Comparison of NMR imaging and aortography for preoperative evaluation of abdominal aortic aneurysm.

Seven patients (five male and two female, age range from 50 to 88) with angiographic proven abdominal aortic aneurysms were evaluated with magnetic resonance (MR) imaging (1.5-kG system) of the abdomen. Images were obtained in transverse, coronal, and saggital planes with three radiofrequency pulse sequences [saturation recovery (SR), inversion recovery (IR), and spin echo (SE)]. All of the aneurysms were identified as to site and relative size with MR images. The lumen in which there was rapidly flowing blood was always dark (low intensity), whereas the aneurysmal area which contained presumed clot or slow flowing blood was brighter (high intensity) on SR images. Although the size, location, and relationship to other blood vessels was best demonstrated on aortography, MR images provided similar information in all cases. MR images correctly demonstrated thrombus in six cases. In conclusion, MR imaging provides a clear delineation of the anatomy of abdominal aortic aneurysms. In addition, it can provide information concerning tissue type, i.e., it distinguished clot from moving blood. It may be possible in the future to further characterize atherosclerotic and other pathological changes in vessel architecture by using various pulse sequences and timing parameters to provide in vivo histological typing.