MURAL THROMBI IN ABDOMINAL AORTIC-ANEURYSMS - MR-IMAGING CHARACTERIZATION-USEFUL BEFORE ENDOVASCULAR TREATMENT

PURPOSE: To evaluate magnetic resonance (MR) imaging accuracy in the c haracterization of mural thrombi in abdominal aortic aneurysms (AAAs). MATERIALS AND METHODS: Forty-five patients (37 men, eight women; mean age, 68 years) with an AAA with mural thrombus thicker than 1 cm at s onography underwent T1- and T2-weighted spin-echo MR imaging. The thro mbi were prospectively classified as one of three signal intensity (SI ) categories: category 1 corresponds to low SI on both T1- and T2-weig hted images; category 2, high SI on T1-and T2-weighted images; and cat egory 3, inhomogeneous SI with hyperintense areas on both T1- and T2-w eighted images. During surgery, thrombi were classified as organized, unorganized, and partially organized. MR imaging and surgical findings were compared. RESULTS: SI category 1 corresponded to organized throm bi in 24 of 24 patients. Category 2 corresponded to unorganized thromb i in 11 of 11 patients. In category 3, focal hyperintense areas corres ponded (both for presence and location) to unorganized portions of par tially organized thrombi in 10 of 10 patients. CONCLUSION: MR imaging is accurate in AAA thrombus characterization.