Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. CT coronary angiography may also be performed as an alternative to coronary catheterization when SPECT/CT MPI shows perfusion deficit or CMR stress perfusion imaging shows ischemia or wall motion abnormality in a vascular distribution [25]. FDG-PET/CT Heart FDG-PET/CT can be used as the alternative method to SPECT/CT MPI for assessing viability when myocardial ischemia is suspected or to assess blood flow to the branch pulmonary arteries after the ASO. FDG-PET/CT can have confirmatory and/or incremental value to TEE and CTA in diagnosing prosthetic endocarditis after RV-PA conduit placement, particularly when anatomic imaging findings are inconclusive or equivocal. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of TGA after arterial switch. MRA Chest MRA chest provides important information regarding extracardiac structures such as the branch pulmonary arteries, ascending aorta, and the aortic arc, and is used in conjunction with CMR for morphology and function to provide comprehensive evaluation of the cardiovascular system after treatment for TGA. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of TGA after arterial switch. MRI Heart Function and Morphology CMR yields accurate and reproducible data regarding both LV and RV size and function, differential pulmonary blood flow, neoaortic root diameter and regurgitant blood flow, coronary artery diameter, myocardial perfusion, and myocardial fibrosis. CMR provides important information regarding myocardial performance and viability, as well as quantitative assessment of valvar function and accurate evaluation of conduits [21]. If the echocardiographic Congenital or Acquired Heart Disease assessment of ventricular parameters or the severity of valve regurgitation is in question, CMR can resolve this uncertainty [26].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. The quantitative data on CMR can be validated by comparing the main pulmonary artery flow to the sum of the branch pulmonary artery flows. CMR using 3-D steady-state free precession navigator respiratory gated sequences can noninvasively evaluate the coronary arteries looking for ostial stenoses or proximal kinking and screen for myocardial injury using perfusion and viability sequences [27,28]. MRI Heart Function with Stress CMR is the most useful imaging modality to screen for myocardial ischemia [28]. CMR coronary angiography can provide good resolution images of coronary lumen especially in adolescents and larger children, but it is inferior in comparison with CTA in young children [26]. Myocardial stress perfusion MRI can also be done when there is a concern for ischemia following arterial switch procedure [28,29]. Radiography Chest Radiography of the chest can be used for the preliminary assessment of stent position, pacemaker and lead position, and as needed during the course of follow-up. SPECT or SPECT/CT MPI Rest and Stress Coronary reimplantation during ASO increases the risk of long-term ischemic complications in the postoperative period. SPECT/CT MPI is used when patient symptoms or ECG findings are concerning for myocardial ischemia [30]. US Echocardiography Transesophageal TEE is useful in patients with poor transthoracic acoustic windows, during intraoperative imaging, and in patients (usually adolescents) who require cardioversion for arrhythmia. It is typically used to assess the adequacy of intraoperative repair. If postoperative access to the transthoracic window is limited, TEE can be used to assess the coronary artery origins and flow patterns in the early postoperative period. Arteriography Coronary with Ventriculography Coronary angiography is traditionally reserved for interventional procedures or when noninvasive diagnostic imaging with CT or MRI is inconclusive. It can correctly identify all types of anomalous coronary arteries.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. However, it lacks optimum 3-D information and the ability to image soft tissue, making it difficult to demonstrate the spatial relationship among the coronary artery course, myocardium, and great vessels. Coronary angiography is essential to clarify the extent of the vulnerable territory of the anomalous vessel (ie, dominant versus nondominant right coronary artery, single coronary, etc). Fractional flow reserve may offer an adjunct to determine the functional significance of AAOCA narrowing or intramyocardial course of the coronary artery, although it is unproven in these settings. Congenital or Acquired Heart Disease In Kawasaki disease, to predict the progress of the disease and determine appropriate treatment and follow-up protocols, it is essential to understand the size and shape of the aneurysms in the early phase. Therefore, traditionally, invasive angiography is performed after the acute stage but, since the advent of CT and MRA invasive coronary angiography, has become second line [33]. Intravascular Ultrasound (IVUS): IVUS affords precise sequential cross-sectional imaging of the coronary lumen and coronary wall thickness with a discriminating power, based on superior spatial resolution. It is particularly useful in stenosis of the anomalous vessel in its intramural course. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. CT Heart Function and Morphology Functional assessment with CT may be considered in the setting of Kawasaki disease for assessment of the consequences of coronary artery compromise. CTA Chest CTA of the chest is rarely helpful for assessment of other vascular involvement in the setting of Kawasaki disease, with axillary artery aneurysms being a common manifestation in the chest.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. MRA of the chest and abdomen is more useful to CTA due to its ability to interrogate a wider vascular territory for screening for aneurysms in the setting of Kawasaki disease [34]. CTA Coronary Arteries CTA of coronary arteries is currently the most useful imaging modality for evaluating coronary arteries. Virtual angioscopic view of coronary CTA helps to evaluate anatomic high-risk features, such as the slit-like morphology of the ostium [35]. CT can identify other anatomic high-risk features, such as acute take-off angle, luminal shape, and proximal narrowing of the anomalous coronaries related to the intramural and interarterial course [35]. Coronary CTA, overall, provides a more accurate depiction of the entire anomalous vessel including the distal coronary segments. Coronary CTA is also useful in the setting of Kawasaki disease to screen for the presence and extent of coronary involvement by ectasia, aneurysm, or stenosis and to diagnose and follow-up the presence of mural thrombus in larger aneurysms. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. MRA Abdomen MRA abdomen is used to screen for extracardiac involvement in Kawasaki disease, with iliac aneurysms being a common manifestation of the disease. MRA Chest MRA chest allows 3-D reconstruction visualization of coronary artery origin and proximal course in AAOCA and the presence of coronary aneurysms in Kawasaki disease, but its spatial resolution is inferior to that of coronary CTA. MRA using 3-D steady-state free precession or 3-D fast gradient echo techniques can be used to evaluate the proximal coronary in AAOCA or the coronary tree in Kawasaki disease. MRA may also be performed with intravenous (IV) contrast to assess the systemic arterial tree for evidence of extracardiac aneurysms in Kawasaki disease [36-38].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. MRI Heart Function and Morphology CMR offers a wealth of additional relevant information including valvular function, ventricular function, regional contractility, and myocardial viability, all of which could be important considerations during the preoperative evaluation or postoperative follow-up in patients who undergo surgical repair of coronary artery. MRI Heart Function with Stress Pharmacological stress CMR cine and MPI can be performed to assess the functional relevance of a coronary anomaly [36,39]. Congenital or Acquired Heart Disease Radiography Chest There is no relevant literature to support the use of chest radiography in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. SPECT or SPECT/CT MPI Rest and Stress Nuclear cardiac imaging modalities play an important role in assessing myocardial perfusion, thus allowing for assessment of the functional relevance of any acquired coronary artery. SPECT MPI and PET MPI may unmask ischemia in asymptomatic and symptomatic patients with anomalous coronary artery [40]. The panel disagreed on SPECT or SPECT/CT MPI rest and stress to screen for myocardial ischemia as the next imaging study after TEE, although its use was supported by expert opinion in centers with pediatric experience with coronary ischemia. US Echocardiography Transesophageal TEE may be useful to visualize coronary artery anatomy perioperatively when the thoracic window is limited. However, TEE is not useful for routine imaging of AAOCA or Kawasaki disease. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of suspected or confirmed congenital or acquired coronary artery abnormality. Variant 5: Child. Known single ventricle physiology. Preoperative evaluation for stage 2 single ventricle palliation. Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Single ventricle lesions are congenital heart anomalies in which one of the 2 ventricular chambers is either absent or so severely hypoplastic that a biventricular repair is impossible. Typically, the atrioventricular valve associated with the absent or hypoplastic ventricle is also absent or hypoplastic. The arterial outflow valve associated with the absent/hypoplastic ventricle is also frequently affected. Single ventricle congenital heart defects cover a wide spectrum including the following: hypoplastic left heart syndrome, tricuspid atresia, unbalanced atrioventricular, pulmonary atresia with intact ventricular septum, Ebstein anomaly, and double outlet left ventricle. The repair of this entity involves 3-staged reconstruction to establish a circulatory system wherein all the deoxygenated blood flows directly into the lungs, bypassing the heart, while the oxygenated blood goes to the functional single ventricle to be pumped out to the systemic circulation. Stage 1 of this repair involves optimizing the pulmonary arterial blood flow, sometimes with a systemic-pulmonary arterial shunt or pulmonary artery band, and is performed shortly after birth. This procedure allows postoperative recovery and growth until stage 2 palliation can be performed. The stage 2 procedure, otherwise known as superior cavopulmonary connection, involves establishing a connection between the systemic venous return from the upper half of the body and the pulmonary arteries to allow deoxygenated blood flow into the pulmonary circulation. Some procedures in stage 2 are bidirectional Glenn, hemi-Fontan, and Kawashima operations. This procedure is typically performed within 6 months of birth. The primary goals of the imaging evaluation before the stage 2 operation include an assessment for obstruction in the pulmonary arteries and veins, the atrial septal defect, ventricular outflow tract, and aortic arch; for the degree and mechanism of valve regurgitation; and ventricular size and function.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Another role of imaging could be to decide if the ventricular volumes and functions still support the patient proceeding down the single ventricle pathway or if the patient is a candidate for a 1.5-ventricle or 2-ventricle repair. A crucial role of imaging in this setting is to demonstrate the pulmonary arterial anatomy, including the distal branches, to evaluate for anatomic obstruction that may impact the Glenn circulation. Knowledge of branch pulmonary artery anatomy adds significantly to the surgical planning process. A complete anatomic assessment of the branch pulmonary arteries to detect stenoses should be performed in all patients undergoing stage 2 repair. Arteriography Coronary with Ventriculography Direct cardiac catheterization and angiography has historically been the standard of care for assessing hemodynamic and anatomic suitability before stage 2 repair. Its routine use is decreasing since the advent of advanced CMR and CT methods. The use of catheter angiography is supported in the literature [41]; for example, in patients with pulmonary atresia and intact ventricular septum, the diagnosis of RV dependent coronary circulation is established by RV and selective coronary angiography and has an important impact upon surgical approach. Congenital or Acquired Heart Disease One of the advantages of cardiac catheterization before bidirectional Glenn operation is that anomalies such as systemic-to-pulmonary collateral vessels and aortic coarctation can be palliated using transcatheter techniques. It particularly pertinent for those who have undergone prior stage 1 palliation with aortic arch reconstruction, which is associated with a 10% to 15% incidence of recurrent coarctation at the distal end of the arch reconstruction [42]. Arteriography Pulmonary Cardiac catheterization is useful for the imaging evaluation before stage 2 repair to assess pulmonary arterial anatomy before surgical repair [41].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Routine cardiac catheterization is less frequently performed before undertaking stage 2 repair, but it has a useful role in the assessment of hemodynamic suitability to adapt to this type of circulation by directly measuring pulmonary vascular resistance. CTA Chest CTA chest is a useful modality and provides accurate means of evaluation of pulmonary arterial anatomy and pulmonary and systemic venous status before stage 2 repair. Thrombosis of the systemic-to-pulmonary arterial shunt may occur in 6% to 17% of cases and constitutes a surgical emergency [44]. CTA can be used as the confirmatory test especially if echocardiography is inconclusive. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of known single ventricle physiology. MRA Chest MRA chest is an excellent imaging technique for the evaluation of pulmonary arterial anatomy before stage 2 repair. It has the advantage that it can be easily combined with MRI heart function and morphology for a complete evaluation of the single ventricle patient. MRA has great diagnostic utility compared with echocardiography and is accurate in comparison to catheter angiography for the diagnosis of pulmonary artery stenoses. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known single ventricle physiology. MRI Heart Function and Morphology CMR allows for the quantification of ventricular volume and function, with abnormal ventricular morphology [42]. This can be useful in decisions regarding stage 1, 1.5, or 2 ventricle repair. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known single ventricle physiology. Radiography Chest Other than evaluation of patent ductus arteriosus or aortopulmonary shunt stent positioning, there is no relevant literature to support the use of radiography chest in the evaluation of known single ventricle physiology.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known single ventricle physiology. Congenital or Acquired Heart Disease FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known single ventricle physiology. US Echocardiography Transesophageal TEE may provide useful information before, during, or after surgery for stage 2 palliation regarding pulmonary arterial or pulmonary venous flow patterns, severity of atrioventricular valve regurgitation, atrial shunt, and cardiac thrombus. Variant 6: Child. Known single ventricle physiology. Preoperative evaluation for stage 3 single ventricle palliation (total cavopulmonary connection). Incomplete or inadequate assessment of cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. The Fontan operation for single ventricle patients is the procedure in which a conduit (the total cavopulmonary connection) is placed to channel the remaining systemic venous return (including the hepatic veins) into the pulmonary arteries. The aim of the diagnostic evaluation before Fontan is to identify those few patients in whom the Fontan operation should not be performed and those who require additional intervention before or at the time of Fontan. The main consideration before Fontan procedure is elevated pulmonary artery pressure, which determines the prognosis during the postoperative course. However, with the modern stage 2 repair techniques, pulmonary resistance is seldom an important issue at the pre-Fontan stage. Arteriography Coronary with Ventriculography Cardiac catheterizations are done when elevated pulmonary artery pressure or elevated ventricular filling pressure is suspected.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Cardiac catheterization also provides an opportunity for interventional procedures before the Fontan operation consisted of embolization of aortopulmonary collateral vessels [45]. Other important indications for cardiac catheterization include severe atrioventricular valve regurgitation semiquantitatively evaluated by means of echo color Doppler, suspected pulmonary vein stenosis at echo or CMR, suspected pulmonary pathway or Glenn anastomosis obstruction, or suspected significant venovenous collaterals at MRA [46]. Arteriography Pulmonary Pulmonary arteriography is performed after echocardiography when there is a suspicion of branch pulmonary artery stenosis because smaller pulmonary arteries are not optimally seen on echocardiography. CTA Chest Pulmonary embolism and thrombosis are known complications in patients undergoing single ventricle palliation. CTA is an effective method for diagnosis of pulmonary embolism in patients presenting with symptoms suspicious for pulmonary embolism [48]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of known single ventricle physiology. MRI Heart Function and Morphology Routine preoperative imaging before Fontan procedure is obtained using CMR for anatomy and to determine the current hemodynamics and physiology [49,50]. CMR is a comprehensive modality for accurate assessment of ventricular function, pulmonary artery, pulmonary venous return, cavopulmonary anastomosis, aortic arch, valves, and any valvular regurgitation. Congenital or Acquired Heart Disease MRA Chest MRA chest provides good assessment of branch pulmonary arteries, their caliber, and presence of thrombus within but often fails to visualize very small aortopulmonary collaterals that may require preoperative embolization. