CT coronary angiography using 16 and 64 simultaneous detector rows: intraindividual comparison

Multislice computed tomography (MSCT) is an emerging noninvasive technique for detecting coronary artery stenoses. An intraindividual study comparing 16- and 64-slice CT coronary angiography is highly desirable but has not been performed thus far. We sought to intraindividually compare MSCT using 16 and 64 simultaneous detector rows for noninvasive coronary angiography.

A total of 33 patients (23 men, 10 women) underwent MSCT coronary angiography using both 16 x 0.5 and 64 x 0.5 mm detector collimation at an interval of 2.1 +/- 0.4 years and were included in this head-to-head evaluation. A comparison of the image quality of noninvasive coronary angiography and effective radiation dose was performed.

The overall coronary vessel lengths visualized and the vessel lengths depicted free of motion artifacts were significantly longer using 64-slice CT compared to 16-slice CT for the left anterior descending (134 +/- 28 vs. 115 +/- 40 mm and 128 +/- 34 vs. 113 +/- 41 mm), left circumflex (106 +/- 31 vs. 90 +/- 39 mm and 105 +/- 30 vs. 86 +/- 36 mm), and right coronary artery (153 +/- 33 mm vs. 137 +/- 47 mm and 142 +/- 44 mm vs. 107 +/- 61 mm) (all: p < 0.05). The overall subjective image quality on a 5-point scale (5 = maximum quality, 1 = minimum quality) was also significantly (p < 0.001) higher with 64-slice than with 16-slice CT for vessel contrast (4.6 +/- 0.7 vs. 4.1 +/- 1.0, p < 0.001), vessel continuity (4.8 +/- 0.6 vs. 4.5 +/- 1.1, p < 0.001), and the depiction of coronary sidebranches (4.9 +/- 0.3 vs. 4.6 +/- 1.1, p < 0.001). The improvement in image quality was mainly due to a significant reduction in the breathhold time necessary for 64-slice CT (8.9 +/- 0.9 sec vs. 28.5 +/- 4.6 sec, p < 0.001). The amount of intravenous contrast agent required was significantly smaller with 64-slice CT (80 +/- 6 ml vs. 108 +/- 11 ml, p < 0.001), while the effective radiation dose was significantly higher for 64-slice CT (16.9 +/- 2.4 mSv vs. 12.1 +/- 2.1 mSv, p < 0.001).

The results indicate that MSCT coronary angiography using 64 simultaneous detector rows yields higher image quality for depiction of the coronary arteries and entails a lower intravenous contrast agent amount but higher radiation exposure.