Focused Issue of This Month ssessment of Coronary rtery ypass Graft Patency Using Multidetector Computed Tomography Joon eom Seo, MD Department of Radiology, University of Ulsan College of Medicine Email : seojb@amc.seoul.kr J Korean Med ssoc 2007; 50(2): 127-133 bstract Coronary artery bypass graft surgery (CG) is the standard of care in the treatment of advanced coronary artery disease. Invasive coronary angiography has been used to assess the status of graft. Recently, multidetector computed tomography (MDCT) has emerged as an important diagnostic tool for the evaluation of graft patency. Many studies have shown that MDCT has a high sensitivity and specificity in detecting graft occlusion or highgrade stenosis. However, there are several diagnostic pitfalls in evaluating CG graft patency due to several factors, including technical factors, patient factors, and flow competition. cknowledgment of these pitfalls and remedies to avoid wrong interpretation is essential to improve diagnostic accuracy. In addition, MDCT yields additional information such as plural effusion, pericardial effusion, sternal infection, pneumonia, pulmonary embolism, and so on. The continuing advance in the MDCT technology suggests that MDCT will be a rapid, convenient, and noninvasive tool in evaluating CG patients in the near future. Keywords : Computed tomography; Coronary artery disease; Coronary artery bypass graft 127
Seo J C Figure 1. Patent internal mammary artery graft anastomosed to left anterior descending artery. Coronal image and volume rendered image ( and ) show the patent, contrastfilled internal mammary artery (arrows), which is well correlated with conventional angiogram (C) 128
Coronary rtery ypass Graft and MDCT Figure 2. Figure 3. C Variable coronary artery bypass grafts. Patent saphenous vein graft from ascending aorta, anastomosed to distal right coronary artery (arrow) is shown in both volume rendered MDCT () and conventional angiogram (). Patent radial artery graft to an obtuse marginal branch is also visualized on both images (C and D). The left internal mammary artery graft to left anterior descending artery is not visualized on MDCT images ( and C). Insteads, multiple surgical clips around left anterior descending artery are shown as nodular lesions (arrowhead in C). Catheter angiogram confirmed the graft failure (not shown) Patent right gastroepiploic artery graft anastomosed to posterior descending artery. oth volume rendered MDCT image () and conventional angiogram () show patent graft D 129
Seo J Figure 4. Figure 5. saphenous graft stenosis. Volume rendered MDCT images () shows vocal narrowing of distal portion of saphenous vein graft (arrow), which is confirmed at conventional angiogram (arrow in ) Saphenous vein graft occlusion in immediate postoperative period due to acute thrombosis. MDCT image shows saphenous vein graft filled with thrombus with soft tissue density (arrows) 130
Coronary rtery ypass Graft and MDCT Figure 6. Figure 7. False negative interpretation due to surgical clip at anastomosis site. Oblique MDCT image () shows good opacification of left internal mammary artery graft (arrow) anastomosed to left anterior descending artery. Metallic surgical clips (arrowhead) hamper the detailed evaluation of anastomosis site. Catheter angiogram () shows focal stenosis, resulting in false negative interpretation of MDCT Vasospasm of graft mimicking significant stenosis. Volume rendered MDCT image () obtained 5 days after CG shows multifocal areas of luminal narrowing at radial artery graft (arrows). MDCT image () obtained 6 months later shows patent graft, confirming the vasospasm at early postoperative period 131
Seo J Table 1. Results of Studies of the Use of MDCT to Evaluate Occlusion and Highgrade Stenosis of Grafts uthors MDCT No. of Patients No. of Grafts Evaluation possible (%) Sensitivity (%) Specificity (%) Ropers, et al. (11) 4MDCT 65 182 174 (135 / 182) 192 (68 / 74) 95 (103 / 108) Nieman, et al. (12) 4MDCT 24 86 187 (75 / 86) 192 (24 / 26) 88 (43 / 49) Marano, et al. (13) 4MDCT 57 122 175 (92 / 122) 189 (34 / 38) 95 (80 / 84) Kim HJ, et al. (10) 16MDCT 48 160 100 (160 / 160) 184 (26 / 31) 95 (123 / 129) Schlosser, et al. (14) 16MDCT 48 131 100 (131 / 131) 196 (21 / 22) 95 (104 / 109) Ropers (15) 64MDCT 50 138 100 (138 / 138) 100 (54 / 54) 94 (79 / 84) Hightgrade stenosis is defined as 50~99% stenosis 1. ourassa MG, Fisher LD, Campeau L, Gillespie MJ, Mc- Conney M, Lesperance J. Longterm fate of bypass grafts: the coronary artery surgery study (CSS) and Montreal Heart 132
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