Image quality of 256-slice computed tomography for coronary angiography

Purpose: To assess the image quality of 256-slice computed tomographic angiography (CTA) and to identify possible impact factors associated with image quality. Methods: From November 2009 to January 2010, 506 patients underwent 256-slice CTA at our institute. A total of 451 patients were enrolled in our study, after 55 patients were excluded because of prior bypass surgery and stenting. CTA image quality was graded by two observers using a 4-point scale: excellent (score 1), good (score 2), moderate (score 3), poor and non-diagnostic (score 4). The coronary arteries were divided into 15 segments. Image quality was correlated to the subjects' age, gender, body mass index, heart rate, and calcium scores. Results: We evaluated 6650 coronary segments from CTA images of our enrolled 451 patients. The mean image quality score of all coronary segments was 1.14. Most coronary segments (99.7%) were assessable, and only 21 segments (0.3%) were non-diagnostic. A total of 5824 coronary segments were classified as having excellent image quality. Forty-two patients (9.3%) required control of heart ratewith beta-blockers before CTA could be performed. Male patients had better image quality than female patients. Heart rate and severity of calcification were impact factors associated with image quality. Conclusions: Examination with 256-slice CTA provides good image quality and can effectively evaluate most coronary segments.