title: Coronary artery bypass grafts: ECG-gated multi-detector row CT angiography--influence of image reconstruction interval on graft visibility.
abstract: OBJECTIVE
  To evaluate the influence of different reconstruction intervals of retrospectively electrocardiographically (ECG)-gated multi-detector row computed tomographic (CT) angiography on image quality of different segments of various types of coronary artery bypass grafts.
  
  
  METHODS
  Twenty consecutive patients with 62 grafts underwent retrospectively ECG-gated four-channel multi-detector row CT angiography and conventional coronary angiography. Raw helical CT data were reconstructed at 0%-90% of the cardiac cycle in increments of 10%. Each graft was separated into three segments (proximal segment, graft body, and distal anastomosis). Three graft types were identified according to site of distal anastomosis. Two readers assessed image quality of segments and graft types. Effective radiation dose was calculated.
  
  
  RESULTS
  Best image quality of all segments was obtained at a reconstruction interval of 50%-70% of the cardiac cycle. Image quality of the proximal segment did not vary significantly with different reconstruction intervals (analysis of variance, P =.8), whereas image quality of the graft body and distal anastomosis changed significantly with varying reconstruction intervals (P <.001). Distal anastomosis and body of types 1 and 2 grafts were best seen at 60%-70% of the cardiac cycle, whereas distal anastomosis and body of type 3 grafts were best visualized at 50%. Accuracy of CT angiography for detection of graft patency was 94% for reader 1 and 95% for reader 2. Effective dose for CT was 11.4 mSv for both men and women. Mean effective dose for angiography was 2.1 mSv for men and women.
  
  
  CONCLUSIONS
  Optimal selection of reconstruction interval improves image quality of the graft body and of distal anastomosis in particular.
authors.affiliation: Institute of Diagnostic Radiology, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland.
authors.forename: Jürgen K
authors.initials: JK
authors.lastname: Willmann
authors.forename: Dominik
authors.initials: D
authors.lastname: Weishaupt
authors.forename: Richard
authors.initials: R
authors.lastname: Kobza
authors.forename: Francis R
authors.initials: FR
authors.lastname: Verdun
authors.forename: Burkhardt
authors.initials: B
authors.lastname: Seifert
authors.forename: Borut
authors.initials: B
authors.lastname: Marincek
authors.forename: Thomas
authors.initials: T
authors.lastname: Boehm
mesh_terms: D000368:Aged; D000714:Anastomosis, Surgical; D016477:Artifacts; D017023:Coronary Angiography / Q000592:standards; D001026:Coronary Artery Bypass / Q000379:methods*; D023903:Coronary Restenosis / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000592:standards; D005260:Female; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007387:Internal Mammary-Coronary Artery Anastomosis; D008297:Male; D008875:Middle Aged; D009204:Myocardial Revascularization; D015588:Observer Variation; D011786:Quality Control; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000592:standards; D014680:Veins / Q000637:transplantation