Ultrasonic evaluation of abdominal aortic thrombus.

Ultrasonograms of 38 patients and computed tomograms of 21 patients with abdominal aortic aneurysms (AAA) were retrospectively reviewed. In 69 per cent of cases in which intraluminal thrombus was demonstrated, sonography revealed a high-amplitude linear echo along the luminal surface of the thrombus. Although calcification could be easily visualized within the aortic wall by computed tomography, it was seen at the lumen--thrombus interface in only one patient. In addition, a resected aortic aneurysm with thrombus, when scanned in a water bath in vitro, demonstrated this echo pattern at the luminal-thrombus interface on sonography but revealed no calcification on pathologic examination. An explanation of the source of this echo pattern and a caution against misinterpretation of this echo pattern as the aortic wall in a dissection or leaking aneurysm with hematoma are presented.