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known single ventricle physiology.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known single ventricle physiology. Radiography Chest Other than evaluation of device or stent positioning, there is no relevant literature to support the use of radiography chest in the evaluation of known single ventricle physiology. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known single ventricle physiology. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known single ventricle physiology. US Echocardiography Transesophageal TEE may provide useful information before, during, or after surgery for stage 3 palliation regarding pulmonary arterial or pulmonary venous flow patterns, severity of atrioventricular valve regurgitation, atrial shunt, and cardiac thrombus. Variant 7: Child or adult. Known single ventricle physiology. Postoperative evaluation after stage 3 single inadequate assessment of ventricle palliation (total cavopulmonary connection). Incomplete or cardiovascular morphology and function after transthoracic echocardiography. Next imaging study. Stage 3 repair for single ventricle palliation involves baffling of all systemic venous drainage directly to the pulmonary arteries, known as total cavopulmonary connection or Fontan operation. This is typically performed between 2 to 4 years of age and most commonly consists of either a lateral tunnel intracardiac baffle or an extracardiac conduit, with or without a fenestration. The Fontan operation also ensures that hepatic blood flow is directed into the lungs via the pulmonary arteries, thus preventing the formation of pulmonary arteriovenous malformations. Today, the estimates of 20-year survival for survivors of the Fontan procedure vary between 61% and 85% [51].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Early diagnosis and management of complications associated with Fontan physiology hold the most promise for improving longevity. Imaging after stage 3 repair can assess anatomy, ventricular and valve function, blood flow, and myocardial fibrosis. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals. Considerations for assessment of flow include quantification of the degree of aortopulmonary and venovenous collateralization, the relative flow within the 2 branch pulmonary arteries, and valvular regurgitation. Considerations for assessment of ventricular function and morphology include screening for systolic and diastolic dysfunction, ventricular type and shape, and myocardial characterization. Arteriography Coronary with Ventriculography Clinical indications for this examination include investigating symptoms associated with decreased ventricular function such as unexplained volume retention, fatigue, exercise limitation, and cyanosis. Cardiac catheterization with coronary angiography can evaluate coronary artery anatomy, and ventriculography can be used to estimate the function of the single ventricle and valvular flow. Cardiac catheterization is also helpful to assess the presence and severity of aortopulmonary, systemic-pulmonary venous, and systemic venovenous collaterals and also provides access to perform embolization of clinically significant collaterals. Cardiac catheterization is also suggested in the Congenital or Acquired Heart Disease assessment of patients with failing Fontan physiology and features of Fontan-associated liver disease. Imaging of a patent fenestration is seen well with direct angiography on cardiac catheterization [52].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Arteriography Pulmonary Cardiac catheterization for pulmonary angiography can be performed when pulmonary artery stenosis is detected on echocardiography or MRI and pulmonary artery angioplasty is indicated [52]. CT Heart Function and Morphology CT heart function and morphology is indicated when MRI is limited by the presence of significant metallic susceptibility artifact obscuring the heart or due to the presence of MR-incompatible pacemakers/devices. CTA Chest CTA is useful for assessment of anatomy after stage 3 repair. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals [52,53]. After Fontan surgery, imaging of coronaries, systemic arteries, and Fontan circuit require different timing and dose considerations, and dedicated contrast injection and scanning protocols designed for the Fontan circulation are needed to optimize the study [48]. CTA Coronary Arteries CTA of the coronary arteries is useful and allows for high spatial resolution evaluation of coronary artery anatomy in patients after stage 3 repair [52]. FDG-PET/CT Heart There is no role for routine performance of FDG-PET imaging after stage 3 palliation in single ventricle. FDG- PET/CT of the heart can be performed in the setting of changes of clinical status that might indicate underlying cardiac dysfunction. MRA Abdomen There is no relevant literature to support the use of MRA abdomen after stage 3 repair. MRA Chest MRA chest can provide accurate anatomic characterization of stage 3 repair. Anatomic considerations include the presence of thrombus in the circuit, the patency of the extracardiac conduit, stenoses within the caval veins and pulmonary arteries, and the size and location of aortopulmonary collaterals and venovenous collaterals [52,53].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Gadolinium-enhanced CMR angiography has been demonstrated to be more accurate in the diagnosis of a collateral vessels in comparison to catheter angiography and offers promise to plan transcatheter interventions in those who prove to have clinically significant collateral vessels. Of note, MRA chest has lower spatial resolution compared with CTA chest for small vessels such as the coronary arteries [52]. MRA Neck There is no relevant literature to support the use of MRA neck after stage 3 repair. MRI Heart Function and Morphology CMR is used regularly in addition to echocardiography for long-term monitoring of Fontan patients. MRI for heart function and morphology is helpful in assessment of anatomy, ventricular and valve function, flows, and myocardial fibrosis. It allows for estimating ventricular function, quantifying valvular regurgitation, quantifying pulmonary and systemic blood flow, and aortopulmonary collaterals [54]. Late gadolinium enhancement CMR is used to detect myocardial fibrosis and infarction [55]. Phase-contrast MRA flow measurements in the branch pulmonary arteries are useful for the quantification of differential pulmonary blood flow in the Fontan patient compared with nuclear scintigraphy, due to venous streaming effects on caval flows [53]. Four-dimensional flow, with or without the use of blood pool contrast agents, has been used to simplify, accelerate, and abbreviate the MR scanning protocol in these patients [56]. MRI Heart Function with Stress There is no role for routine performance of vasodilator stress perfusion after stage 3 palliation in single ventricle. There is some evidence that vasodilator stress perfusion MRI can be used to assess latent diastolic dysfunction after stage 3 repair [57,58]. Congenital or Acquired Heart Disease Radiography Chest There is no relevant literature to support the routine use of chest radiography after stage 3 palliation in single ventricle.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. However, chest radiography may be used to screen for the location of devices and metallic implants that are placed in this patient population. SPECT or SPECT/CT MPI Rest and Stress There is no role for routine performance of vasodilator stress perfusion after stage 3 palliation in single ventricle. SPECT or SPECT/CT MPI rest and stress tests are used in the setting of changes of clinical status that might indicate underlying cardiac dysfunction. US Echocardiography Transesophageal TEE can be used for comprehensive evaluation of the heart and central vascular anatomy, ventricular and valvular function, and flows in areas that are difficult to assess by TTE. One area in which it is better than TTE is in the detection of intracardiac thrombus. Variant 8: Child or adult. Known or suspected anomalous pulmonary venous return with inadequate evaluation after transthoracic echocardiography. Next imaging study. Total anomalous pulmonary venous connection (TAPVC) refers to the condition in which all of the pulmonary veins drain into the right atrium, either directly or indirectly through other systemic pathways. TAPVC is rare, with prevalence estimated at approximately 0.01% [59]. The contexts of imaging in TAPVC management are to define the surgical anatomy, when one or more pulmonary veins are not visualized by TTE, a TTE showing right-sided cardiac chamber dilation with unclear delineation of the pulmonary venous anatomy, when obstruction is suspected, or when there is an associated abnormality like a varix that is not characterized adequately by TTE. There is also an important role for imaging in the postoperative period after TAPVC repair to screen for recurrent obstruction. Partial anomalous pulmonary venous connection (PAPVC) is where one or more pulmonary veins drains into the right atrium, either directly or indirectly. PAPVC is more common with a prevalence at approximately 1% [59]. PAPVC has a few common variants.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. The most common form is where the left upper pulmonary vein connects to the left brachiocephalic vein into the superior vena cava. Another type is where the right upper pulmonary veins connect directly into the superior vena cava, which is commonly associated with other left to right shunts, including atrial septal and superior sinus venosus defects. Another unique variant of PAPVC is Scimitar syndrome, in which part or all of the right pulmonary veins connect to the inferior vena cava through the diaphragm. The right lung is often hypoplastic and/or has anomalous bronchial or arterial anatomy in addition to the PAPVC. The ultimate management of PAPVC is usually surgical correction, but unlike TAPVC, this does not always happen shortly after birth due to delayed diagnosis or mild symptoms. Advanced imaging in diagnosis of PAPVC is usually requested in the setting in which a TTE shows right-sided cardiac chamber dilation with unclear delineation of the pulmonary venous anatomy. The role of imaging in PAPVC management is to confirm the diagnosis, define the surgical anatomy, and quantify the shunt to help decide on need for and timing of intervention. Arteriography Coronary with Ventriculography Cardiac catheterization was traditionally the imaging modality used for the diagnosis of TAPVC and PAPVC; however, it has mostly been replaced by less invasive modalities [60]. Cardiac catheterization can be used to demonstrate the anatomy and quantify the degree of shunting using oximetry. However, cardiac catheterization has been shown by some studies to be less accurate in the setting of PAPVC [61]. Occasionally, simultaneous depiction of systemic and pulmonary vascular systems may be difficult in catheter angiography due to overlapping views of adjacent vascular structures. Moreover, it carries high risk of mortality in obstructive TAPVC.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. The main role for a cardiac catheterization is now in the rare patient with TAPVC who requires interventional cardiac palliation before complete repair, such as atrial septostomy or stent placement [62,63]. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. CT Heart Function and Morphology CT heart function and morphology is indicated when MRI is limited by the presence of significant metallic susceptibility artifact obscuring the heart or due to the presence of MR-incompatible pacemakers/devices. Congenital or Acquired Heart Disease CTA Chest CTA chest is useful for the anatomical definition of anomalous pulmonary venous drainage anatomy. CTA chest can also be used in the critical setting of possible obstructed TAPVC to define the level and degree of obstruction, especially in children with infracardiac and mixed TAPVC [64,65]. In obstructed infradiaphragmatic TAPVC, CTA chest can correctly depict the drainage site of the common pulmonary vein, stenosis of the vertical vein, and the course of the atypical vessel into the systemic vein, especially outside the usual echocardiographic windows [66]. In other types of TAPVC and PAPVC, CTA chest has excellent spatial resolution and can help define the complete anomalous drainage pathways of the pulmonary veins. CTA chest has the added advantage of being an excellent modality for evaluating the pulmonary parenchyma to look for associated pulmonary and bronchovascular abnormalities (eg, pulmonary sequestration, hypoplastic lung, abnormal bronchial branching) [64,67,68]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. MRA Abdomen Vascular imaging of the abdomen may be helpful in the cases of infracardiac TAPVC or PAPVC to demonstrate the drainage of pulmonary vein into hepatic vein or portal vein. It may be needed to assess the resulting complications such as portal venous system aneurysm formation and collaterals. MRA Chest MRA chest is excellent at identifying the anatomy, specifically the anomalous course and connections of the pulmonary veins [68,69]. A small case study showed that MRA chest was more accurate than both echocardiography and cardiac catheterization in accurately identifying the anomalous veins in 7 patients with TAPVC [70]. MRI Heart Function and Morphology MRI heart function and morphology is complementary to MRA chest and can be performed during the same imaging session. MRI heart function and morphology is useful in cases of PAPVC, because it is the ideal noninvasive modality to quantify the shunt amount by means flow rate assessment, ventricular muscle masses, and ventricular volumes and function [68,71]. The shunt quantification is usually performed using phase-contrast imaging through the aorta and pulmonary vein. MRI Heart Function with Stress There is no relevant literature to support the use of MRI heart function with stress in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. Radiography Chest Chest radiography may demonstrate additional findings such as associated dextrocardia, signs of vascular congestion, and pulmonary edema, which may point towards obstructed TAPVC [65]. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of known or suspected anomalous pulmonary venous return with inadequate evaluation after TTE. US Echocardiography Transesophageal TEE can be used in cases of PAPVC in which TTE does not completely delineate the partial veins and cardiac chamber enlargement [72,73]. However, the procedure is more invasive than CT or MRI, and it can suffer from Congenital or Acquired Heart Disease airways obscuring some of the acoustic windows, especially for anomalous venous drainage that occurs superior to the right atrium. TEE is also less accurate than MRI for some pulmonary vein anatomy and shunt quantification [72]. TEE has just recently been shown to be safe in patients with TAPVC, but only after median sternotomy [74]. There is no published role for TEE as the most useful imaging modality after an insufficient TTE with suspicion for TAPVC. Variant 9: Child or adult. Suspected aortic coarctation with inadequate evaluation after transthoracic echocardiography. Next imaging study. Coarctation of aorta (CoA) refers to discrete or diffuse narrowing in the aorta causing obstruction to the flow of blood. It accounts for 6% to 8% of all CHDs [75]. Aortic coarctation can be more commonly associated with other cardiac lesions such as bicuspid aortic valve, aortic arch hypoplasia, aberrant aortic branch vessels, and other intracardiac and conotruncal defects. This variant will focus on imaging recommendations for aortic coarctation and associated aortic arch pathology. If a patient has associated intracardiac or conotruncal abnormalities, please refer to those variants for recommendations on how to image those concurrent diseases. Aortic coarctation is managed by surgical treatment, transcatheter balloon angioplasty, and transcatheter stent placement.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Arteriography Coronary with Ventriculography Before advances in echocardiography, cardiac catheterization was the mainstay for making the diagnosis of CoA. The pressure gradient across the coarctation segment and the collateral vascularity can be accurately assessed with direct angiography. In the current era, it is primarily used when as catheter-based investigation such as balloon angioplasty or stent insertion are being considered [76]. Arteriography Pulmonary There is no relevant literature to support the use of pulmonary arteriography in the evaluation of known or suspected aortic coarctation. CT Heart Function and Morphology There is no relevant literature to support the use of CT heart function and morphology in the evaluation of suspected aortic coarctation, although its use was supported in adults by expert opinion in situations in which TEE windows are inadequate. The panel agreed that CT for function is not useful for a child in this clinical scenario. CTA Chest CTA chest is a complementary imaging modality in patients with suspected aortic coarctation after echocardiography. In patients with suboptimal arch imaging with echocardiography, CTA chest works as a great tool to assist with surgical planning [77-79]. Aortic coarctation is often associated with a hypoplastic aortic arch, and CTA chest is helpful in identifying the severity of arch hypoplasia, the length of the hypoplasia, and the relative origins of the aortic arch branch vessels in relation to the coarctation and arch hypoplasia [79]. CTA Coronary Arteries There is no relevant literature to support the use of CTA coronary arteries in the evaluation of suspected aortic coarctation. MRA Abdomen There is no relevant literature to support the use of MRA abdomen in the evaluation of suspected aortic coarctation. MRA Chest MRA chest can be used as the second line of imaging after echocardiography in young children who do not require sedation and adolescents [79,80].


