High-Pitch Dual-Source CT Angiography of the Thoracic and Abdominal Aorta: Is Simultaneous Coronary Artery Assessment Possible?

OBJECTIVE. The purpose of this study was to prospectively evaluate the average heart rate and heart rate variability required for diagnostic imaging of the coronary arteries with high-pitch dual-source CT angiography of the thoracic and thoracoabdominal aorta. SUBJECTS AND METHODS. One hundred consecutively registered patients (82 men, 18 women; mean age, 68 +/- 13 years) underwent clinically indicated CT angiography of the thoracic (n = 33) and thoracoabdominal (n = 67) aorta with a dual-source 128-MDCT scanner in ECG-synchronized high-pitch (pitch, 3.2) data acquisition mode. No beta-blockers were administered. The image quality of the coronary arteries was graded on a 3-point scale by two independent blinded readers. The average heart rate and heart rate variability before data acquisition were noted. Effective radiation doses were calculated. RESULTS. Interobserver agreement on grade of image quality for the 1,414 coronary segments evaluated by both observers was good (kappa = 0.68). Diagnostic image quality was found for 1,375 of the 1,414 segments (97.2%) in 83 of 100 patients (83%). In 17% of the patients, image quality was nondiagnostic for at least one coronary artery segment. Average heart rate and heart rate variability (each p < 0.05) were significantly higher in patients with at least one nondiagnostic coronary segment compared with those without. All patients with an average heart rate less than 63 beats/min and heart rate variability less than 1.2 beats/min had diagnostic image quality in all coronary segments. Effective radiation doses were 2.3 +/- 0.3 mSv for thoracic and 4.4 +/- 0.5 mSv for thoracoabdominal CT angiography. The average scan times were 0.88 +/- 0.06 second for thoracic and 1.67 +/- 0.15 seconds for thoracoabdominal CT angiography. CONCLUSION. For patients with an average heart rate less than 63 beats/min and heart rate variability less than 1.2 beats/min, dual-source CT angiography of the thoracoabdominal aorta at a high pitch of 3.2 delivers diagnostic depiction of the coronary arteries at a low radiation dose.