload result in myocardial thinning [52]. Cardiac amyloidosis is usually of AL type or transthyretin-related amyloidosis (ATTR type), resulting in myocardial and valvular thickening and presenting with HF or arrhythmia. Myocardial involvement occurs in 25% of patients with systemic sarcoidosis in the United States [53]. Cardiac sarcoidosis is characterized by myocardial infiltration with noncaseating granulomas and presents with conduction abnormalities, arrhythmias, sudden cardiac death, HF, pericardial effusion, or ventricular aneurysms [2]. Diagnosis is based on the Japanese Ministry of Health and Welfare guidelines [54] or expert consensus recommendations [55].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Siderotic cardiomyopathy is characterized by iron deposition from frequent blood transfusions and altered iron hemostasis in hemoglobinopathy patients. Siderotic cardiomyopathy presents in advanced stages with HF, conduction abnormalities, or sudden death [2]. Scleroderma involves the heart in 80% (in autopsy) of cases, manifesting as HF, arrhythmia, CAD, peripheral vascular disease, or sudden death [2]. Endomyocardial fibrosis (Loeffler endocarditis in nontropical regions) is a spectrum of hyperesoinophlic syndrome (eosinophils >1,500/mm3; >6 months), with cardiac involvement seen in 50% of these patients [56]. There is an early necrotic phase followed by thrombotic and fibrotic phases. Myocardial oxalosis presents with LV thickening, heart block, and conduction abnormalities. Friedreich ataxia is characterized by mitochondrial iron accumulation, with cardiomyopathy seen in 63% of these patients [52]. Mucopolysaccharidoses has variable phenotypic expression. Infiltrative disease is generally evaluated with history, clinical examination, ECG, serology, and imaging tests [52]. Endomyocardial biopsy may be ultimately required for definitive diagnosis. Arteriography Coronary There is no relevant literature to support the use of coronary arteriography for the evaluation of restrictive cardiomyopathy. Arteriography Coronary with Ventriculography There is no relevant literature to support the use of coronary arteriography with ventriculography for infiltrative cardiac diseases. Right heart catheterization is used for the evaluation of hemodynamics, which is useful in the diagnosis of pulmonary hypertension and has prognostic value. In addition, right and left heart catheterization can be used to evaluate for constrictive pericarditis, which often has to be distinguished from restrictive cardiomyopathy. CT Chest There is no relevant literature to support the use of CT chest for evaluation of restrictive cardiomyopathy.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . CT chest may show mediastinal lymphadenopathy and lung changes in systemic sarcoidosis. Pericardial calcification points toward a pericardial constriction rather than restrictive cardiomyopathy. CT Coronary Calcium There is no relevant literature to support the use of CT coronary calcium for the evaluation of restrictive cardiomyopathy. Incidental pericardial calcification points toward a pericardial constriction rather than restrictive cardiomyopathy. CT Heart Function and Morphology Abnormal first-pass perfusion, delayed iodine enhancement, and high ECV values have been shown with CT in cardiac amyloidosis [57,58]. Subepicardial or mid myocardial delayed iodine enhancement has also been shown to identify cardiac sarcoidosis [59]. Pericardial calcification points toward a pericardial constriction rather than restrictive cardiomyopathy. Nonischemic Myocardial Disease CTA Coronary There is no relevant literature to support the use of coronary CTA for the evaluation of restrictive cardiomyopathy when ischemic cardiomyopathy has already been excluded. Nuclear Medicine Tc-DPD and Tc-PYP have high specificity in the diagnosis of cardiac amyloidosis. Ga-67 scintigraphy shows high uptake in cardiac sarcoidosis, with the intensity correlating with degree of inflammation [55]; however, it has low sensitivity [55]. Perfusion defects seen in thallium-201 and Tc-99m myocardial scintigraphy, as well as Rb- 82, can be distinguished from ischemia by using PET/CT [55]. FDG-PET/CT Heart FDG-PET performed after suppressing normal glucose metabolism shows high uptake in cardiac sarcoidosis, with reverse distribution in thallium-201 scans. FDG-PET had an 82% to 100% specificity and 39% to 91% specificity in the diagnosis of cardiac sarcoidosis [54]. FDG has higher sensitivity than Ga-67 scintigraphy, although Ga-67 scintigraphy is included in the imaging criteria [54].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . A meta-analysis showed 89% sensitivity, 78% specificity, and area under the receiver operator characteristic curve of 93% for diagnosis of cardiac sarcoidosis [60]. The FDG activity can be quantified to improve the diagnostic accuracy, assess disease activity, and evaluate prognosis [60]. Simultaneous PET/MRI has been shown to be feasible with diagnostic image quality to evaluate cardiac sarcoidosis [61]. MRI Chest There is no relevant literature to support the use of MRI chest for the evaluation of restrictive cardiomyopathy. MRI chest may show mediastinal lymphadenopathy and lung changes in systemic sarcoidosis. MRI Heart Function and Morphology MRI has distinctive appearances in several infiltrative disorders and restrictive cardiomyopathies. Cardiac amyloidosis produces concentric thickening of ventricles, atria, interatrial septum, and valves, with low signal in T2-weighted images [62]. Diffuse subendocardial LGE is seen in early stages, which progresses to transmural LGE. Abnormal LGE has a pooled specificity of 92% and sensitivity of 85% in the diagnosis of cardiac amyloidosis [63]. Dark blood pool and earlier nulling of myocardium is also seen in cardiac amyloidosis. High native T1 and ECV values are more sensitive than LGE and reliably distinguish amyloidosis from HCM [64]. MRI can distinguish AL and ATTR types, with ATTR amyloidosis showing more LV thickening and mass, lower left ventricular ejection fraction (LVEF), greater LGE, more transmural LGE, and lower T1 values than the AL type [64]. An LGE-based scoring system was shown to have 87% sensitivity and 96% specificity in distinguishing AL and ATTR amyloidosis [64]. LGE, T1, and ECV abnormalities all correlate with prognosis in cardiac amyloidosis [65]. Transmural LGE is a predictor of adverse events including death [66]. Postcontrast difference in T1 between subepicardium and subendocardium of >23 ms predicts mortality with high accuracy [67].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Low T2 value and short T1 in >50% of myocardium T1 scout image are also poor prognostic factors [2]. MRI has sensitivity of 75% to 100% and specificity of 75% to 77% in the diagnosis of cardiac sarcoidosis [54,68,69]. In the acute stage, MRI shows wall thickening, high T2 signal (due to edema), high native T1 and T2 values, RWMA, and LGE. LGE is more common in the basal septal and lateral walls of the LV in a subepicardial or mid myocardial distribution. In the chronic stage, wall thinning, aneurysms, RWMA, and LGE may be seen (mid myocardial, subepicardial, and/or transmural) [70]. LGE correlates with prognosis with a hazard ratio of 32 for lethal events [71]. There is a good response to steroids in patients with lower LGE at initiation of therapy [72]. High native T1 and T2 values provide higher discriminatory accuracy compared with traditional criteria and help in evaluating the response to treatment [73]. Myocardial iron deposition can be reliably quantified using T2* techniques. Myocardial T2* <20 ms indicates significant iron deposition and <10 ms indicates advanced iron deposition with high accuracy [74]. T1-mapping is more reproducible and sensitive, with low T1 values seen in 32% of patients with normal T2* [75]. With appropriate use of chelation therapy, improvements in T2* and LVEF has been reported [76]. The use of MRI has resulted in improved outcomes with death rates declining to 2.3 per 1,000 compared with 7.9 per 1,000 prior to the use of MRI [76]. Linear mid myocardial LGE is seen in 66% of patients with scleroderma, either in the ventricular septum or the LV free wall at the basal and mid levels [77]. Patchy RV insertion enhancement can be seen in 17% of patients (76). LGE is more severe in patients with longer duration of Raynaud disease [78]. High native T1 and ECV values are seen in asymptomatic patients with no known cardiac involvement, due to inflammation, and are