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. One advantage of MRA chest is that it can be combined with MRI heart function and morphology to quantify the degree of collaterals around the coarctation, more accurately estimate pressure gradients across the coarctation, and assess associated cardiac and conotruncal abnormalities [81,82]. MRI Heart Function and Morphology MRI heart function and morphology can quantify the degree of collaterals around the coarctation. It can also be easily combined with an MRA chest to provide more comprehensive evaluation in patients with aortic coractation and associated cardiac and conotruncal abnormalities [75]. Congenital or Acquired Heart Disease MRI Heart Function with Stress There is no relevant literature to support the additional use of MRI heart function with stress in the evaluation of suspected aortic coarctation. MRA Neck There is no relevant literature to support the use of MRA neck in the evaluation of suspected aortic coarctation. Radiography Chest Radiography chest has limited clinical utility in diagnosis. Conventional signs on the chest radiograph may be subtle and not always easy to appreciate but may provide clues about the presence of an aortic coarctation. SPECT or SPECT/CT MPI Rest and Stress There is no relevant literature to support the use of SPECT or SPECT/CT MPI rest and stress in the evaluation of suspected aortic coarctation. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of suspected aortic coarctation. US Echocardiography Transesophageal TEE is used for intraoperative imaging when other cardiac abnormalities are present in conjunction with CoA. The role of TEE for Doppler examination is limited because the ultrasound beam is almost perpendicular to the line of blood flow, leading to inaccuracies in velocity estimation.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Common manifestation of Marfan syndrome include annuloaortic ectasia with or without aortic valve insufficiency, aortic dissection, aortic aneurysm, pulmonary artery dilatation, and mitral valve prolapse. Aortic root aneurysms are present in up to 98% of patients with Loeys-Dietz syndrome, with thoracic aortic dissection being the leading cause of death (67%), followed by abdominal aortic dissection. Arterial tortuosity is a distinguishing feature of Loeys-Dietz syndrome, and there is a propensity for involvement of the extracranial carotid arteries and vertebral arteries [83]. Other cardiovascular abnormalities described in Loeys-Dietz syndrome include coronary artery aneurysms, pulmonary artery aneurysms, and aneurysms of the ductus arteriosus. Ehlers-Danlos syndrome also predisposes to aortic dissections. Nearly 25% of people with bicuspid aortic valve may experience severe aortic valve dysfunction, ascending aortic aneurysm, cardiac death, hospital admission for heart failure, and aortic dissection or rupture [84]. Children with aortopathy require regular imaging surveillance to measure the aortic diameter, status of the aortic valve, and cardiac functional status. Current surgical mandate is based on aortic diameter cutoffs to decide the time of surgical intervention [85,86]. The guidelines from the American Heart Association provide thresholds for prophylactic replacement of the aorta, based primarily on aortic diameter or rapid aortic enlargement [87,88]. Arteriography Coronary with Ventriculography Coronary artery ectasia can be an associated finding in many connective tissue diseases like bicuspid aortic valve [89], Marfan syndrome, and systemic lupus erythematosus. Coronary arteriography has been useful for imaging, but in current practice, it is used only if coronary CTA or coronary MRA provide insufficient information.


