HELICAL CT OF AORTA AFTER ENDOLUMINAL STENT-GRAFT THERAPY - VALUE OF BIPHASIC ACQUISITION

OBJECTIVE. We report our prospective study evaluating biphasic helical CT of the aorta after endoluminal stent-graft placement. SUBJECTS AND METHODS. Biphasic helical CT scans in 95 patients with abdominal and thoracic aortic aneurysms who had undergone endoluminal stent-graft pl acement were reviewed. After a test bolus injection of 15 ml of contra st media at a rate of 3.5 ml/sec for the measurement of the optimal st art delay, the aorta was scanned using the following parameters: colli mation of 5 mm, table speed of 7 mm per rotation, tube rotation time o f 0.75 sec, 120 kV, and 295 mA, A delayed helical CT scan was obtained 15 sec after the initial acquisition using the same parameters. RESUL TS. Biphasic helical CT scans showed perigraft leakage in 45 (47%) of 95 patients. Leakage was shown only on arterial phase CT in eight pati ents and only on the delayed scans in three patients. In two patients, leakage shown on the delayed acquisition was retrospectively seen on the first scan. Leakage and outflow vessels were most visible on the a rterial phase acquisition in 17 patients and on the second acquisition in six patients. Overall, biphasic acquisition was superior to arteri al phase acquisition alone in 15 (16%) of 95 patients. CONCLUSION. The diagnostic value of biphasic helical CT is superior to arterial phase acquisition alone for the evaluation of the aorta after endoluminal s tent-graft therapy.