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Nonischemic Myocardial Disease associated with low diastolic and systolic strain rates [78]. Focal edema and fibrosis are also seen. Pericarditis, pericardial effusion, and adhesions may be seen. In endomyocardial fibrosis, the apical wall is thickened and has a high T2 signal. A characteristic 3-layered pattern of LGE is seen with an inner layer of dark nonenhancing thrombus, middle layer of subendocardial LGE due to diffuse fibrosis (from LVOT to apex), and outer layer of nonenhancing normal myocardium [56,79]. LGE was associated with poor functional class and higher chance of surgery [56]. In Churg Strauss syndrome, LGE is seen in apical and mid segments and in anterior and anteroseptal segments in a subendocardial distribution. In myocardial oxalosis, concentric LV thickening and diastolic dysfunction are seen. In Friedreich ataxia, concentric or asymmetric LV thickening, diastolic dysfunction, and fibrosis may be seen. Mucopolysaccharidoses have variable expression, including asymmetric septal thickening, mitral or aortic valve pathologies, and normal EF [52]. MRI Heart Inotropic Stress There is no relevant literature to support the use of MRI heart inotropic stress for the evaluation of restrictive cardiomyopathy. Ischemia has already been excluded. MRI Heart Vasodilator Stress There is no relevant literature to support the use of MRI heart vasodilator stress for the evaluation of restrictive cardiomyopathy. Ischemia has already been excluded. Echocardiography Transesophageal There is no relevant literature to support the use of transesophageal echo for the evaluation of restrictive cardiomyopathy. Echocardiography Transthoracic Resting Echocardiography is often the initial imaging test that identifies possible restrictive cardiomyopathy. Echocardiography can evaluate diastolic function with high accuracy, which is often impaired in early stages of several restrictive cardiomyopathies.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Decreased systolic and diastolic mitral annular velocities, restrictive pattern in mitral valve such as high velocity (E wave), short deceleration time and low late diastolic filling (A wave), and elevated filling pressures (E/e ratio) are seen [12,80]. Before the widespread use of harmonic imaging, the myocardium was described as having a characteristic speckled (starry sky) appearance [64], a finding now considered obsolete with the widespread use of harmonic imaging techniques. A relative apical sparing of longitudinal strain of 1.0 (average apical longitudinal strain/average of basal and mid longitudinal strain) has a high sensitivity (93%) and specificity (82%) in distinguishing cardiac amyloidosis from controls [81]. Apical thickening may be seen in endomyocardial fibrosis. In sarcoidosis, echocardiography shows ventricular septal thickening and diastolic dysfunction in the acute phase but thinning in the chronic phase with associated RWMA, aneurysm, and global systolic dysfunction [55]. Echocardiography Transthoracic Stress There is no relevant literature to support the use of echocardiography transthoracic stress for the evaluation of restrictive cardiomyopathy. Ischemia has already been excluded. Variant 3: Suspected nonischemic dilated and unclassified cardiomyopathy. Ischemic cardiomyopathy already excluded. Initial imaging. DCM is characterized by a dilated ventricle and global systolic dysfunction. Ischemia is the most common cause of DCM and is excluded as discussed above. Approximately 50% of nonischemic DCM is idiopathic and is usually seen in a younger age group [2]. Other etiologies include toxins, familial inheritance, infections, infiltrative disorders, autoimmune conditions, metabolic derangements, and arrhythmias. Alcoholic cardiomyopathy is seen in heavy drinkers with probable genetic susceptibility, more common in men 30 to 55 years of age [2,82].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Chemotherapeutic agents such as anthracyclines, tyrosine kinase inhibitors, trastuzumab, and interferons induce cardiomyopathy. There is a higher risk for cardiomyopathy with higher cumulative dose of chemotherapy, combination with other chemotherapeutic agents, associated radiation, and higher age. Acute cardiac changes can be seen as early as in a few hours after initiation, whereas late changes may be seen over decades with LV dilation and EF decrease, which limits the aggressive use of chemotherapy [83]. Peripartum cardiomyopathy is an idiopathic cardiomyopathy seen either in the late stage of pregnancy or in the first 5 months after delivery [84]. It is seen in 1 in 2,500 to 4,000 births in the United States [84]. Risk factors for peripartum cardiomyopathy include age >30 years, nonwhite background, multiparity, poor socioeconomic status, Nonischemic Myocardial Disease prolonged tocolytic therapy, hypertension, preeclampsia, and cocaine use [85]. These patients are evaluated with ECG, serological biomarkers, and imaging tests. Endomyocardial biopsy may be needed to exclude myocarditis. Several types of inherited muscular dystrophies can also produce DCM. These muscular dystrophies present with HF, arrhythmia, or sudden death by thromboembolism. There are several unclassified NICMs. LV noncompaction is characterized by prominent trabeculations due to persistent embryonic sinusoids, leading to LV failure, thromboembolism, and arrhythmias [86]. Stress-induced cardiomyopathy (also known as Takotsubo cardiomyopathy) is characterized by transient LV systolic dysfunction attributed to catecholamine release, possibly following a stressful event. It presents similarly to acute myocardial infarction with chest pain, ST-segment elevation on ECG, and elevated cardiac enzymes. It accounts for 2% of myocardial infarction with nonobstructive coronary arteries (MINOCA) [87].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . One study found that incidental CAD was found in 10% of patients with stress-induced cardiomyopathy [88]. Diagnosis is made based on the Mayo Clinic or InterTAK diagnostic criteria [89]. LVOT obstruction, arrhythmia, shock, ventricular rupture, thrombus, and death may also be seen [2]. Cardiomyopathy can be seen in cirrhotic patients, independent of alcohol exposure. Patients with DCM are evaluated with history, clinical examination, lab tests, ECG, coronary angiography, and imaging. Arteriography Coronary There is no literature to support the use of coronary arteriography for the evaluation of nonischemic dilated or unclassified cardiomyopathy when ischemia has already been excluded. Stress-induced cardiomyopathy has been reported to be triggered by acute myocardial ischemia [90]. Arteriography Coronary with Ventriculography There is no relevant literature to support the use of coronary arteriography with ventriculography for the evaluation of nonischemic dilated or unclassified cardiomyopathy when ischemia has already been excluded. If performed, RWMA not explained by a culprit lesion may be seen in left ventriculography [90]. With LV apical ballooning patterns and normal coronaries on CTA or coronary angiography, stress-induced cardiomyopathy can be confirmed, except in patients with red flags for acute myocarditis, in which MRI is indicated. CT Chest There is no relevant literature to support the use of CT chest for the evaluation of nonischemic dilated or unclassified cardiomyopathy. CT Coronary Calcium There is no relevant literature to support the use of CT coronary calcium for the evaluation of nonischemic DCM or unclassified cardiomyopathy. CT Heart Function and Morphology CT can be used for morphological and functional evaluation in patients in whom echocardiogram is suboptimal. CT is accurate in distinguishing idiopathic from ischemic DCM [91].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . CT has been shown to be accurate in the diagnosis and characterization of LV noncompaction using the standard MRI criteria of end-diastolic noncompacted LV myocardial thickness to compacted LV myocardial thickness ratio of >2.3 [92]. CT can show the abnormalities of stress-induced cardiomyopathy, including absence of delayed enhancement [93,94]. CTA Coronary There is no relevant literature to support the use of CTA coronary for the evaluation of nonischemic DCM or unclassified cardiomyopathy when ischemic cardiomyopathy has already been excluded. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT as the first-line imaging modality in the evaluation of nonischemic or unclassified cardiomyopathy. One study found that nearly 50% of patients with unexplained cardiomyopathy and arrhythmia demonstrate focal inflammation in FDG-PET/CT, which is indicative of inflammatory cardiomyopathy [96]. Nonischemic Myocardial Disease MRI Chest There is no relevant literature to support the use of MRI chest for the evaluation of nonischemic DCM or unclassified cardiomyopathy. MRI Heart Function and Morphology In DCM, MRI helps in establishing the etiology and quantifying the abnormalities. Dilated ventricles, secondary tricuspid and/or mitral regurgitation due to annular dilation, regional ventricular dysfunction, ventricular wall thinning, and eccentric remodeling are seen. Myocardial infarct is diagnosed if there is subendocardial or transmural pattern of LGE in a vascular distribution. In idiopathic DCM with nonobstructed coronary arteries, linear or patchy mid myocardial LGE, primarily at the base and mid septum, is seen in 28% of patients. No LGE is seen in 59%. Subendocardial LGE is seen in 13% of these patients that is either due to atypical nonischemic fibrosis or silent ischemia from coronary embolus or recanalized plaque rupture [97].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Using LGE, 19% of additional patients gained an indication for ICD, and 11% avoided a previously planned ICD compared with standard of care [98]. High T1 and ECV values show more sensitivity than LGE [68]. Native T1 value, ECV value, presence and extent of LGE, and EF correlate with adverse prognosis [99]. In chemotherapy cardiomyopathy, MRI helps in arbitrating discrepancies between imaging modalities, which may affect management. A reduction of EF by >10% or a reduction of EF >5% in symptomatic individuals is diagnostic of this entity (as long as the resultant EF is <53%) [83,100]. Early markers of cardiac involvement include elevated LV end-systolic volume (seen within 1 month); increased LV mass (due to edema); RWMA (decreased mid wall circumferential strain); high T1, T2, and ECV values; high signal in T2-weighted images (edema); and EGE [83]. Patients with edema are more likely to have right ventricular ejection fraction (RVEF) reduction at follow-up [100]. LGE can be seen in 0% to 100% of patients, either in mid myocardial or subepicardial distribution and rarely diffuse, indicating irreversible damage [101]. In late-onset cardiomyopathy in cancer survivors, abnormal or subnormal LVEF and RVEF, as well as high LV volumes without LGE, were seen at a median of 7.8 years after anthracycline therapy [102]. Increased ECV has been shown in cancer survivors [100]. LGE has been shown in 9% to 18% in mid myocardial, subepicardial, or RV insertion point distributions [101]. In peripartum cardiomyopathy, MRI provides additional information pertaining to diagnosis and prognosis, which are not obtained in echocardiography. Gadolinium contrast is avoided until after delivery. LV dilation, global LV systolic dysfunction, RV dysfunction, and LGE are seen [84].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . LGE is seen in 40% in a subepicardial or mid myocardial distribution in the anterior and anterolateral LV segments (occasionally subendocardial or transmural), more commonly in scans taken >7 days after the acute phase [84]. High T1 and T2 values and EGE are also seen in the acute stages [103]. Patients with LGE showed higher decompensation and did not regain LVEF [84]. Muscular dystrophies may present with ventricular dilation, and mid myocardial/subepicardial pattern of LGE, with occasional noncompacted myocardium. LGE may be present when echocardiography is still normal [104] and is an adverse prognostic determinant [84]. A higher amount of LGE is associated with lower LVEF, but LGE has a variable association with arrhythmia [104]. With longer duration of steroid treatment, lower increase in fibrosis burden was seen over time [105]. T1 and ECV values are also abnormal, which were associated with arrhythmia. Strain imaging shows abnormalities in earlier stages, before onset of overt HF, shows better serial decline in LV function, and provides reliable monitoring of progression of dystrophy [106]. LGE is also seen in mutation carriers [104]. Nonischemic Myocardial Disease used MRI diagnostic criteria for noncompaction, indicating that these criteria have poor specificity. This may, therefore, represent a variant anatomical phenotype than cardiomyopathy [112,113]. MRI in stress-induced cardiomyopathy shows reversible global systolic dysfunction and LV apical ballooning with normal or hyperkinetic basal segments and akinetic/hypokinetic apical segments. There are also reverse and mid ventricular variants. RV is involved in 40% of cases, which is associated with a worse prognosis [114]. Myocardial edema may be present, leading to a high signal in T2-weighted images, high native T1, and high T2 values, typically confined to the abnormal segment [115].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Edema diffuses more than myocardial ischemia and decreases within a few weeks unlike myocardial ischemia, which may take up to 3 months to diminish [115]. Typically, there is no LGE. However, recent studies have shown that LGE may be present in up to 40% of patients, typically in the areas of RWMA. This is usually of lower signal intensity (<5 SD above remote normal myocardium) than the LGE of myocardial infarction [87]. These patients may have irreversible damage with worse prognosis and longer recovery time [116,117]. MR diagnosis of stress-induced cardiomyopathy is made based on a typical pattern of LV dysfunction in a noncoronary pattern, myocardial edema corresponding to areas with RWMA, absence or insignificant LGE (<5 SD above remote normal myocardium), and markers for myocardial inflammation (EGE ratio > 4.0) [114]. MRI is superior to echocardiography in evaluating the RV involvement and complications [114]. Functional improvement occurs usually in 3 to 4 months but may take up to 12 months in 5% of patients; it may recur in 5% to 11% of patients [87]. Although stress-induced cardiomyopathy was typically thought to be completely reversible, recent literature indicates long-term clinical consequences [118]. MRI Heart Inotropic Stress There is no relevant literature to support the use of MRI heart inotropic stress for the evaluation of nonischemic DCM or unclassified cardiomyopathy when ischemia has already been excluded. MRI Heart Vasodilator Stress There is no relevant literature to support the use of MRI vasodilator stress for the evaluation of nonischemic DCM or unclassified cardiomyopathy when ischemia has already been excluded. Echocardiography Transesophageal There is no relevant literature to support the use of transesophageal echocardiography for the evaluation of nonischemic DCM or unclassified cardiomyopathy.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Echocardiography Transthoracic Resting Echocardiography can evaluate the function in several types of nonischemic DCM. It does not provide tissue characterization to identify the specific cause of cardiomyopathy, but the presence of systolic dysfunction in patients on chemotherapy, postpartum, and alcoholic patients is suggestive of cardiomyopathy. In chemotherapy, a reduction of EF by >10% or a reduction of EF >5% in symptomatic individuals is diagnostic of this entity (as long as the resultant EF is <53%). Calculation of LVEF by 3-D echocardiography is more reproducible and accurate than by 2-D echocardiography and is preferred for the evaluation and longitudinal assessment of patients treated with chemotherapy [100]. A 10% to 15% reduction of peak systolic global longitudinal strain by speckle-tracking echocardiography is the most useful parameter to predict cardiotoxicity [119]. Global radial and circumferential strains are abnormal in late survivors, but their clinical value is less proven [119]. Decreased global longitudinal strain with preserved EF is the most common echocardiographic abnormality in cancer survivors [100]. Echocardiography can confirm, quantify, and detect associated abnormalities and complications, as well as risk stratify patients [120]. In LV noncompaction, echocardiography shows a 2-layered structure with prominent LV trabeculations (end- systolic ratio >2) and deep perfused intertrabecular recesses in color Doppler [86,121]. The sensitivity and reproducibility of echocardiography is improved by using LV contrast [122]. LV strain is decreased in noncompacted as well as compacted segments [122]. Transient reversible global systolic dysfunction as well as RWMA (apical, mid ventricular, basal, or focal in anterolateral segment) are seen in stress-induced cardiomyopathy [95].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Wall motion abnormalities show circular pattern in speckle echocardiography with improved detection using IV contrast [95]. Echocardiography Transthoracic Stress There is no relevant literature to support the use of echocardiography transthoracic stress for the evaluation of nonischemic DCM or idiopathic cardiomyopathy when ischemia has already been excluded. Arteriography Coronary There is no relevant literature to support the use of coronary arteriography for the evaluation of arrhythmogenic cardiomyopathies. Arteriography Coronary with Ventriculography Imaging is initially performed with noninvasive tests such as MRI or CT. However, the 2010 criteria specifies RV angiographic criteria for ARVD, including regional RV akinesia, RV dyskinesia, or RV aneurysm [123]. CT Chest There is no relevant literature to support the use of CT chest for the evaluation of arrhythmogenic cardiomyopathies. CT Coronary Calcium There is no relevant literature to support the use of CT coronary calcium for the evaluation of arrhythmogenic cardiomyopathies. CT Heart Function and Morphology ECG-gated cardiac CT shows wall motion abnormalities and allows quantification of ventricular volumes and function. RV myocardial fat may be seen but is nonspecific. A single study showed that a CT-based scoring system based on fatty tissue, bulging appearance, and dilation of RV had 87% sensitivity, 94.4% specificity, positive predictive value of 87%, negative predictive value of 94.4%, and accuracy of 92.2% for diagnosis of definitive ARVD [127]. CTA Coronary There is no relevant literature to support the use of coronary CTA for the evaluation of arrhythmogenic cardiomyopathies. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT for the evaluation of arrhythmogenic cardiomyopathies. MRI Chest There is no relevant literature to support the use of MRI chest for the evaluation of arrhythmogenic cardiomyopathies.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . MRI Heart Inotropic Stress There is no relevant literature to support the use of MRI heart inotropic for the evaluation of arrhythmogenic cardiomyopathies. MRI Heart Vasodilator Stress There is no relevant literature to support the use of MRI heart vasodilator stress for the evaluation of arrhythmogenic cardiomyopathies. Echocardiography Transesophageal There is no relevant literature to support the use of transesophageal echocardiography for the evaluation of arrhythmogenic cardiomyopathies. Echocardiography Transthoracic Stress There is no relevant literature to support the use of echocardiographic transthoracic stress for the evaluation of arrhythmogenic cardiomyopathies. Variant 5: Suspected inflammatory cardiomyopathy. Ischemic cardiomyopathy already excluded. Initial imaging. Inflammatory myocardial disease can present either in acute or subacute fashion. Acute myocarditis is due to infections (viral, bacterial, fungal, or tuberculosis), toxins, drugs, injuries, or idiopathic etiology. It can present with acute chest pain, elevated cardiac enzymes, and ECG changes that may mimic acute coronary syndrome (MINOCA). Other presentations include LV dysfunction, arrhythmias, and sudden cardiac death. Acute myocarditis accounts for up to 75% of patients who present with MINOCA, 12% of those with sudden death, and 9% of DCM [132]. Patients may recover or progress to DCM. Sarcoidosis may occasionally present in an acute fashion similar to acute myocarditis. Myocarditis can also be seen in rheumatological diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis [133]. Chagas diseases are caused by a parasite, Trypanosoma cruzi, which is endemic in Central and South America, with 13% of the population at risk and 11% affected [134].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Chagas disease has an acute, a long indeterminate, and a chronic cardiac phase, with one-third of seropositive individuals developing chronic heart disease [135]. Cardiac Chagas presents as HF, arrhythmia, heart block, sudden death, and thromboembolic events [2]. Human immunodeficiency virus can cause cardiomyopathy in 8% of asymptomatic individuals [2]. There is no single test that can accurately diagnose inflammatory cardiomyopathy are evaluated using history, clinical examination, serology, ECG, and noninvasive imaging tests. Nonischemic Myocardial Disease Endomyocardial biopsy with histopathology, immunohistology, and molecular techniques may be necessary for diagnosis. Arteriography Coronary There is no relevant literature to support the use of coronary arteriography for the evaluation of inflammatory myocardial disorders when ischemia has already been excluded. Arteriography Coronary with Ventriculography There is no relevant literature to support the use of coronary arteriography for the evaluation of inflammatory myocardial disorders. CT Chest There is no relevant literature to support the use of CT chest for the evaluation of inflammatory myocardial disorders. CT Coronary Calcium There is no relevant literature to support the use of CT coronary calcium for the evaluation of inflammatory myocardial disorders. CT Heart Function and Morphology CT has been shown to display focal or multifocal enhancement and absence of coronary stenosis correlating with MRI [136]. CTA Coronary There is no relevant literature to support the use of CTA coronary arteries for the evaluation of inflammatory myocardial disorders. FDG-PET/CT Heart FDG-PET/CT may be useful in the evaluation of inflammatory cardiomyopathies, particularly in the evaluation of acute presentation of cardiac sarcoidosis [54,60]. FDG-PET/CT is not commonly used in the diagnosis of myocarditis. However, if performed, high uptake may be seen in FDG-PET/CT.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . In 111-antimyosin antibody can be used to identify myocarditis [14]. MRI Chest There is no relevant literature to support the use of MRI chest for the evaluation of inflammatory myocardial disorders. MRI Heart Function and Morphology In acute myocarditis, MRI is performed in patients with symptoms of myocarditis, evidence of myocardial injury, and suspected viral etiology. MRI has been shown to have an impact on making a decision in >50% of patients and provides a new diagnosis in 11% of patients [115]. One study showed that using MRI at a lower threshold in patients with MINOCA (ie, using MRI independent of clinical likelihood of myocarditis) led to a 6.3-fold increase in the incidence of myocarditis with doubling of MRIs positive for myocarditis, indicating that myocarditis is currently an underdiagnosed entity [137]. MRI shows functional abnormalities (global systolic dysfunction or focal wall motion abnormalities), capillary hyperemia (high signal in EGE), edema (high signal in T2-weighted images, high native T1 and T2 values, increased ECV), necrosis/fibrosis (LGE in mid myocardial/subepicardial; high T1 and ECV), and pericardial effusion. The Lake Louise criteria, which were used in the diagnosis of acute myocarditis, required two out of the three criteria (edema, EGE, and/or LGE) to be positive [138]. A combination of all three is required if high positive predictive value is desired (positive likelihood ratio of 7.7, accuracy of 80%, specificity of 90%, sensitivity of 77%, positive predictive value of 96%, and negative predictive value of 53%), whereas T2 or LGE criteria are adequate for high sensitivity (91% sensitivity, 84% accuracy) [138]. Removing EGE as a criterion does not change the accuracy (80% with, 84% without) but reduces sensitivity (90% with, 60% without) [138].