Congenital or Acquired Heart Disease

Congenital or Acquired Heart Disease. Arteriography Pulmonary Pulmonary arteriography is seldom required for diagnosis or surveillance of pulmonary artery dilatation which can occur in Marfan syndrome. CTA Chest CTA chest may be used for imaging surveillance to measure the aortic diameter, and to screen for involvement of the arterial tree in the chest. CTA is especially useful in the emergent setting. ECG gating is critical for accurate assessment of the aortic root. CTA Coronary Arteries CTA is the most useful modality for the evaluation of coronary ectasia or aneurysms, which are often seen in the setting of connective tissue diseases. The diagnostic utility of CTA is very useful compared to coronary MRA in terms of spatial resolution and shorter scan duration. FDG-PET/CT Heart There is no relevant literature to support the use of FDG-PET/CT heart in the evaluation of suspected aortopathy or connective tissue disorder. MRA Chest MRA is the most useful modality for aortic assessment when TTE is suboptimal for assessment of aortopathy in pediatric patients due to its ability to screen multiple territories with the same contrast injection, including the head, neck, chest, and abdomen. To avoid multiple administrations of gadolinium-based contrast agents, follow-up imaging of the aortic root may be performed with noncontrast MRA techniques like cine gradient echo and navigator respiratory gated 3-D steady-state free precession. MRA may offer further valuable information, when complemented with phase-contrast flow data in bicuspid aortic valve, about the possibility of associated valvular regurgitation and alterations in shear stress that may predispose to progressive dilation [91-93]. MRA Neck MRA neck is frequently performed at the same setting as MRA chest to screen for extracardiac vascular involvement in connective tissue disease and in all cases of aortopathy to measure vertebral artery tortuosity, which is used as a prognostic marker to determine risk of aortic dissection [94].


