Heart: Low-dose CCTA delivers accuracy, less radiation than angio
Low-dose cardiac computed tomography angiography (CCTA) allows for the accurate evaluation of coronary artery disease, but with significantly less effective radiation dose to patients compared with coronary angiography, according to a study in the October issue of Heart.

According to Philipp A. Kaufmann, MD, director of nuclear cardiology at University Hospital in Zurich, Switzerland, although coronary angiography has been the “gold standard” for detecting coronary lesions, “its associated costs, morbidity and mortality have driven a search for alternatives like CCTA.”

A newer scanning protocol using prospective ECG-triggering—where scanning is limited to a narrow predefined end-diastolic phase resulting in a massive reduction in radiation exposure—has been “well received,” the authors wrote. Kaufmann and colleagues compared coronary angiography versus CCTA with prospective ECG-triggering in the same patients on a head-to-head basis.

For purposes of the study, 42 patients referred for suspected coronary artery disease (CAD) were prospectively enrolled to undergo a low-dose CCTA without calcium scoring a day before coronary angiography. The symptoms for CAD included dyspnea (nine participants), typical angina pectoris (seven participants), atypical chest pain (19 participants) and pathological exercise test or ECG (14 participants).

The dose-area product of coronary angiography and dose-length product of CCTA were measured, converted into effective radiation dose and compared using Mann-Whitney U tests. Accuracy of CCTA to detect CAD was assessed using coronary angiography as the reference standard.

Kaufmann and colleagues estimated the mean effective radiation dose was approximately 8.5 mSv for coronary angiography and 2.1 mSv for CCTA. Forty patients were correctly classified as having CAD (23/23) or no CAD (17/19). More than 97 percent of segments were evaluated.

Vessel-based analysis revealed sensitivity, specificity, positive and negative predictive value of 94.2 percent, 94.8 percent, 89 percent and 97.4 percent, respectively, and an accuracy of 94.6 percent.

The authors concluded their results not only confirm the feasibility and reliability of this CCTA protocol, but with less effective radiation dose to patients compared with coronary angiography.