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . Native T1-mapping is useful in detecting subtle, focal disease with sensitivity of 90%, specificity of 91%, and accuracy of 91%, which is superior to T2-weighted MRI and LGE techniques [115]. The updated Lake Louise criteria requires at least one T2-based criterion (global/regional elevation of myocardial T2 or increased T2 signal of myocardium) with at least one T1-based criterion (elevated myocardial T1, elevated ECV, or LGE) for diagnosing acute myocarditis with high specificity [139]. Having only one criterion will still support a diagnosis of acute myocarditis but has lower specificity than with two criteria [139]. Different LGE patterns have been reported based on the viral etiology, with parvovirus B19 showing subepicardial or mid myocardial distribution LGE in the LV inferolateral wall and recovering Nonischemic Myocardial Disease without serious damage, whereas HHV-6 infection involves the LV basilar septum in linear mid myocardial LGE pattern, often rapidly progressing to HF [140]. Myocardial edema without fibrosis indicates good potential for recovery, whereas a high amount of EGE and LGE indicate adverse prognosis, particularly if LGE is persistent at 4 weeks after onset [2]. LGE may not correlate with the clinical and lab markers, indicating it is an independent risk assessment tool [141]. A normal MRI in patients with suspected myocarditis indicates a good long-term prognosis, independent of clinical and other findings [142]. In Chagas disease, patients are typically not imaged in the acute phase, but the indeterminate phase may show changes including RWMA and diastolic dysfunction without overt systolic dysfunction. The chronic phase shows global systolic dysfunction, apical aneurysm, and thrombus. LGE is seen in up to 72% of patients [135] and in 100% of those with arrhythmias, more common in apical and basal inferolateral segments.