Hemoptysis

Hemoptysis.  Initial Imaging Definition Imaging is considered at the beginning of the care episode for the medical condition defined by the variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when: aRadiology Imaging Associates, Englewood, Colorado. bResearch Author, Keck School of Medicine of USC, Los Angeles, California. cPanel Chair, Vanderbilt University Medical Center, Nashville, Tennessee. dPanel Vice-Chair, University of California San Francisco, San Francisco, California. eStanford University Medical Center, Stanford, California; The Society of Thoracic Surgeons. fSchmidt College of Medicine, Florida Atlantic University, Boca Raton, Florida. gUniversity of Southern California, Los Angeles, California. hBeaumont Health System, Royal Oak, Michigan: American College of Emergency Physicians. iNaval Medical Center Portsmouth, Portsmouth, Virginia. jUniversity of Iowa Hospitals and Clinics, Iowa City, Iowa. kVanderbilt University Medical Center, Nashville, Tennessee; American College of Chest Physicians. lUniversity of Wisconsin, Madison, Wisconsin. mMallinckrodt Institute of Radiology, Saint Louis, Missouri. nJohn H. Stroger, Jr. Hospital of Cook County, Chicago, Illinois; American College of Physicians. oDuke University School of Medicine, Durham, North Carolina; The Society of Thoracic Surgeons. pThe University of Texas MD Anderson Cancer Center, Houston, Texas. qSpecialty Chair, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. 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 All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings.


Hemoptysis

Hemoptysis. 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 Current Procedural Terminology codes. Massive hemoptysis due to an unknown cause (ie, cryptogenic hemoptysis) has similar BAE outcomes compared with hemoptysis from a known cause. An early study treating cryptogenic hemoptysis with BAE was published in 2010 [22]. In this study, 39 patients with cryptogenic hemoptysis who presented with varying severity of hemorrhage were all treated medically. Hemoptysis remained uncontrolled in 21 patients, who subsequently underwent successful BAE; 2 patients had recurrent hemoptysis. A second retrospective review compared BAE outcomes of 26 patients with cryptogenic hemoptysis to 152 patients with a known cause of hemoptysis over the same interval. Both groups showed a 100% immediate success rate following BAE, and both groups demonstrated similar recurrence rates (12% versus 25%, respectively, which was not statistically different) [8]. Over 90% of massive hemoptysis is due to a systemic arterial supply, and therefore conventional pulmonary arteriography is rarely performed. An early study documenting this was authored by Sbano et al [23], reporting a pulmonary arterial bleeding origin in 8 of 76 patients with massive hemoptysis. Although all of these patients were initially treated with BAE, 7 out of 8 patients required additional pulmonary artery embolization. Shin et al [24] identified 10 patients with pulmonary artery pseudoaneurysms (PAPs) out of 286 patients presenting with massive hemoptysis undergoing BAE. These authors reported a pulmonary artery embolization success rate above 90%. Khalil et al [25] retrospectively reviewed 272 patients, 13 of whom had bleeding from a pulmonary artery origin. Of these 13 patients, 11 underwent pulmonary artery embolization, all of which were successful.


Hemoptysis

Hemoptysis. The largest study to date isolating patients with massive hemoptysis due to a pulmonary arterial source identified 24 patients from a cohort of 712 patients presenting with massive hemoptysis [26]. This study reported an 88% pulmonary artery embolization success rate. Overall, BAE is now universally accepted as a safe and effective intervention for the treatment of massive hemoptysis. CT Chest with IV Contrast The utility of CT in determining the cause for hemoptysis was first established in the late 1990s. Naidich et al [27] reported CT-bronchoscopic correlations of 58 patients with hemoptysis (severity not specified), showing CT was superior to bronchoscopy in both the diagnosis of lung cancer (17 CT positive versus 15 bronchoscopy positive) and definitive staging of lung cancer (48% versus 14%, respectively). They also established that CT was superior to radiography. Of the 23 normal chest radiographs, subsequent CT provided a definitive cause in 9 patients. Revel et al [28] published data from 80 patients with massive hemoptysis demonstrating CT was more efficient than the previous reference standard of bronchoscopy in identifying the etiology of hemoptysis (77% versus 8%, respectively; P < . 001). Based on these studies, CT can facilitate BAE planning by potentially identifying a specific lesion or isolating the bleeding artery based on increased arterial diameter and wall irregularity in a high percentage of cases. CT Chest without IV Contrast Several early studies have established the use of CT in the diagnosis of hemoptysis used high-resolution CT (HRCT). For example, Tsoumakidou et al [32] followed 184 patients with varying degrees of hemoptysis, demonstrating that HRCT identified a cause in 41% of patients with a normal chest radiograph. In 2008, Khalil et al [25] reported on the utility of performing HRCT in the emergent management of hemoptysis in the intensive care unit.


Hemoptysis

Hemoptysis. With the advancement of technology, the vast majority of CT examinations can be reformatted to the resolution of the previously ordered HRCT, and there is rarely an added benefit of HRCT to a routine CT. Khalil et al [33] subsequently published a study retrospectively evaluating patient outcomes comparing a cohort of patients who had a CT without IV contrast with a cohort of patients who underwent CTA. There was a statistically significant difference in the number of emergent surgical resections following embolization in patients who did not have a CTA preceding the BAE (10% CT without cohort versus 4.5% CTA cohort). IV contrast is also well established as an agent that significantly improves the visualization of mediastinal structures. As discussed above, IV contrast shows an added benefit to preprocedural embolization planning. Therefore, CT chest without IV contrast is only warranted in the diagnosis of massive hemoptysis in patients with poor renal function or life-threatening contrast allergy. CT Chest without and with IV Contrast Although early studies used CT chest protocols without IV contrast followed by with IV contrast, there are no data to support any added value of a CT chest without IV contrast prior to administering contrast in the diagnosis of hemoptysis or in preprocedural planning for BAE. CTA Chest CTA has also proven to be beneficial in detecting bronchial and nonbronchial arteries in preprocedural planning. Remy-Jardin et al [34] documented the utility of CTA for BAE preprocedural planning, demonstrating an 86% concordance rate between the 58 abnormal arteries identified on CTA compared with the gold standard of conventional arteriography. Hartmann et al [35] retrospectively reviewed 251 patients (with varying severity of hemoptysis) who were imaged by CTA. Of these 251 patients, 214 had CTAs that were of diagnostic quality without confounding central mediastinal pathology.


Hemoptysis

Hemoptysis. The purpose of this study was to analyze the frequency of aberrant and ectopic locations of bleeding arteries. Of the 24 patients who required BAE, 36% had aberrant bronchial origins, and the authors asserted that CTA information guided successful and rapid catheterization in 22 patients and precluded repeated arteriograms. CTA information changed treatment strategy in 2 of the 24 patients with aberrant arteries, resulting in initial treatment with surgical ligation rather than BAE because of an anticipated high risk of Hemoptysis embolization based on vascular location. Mori et al [36] were also early in advocating CTA for preprocedural planning, identifying bronchial artery diameter as an important diagnostic clue on CTA in determining the bleeding artery requiring embolization. Jiang et al [37] reported results from 818 patients obtaining a CTA for preprocedural BAE planning, which isolated 6 aberrant arteries that would not have been detected by standard angiographic procedures. Lin et al [38] also reported a high concordance rate between CTA and conventional arteriography, reporting that 107 of the 110 arteries embolized (97%) were prospectively identified on CTA. This article noted that CTA was useful in both identifying the number of vessels involved in hemoptysis as well as identifying collateral vessels and shunts that increase the risk of complications during arterial embolization. As discussed in the section above, approximately 10% of massive hemoptysis is due to a pulmonary arterial source, which can be occult on bronchial arteriography. Khalil et al [25] retrospectively reviewed 272 patients, 13 of whom had bleeding from a pulmonary artery origin. Of these 13 patients, 8 were initially and successfully treated with pulmonary artery embolization based on the CTA findings, and 3 more patients were subsequently imaged and successfully treated with pulmonary artery embolization after BAE failed to treat the hemoptysis. This study highlighted CTA guiding embolization therapy.


