Diagnostic quality of dual-source coronary CT examinations performed without heart rate control: importance of obesity and heart rate on image quality.

ABSTRACT

OBJECTIVES: For dual-source cardiac computed tomography (CT) scans without heart rate (HR) control, the influence of body habitus on quality is uncertain. We evaluated study quality across a range of HRs and body size. METHODS: One hundred sixty subjects were randomly selected for 4 HR groups (<70, 70-79, 80-89, ≥90 beats per minute) from 703 subjects who underwent cardiac CT without premedication. Coronary visualization quality was scored on a 3-point scale (1, nondiagnostic; 2, diagnostic; 3, excellent). RESULTS: Ninety-nine percent of coronaries were diagnostic quality. Six vessels were nondiagnostic, mostly due to motion. Nondiagnostic or diagnostic scores (<3) were greatest in the group with HR of more than or equal to 90 beats per minute. All normal weight subjects had excellent quality, but 6% of vessels in overweight and 17% in obese subjects had diagnostic scores less than 3. The mean effective dose was 11.4 mSv and correlated with body size. CONCLUSIONS: Diagnostic quality cardiac CT examinations can be obtained without premedication regardless of body size.