Nonischemic Myocardial Disease with Clinical Manifestations Ischemic Cardiomyopathy Already Excluded . LGE has been reported in all the phases, including early indeterminate [135]. LGE is subendocardial in 27%, transmural in 36%, mid myocardial in 14%, and subepicardial in 23% of patients [143]. Hence, the pattern is not specific, with contributions possibly from myocarditis and microvascular dysfunction. The diagnosis is therefore made in the context of appropriate epidemiological history [143]. EGE and myocardial edema similar to that of acute myocarditis can also be seen in all phases [135]. All these parameters correlated directly with disease severity [143]. MRI Heart Inotropic Stress There is no relevant literature to support the use of MRI heart inotropic stress for the evaluation of inflammatory myocardial disorders. Ischemia has already been excluded. MRI Heart Vasodilator Stress There is no relevant literature to support the use of MRI heart vasodilator stress for the evaluation of inflammatory myocardial disorders. Ischemia has already been excluded. Echocardiography Transesophageal There is no relevant literature to support the use of echocardiography transesophageal for the evaluation of inflammatory myocardial disorders. Echocardiography Transthoracic Resting Echocardiography shows global and regional functional abnormalities in acute myocarditis. Pericardial effusion may also be seen. Echocardiography is a first-line imaging modality in the evaluation of Chagas disease. It may present with hypokinetic dilated LV with diminished LVEF or biventricular dilation. Aneurysms, thrombus, and valvular disease (mitral and tricuspid regurgitation) may be seen [144]. Global longitudinal strain correlates with the amount of myocardial fibrosis in MRI [145]. 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.


Imaging of Deep Inferior Epigastric Arteries for Surgical Planning Breast Reconstruction Surgery .  Introduction/Background Breast cancer is the most common malignancy in women in the United States, with surgical options including lumpectomy and mastectomy. Breast reconstruction options following mastectomy range from saline or silicone implants to autologous breast reconstruction. The latter procedure uses skin, fat, blood vessels, and/or muscle from the upper back, abdomen, buttocks, or hips. Transverse rectus abdominis muscle flap procedure is a traditional method of breast reconstruction that harvests underlying muscle. This can result in increased donor site morbidity. The deep inferior epigastric perforator (DIEP) flap is a muscle-sparing perforator free flap breast reconstruction technique, which uses the deep inferior epigastric artery (DIEA) perforators to create a vascular pedicle [1]. Compared with transversus rectus abdominus muscle flaps, DIEP flaps result in less fat necrosis and loss of function at the donor site. The DIEP tissue harvesting procedure involves dissecting the anterior abdominal wall subcutaneous tissues to locate and visually identify the most suitable vessel to serve as the vascular pedicle. Although the DIEA is reliably identified because of its consistent take off from the external iliac artery, the anatomy of the perforators used in DIEP flap is variable. Lack of preoperative imaging can lead to increased operative times given the time-consuming nature of identifying the variable vascular anatomy. The efficiency of the vascular pedicle selection process can be significantly improved with preoperative imaging [2]. Multiple perforators are identified by imaging, which are typically ranked based on size, location, and intramuscular course. The ideal perforator is the largest caliber [1,3] and is medially located within the flap with an extended vascular territory beyond the midline to provide optimal perfusion.


Imaging of Deep Inferior Epigastric Arteries for Surgical Planning Breast Reconstruction Surgery . Dissection of the selected perforator should preserve muscle innervation and avoid fat necrosis [1,3,4]. A short intramuscular course allows for successful dissection [3,14,15]. Perforators are reported by the location where they pierce the anterior rectus sheath in relation to the umbilicus. This is important because, although the perforator can move within the subcutaneous tissues with applied pressure, its position at the rectus sheath is fixed relative to the umbilicus [5]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org OR Discussion of Procedures by Variant Variant 1: Imaging of deep inferior epigastric arteries for surgical planning (breast reconstruction surgery). Initial imaging. The goal of preoperative imaging is to aid the surgical team in preoperative planning given the variability of the DIEA perforator branches anatomy between patients, and even between the left and right hemiabdomen of the same patient.