Hemoptysis

Hemoptysis. A study by Shin et al [24] also documented the importance of detecting a pulmonary artery source of hemoptysis prior to embolization. In his study of 286 patients presenting with massive hemoptysis, they used CTA to identify 10 patients for a total of 11 PAPs as the source of the massive hemoptysis by CTA prior to undergoing BAE. Of these 11 PAPs, 6 PAPs detected on CTA could not be detected prospectively on conventional pulmonary arteriography, but CTA guided subselection pulmonary arteriography and resulted in successful embolization of the bleeding artery. The authors reported a pulmonary artery embolization success rate of over 90%. A subsequent study by Shin et al [26] also identified patients presenting with massive hemoptysis due to a pulmonary arterial source. Out of 712 patients with massive hemoptysis, 24 patients demonstrated PAPs on their preprocedural CTA examination. Fifteen of these PAPs identified on CTA were also visualized on pulmonary arteriography, all of which were successfully embolized. The remaining 9 PAPs identified on CTA were not detectable on conventional pulmonary arteriography and were subsequently treated with bronchial and systemic nonbronchial embolization, resulting in a 33% rate of hemoptysis cessation. Persistently symptomatic PAPs were subsequently treated by percutaneous or surgical interventions based on CTA findings. There are no recent data comparing the diagnostic advantages between routine CT with IV contrast with CTA. However, CTA may offer a slight advantage over routine CT with IV contrast when the intention is to treat massive hemoptysis with BAE because CTA typically provides slightly better opacification of vessels, possibly improving detection of abnormal arteries potentially causing hemoptysis. At present, the vast majority of publications reporting BAE outcomes obtain CTA chest CTs prior to BAE for preprocedural planning.


Hemoptysis

Hemoptysis. Radiography Chest Chest radiography has long been established as the initial imaging examination of choice given its portability, rapid acquisition, and interpretation time. Fartoukh et al [12], in a large retrospective study of 1,087 patients, correlated morbidity and mortality to findings on chest radiographs. However, there is discrepancy in the literature regarding the usefulness of radiographs in determining the etiology of hemoptysis. In a study of 70 patients undergoing bronchial artery embolization for massive hemoptysis, causative radiologic abnormalities were seen in 86% of the chest radiographs [39]. This was similar to an earlier study showing 82% of chest radiographs could detect the side and predict the cause of bleeding [40]. However, in a comparable study of 80 patients with massive hemoptysis, chest radiographs demonstrated the cause of bleeding in only 35% of cases, most of whom had tuberculosis or malignancy [28]. Although radiography can be useful in directing treatment to the correct site of bleeding, a study of 20 patients undergoing BAE for massive hemoptysis showed that radiography localized the site of hemoptysis in only 35% of patients [41]. Similar findings were reported in a larger study of 348 patients, which included both massive and moderate recurrent hemoptysis patients [17]. Chest radiographs were performed in all patients and were abnormal in 313 patients (90%). However, these radiographs were suggestive of the etiology of hemoptysis in only 90 patients (26%). These findings indicate that additional imaging in conjunction with chest radiograph is warranted in massive hemoptysis. Hemoptysis 44]. However, these prior variables excluded a significant portion of patients with nonmassive hemoptysis. In addition, imaging recommendations did not significantly differ between the two prior nonmassive hemoptysis variables. For these reasons, these risk factors have been removed, and there is a single nonmassive variable.


Hemoptysis

Hemoptysis. Additional recent studies reporting BAE as a viable therapeutic option for nonmassive hemoptysis includes Dave et al [46], who reported BAE outcomes on 58 patients. In this study, 17% of the population presented with nonmassive hemoptysis, and the top two causes of hemoptysis were bronchiectasis and malignancy. The success rates proved to be similar between patients presenting with nonmassive versus massive hemoptysis. This study asserted that nonmassive hemoptysis might be the harbinger of future episodes of massive hemoptysis, especially in patients with underlying lung disease. These results justify BAE as a treatment of nonmassive hemoptysis. Woo et al [18] reported BAE outcomes on 406 patients, 30% of whom presented with nonmassive hemoptysis. This study also demonstrated similar success rates between patients with nonmassive versus massive hemoptysis. Shin et al [19] reported BAE outcomes on 163 patients, including 41% presenting with nonmassive hemoptysis; outcomes were not stratified by hemoptysis severity. Bhalla et al [15] reported similar post-BAE outcomes between patients presenting with nonmassive versus massive hemoptysis. Ishikawa et al [47] published the largest study on outcomes for nonmassive hemoptysis. Elective BAE was performed on 489 noncancer patients from Japan with varying degrees of nonemergent hemoptysis. They reported immediate bleeding cessation in 93% of patients, with 87% and 58% of patients remaining free of hemoptysis at 1 and 3 years, respectively. The most common causes of hemoptysis in this study were bronchiectasis (34%) and nontuberculous mycobacterium (24%). Cryptogenic nonmassive hemoptysis has demonstrated a very high immediate and long-term success rate following BAE. In a retrospective study [48] reviewing 319 patients, 35 patients were identified as having cryptogenic hemoptysis, 23 of whom reported nonmassive hemoptysis.


Hemoptysis

Hemoptysis. Thirty-three of the 35 patients with cryptogenic hemoptysis were successfully treated with BAE, and 97% of these patients remained free of hemoptysis at 20 months. The authors reported that there was no correlation between severity of hemoptysis and the diameter of the embolized bronchial artery. These results were not compared to the patients with a known cause of hemoptysis. CT Chest with IV Contrast As with massive hemoptysis, CT with IV contrast is the primary modality to determine hemoptysis etiology. Thirumaran et al [44], in an early study establishing CT as a diagnostic tool for nonmassive hemoptysis, retrospectively studied 270 patients with hemoptysis and a normal chest radiograph, with 94% reporting mild hemoptysis, and commonly with repeated episodes. Although the most common cause of hemoptysis was acute bronchitis (63%), the second most common cause was a respiratory tract neoplasm, the majority of which was a lung primary malignancy (n = 22/270). Lee et al [49] reported performing CT examinations on all 221 patients evaluated for hemoptysis, 48% with nonmassive hemoptysis and 52% with massive hemoptysis. Interestingly, both cohorts had similar etiologies, with bronchiectasis followed by active tuberculosis as the leading causes for hemoptysis, and CT proved to be the superior diagnostic imaging modality over bronchoscopy and arteriography for identifying the cause of hemoptysis. CT with IV contrast is now the established imaging modality to determine the etiology of nonmassive hemoptysis, and therefore, there are no recent publications comparing its efficacy to other imaging modalities. CT Chest without IV Contrast As discussed in Variant 1, CT chest without IV contrast is only warranted in the diagnosis of hemoptysis in patients with poor renal function or life-threatening contrast allergy. The limited number of studies reviewing the utility of


Hemoptysis

Hemoptysis. Hemoptysis CT chest without IV contrast for the evaluation of hemoptysis did not differentiate between massive versus nonmassive quantities of hemoptysis. CT Chest without and with IV Contrast Although very early publications studying the utility of CT in patients presenting with nonmassive hemoptysis performed chest protocols including acquisitions both without IV contrast followed by acquisitions with IV contrast, there are no data to support that there is any added value of CT chest without IV contrast prior to the administration of IV contrast in the diagnosis of nonmassive hemoptysis or in the preprocedural planning of BAE. CTA Chest There are no recent studies comparing the benefits of a routine chest CT with IV contrast to CTA in patients with nonmassive hemoptysis. As previously discussed, preprocedural CTA or routine CT with IV contrast has become the standard of care for arterial planning of BAE. In a recent study reporting the outcomes of BAE in patients with primarily nonmassive hemoptysis, all 489 noncancer patients underwent a CTA prior to embolization [47]. The authors noted that conventional aortography previously used to detect origins of the bleeding bronchial arteries was effectively replaced by arterial mapping information provided by CTA. Radiography Chest Chest radiographs continue to be a reasonable initial imaging choice in patients with nonmassive hemoptysis, especially when used to confirm a clinical diagnosis for benign disease such as acute bronchitis or pneumonia. There are no recent studies comparing the utility of chest radiographs with other imaging modalities. Variant 3: Recurrent hemoptysis. Initial imaging. Recurrent hemoptysis is a new variant for this update. It is defined as repeated episodes of hemoptysis following initial treatment with either medical therapy or BAE. Typically, the etiology of recurrent hemoptysis is known and usually not life threatening, although there is a wide range of hemoptysis severity.


