Accuracy of low-dose prospectively gated axial coronary CT angiography for the assessment of coronary artery stenosis in patients with stable heart rate

Background

Desirable methods for cardiac CT angiography would both reduce radiation exposure from cardiac CT angiography and preserve accuracy.

Objectives

We assessed image quality, radiation dose, and diagnostic accuracy of a low-dose, prospectively gated axial cardiac CT angiography protocol for the evaluation of patients with suspected coronary artery disease (CAD).

Methods

Fifty consecutive patients referred for diagnostic invasive coronary angiography (ICA) and with a stable heart rate < 60 beats/min after β-blocker administration were prospectively enrolled in a single center study. Subjects underwent CT angiography with a 64-row multidetector CT scanner with a prospectively gated axial imaging protocol. If the examination was determined to be nondiagnostic, then a retrospectively gated helical scan was performed. Two reviewers independently assessed image quality and the presence of significant coronary artery stenosis (>50%).

Results

Prospectively gated CT angiography was successfully performed in 46 of 50 patients. Of 794 coronary segments, 777 were determined to be of diagnostic image quality. The overall patient-based sensitivity (95% CI), specificity, positive predictive value, negative predictive value, and accuracy for the diagnosis of significant coronary stenosis were 100% (87%–100%), 75% (53%–90%), 81% (64%–93%), 100% (81%–100%), and 88% (81%–95%), respectively. The mean effective radiation dose for CT angiography and ICA were 3.4 ± 0.4 mSv and 6.9 ± 0.8 mSv, respectively.

Conclusions

Cardiac CT angiography performed in a prospectively gated axial mode with 64-row multidetector CT provides an accurate, low-dose alternative for the detection of CAD.

Keywords: Computed tomography, Coronary angiography, Coronary artery disease, Prospective ECG triggering, Radiation exposure