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Invited Commentary

Department of Radiology, Albert Einstein Medical Center Philadelphia, Pennsylvania

It is indeed a pleasure to comment on the fine overview article by Lopera et al (1) in this issue of RadioGraphics. The authors present a comprehensive review of the breadth of infrainguinal bypass grafts. The perception in the community is that the frequency with which bypass grafts are performed may be decreasing with the greater emphasis on percutaneous lesser invasive procedures. This is confirmed by review of the 2005 Medicare utilization data, which show a 40% reduction in femoral-popliteal and femoral-tibial bypass grafts from 1995 to 2005 (Dawn Hopkins, Society of Interventional Radiology, written communication). Nevertheless, this fine pictorial review provides a timely resource given the decreasing frequency with which these grafts are performed.

The contention that CT angiography may be the next step in patients in whom standard Doppler US surveillance has suggested a failing graft is attractive, but has yet to be proved. However, the appeal of a noninvasive tool allowing a more thoughtful intervention is undeniable. The importance of correcting a failing graft prior to thrombosis is well documented (2). Both the initial success and subsequent patency rates are higher for those grafts in which intervention is performed prior to failure.

CT angiography has become an indispensable tool to directly image the abnormal anatomy before an invasive procedure, and the results may indeed affect the approach and performance of a subsequent intervention. Meticulous attention to detail is required to obtain consistent diagnostic quality studies, and readers are encouraged to pay careful attention to the techniques section. Many centers may have initial discouraging results that hamper full utilization of the procedure owing to improper technique in the early learning curve of CT angiography for complex cases. In experienced hands, multidetector CT angiography has been shown to be an effective alternative to digital subtraction angiography for the evaluation of peripheral arterial disease (3–5). Similar if not superior results can be seen in the postoperative setting.

One Achilles heel of CT angiography for evaluation of peripheral arterial disease has been coexistent calcific native arterial changes (6). Volume techniques are fraught with false patency errors, frequently requiring two-dimensional maximum intensity projection thin-section evaluation to ascertain luminal anatomy. The difficulty in discriminating calcium from a contrast material–filled lumen is well documented. Bypass grafts are generally devoid of calcium when created with a preference for noncalcified areas of origin and final graft implantation. I believe that this fact improves the efficacy of this tool over its use in evaluation of the native circulation.

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1. Lopera JE, Trimmer CK, Josephs SG, et al. Multi-detector CT angiography of infrainguinal arterial bypass. RadioGraphics 2008;28(2):529–549.[Abstract/Free Full Text]
2. Brewster DC, Lasalle AJ, Strayhorn EC, et al. Femoropopliteal graft failures: clinical consequences and success of secondary reconstructions. Arch Surg 1983;118(9):1043–1047.[Abstract/Free Full Text]
3. Albrecht T, Foert E, Holtkamp R, et al. MDCT angiography of aortoiliac and lower extremity arteries: comparison with digital subtraction angiography. AJR Am J Roentgenol 2007;189(3): 702–711.[Abstract/Free Full Text]
4. Toomay SM, Dolmatch BL. CT angiography of lower extremity vascular bypass grafts. Tech Vasc Interv Radiol 2006;9(4):172–179.[CrossRef][Medline]
5. Portugaller HR, Schoellnast H, Hausegger KA, Tiesenhausen K, Amann W, Berghold A. Multislice spiral CT angiography in peripheral arterial occlusive disease: a valuable tool in detecting significant arterial lumen narrowing? Eur Radiol 2004;14(9):1681–1687.[Medline]
6. Heuschmid M, Krieger A, Beierlein W, et al. Assessment of peripheral arterial occlusive disease: comparison of multislice-CT angiography (MS-CTA) and intraarterial digital subtraction angiography (IA-DSA). Eur J Med Res 2003;8(9):389–396.[Medline]

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