Hemoptysis

Hemoptysis. Recent literature shows a trend of more commonly treating patients with nonmassive recurrent hemoptysis with interventional or surgical procedures rather than conservative therapies compared with patients with an initial presentation of nonmassive hemoptysis. Therefore, imaging recommendations differ between patients initially presenting with nonmassive hemoptysis and patients presenting with recurrent nonmassive hemoptysis. Hemoptysis outcomes were due to sequelae from BAE or sequelae from recurrent hemoptysis. Of the handful of studies documenting lack of clinically significant change following BAE, Tom et al [4] specifically studied long-term clinical parameters of patients prior to and following BAE. Of the 69 patients with hemoptysis initially treated with BAE, 17 patients had at least 5 years of clinical data before and 5 years of clinical data after the initial BAE. The authors identified that pulmonary function parameters declined at the same rate prior to the initial BAE as they had following BAE. CT Chest with IV Contrast Patients with recurrent hemoptysis typically have a known cause. Bronchiectasis due to repeated or indolent infection is the most common cause for recurrent hemoptysis in most large studies. In patients with cystic fibrosis, for example, recurrent hemoptysis may be an indicator of acute infection [60], and CT may not be indicated. There are limited data evaluating the utility of CT chest with IV contrast in the setting of a known cause of hemoptysis. CT Chest without IV Contrast There is no relevant literature supporting the use of CT chest without IV contrast in the assessment of recurrent hemoptysis. CT Chest without and with IV Contrast There is no relevant literature supporting the use of CT chest without IV contrast prior to a CT performed with IV contrast in patients with recurrent hemoptysis. CTA Chest There are no recent data comparing the diagnostic advantages between routine CT with IV contrast with CTA in patients with recurrent hemoptysis.


Workup of Noncerebral Systemic Arterial Embolic Source.  Introduction/Background Noncerebral systemic arterial embolism is an important cause of patient morbidity and mortality [1]. Arterial emboli can originate from a variety of cardiac and noncardiac sources. Cardiac sources include thrombus within the left atrium and left ventricle, valvular disease such as endocarditis, and cardiac neoplasms. Noncardiac sources of arterial embolism include thrombus and atherosclerosis within the aorta and peripheral arteries. Intracardiac thrombus has been thoroughly described in the cardiology and neurology literature with several factors that predispose its formation and the potential for arterial embolization. For example, atrial fibrillation has been shown to be a significant risk factor for atrial thrombogenesis [2,3]. Complex left atrial appendage morphology also confers increased likelihood of thrombus development [4]. Myocardial infarction often results in focal hypokinesis or akinesis of the left ventricular myocardium, which predisposes to thrombus formation [5,6]. Aortic and mitral valve endocarditis as well as valvular neoplasms are other potential sources for arterial embolism detectable with imaging [7,8]. Aortic thrombi tend to be associated with aortic pathology including dissection, aneurysm, or ulcerative lesions [9,10]. Thrombus formation can also occur in the aorta secondary to hypercoagulable states such as malignancy, trauma, postoperative states, hormonal therapy, and inherited hypercoagulable disorders [1,11,12]. When a cardiac or noncardiac embolic source dislodges, the resulting embolus can occlude a variety of peripheral and visceral arteries causing ischemia [1,9,11,12]. Characteristic locations for noncerebral arterial occlusion include the upper extremities, abdominal viscera, and lower extremities [1,9,11]. Ischemia in these regions can progress to tissue infarction resulting in limb amputation, bowel resection, or nephrectomy.


Workup of Noncerebral Systemic Arterial Embolic Source. Determining the source of arterial embolism is essential in order to direct treatment decisions. Treatment options vary and include anti-coagulation, endovascular or surgical embolectomy, and peripheral arterial angioplasty with or without stenting to maintain long- term vascular patency [1,9,11-14]. The variants in this document assume that the diagnosis of an arterial occlusion has already been established by other means. For example, in the setting of an acute onset cold painful leg, the use of lower extremity arteriography, CT angiography (CTA), or MR angiography (MRA) could be employed to demonstrate arterial occlusion. This document specifically pertains to the workup of a suspected embolic etiology of the already known arterial occlusion. aResearch Author, University of Texas Southwestern Medical Center, Dallas, Texas. bUT Southwestern Medical Center, Dallas, Texas. cNaval Medical Center Portsmouth, Portsmouth, Virginia. dPanel Chair, Emory Healthcare, Atlanta, Georgia. ePanel Chair, Duke University Medical Center, Durham, North Carolina. fPanel Vice-Chair, University of Michigan, Ann Arbor, Michigan. gPanel Vice-Chair, Massachusetts General Hospital, Boston, Massachusetts. hUniversity of Michigan, Ann Arbor, Michigan. iAllegheny Health Network, Pittsburgh, Pennsylvania. jUniversity of North Carolina School of Medicine, Chapel Hill, North Carolina. kSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. lVA Palo Alto Health Care System, Palo Alto, California and Stanford University, Stanford, California. mThe University of Texas MD Anderson Cancer Center, Houston, Texas; Commission on Nuclear Medicine and Molecular Imaging. nDuke University Medical Center, Durham, North Carolina, Primary care physician. oMayo Clinic, Rochester, Minnesota; Society of Cardiovascular Computed Tomography. pSpecialty Chair, UT Southwestern Medical Center, Dallas, Texas.


Workup of Noncerebral Systemic Arterial Embolic Source. qSpecialty Chair, Emory University Hospital, Atlanta, Georgia. 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 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. OR Discussion of Procedures by Variant Variant 1: Known upper extremity arterial occlusion. Suspected embolic etiology. Next imaging study to determine source. The variant assumes that an upper extremity arterial occlusion has already been established. Typically, this diagnosis is made by CTA, arteriography, or MRA, although the clinical examination or another imaging study could also be used. Aortography Chest Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of upper extremity arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to transesophageal echocardiography (TEE) [18-27].


Workup of Noncerebral Systemic Arterial Embolic Source. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared with intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31]. Complex left atrial appendage morphologies which predispose to thrombus formation can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast Multidetector chest CTA with intravenous (IV) contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without IV Contrast Chest MRA without IV contrast is an imaging study, which can detect the presence of thrombus in the thoracic aorta. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44].


Workup of Noncerebral Systemic Arterial Embolic Source. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities are lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast-enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45].


Workup of Noncerebral Systemic Arterial Embolic Source. Furthermore, cine cardiac MR had an 82% sensitivity and a 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared with a standard delayed enhancement cardiac MR [49]. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler ultrasound (US) of the abdomen as an initial imaging modality in the evaluation of the source of known embolic upper extremity arterial occlusion. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting Transthoracic echocardiography (TTE) is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the


Workup of Noncerebral Systemic Arterial Embolic Source. 5 Workup of Noncerebral Systemic Arterial Embolic Source transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and a 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Aortography Chest and Abdomen Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of mesenteric or renal arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared to intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31].


Workup of Noncerebral Systemic Arterial Embolic Source. Complex left atrial appendage morphologies that predispose to thrombus formation can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall, with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta, and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. CTA Chest and Abdomen With IV Contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57].


Workup of Noncerebral Systemic Arterial Embolic Source. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42]. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in 6 Workup of Noncerebral Systemic Arterial Embolic Source a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking.


Workup of Noncerebral Systemic Arterial Embolic Source. MRA Chest and Abdomen Without and With IV Contrast MRA of the chest and abdomen without and with IV contrast can be used to evaluate for presence of an embolic source in the aorta in its entirety. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast-enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data are insufficient [56-58]. Data comparing MRA of the chest and abdomen to other imaging modalities are lacking. MRA Chest and Abdomen Without IV Contrast Chest and abdomen MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the detection of abdominal aortic intraluminal thrombus, although there are insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest and abdomen to other imaging modalities are lacking.


