W B Mehard1, J P Heiken, G A Sicard. 1. Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110.
Abstract
PURPOSE: To determine whether a peripheral high-attenuating crescent in an abdominal aortic aneurysm (AAA) on unenhanced computed tomographic (CT) scans is a sign of impending or active aneurysm rupture. MATERIALS AND METHODS: CT scans were reviewed of 149 consecutive patients operated on because of AAA who had undergone preoperative unenhanced CT scanning. The presence of a peripheral high-attenuating crescent on CT scans was correlated with surgical findings of aneurysm complication. Aneurysm diameter was correlated with presence or absence of pain at the time of CT, high-attenuating crescent, and aneurysm complication. RESULTS: Sensitivity of the high-attenuating crescent sign as an indication of complicated aneurysm was 77%; specificity, 93%; and positive predictive value, 53%. The sign showed a statistically significant correlation with large aneurysm size (P < .001) and presence of pain at the time of CT (P < .003). CONCLUSION: In patients without CT evidence of frank aneurysm leak, the high-attenuating crescent sign should be regarded as a sign of impending AAA rupture, particularly in patients with pain.
PURPOSE: To determine whether a peripheral high-attenuating crescent in an abdominal aortic aneurysm (AAA) on unenhanced computed tomographic (CT) scans is a sign of impending or active aneurysm rupture. MATERIALS AND METHODS: CT scans were reviewed of 149 consecutive patients operated on because of AAA who had undergone preoperative unenhanced CT scanning. The presence of a peripheral high-attenuating crescent on CT scans was correlated with surgical findings of aneurysm complication. Aneurysm diameter was correlated with presence or absence of pain at the time of CT, high-attenuating crescent, and aneurysm complication. RESULTS: Sensitivity of the high-attenuating crescent sign as an indication of complicated aneurysm was 77%; specificity, 93%; and positive predictive value, 53%. The sign showed a statistically significant correlation with large aneurysm size (P < .001) and presence of pain at the time of CT (P < .003). CONCLUSION: In patients without CT evidence of frank aneurysm leak, the high-attenuating crescent sign should be regarded as a sign of impending AAA rupture, particularly in patients with pain.