Imaging of Deep Inferior Epigastric Arteries for Surgical Planning Breast Reconstruction Surgery . Improved clinical outcomes with preoperative imaging have been shown to include decreased length of surgery, decreased flap loss rate, decreased hernia rate, decreased intraoperative blood loss, shorter mean inpatient stay, reduced learning curve when compared with hand-held Doppler, and increased surgeon confidence [7-15]. Arteriography Abdomen and Pelvis Although catheter directed arteriography can aid in delineation of variant anatomy of the DIEA to guide surgical planning for breast reconstruction, it is an invasive procedure with risks that outweigh benefits compared to current alternative noninvasive imaging methods. Additionally, given the small caliber of the vessels and potentially tortuous course, this would likely lead to prolonged procedure times and potentially unreliable assessment of vessel caliber given variable source and detector distances. Furthermore, the course of perforator arteries in the abdominal wall musculature and subcutaneous tissues is not easily assessed with catheter directed arteriography. There is no relevant literature supporting the use of arteriography in evaluation of imaging of deep inferior epigastric arteries for surgical planning. CT Abdomen and Pelvis With IV Contrast To date, there is no relevant literature supporting the use of CT abdomen and pelvis with intravenous (IV) contrast in the evaluation of imaging of deep inferior epigastric arteries for surgical planning. CT Abdomen and Pelvis Without and With IV Contrast There is no relevant literature supporting the use of CT abdomen and pelvis without and with IV contrast in the evaluation of imaging of deep inferior epigastric arteries for surgical planning. CT Abdomen and Pelvis Without IV Contrast There is no relevant literature supporting the use of CT abdomen and pelvis without IV contrast in the evaluation of imaging of deep inferior epigastric arteries for surgical planning.


Imaging of Deep Inferior Epigastric Arteries for Surgical Planning Breast Reconstruction Surgery . CTA Abdomen and Pelvis With IV Contrast CTA is currently beneficial in evaluating the perforator anatomy for preoperative planning before DIEP flap breast reconstruction. Perforator size, perforator location relative to abdominal landmarks, branching pattern of DIEA, presence of superficial inferior epigastric vessels, subcutaneous course, and intramuscular course all affect operative techniques, operative time, and outcomes. CTA is a fast, efficient, and highly reproducible modality, capable of yielding excellent opacification of the small caliber perforator arteries with optimal contrast bolus timing. CTA evaluation performed with the use of specific postprocessing and display techniques may yield more accurate assessment of the optimal vessel for selection for breast reconstruction when compared to color Doppler ultrasound (CDU) [2,8,16]. Some studies have demonstrated superiority of CTA over CDU utilization [17,18], suggesting a routine use of preoperative CTA. A virtual 3-D plan based on CTA can be preoperatively projected onto the abdomen intraoperatively, which can aid in identifying perforator locations and thus decreasing operative time [19]. CTA is also helpful in predicting which DIEA perforators are the most clinically useful in patients with scarred abdomens [20]. Therefore, preoperative imaging is essential for DIEP flap surgery [17,21-28]. Preoperative CTA evaluation can also reliably estimate the volume of abdominal tissue for DIEP flap breast reconstruction [19,29]. Imaging of Deep Inferior Epigastric Arteries Preoperative mapping allows calculation of a flap viability index, which predicts the amount of tissue which will survive based on perforator diameter as well as flap weights [30]. CTA evaluation also allows for the assessment of factors, which may lead to venous congestion of the flap and, therefore, flap failure [31].


Imaging of Deep Inferior Epigastric Arteries for Surgical Planning Breast Reconstruction Surgery . A superficial inferior epigastric vein larger than the deep inferior epigastric vein as well as axial nonarborizing superficial venous system are highly predictive of subsequent venous congestion. Knowledge of these findings can aid in preoperative discussion with patients, which may alter management [32]. Preoperative use of CTA allows estimation of contralateral abdominal perfusion and therefore allows for efficient breast reconstruction and decreased complications [33]. Use of preoperative CTA has been shown to result in the increased use of single perforators, increased use of medial- row perforators, significantly reduced operative time, decreased intraoperative blood loss, decreased inpatient hospital stay, and decreased complications such as hernias [9,11,12,14,34]. CTA evaluation allows for faster selection of laterality of dissection, as well as reduced flap loss rates [15]. MRA Abdomen and Pelvis Without and With IV Contrast Donor site preoperative imaging for mapping the perforator artery anatomy results in improvement in perforator selection, reduces operative time, and reduces donor site morbidity. Although CTA is considered most helpful, emerging literature supports MR angiography (MRA) as an alternative imaging tool with accurate assessment of DIEA perforator anatomy [35-44]. A recent meta-analysis demonstrates that CT and MRI appear to have similar accuracy in preoperative DIEP mapping [44]. MRA evaluation is limited by increased scanning times relative to CTA evaluation. Continued research is needed to evaluate the accuracy of the new emerging MRA techniques and their role in preoperative perforator branch imaging. MRA Abdomen and Pelvis Without IV Contrast The literature review yields one study that used noncontrast MRA for preoperative planning in 56 women who underwent DIEP flap with preoperative planning using MRA without IV contrast.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo.  Introduction/Background Clinical assessment and audiometric testing can determine the type of hearing loss as conductive, sensorineural, or mixed [1,2] and guide the appropriateness of subsequent imaging. Conductive hearing loss results from diseases affecting the conduction of mechanical sound wave energy to the hair cells of the organ of Corti within the cochlea. These serve as the auditory receptors, converting the mechanical energy of sound waves into electrical neural impulses that are then transmitted along the auditory pathways to the auditory cortex [1]. Sensorineural hearing loss is caused by diseases that impair the cochlear function or the transmission of electrical signal along the auditory pathway, including the cranial nerve nucleus in the brainstem through the superior olive, inferior colliculus, medial geniculate body of the thalamus, and auditory cortex in the temporal lobe. Given the proximity of the cranial nerves and their nuclei, disorders that affect hearing may also affect vestibular function and vice versa. The vestibule and semicircular canals are the end organs responsible for balance and equilibrium. Central vestibular pathways involve extensive connections between the vestibular nuclei within the brainstem and the cerebellum, extraocular nuclei, and spinal cord. Vertigo is a sensation that you or the environment around you is moving or spinning. Although vertigo often indicates dysfunction of the vestibule or semicircular canals, patients commonly report dizziness, a less specific term that may imply disequilibrium, light- headedness, or presyncope [3-5]. Accordingly, imaging workup in these patients may require assessment for disease processes that produce symptoms reported as dizziness rather than vertigo.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. Appropriateness of imaging often depends upon clinical categorization of vertigo into peripheral (vestibular) and central (affecting central vestibular pathways) categories based upon factors such as onset, duration, persistence, aggravating factors, and results of clinical testing [3-7]. In some cases however, this categorization may be difficult on clinical assessment, especially in less subspecialized care [3]. 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. Reprint requests to: publications@acr.org Hearing Loss and/or Vertigo Given the density of temporal bone and the rather small size of individual structures of interest, such as ossicles, details of temporal bone morphology are only evident on bone windows. Accordingly, intravenous (IV) contrast is not beneficial for evaluation of temporal bone in patients with conductive hearing loss. CT Head There is no evidence to support use of CT head in patients with conductive hearing loss. CTA Head There is no evidence to support use of CT angiography (CTA) in patients with conductive hearing loss. MRI Head and Internal Auditory Canal MRI of the temporal bone is insufficient in delineation of the bony details usually needed for evaluation of patients with conductive hearing loss, and there is no evidence to support its use as a first-line imaging modality in these patients. MRA Head There is no evidence to support use of MR angiography (MRA) for initial evaluation of patients with conductive hearing loss. MR Venography Head There is no evidence to support use of MR venography (MRV) for initial evaluation of patients with conductive hearing loss.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. Variant 2: Acquired conductive hearing loss secondary to cholesteatoma or neoplasm with suspected intracranial or inner ear extension. Surgical planning. CT Temporal Bone High-spatial resolution CT of the temporal bone is helpful in defining small inflammatory or neoplastic masses within the middle ear cavity [1,2,13]. In addition, CT can help in surgical planning by demonstrating erosions of ossicles or other inner ear structures (such as perilymphatic fistulae) caused by such masses [14]. Given the surrounding dense bone, IV contrast is usually not beneficial in studying enhancement characteristics of middle ear masses. However, contrast enhancement may help delineate extraosseous soft tissue associated with invasive neoplasms. CT Head There is no evidence to support use of CT head for assessment of patients with conductive hearing loss and middle ear mass identified on otoscopy. CTA Head There is no definite evidence to support use of CTA as a first-line modality for assessment of patients with conductive hearing loss and middle ear mass identified on otoscopy. However, in patients with high clinical suspicion of middle ear paraganglioma, CTA is sometimes used initially for diagnostic confirmation and for planning further management. MRI Head and Internal Auditory Canal Extent of a middle ear cavity mass identified on otoscopy in a patient with conductive hearing loss is much better defined using MRI obtained without and with IV contrast [2,5,13,15]. This assessment is better done using thin sections across the temporal bone as part of a dedicated internal auditory canal (IAC) protocol rather than a routine brain MRI. Excellent soft-tissue contrast afforded by even a noncontrast MRI often complements the bony details seen on temporal bone CT for complete evaluation of such patients prior to surgical intervention. MRA Head MRA is usually not used as a first-line imaging modality in patients presenting with conductive hearing loss.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. However, it may be helpful in assessing patency of the carotid artery if initial imaging raises suspicion of vascular involvement. MR Venography Head Although not used as the initial imaging modality, MRV may be helpful in assessing patency of jugular vein for surgical planning in patients with documented middle ear masses. Hearing Loss and/or Vertigo Variant 3: Acquired sensorineural hearing loss. Initial imaging. CT Temporal Bone CT of the temporal bone is insensitive in detection of soft-tissue abnormalities that commonly cause sensorineural hearing loss. Small size and proximity to the dense bone of inner ear structures and IAC also precludes visualization of intralabyrinthine or intracanalicular enhancement following IV contrast administration. It may demonstrate labyrinthine ossification [16] resulting from prior infection or give an indirect clue to presence of a vestibular schwannoma in the form of bony remodeling of the IAC. In post-traumatic sensorineural hearing loss, CT can demonstrate fractures extending across the otic capsule [2,13]. CT Head Contrast-enhanced head CT is a less-sensitive imaging modality to detect tumors, such as vestibular schwannomas [17], or assess the IAC, cerebellopontine angle cisterns, or the brainstem compared to MRI. CTA Head There is no evidence to support use of CTA in the initial workup of patients presenting with isolated sensorineural hearing loss. MRI Head and Internal Auditory Canal Imaging evaluation of patients presenting with sensorineural hearing loss involves detailed assessment of the cochlear contents, vestibulocochlear nerve, and auditory pathways. MRI is the imaging modality of choice for evaluating these soft-tissue structures [2,5,18-20].


