1Department of Clinical Pathology, Jichi Medical School, 2Department of Surgery, Jichi Medical School
Color Doppler flow imaging, Dissecting aneurysm, Superior mesenteric artery, Ultrasonography
Abdominal ultrasonography was performed on a 66-year-old man who first appeared at this institution complaining of general fatigue and watery diarrhea. B-mode scan showed a fusiform dilatation of the superior mesenteric artery (SMA) about 3 cm distal to its separation from the abdominal aorta. A membranous structure divided the dilated lumen into ventral and dorsal parts. Color Doppler flow imaging showed blood flow in the ventral part to differ from that in the dorsal part; pulsed Doppler ultrasonography also showed a different flow pattern in each of these parts, on the basis of the ultrasonographic images, the lesion was diagnosed as an isolated dissecting aneurysm of the SMA, and the diagnosis was confirmed on abdominal computed tomography and angiography. Earlier studies place the occurrence of isolated dissecting aneurysms of the SMA at about 0.01% at necropsy. This appears to be the first use of transabdominal ultrasonography to successfully diagnose such a lesion in vivo. Previous diagnoses were either made at necropsy or, when symptoms were apparent, were based on angiographic findings. We found abdominal ultrasonography extremely useful for diagnosing and evaluating blood flow in this case.