Prospective ECG-Gated Coronary 320-MDCT Angiography With Absolute Acquisition Delay Strategy for Patients With Persistent Atrial Fibrillation

OBJECTIVE: The purpose of this study was to evaluate image quality and radiation dose when patients with atrial fibrillation undergo coronary CT angiography (CTA) using prospectively ECG-gated 320-MDCT technology with an absolute-delay strategy. MATERIALS AND METHODS: A cohort of 75 consecutive patients (60 men and 15 women; age (± SD), 71 ± 10 years) who underwent prospectively ECG-gated coronary CTA using a 320-MDCT scanner during atrial fibrillation was matched with 75 control patients imaged in sinus rhythm. All coronary CTA for the atrial fibrillation cohort used absolute-delay strategy. Subjective image quality score and the dose-length product (DLP) were compared between the two cohorts and, for the atrial fibrillation cohort, among those patients imaged over a different number of heartbeats. The accuracy of stenosis detection was evaluated in 17 studies of the atrial fibrillation cohort using catheter angiography as a reference standard. RESULTS: For those patients imaged in atrial fibrillation, one- and two-beat acquisitions were performed in 26.7% (n = 20) and 40% (n = 30) of patients, respectively. There was no significant difference in image quality between the atrial fibrillation (2.9 ± 0.4) and sinus rhythm (2.9 ± 0.3) cohorts, nor was there a difference in image quality with respect to the number of heartbeats used in the acquisition. The atrial fibrillation cohort had an 80% higher DLP (680 ± 470 vs 372 ± 236 mGy × cm, p < 0.0001). The patient-based sensitivity and negative predictive value for stenosis detection were both 100%. CONCLUSION: Using an absolute-delay strategy, two thirds of patients who underwent prospectively ECG-gated coronary CTA using a 320-MDCT scanner were imaged within two heartbeats or fewer. Compared with patients imaged in sinus rhythm, the image quality was comparative and the radiation dose was 1.8-fold higher.