CT calcium scoring also useful for diagnosing artery anomalies

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 - cCTA vs CCS
A 40-year-old female presenting with exertional shortness of breath. (a) Transverse image of a noncontrast-enhanced calcium scoring study demonstrates an anomalous origin (arrow) of the right coronary artery (RCA) from the pulmonary artery. (b) Transverse contrast enhanced computed tomography angiogram at the same level verifies the abnormal origin. (c) Three-dimensional reconstruction with arrow indicating the RCA origin.
Source: Acad. Rad. 2013;20:554-9

Coronary artery anomalies—both benign and malignant—can be detected with relatively high accuracy on noncontrast-enhanced coronary artery calcium scoring (CCS) studies, according to a study published in the May issue of Academic Radiology.

While contrast-enhanced coronary CT angiography (cCTA) provides an accurate diagnostic tool, the results of the study show CCS could serve as a contrast-free technique of spotting abnormalities, according to Christian Thilo, MD, of Medical University of South Carolina, Charleston, and colleagues.

“In addition to their use for the detection and quantification of coronary calcium, CCS studies should be carefully reviewed for malignant coronary artery anomalies which may have an impact on patient care,” wrote the authors.

Findings were based on a study of 126 patients, mean age of 62 years, who underwent both CCS and cCTA. A pair of readers were blinded to patient information and evaluated each CCS study for visibility of coronary artery origins, detection of anomalies and a benign or malignant course, with cCTA serving as the reference standard.

Results showed the study population contained 33 coronary anomalies, of which 16 were benign and 17 were malignant. The rates in which both the readers correctly identified the left main origin, left anterior descending origin, the circumflex origin and right coronary artery origin were all relatively high, between 81.7 and 99.2 percent, according to the authors.

Reader 1 and reader 2 identified 34 and 27 coronary anomalies and classified 19 and 15 as malignant, respectively. On average, Thilo and colleagues reported that coronary artery anomalies were diagnosed with 85.2 percent sensitivity, 96.4 percent specificity, 90.5 percent positive predictive value and 94.1 percent negative predictive value on CCS studies.

Reader 2 had a number of false negatives, and the authors speculated this was likely due to differing reader assumptions. When reader 2 could not detect the origin of a coronary artery, he did not suspect an anomaly, whereas reader 1 diagnosed anomalies in cases where origins were not detected.

“Increased risk of myocardial ischemia results from malignant coronary anomalies with their course between the aorta and the main pulmonary artery. Excluding atherosclerotic disease, the frequency of implication of coronary anomalies in sudden cardiac death is second only to hypertrophic cardiomyopathy,” wrote Thilo and colleagues. They added that detection of anomalies ahead of symptoms allows for treatment using beta-blockers, coronary angioplasty with stent or surgical repair.