Follow-Up of Coronary Artery Bypass Graft Patency by Multislice Computed Tomography Emilio Chiurlia, MD, Mila Menozzi, MD, Carlo Ratti, MD, Renato Romagnoli, MD, and Maria Grazia Modena, MD Fifty-two consecutive asymptomatic patients with a total of 166 bypass grafts were investigated by 16- slice computed tomography (CT) 15  5 days before invasive coronary angiography. Overall, 165 grafts (99.4%) were assessable with multislice CT (MSCT). Coronary angiography showed that 111 grafts (67%) were patent and 54 (33%) were occluded. Of the patent grafts, 22 had high-grade stenoses. MSCT cor- rectly classified 111 grafts as patent and 54 as oc- cluded. Of the patent grafts, 16-slice CT correctly detected 21 bypass stenoses (95%). These results yielded 100% sensitivity and specificity of 16-slice CT for detecting bypass grafts occlusion and 96% sensi- tivity and 100% specificity for detecting high-grade stenoses in patent grafts. 2005 by Excerpta Med- ica Inc. (Am J Cardiol 2005;95:1094 –1097) C oronary angiography is the gold standard to eval- uate the status of grafts, but it is an invasive procedure that includes x-ray exposure, requires hos- pitalization, and includes a (small) risk for complica- tions. 1,2 These disadvantages make use of coronary angiography less attractive as a diagnostic method for the evaluation of early and late postoperative grafts patency. Electron beam computed tomography (CT) and magnetic resonance imaging have been investi- gated for noninvasive coronary artery and bypass graft imaging. 3–5 However, neither of these approaches has resulted in an accurate diagnostic procedure that is widely accepted. Multislice CT (MSCT) with 4 rows of detectors has shown promising results, despite a large percentage of nonassessable bypass grafts due to inadequate spatial and temporal resolution and to a scan time of approximately 40 seconds. 6 Our aim was to compare the newest generation of cardiac MSCT scanners that permit the simultaneous acquisition of up to 16 submillimeter slices per rotation, with con- ventional angiography for the evaluation of graft oc- clusion and the presence of significant coronary ste- noses. ••• From January to May 2004, 52 consecutive asymp- tomatic patients (45 men and 7 women; mean age 63 years, range 35 to 84) with a total of 166 bypass grafts (117 venous and 49 arterial grafts) were investigated by 16-slice CT 15  5 days before invasive coronary angiography. The mean time between bypass opera- tion and MSCT investigation was 95 months (range 36 to 168). Only patients in sinus rhythm and stable clinical condition, without implanted pacemakers and contraindications to the administration of iodin- ated contrast agent, were included in the study. All patients gave their written informed consent, and the ethics committee of our university approved the study protocol. Each patient was placed within the gantry of a multidetector row CT scanner (LightSpeed Ultra 16, GE Healthcare, Waukesha, Wisconsin) in a supine position. Leads were attached for simultaneous elec- trocardiographic and image recording, which is nec- essary for inter-related image reconstruction. Our im- aging protocol consisted of the following steps. First, a noncontrast coronal view of the chest was obtained to determine the position of the heart, define the scan volume for further imaging, and recognize eventual coronary calcification. Then, the patient contrast agent transit time was measured from the injection into a peripheral vein of a 20-ml bolus of contrast agent (Iomeron 350, Bracco Ltd., Milan, Italy) to the in- crease in density within the ascending aorta. At last, the volume data set for coronary bypass imaging was acquired in spiral mode with the simultaneous acqui- sition of 16 parallel slices using the algorithm of 180° multislice cardiac interpolation, during the intrave- nous injection of 120 ml of contrast agent at a rate of 3.5 ml/s. Scan parameters were as follows: detector collimation 16  0.625, tube current 440 mA, and tube voltage 120 kVp. Depending on patient heart From the Departments of Cardiology and Radiology, University of Modena and Reggio Emilia, Policlinico Hospital, Modena, Italy. Dr. Chiurlia’s address is: Via del Pozzo 71, 41100 Modena, Italy. E-mail: emiliochiurlia@virgilio.it. Manuscript received October 13, 2004; revised manuscript received and accepted December 20, 2004. FIGURE 1. Volume rendering images before (A) and after (B) the automatic removal of large cardiac chambers. Three patent grafts, a left IMA (LIMA) graft and 2 saphenous vein grafts (SVGs), are visible simultaneously. 1094 ©2005 by Excerpta Medica Inc. All rights reserved. 0002-9149/05/$–see front matter The American Journal of Cardiology Vol. 95 May 1, 2005 doi:10.1016/j.amjcard.2004.12.067