Researchers outline expanded role for cardiac CT

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CHICAGO—Researchers defined a series of promising cardiac CT applications at the 94th annual meeting of the Radiological Society of North America (RSNA). In several studies, functional cardiac CT competed well with other modalities including MRI and various forms of echocardiography.
Xiao-Chun Zhang, MD, of Sichuan University in Chengdu, China, presented results of three studies comparing cardiac CT with MRI, transesophageal echocardiography (TEE) and real-time 3D echo. The first study demonstrated that 64-slice CT, compared with MRI, can accurately assess right ventricular systolic and left ventricular diastolic function to quantify the severity of pure rheumatoid mitral stenosis. Researchers also reported that the CT results were highly reproducible.
The second study found that CT fared well compared to TEE to quantify pure rheumatoid mitral stenosis. The third study found that CT accurately assessed the right ventricular function and size in patients with mitral regurgitation compared with MRI and real-time 3D echo.
Troy LaBounty, MD, of Weill Cornell Medical College in New York City, presented a pair of studies. The first one retrospectively compared transthoracic echocardiography (TTE) and CT studies of 33 patients to evaluate mechanical aortic valve replacements. The utility of echocardiography is limited in such cases because of shadowing artifacts. LaBounty reported high intra-observer agreement on CT studies and concluded that CT may be useful in evaluating valve functioning in patients with Medtronic Hall and St. Jude valves.
Next, LaBounty shared data showing that both TEE and CT can be used to detect aortic valve calcification, which is associated with increased adverse events, and concluded that CT may provide useful prognostic information in patients with aortic stenosis.
Another clinical cardiac application where CT could replace TEE is pre-operative characterization of aortic valve features in patients with aortic stenosis. Diagnostic imaging provides critical information used to guide clinical decision-making about the procedure and prosthesis. A research team led by Baskaran Sundaram, MBBS, of the University of Michigan in Ann Arbor, retrospectively reviewed 80 patients. The researchers found that aortic valve assessment using dynamic CT is feasible and determines leaflet morphology precisely. CT grading of aortic valve calcifications, mobility, and thickening had fair to moderate agreement with TEE.
Jin Hur, MD, of Yonsei University in Seoul, South Korea presented the final study, which showed that two-phase 64-slice coronary CT angiography offers a noninvasive and sensitive modality for detecting left atrial appendage thrombus and differentiating between thrombus and spontaneous echocardiographic contrast (SEC) in stroke patients.