Prospective electrocardiogram-gated axial 64-detector computed tomographic angiography vs retrospective gated helical technique to assess coronary artery bypass graft anastomosis: comparison of image quality and patient radiation dose.
BACKGROUND
In the present study the effective dose and image quality at distal anastomoses were retrospectively compared between prospective electrocardiogram (ECG)-gated axial and retrospective ECG-gated helical techniques on 64-detector computed tomographic (CT) angiography following coronary artery bypass graft surgery.


RESULTS
Following bypass surgery, 52 patients with a heart rate <65 beats/min underwent CT angiography: 26 patients each with prospective and retrospective ECG gating techniques. The effective dose was compared between the 2 groups using a 4-point scale (4, excellent; 1, poor) to grade the quality of curved multiplanar reformation images at distal anastomoses. Patient characteristics of the 2 groups were well matched, and the same CT scan parameters were used for both, except for the interval between surgery and CT examination, tube current, and image noise index. Image quality scores did not differ significantly (3.26+/-0.95 vs 3.35+/-0.87; P=0.63), but the effective dose was significantly lower in the prospective (7.3+/-1.8 mSv) than in the retrospective gating group (23.6+/-4.5 mSv) (P<0.0001).


CONCLUSIONS
Following bypass surgery, 64-detector CT angiography using prospective ECG gating is superior to retrospective gating in limiting the radiation dose and maintaining the image quality of distal anastomoses.
Department of Radiology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan. machira@dnh.twmu.ac.jp
Haruhiko
H
Machida
Ai
A
Masukawa
Isao
I
Tanaka
Rika
R
Fukui
Kazufumi
K
Suzuki
Eiko
E
Ueno
Kojiro
K
Kodera
Kiyoharu
K
Nakano
Yun
Y
Shen
D000368:Aged; D000714:Anastomosis, Surgical; D017023:Coronary Angiography / Q000379:methods*; D001026:Coronary Artery Bypass; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000601:surgery*; D003952:Diagnostic Imaging / Q000592:standards; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*