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. MRI can demonstrate signal alterations induced by inflammation or hemorrhage within the cochlear contents, identify neoplasms within the cochlear labyrinth or IAC, assess the size of vestibular aqueducts, and visualize abnormalities affecting the brain parenchyma along the auditory pathways [21-25]. Although differential considerations may vary based upon sudden, fluctuating, or progressive nature of sensorineural hearing loss, MRI remains the imaging modality of choice for all these subcategories. MRI should be done using dedicated IAC protocol using thin sections across the IAC and the inner ear. These protocols include evaluation of the brainstem and thalami. Given the extreme rarity of cortical deafness, there is no strong evidence to recommend routine assessment of the entire brain parenchyma in addition to the MRI IAC protocol in patients presenting with isolated sensorineural hearing loss [26,27]. High-resolution 3-D T2-weighted images providing submillimeter assessment of fluid-filled inner ear structures and the IAC are highly sensitive for detection of diseases presenting with sensorineural hearing loss [27,28]. Visualization of inflammatory changes (eg, labyrinthitis, neuritis) as well as neoplasms, such as vestibular schwannomas, can be facilitated by administration of IV contrast [29,30]. However, there is insufficient evidence to prove incremental benefit of contrast administration beyond an MRI IAC protocol performed without IV contrast [27,28]. MRA Head There is no evidence to support use of MRA in the initial workup of patients presenting with isolated sensorineural hearing loss. MR Venography Head There is no evidence to support use of MRV in the initial workup of patients presenting with isolated sensorineural hearing loss. Variant 4: Mixed conductive and sensorineural hearing loss. Initial imaging. CT Temporal Bone CT scan of the temporal bones can delineate changes of otospongiosis, a common cause of mixed conductive and sensorineural hearing loss.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. In some patients with clinical suspicion of otospongiosis, it may suggest alternate diagnoses to explain hearing loss. [31,32]. Administration of IV contrast is usually not beneficial for assessment of temporal bone. CT Head Relative to MRI, CT head is much less sensitive in detecting or excluding retrocochlear pathology to account for the sensorineural component of the hearing loss [17]. CTA Head There is no evidence to support use of CTA in the initial workup of patients presenting with mixed hearing loss. Hearing Loss and/or Vertigo MRI Head and Internal Auditory Canal MRI obtained using IAC protocol can be helpful in looking for any retrocochlear pathology responsible for a sensorineural component of the hearing loss. In case IV contrast is administered, punctate enhancement can be seen within the bony otic capsule in the presence of otospongiosis [2]. MRA Head There is no evidence to support use of MRA in the initial workup of patients presenting with mixed hearing loss. MR Venography Head There is no evidence to support use of MRV in the initial workup of patients presenting with mixed hearing loss. Variant 5: Congenital hearing loss or total deafness or cochlear implant candidate. Surgical planning. CT Temporal Bone High-spatial resolution provided by CT of the temporal bone is valuable prior to cochlear implantation surgery in patients with profound hearing loss. It can provide preoperative delineation of underlying cochlear malformation in patients with congenital hearing loss, detect changes of otospongiosis, suggest round window occlusion, identify labyrinthitis ossificans, congenital bony fusion of the ossicles, and alert the surgeon regarding underlying otomastoiditis or variant anatomy (such as that of the facial nerve) [33,34]. It can also delineate the size of cochlear and vestibular aqueducts, alerting the surgeon for possibility of intraoperative cerebrospinal fluid gusher [24,35,36].


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. CT Head High-spatial resolution of CT head is insufficient in providing anatomic details of temporal bone needed for surgical planning prior to cochlear implantation. Accordingly, there is no evidence to support routine use of CT head for this indication. CTA Head There is no evidence to support routine use of CTA for surgical planning prior to cochlear implantation in patients with deafness. MRI Head and Internal Auditory Canal MRI may provide a complementary role to temporal bone CT in preoperative assessment of patients prior to cochlear implantation. Exquisite details of inner ear structures visible on high-resolution T2-weighted images can help in detecting abnormalities, such as cochlear malformations or cochlear nerve deficiency, that directly impact surgical approach [37,38]. In addition, MRI may reveal unexpected soft-tissue abnormalities, such as vestibular schwannomas that may impact the planned surgery [39]. MRA Head There is no evidence to support routine use of MRA for surgical planning prior to cochlear implantation in patients with deafness. MR Venography Head There is no evidence to support routine use of MRV for surgical planning prior to cochlear implantation in patients with deafness. Variant 6: Episodic vertigo with or without associated hearing loss or aural fullness (peripheral vertigo). Initial imaging. CT Temporal Bone CT of the temporal bone provides excellent delineation of the bony labyrinth and is helpful in detecting a number of pathologies resulting in peripheral vertigo. It is highly sensitive in detecting temporal bone fractures in patients with post-traumatic vertigo, assessing for superior semicircular canal dehiscence in patients with vertigo provoked by loud noises, and diagnosing erosions in the bony labyrinth from inflammatory or iatrogenic causes [5,8,9,14]. CT Head CT head provides insufficient details of the inner ear to be useful in patients with peripheral vertigo.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. Accordingly, diagnostic yield of CT head in patients presenting with vertigo is low [40]. Hearing Loss and/or Vertigo CTA Head and Neck There is no evidence to support use of CTA in patients presenting with peripheral causes of vertigo. In patients with episodic vertigo that cannot be confidently categorized as peripheral, CTA can be used to detect underlying vertebrobasilar insufficiency [41]. MRI Head and Internal Auditory Canal Based on clinical assessment, peripheral vertigo in many patients is presumed to be secondary to benign processes such as benign paroxysmal positional vertigo or Meniere disease, and these patients are often managed successfully without images are capable of delineating endolymphatic sac, and delayed 3-D FLAIR images can demonstrate hydrops associated with Meniere disease following IV or intratympanic contrast administration as contrast accumulates in perilymphatic but not endolymphatic space. However, the role of such studies in management of these patients is still not clearly established [42-53]. IV contrast can be helpful in showing enhancement of vestibule or semicircular canals in patients with labyrinthitis. MRI of the brain can be used to detect rare but significant central causes of vertigo in cases where distinction between peripheral and central categories is not clinically evident [54]. MRA Head and Neck There is no evidence to support use of MRA in patients presenting with peripheral causes of vertigo. In patients with episodic vertigo that cannot be confidently categorized as peripheral, MRA without and with IV contrast can be used to detect underlying vertebrobasilar insufficiency [55]. MR Venography Head There is no evidence to support use of MRV in the initial workup of patients presenting with vertigo; however, in patients who may have vertigo as a symptom of pseudotumor cerebri, MRV may show narrowing of the transverse sinuses. Variant 7: Persistent vertigo with or without neurological symptoms (central vertigo). Initial imaging.