Workup of Noncerebral Systemic Arterial Embolic Source. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies. A meta-analysis of 7 studies showed that delayed contrast-enhanced cardiac MR had a pooled sensitivity of 100% and a specificity of 99% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. In another meta-analysis, there was no significant difference in sensitivity and specificity between cardiac CT and cardiac MR in the detection of left atrial appendage thrombus [29]. Contrast- enhanced cardiac MR had a sensitivity of 88% and a specificity of 99% compared to surgical or pathological confirmation of left ventricular thrombus [46]. Cardiac MR is also an accurate imaging modality for the evaluation of valvular disease, including aortic and mitral valve vegetations, which can dislodge and result in arterial embolism [37,47]. Additionally, cardiac MR offers detailed soft tissue characterization for the analysis of benign and malignant intracardiac neoplasms [39,48]. MRI Heart Function and Morphology Without IV Contrast Cardiac MR without contrast provides a detailed anatomic evaluation of the heart chambers. In the workup of embolic sources, the primary role of cardiac MR is in the identification of intracardiac thrombus. A meta-analysis of 7 studies showed that cine cardiac MR had a pooled sensitivity of 91% and a specificity of 93% for detecting left atrial and left atrial appendage thrombus in patients with atrial fibrillation [45]. Furthermore, cine cardiac MR had an 82% sensitivity and 100% specificity in detecting left ventricle thrombus in postmyocardial infarction patients compared to a standard delayed enhancement cardiac MR [49].


Workup of Noncerebral Systemic Arterial Embolic Source. Cardiac MR without contrast is also capable of identifying valvular pathology and cardiac neoplasms, although data on its applicability in the setting of systemic arterial embolism are lacking. US Duplex Doppler Abdomen There is no relevant literature to support the use of Doppler US of the abdomen as an initial imaging modality in the evaluation of the source of known embolic mesenteric/renal arterial occlusion. However, some imaging 7 Workup of Noncerebral Systemic Arterial Embolic Source protocols may include limited views of the abdominal aorta that may detect intraluminal aortic thrombus or significant atherosclerotic disease [56]. US Echocardiography Transesophageal TEE is an invasive diagnostic study with the ability to detect cardiac pathology predisposed to embolism. TEE has a sensitivity of 93% to 100% and a specificity of 95% to 99% for detecting left atrial appendage thrombus when compared to intraoperative findings [31,50,51]. Furthermore, TEE can evaluate left ventricular systolic dysfunction, spontaneous echo contrast, slow left atrial appendage peak flow velocities, and complex left atrial appendage morphologies, which are all associated with left atrial thrombus and thromboembolic risk [2,4]. In addition, TEE can detect left ventricular thrombus, with 1 study reporting a 40% sensitivity and a 96% specificity for the modality compared to findings at surgery or pathology [46]. Proximal aortic thrombus can also be assessed using TEE, although evaluation is limited by blind spots (distal ascending aorta and proximal aortic arch) owing to air in the trachea [10,13]. Detection of valvular disease and intracardiac neoplasms can also be accomplished with TEE. US Echocardiography Transthoracic Resting TTE is a noninvasive imaging modality capable of detecting cardiac pathology susceptible to embolism.


Workup of Noncerebral Systemic Arterial Embolic Source. TTE is inferior to TEE in the assessment of left atrial appendage thrombus because the transducer is distant from the left atrium when placed on the chest [52]. In 1 study, a cardiac embolic source was detected by TEE in about 40% of patients with normal TTE [53]. In another study, a cardiac embolic source was identified by TTE in 15% of the study group compared with 57% by TEE [54]. Sensitivity and specificity were 23% and 96%, respectively, for the detection of left ventricular thrombus compared to findings at surgery or pathology [46]. In the detection of left ventricle thrombus, contrast-enhanced TTE had a 64% sensitivity and 99% specificity compared to a delayed enhancement cardiac MR standard [49]. TTE can also be applied for the diagnosis of valvular disease and cardiac neoplasms. There is no evidence to support the use of TTE in the evaluation of aortic thrombus. Aortography Chest, Abdomen, and Pelvis Conventional catheter aortography has largely been replaced by noninvasive imaging modalities such as CTA and MRA given their high sensitivity/specificity for detecting aortic pathologies such as mural thrombus [16,17]. Aortography is typically used as an alternative diagnostic strategy following initial noninvasive imaging and when therapeutic interventions are being considered [11,17]. CT Heart Function and Morphology With IV Contrast The primary role of cardiac CT in the initial evaluation of lower extremity arterial embolic occlusion is in the workup of cardiac thrombus as a source. Multiple studies have established high rates of atrial thrombus detection by cardiac CT compared to TEE [18-27]. Meta-analyses have found sensitivities of 96% to 99% and specificities of 92% to 94% for detection of left atrial or left atrial appendage thrombus with cardiac CT compared to a TEE reference standard [28-30]. When compared to intraoperative findings, cardiac CT was 100% sensitive and 85% specific for finding left atrial thrombus [31].


Workup of Noncerebral Systemic Arterial Embolic Source. Complex left atrial appendage morphologies, which predispose to thrombus formation, can also be characterized by cardiac CT [32-34]. Additionally, cardiac CT can differentiate left ventricular thrombus from the myocardial wall with 1 study demonstrating a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively [35]. Studies have also demonstrated cardiac CT to have comparable accuracy to TEE for identification of vegetations in the setting of infective endocarditis, another potential source of arterial embolism [36-38]. Cardiac CT can identify cardiac neoplasms, both benign and malignant, which have the potential to shed and embolize to distal arterial beds [39,40]. CTA Chest With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and a CTA limited to the chest may be diagnostic. As such, multidetector chest CTA with IV contrast can be used to evaluate for at-risk atherosclerotic plaque or the presence of thrombus in the thoracic aorta. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. A number of small studies have used chest CTA to detect aortic mural thrombus that was CTA Chest, Abdomen, and Pelvis With IV Contrast Multidetector CTA with IV contrast can be used to evaluate for the presence of at-risk atherosclerotic plaque or thrombus in the aorta in its entirety. CTA is useful in the assessment of the size, extent, and location of an embolic source in the aorta, which can aid in management decisions [13,41]. Aortic intraluminal thrombus is oftentimes associated with aneurysm, particularly in the abdomen, which is readily detected by CTA [56,57]. A number of small studies have used CTA to detect aortic mural thrombus that was suspected of embolization [1,12-14,42].


Workup of Noncerebral Systemic Arterial Embolic Source. Specific data on the sensitivity and specificity of this imaging modality are lacking. MRA Chest Without and With IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Data comparing MRA of the chest to other imaging modalities are lacking. MRA Chest Without IV Contrast In some conditions or clinical scenarios, there may be a high suspicion that the embolic source is in the thoracic aorta and an MRA limited to the chest may be diagnostic. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady- state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard; however, this analysis only included 1 case of mural thrombus [43]. Data comparing MRA of the chest to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast MRA of the chest, abdomen, and pelvis without and with IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety.


Workup of Noncerebral Systemic Arterial Embolic Source. In 1 study, detection of thoracic aorta pathology by contrast-enhanced chest MRA was equivalent in sensitivity, specificity, and diagnostic accuracy compared to noncontrast MRA, although only a single case of thrombus was included in the analysis [43]. On the other hand, in a small analysis which included 9 patients with aortic thrombus, contrast-enhanced MRA had a lower thrombus detection rate compared to a noncontrast examination, although this finding was not statistically significant [44]. Contrast- enhanced MRA of the abdomen has been used for intraluminal thrombus detection in the setting of aneurysms, although comparative data is insufficient [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRA Chest, Abdomen, and Pelvis Without IV Contrast Chest, abdomen, and pelvis MRA without IV contrast can be used to evaluate for the presence of an embolic source in the aorta in its entirety. One small study found this examination to have a higher detection rate for aortic thrombus when compared with contrast-enhanced MRA, although the difference was not statistically significant [44]. In another study, sensitivity, specificity, and diagnostic accuracy of unenhanced steady-state free precession MRA were 100% for the detection of thoracic aorta pathology compared to a contrast-enhanced MRA reference standard, however this analysis only included 1 case of mural thrombus [43]. Noncontrast MRA has been used for the detection of abdominal aortic intraluminal thrombus, although there is insufficient data comparing it to contrast- enhanced MRA [56-58]. Data comparing MRA of the chest, abdomen, and pelvis to other imaging modalities is lacking. MRI Heart Function and Morphology Without and With IV Contrast Cardiac MR is a noninvasive imaging study that can reliably detect intracardiac thrombus as well as valvular and neoplastic pathologies.