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.