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AJNR - American Journal of Neuroradiology

Publication Preview: Published March 27, 2008

American Journal of Neuroradiology 2008;29:1071.

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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1040

INTERVENTIONAL

Subtraction 3D CT Angiography with the Orbital Synchronized Helical Scan Technique for the Evaluation of Postoperative Cerebral Aneurysms Treated with Cobalt-Alloy Clips

Y. Watanabe, N. Kashiwagi, N. Yamada, M. Higashi, T. Fukuda, S. Morikawa, Y. Onishi, K. Iihara, S. Miyamoto and H. Naito

From the Departments of Radiology (Y.W., N.Y., M.H., T.F., S. Morikawa, Y.O., H.N.) and Neurosurgery (K.I., S. Miyamoto), National Cardiovascular Center, Osaka, Japan; and Department of Radiology (N.K.), Osaka Medical Center for Cancer and Cardiovascular Disease, Osaka, Japan.

Please address correspondence to Yoshiyuki Watanabe, MD, PhD, 5-7-1 Fujishirodai, Suita Osaka, Japan 565-8565; e-mail: ywatanab{at}hsp.ncvc.go.jp

BACKGROUND AND PURPOSE: We investigated the clinical usefulness of subtraction CT angiography (CTA) by using the orbital synchronized helical scan technique (OSHST) for evaluating intracranial aneurysms surgically treated with cobalt-alloy clips.

MATERIALS AND METHODS: We scanned an agar gel phantom with a cobalt-alloy clip mounted in the center by using subtraction CT with and without OSHST. Eighteen patients (20 aneurysms) who underwent surgery with cobalt-alloy clips were postoperatively evaluated with subtraction CTA with OSHST, and the results were compared with those from digital subtraction angiography. Two neuroradiologists independently evaluated the 3D CTA images and source images with and without subtraction for the presence of residual flow in the aneurysm and stenotic change in parent or neighboring arteries.

RESULTS: For the phantom study, significantly fewer artifacts from clips were noted on images obtained by using subtraction CT with OSHST than on those obtained without OSHST. For the clinical study, subtraction CTA with OSHST also showed fewer clip artifacts than did conventional CTA. Image quality was poor, and we were unable to diagnose residual neck for 5% (1/20) with subtraction CTA with OSHST and 75% (15/20) with conventional CTA. For evaluation of adjacent vessels, image quality was poor for none (0/20) with subtraction CTA with OSHST and for 55% (11/20) with conventional CTA. For subtraction CTA with OSHST, sensitivity in detecting residual neck was 1.0, and specificity was 0.94. For conventional CTA, sensitivity and specificity were both 0.25.

CONCLUSIONS: OSHST is a useful technique for subtracting cobalt-alloy clips, and subtraction CTA with OSHST is available for evaluating aneurysms after clipping with cobalt-alloy clips.