Hearing Loss and or Vertigo

Hearing Loss and or Vertigo. CT Temporal Bone CT of the temporal bone is not useful in looking for central causes of vertigo. CT Head Head CT without or with IV contrast may be used to look for central causes of dizziness, albeit with lesser sensitivity than MRI [40,54]. IV contrast may help in either detection or characterization of various neoplastic or inflammatory disease processes affecting the central nervous system. In patients presenting to the emergency department with acute onset of symptoms, CT may demonstrate intracranial hemorrhage as a rare central cause of dizziness [56]. CTA Head and Neck In patients suspected of vertebrobasilar insufficiency as a cause of episodic vertigo, CTA can be used to detect vascular stenosis or occlusion [41]. MRI Head and Internal Auditory Canal MRI is the modality of choice in evaluation of the brain in patients suspected to have central cause for vertigo. It can detect posterior fossa neoplasms, Chiari malformation, posterior fossa infarcts, and demyelinating lesions that may result in dizziness or vertigo [3,54,56-58]. Contrast administration can be helpful in detection or characterization of such lesions [58]. Compared to CT, MRI has a much higher sensitivity of detecting acute infarcts in patients with dizziness [40]. It should be noted that infarcts causing isolated vestibular symptoms are usually small, and normal initial MRI does not entirely exclude brain infarction as a cause for vertigo [59]. MRA Head and Neck In patients suspected of vertebrobasilar insufficiency as a cause of episodic vertigo, MRA can be used to detect vascular stenosis or occlusion [55]. MR Venography Head There is no evidence to support use of MRV in the initial workup of patients presenting with isolated vertigo. Summary of Recommendations Variant 1: CT temporal bone without IV contrast is the first-line imaging modality in patients presenting with acquired conductive hearing loss without any mass lesion seen within the middle ear cavity.


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up.  Multiple studies have shown significantly decreased length of hospital stay and decreased perioperative morbidity with EVAR [8-11] compared to open repair [12-14]. Despite this, open repair is still performed in patients with unsuitable aneurysm morphology for EVAR and in those with failed EVAR [15]. For patients who present de novo for treatment of AAA without any prior imaging available, the entire aorta (including the thoracic portion) should be assessed to fully characterize the aneurysm and exclude a concomitant thoracic aortic aneurysm. Preoperative imaging for open repair of AAA has one primary focus: to determine the need for surgery based on aneurysm size, extent, and rate of growth. Additional information regarding potential variant anatomy can also be helpful in guiding appropriate treatment and preventing unexpected complications at the time of repair. 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. Reprint requests to: publications@acr.org AAA: Interventional Planning & Follow-Up In recent years, new devices have become available to mitigate unfavorable aortic neck anatomy. Several designs feature an uncovered proximal portion that allows for placement of the stent directly at the origin of aortic branches, whereas others possess ready-made vessel origins for placement within the renal and mesenteric arteries [18]. FEVAR is an alternative approach for those with aortic necks of inadequate length. In FEVAR, fenestrations within the graft material allow for perfusion of major visceral arteries while securing an adequate proximal seal [7].


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. A variant of the FEVAR technique describes the placement of bridging stents through these fenestrations [23]. Such devices may be especially favorable in women, as these patients are less likely to have aneurysm neck and iliac diameters sufficient for traditional EVAR [16]. FEVAR obviates the need for open femoral exposure and offers the benefit of shorter procedure times, lower complication rates, and shorter hospital stays [5]. FEVAR requires common femoral artery anatomy that is suitable for percutaneous access and free of significant calcification. Candidates for FEVAR should be carefully selected, as the presence and degree of vessel calcification is a major determinant of technical failure [24]. The advantages of EVAR come at a cost of lifelong imaging surveillance. This is due to a higher rate of complications that require reintervention when compared to open repair [11,25]. Complications of EVAR include stent graft migration, kinking, infection, thrombosis, and renal dysfunction. The most important complication to detect is continued aneurysm expansion leading to eventual rupture, which can occur even after successful EVAR [26]. The most common complication of EVAR is endoleak formation, which may contribute to aneurysm sac enlargement and rupture [27]. Endoleaks are classified by their etiology, with Types I and III most commonly leading to rupture [15,28]. Appropriate classification is therefore crucial for subsequent management and should be clarified whenever possible. Although EVAR is safe and has a low mortality rate [29], the possibility of complications and need for reintervention remains high [12-14], thereby requiring life-long monitoring. The ultimate goal of endovascular therapy is to prevent aneurysm rupture. Follow-up imaging is the most useful tool for evaluating post-therapeutic outcomes and monitoring potential complications.


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. Successful therapy results in an aneurysm that remains stable or decreases in size over serial follow-up imaging examinations, with decreasing size of the aneurysm sac believed to indicate a low risk of future rupture [30,31]. All available imaging modalities have been investigated over time for their efficacy in post-EVAR follow-up. According to Society of Interventional Radiology guidelines, the imaging modality of choice should allow at least (1) measurement of aortic aneurysm diameter, (2) detection and classification of endoleaks, and (3) detection of morphologic details of the stent grafts [32]. Imaging modalities should be assessed by their effectiveness in satisfying these three requirements, as well as their respective safety profiles and use of potentially nephrotoxic contrast material. Overview of Imaging Modalities CT and CTA Computed tomography (CT) is a cross-sectional imaging modality that offers excellent spatial resolution, fast image acquisition times, and widespread availability. However, without contrast material administration, its ability to assess vascular structures is limited. Evaluation of the vessel lumen is accomplished through CT angiography (CTA), a technique that utilizes the administration of iodinated contrast material. The addition of 3- D volumetric postprocessing techniques allow the abdominal aorta and associated vasculature to be viewed in any obliquity and affords quantification of luminal diameter, cross-sectional area, and sac volume. A disadvantage of CTA includes potential nephrotoxicity from administered contrast material [33-35]. For the purposes of distinguishing between CT and CTA, the ACR Appropriateness Criteria topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [36]: All procedure elements are essential: (1) timing, (2) recons/reformats, and (3) 3-D renderings.


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that CMS has applied to the CPT codes. CTA imaging may be performed as a single arterial phase, biphasic study (noncontrast and arterial or arterial and delayed phases), or as a triphasic study (noncontrast, arterial, and delayed phases). To reduce the cumulative lifetime radiation dose of patients undergoing CTA surveillance, several authors have proposed eliminating either AAA: Interventional Planning & Follow-Up the arterial phase [37] or delayed phase [38,39], although one author has suggested eliminating noncontrast scans from all surveillance examinations with the exception of an initial 1-month follow-up [40]. Several studies have reported significant dose reduction using dual-energy CT with acquisition of delayed-phase images only [41,42]. Accompanying software allows for the isolation of iodine from a selected region and enables reconstruction of virtual noncontrast images. A colored overlay can be applied to voxels containing iodine, rendering detection of contrast material within the aneurysm sac external to the stent-graft more visible [41]. Dual-phase dual-energy CT can potentially reduce the radiation dose by 19.5% when compared to a standard triphasic CT examination [34]. Additional dose reduction techniques include the use of automatic exposure control and iterative reconstruction algorithms [34]. Determining the optimal dose-efficient CT technique is a work in progress that will continue to evolve with increased experience and technological advancement. Aortography Aortography is an invasive imaging modality that can accurately assess aortic side branch patency, knowledge of which is crucial for deployment of conventional and fenestrated endografts with or without bridging stents.


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. However, it fails to demonstrate mural thrombus, thereby limiting diameter measurements and landing zone assessment. Though less sensitive than CTA in detecting endoleaks, aortography is able to demonstrate the direction of blood flow in or out of the aneurysm sac, rendering it more accurate than CTA in classifying endoleaks [43]. Although traditional aortography relies on iodinated contrast material, recent studies suggest that carbon dioxide may be an acceptable alternative for evaluating endoleaks in patients at risk for contrast-related nephropathy [44,45]. MRA The major advantage of MR angiography (MRA) relative to CTA is improved soft tissue characterization. Despite relatively low nephrotoxicity, gadolinium-based contrast media (GBCM) have been linked to nephrogenic systemic fibrosis (NSF) [46]. As such, evaluation of renal function in high-risk patients before administering a GBCM long scanning duration, patient claustrophobia, decreased spatial resolution, and contraindication in patients with certain implantable devices. MRA is also limited in its ability to detect intimal calcification [33]. Additionally, susceptibility artifact from the metal interstices of the stent graft presents a diagnostic challenge for assessing device integrity and may mimic graft stenosis. Although the presence of an implanted cardiac pacemaker was previously an absolute contraindication to MRI, several new models are FDA-approved for conditional use. Superior soft-tissue characterization inherent to MRA may assist clinicians in differentiating slow-growing aneurysms from fast-growing aneurysms. A recent study demonstrated that AAAs containing intraluminal thrombus that have high T1-weighted signal intensity are associated with higher growth rates [47]. US Color duplex ultrasound (CDUS) is a noninvasive imaging modality that is portable and safe, sparing patients from nephrotoxic contrast material administration.


