Cardiac CT Imaging in Patients with Atrial Fibrillation Cardiac CT (CCT) scanning remains problematic in atrial fibrillation (AF) in several ways because of inadequate temporal resolution: □ The heart rate tends to be higher in patients with AF ( Table 22-1 ). TABLE 22-1 CTA Characteristics of Patients in Sinus Rhythm and in Atrial Fibrillation Data from Wolak A, Gutstein A, Cheng VY, et al. Dual-source coronary…

Recent technical advances in cardiac CT (CCT) have been driven largely by the requirements for accurate noninvasive coronary angiography. As a consequence of improved image quality and temporal resolution, attention has also turned to the broader application of cardiac CT assessment to other disease entities. The role of CT in the assessment of cardiomyopathy has, to date, been largely restricted to the measurement of left ventricle…

Myocardial Crypts Myocardial crypts (or clefts) have been defined as discrete V-shaped extensions of the blood pool inserting more than 50% into the compact myocardial wall that tend to be less visible during systole and are not associated with local hypokinesis or dyskinesia. Increased prevalence of crypts has been reported in carriers of the gene for hypertrophic cardiomyopathy (as much as 81%). However, myocardial crypts also…

Assessment of Left Ventricular Volumes And Systolic Function The excellent spatial resolution of contrast-enhanced cardiac CT (CCT) permits the delineation of accurate endocardial and epicardial borders to a degree exceeding that of cardiac MRI. The avoidance of epicardial chemical shift artifact and the clear distinction between blood pool and myocardium (due to less blurring from partial volume effects and elimination of flow artifacts on cine gradient…

Infectious Endocarditis Although it is still early in the process of validating cardiac CT (CCT), this test may have a role to play in the assessment of aortic valve endocarditis—less to assess vegetations than to assess the aortic root for abscesses. The erratic oscillatory motion of many vegetations, and their irregular surfaces, render the lesions underrepresented, principally due to partial volume averaging effects. Complications of endocarditis…

Currently, only preliminary data are available on the evaluation of prosthetic cardiac valves by CCT, although contemporary CCT, if cardiac gated, can yield excellent images of many prosthetic valves. Prosthetic valve disease, though, is prone to many of the factors that pose significant technical limitations or usual exclusions to cardiac CT, such as a high incidence of atrial fibrillation associated with prostheses in the mitral valve…

At the present time only preliminary data exist on the evaluation of cardiac valves by cardiac CT (CCT), although contemporary CCT, if cardiac gated, can yield excellent images of native valves. Valve disease, however, is subject to many of the factors that present significant technical limitations or usual exclusions to CCT. Atrial fibrillation, which often coexists with mitral value disease, is an example of such a…

Pericardial diseases are numerous and diverse, and imaging has a central role in their evaluation. Currently, echocardiography is the principal test for pericardial disease assessment, because two-dimensional imaging and Doppler assessment are highly feasible by echocardiography, the test is portable, and it can be used to guide drainage procedures. However, several forms of pericardial disease—notably pericarditis and constrictive pericarditis, as well as cysts and congenital absence…

In many laboratories, calcium scoring is performed before coronary CT angiography (CTA) is (contingently) performed. If the score (for example, the Agatston score) is above a certain amount (for example, >600) the coronary CTA is not performed, because the CTA image quality is not likely to be adequate in the presence of extensive calcification. Thus, calcium scoring as an initial scan may obviate the radiation exposure…

Lesions of the coronary artery ostia and of the left main stem coronary artery are of higher clinical and angiographic risk. Left main coronary ostial lesions are notable for being found more commonly among middle-aged women with fewer conventional coronary artery risk factors and for lower long-term patency of internal thoracic grafts. Although conventional angiography is the gold standard for assessment of ostial and left main…

Although coronary artery dissections are rare overall (0.1–0.3% incidence in angiographic series), when they do occur it is usually within the settings of the pregnant or peripartum state, blunt chest trauma, iatrogenesis, or severe exertion or stress, or associated with one of several medical conditions (see Etiologies and Associations). Coronary artery dissections may be single or multiple and may involve all three coronary arteries and the…

Coronary aneurysms have been identified in 0.5% to 4% of patients undergoing coronary angiograms. The incidence among patients undergoing coronary CT angiography (CTA) has not been determined. The most common definition of a coronary artery aneurysm is focal dilation of the artery, 1.5 times normal (adjacent reference segment or elsewhere maximal vessel) diameter, and limited to spherical or saccular dilation—a standard and borrowed convention of the…

Coronary Artery Fistulae A coronary artery fistula (CAF) is a solitary communication between a coronary artery and one of any of the following: cardiac chambers or arterial venous, coronary venous, or pulmonary arterial conduits—that is, a disorder of coronary artery termination. Coronary artery fistulae also may be of anomalous origin. The incidence of CAFs in the population is unknown. The incidence within angiographic series is 0.1%…

A wide range of coronary artery anomalies have been described, reflecting the many permutations of abnormalities of the following anatomic details: □ The location of the ostium: Which sinus of Valsalva Where in the sinus of Valsalva Ascending aorta The aortic arch The descending aorta The innominate artery The common carotid artery The internal thoracic artery The pulmonary artery A bronchial artery The left ventricle □…

Coronary Bypass Graft Assessment Coronary bypass grafts, both venous and arterial, are more readily evaluated by CT angiography (CTA) than are coronary arteries, because of: □ Their large diameter (more so for venous than arterial conduits) □ Their minimal motion, when compared with coronary arteries, because they are largely extracardiac □ Their general lack of calcification, versus the common and often extensive calcification of native coronary…

CCT Imaging of Coronary Stents The accurate assessment of coronary stents remains a major challenge for cardiac CT (CCT), and although the stent itself is readily imaged, the lumen within it is not, because the stent material confers “blooming” artifact. Stents with a denser “weave” are harder to image. A stent deployed within a stent for restenosis leaves little chance of accurately depicting the lumen. Small…

ACC/AHA 17-Segment Coronary Model Comparative studies of coronary CT angiography (CTA) versus angiographic quantitative coronary analysis (QCA) assessment of coronary anatomy usually are performed comparing the presence or absence of angiographically significant stenosis (>50%) among the “17-segment model” of coronary anatomy. Imaging Coronary Arteries: Luminal Assessment Imaging of the coronary artery lumen is a particular challenge for CT scanning, given: □ The small luminal size (especially…

All forms of imaging are subject to artifacts, and proficiency with artifact recognition and suppression is critical for best practice of any form of imaging, including cardiovascular CT (CVCT). In terms of diagnostic imaging, what sets the heart apart from all other organs is the rapidity of its motion. Motion of any sort remains one of the most common causes of artifacts for all modalities of…

Optimal Enhancement Vascular and cardiac blood pool contrast enhancement is determined by the interaction of iodine administration and blood flow. The goals of contrast administration are: □ Adequate opacification of cavities and vessel lumen □ Avoidance of both under- and over-opacification. It is important to recognize that excessive contrast concentration generates high attenuation artifact. Starburst high-attenuation artifacts from the superior vena cava (SVC) are among the…

Context and Perspective Although the risk per single CT scan is small, given the enormous numbers of CT scans performed, this risk is neither small nor dismissible. Approximately 60 to 65 million CT scans of all types were performed in the United States in 2006 —one per five citizens. The rate is increasing at 10% to 25% per year. Approximately two thirds of a billion CT…