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. CDUS is able to assess blood flow dynamics in real-time and allows for quantification of luminal diameter and cross-sectional area. Image quality in CDUS is highly dependent on operator experience, patient cooperation, and patient body habitus [48,49]. Although excellent correlation between AAA diameter measurements made by CT and CDUS is well documented, there is general agreement that conventional ultrasound (US) techniques systematically underestimate aneurysm diameter by ~2 mm [35,50-52]. Contrast-enhanced ultrasound (CEUS) utilizes the infusion of stabilized sodium hexafluoride gas to visualize the vessel lumen. Unlike iodinated contrast materials used in CTA, this gas is not nephrotoxic and is safely eliminated via the respiratory system. The advent of 3-D CEUS utilizes positional information for magnetic field emitters to assemble collected US reflections into a high-resolution 3-D image, which results in improved image quality relative to CDUS [53]. 3-D CEUS is reported to be more accurate than 2-D methods in quantifying maximum vessel diameter, as the former allows measurements to be made orthogonal to vessel centerline [50]. For patients with absolute contraindications to iodinated contrast material, whether due to severe renal impairment or life-threatening contrast allergy, US is an important adjunct to nonenhanced CT. AAA: Interventional Planning & Follow-Up Discussion of Procedures by Variant Variant 1: Planning for pre-endovascular repair (EVAR) or open repair of AAA. Radiography Radiographs are unable to adequately visualize the abdominal aorta, thereby prohibiting proximal landing zone assessment and luminal diameter quantification. As such, there is no role for radiography in the preoperative evaluation of AAA. However, given the high spatial resolution of radiography, this modality affords optimal visualization of stent graft geometry.


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. When utilizing consistent centering protocols, this allows for reliable detection of kinks and stent graft migration to within 2 mm [54]. CT and CTA Due to its superior spatial resolution and rapid image acquisition, CTA with 3-D volumetric reconstruction and vessel analysis has gained wide acceptance as the gold standard for pre-EVAR evaluation. The utilization of 3-D reconstruction software has become paramount in EVAR planning, as it diminishes the impact of vessel tortuosity on diameter and length measurements, in addition to reducing intraobserver variability [55]. One author found that routine 3-D analysis of pre-EVAR images led to a significant reduction in Type I endoleaks [56]. Reformatted CTA images in the coronal and sagittal planes should be utilized for increased diagnostic accuracy. In most cases, a CTA of the abdomen and pelvis is appropriate to ensure coverage of the entire aneurysm and vascular access. The CTA should include the chest in patients with thoracoabdominal aortic aneurysms (TAAA). Aortography As aortography and radiography are unable to accurately provide aneurysm sac diameter measurements and landing zone assessment, these modalities are inadequate for pre-EVAR or open repair evaluation. However, aortography may be of value in assessing branch vessel patency and is usually part of branch vessel occlusion procedures before aneurysm repair. MRA For the purpose of pre-EVAR planning, T1-weighted spin-echo images and flow-based methods such as time of flight or phase contrast provide adequate details regarding aneurysm morphology and relevant vascular anatomy. However, these techniques are limited by low spatial resolution and signal-to-noise ratio and are therefore suboptimal for evaluating small-vessel lesions or diminutive side branches [33]. Furthermore, flow-based sequences are susceptible to flow artifacts that may overestimate the degree of stenosis or falsely demonstrate an occlusion [57].


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. To overcome these limitations, contrast-enhanced MRA (CE-MRA) should be added to conventional T1- and T2-weighted spin-echo sequences. CE-MRA is much less susceptible to flow and susceptibility artifacts and has a high signal-to-noise ratio for evaluating small vessels and fine structural details. The effectiveness of CE-MRA has been found to be comparable to that of CTA in assessing the suitability of aneurysms for EVAR [58]. In most cases, an MRA of the abdomen and pelvis is appropriate to ensure coverage of the entire aneurysm and vascular access. The MRA should include the chest in patients with TAAA. Acquisition of noncontrast balanced steady state free precession (bSSFP) images may be useful in the preoperative evaluation of patients who poorly tolerate GBCM or are at risk for NSF. One study found that AAA measurements obtained by noncontrast MRA were not significantly different from those measured by CTA [59]. US Although the United States Preventative Services Task Force currently recommends one-time US screening for AAA in men ages 65 to 75 years who have ever smoked [60], no evidence is present within the medical literature to support the use of either CDUS or CEUS in the formal preoperative evaluation of AAA. Variant 2: Follow-up for post-endovascular repair (EVAR) or open repair of AAA. CT and CTA The exceptional spatial resolution and fast imaging speeds of CTA has made it the de facto gold standard for post- EVAR and post-open repair imaging surveillance. After EVAR, the most widely used surveillance regimen utilizes multiphasic contrast-enhanced CT at 1 month, 12 months, and yearly thereafter. If an abnormality is detected 1 month post-EVAR, a follow-up scan at 6 months is performed. In the absence of adverse outcomes at the 1-month follow-up imaging, the intensity and frequency of the surveillance program may be modulated accordingly [61-64].


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. Compared to aortography, CTA has higher sensitivity in detecting endoleaks after EVAR. Compared to US, CTA is better able to visualize kinking and migration of the stent-graft and is equivalent in quantifying aneurysm sac size [34] . AAA: Interventional Planning & Follow-Up Initial post-EVAR surveillance studies monitored the maximum diameter of the aneurysm sac as a marker for response to therapy [65]. This method has been shown to be unreliable due to substantial interobserver variability [66]. Volume analysis of the aneurysm sac has since proven to be the most reliable indicator for aneurysm rupture and/or need for reintervention [67-69]. In an effort to reduce radiation dose and contrast material exposure, several authors have proposed using serial volumetric analysis of AAAs with noncontrast CT as the sole screening test for post-EVAR follow-up [70-73]. Volume discrepancy due to interoperator variability has been demonstrated to be less than 2% when the procedure is performed by experienced personnel [72,74]. In patients in whom contrast materials are contraindicated, serial volume measurements of the nonenhanced aneurysm sac provides valuable information in guiding management [75]. In most cases, a CTA of the abdomen and pelvis is appropriate to ensure coverage of the treated aneurysm and stent graft. The CTA should include the chest in patients with TAAA. Aortography Due to the relatively invasive nature of aortography, it is not practical for routine post-EVAR surveillance. However, in the setting of a known endoleak, aortography may be more accurate than CTA in classifying endoleaks. One study revealed only 86% agreement in endoleak classification between aortography and CTA, in which subsequent correct classification by aortography significantly improved patient management [43].


Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. It therefore stands to reason that aortography may be best utilized as a second-line imaging modality in post-EVAR patients, playing a vital role in endoleak classification and reintervention [35]. MRA When considering using MRA for post-EVAR surveillance, stent material and orientation are important considerations. Typical stent construction employs nitinol, elgiloy, or stainless steel. Nitinol is a nickel-titanium alloy that causes relatively few artifacts on MRA, while allowing adequate visualization of the stent lumen and adjacent structures. Elgiloy is an alloy of cobalt, chromium, and nickel that may obscure the stent lumen but still allows for visualization of adjacent structures. Patients with nitinol stents are the optimal candidates for MRA, while those with elgiloy or stainless steel stents may experience significant artifacts that compromise visualization of the stent lumen and limit morphological resolution of the stent wall [76]. However, artifacts may arise even with nitinol stents secondary to stent geometry [77]. Due to severe susceptibility artifact associated with stainless steel embolization coils, MRA is poor in the follow-up of patients who have undergone coil embolization of the internal iliac artery before EVAR [35]. MRA of the post-EVAR aorta shares multiple features with CTA. Like CTA, isotropic 3-D MRA images may be reformatted in any plane for volume analysis or orthogonal diameter measurements. In patients with nitinol stents, aortic diameter measurements for MRA have been shown to be as reliable as those obtained with CTA [78]. MRA has been shown to be more sensitive than CTA for the detection of endoleaks [35,79]. Consequently, the higher rate of endoleak detection seen by MRA in cases with a negative CTA may shed light on the phenomenon of endotension [80].