Vascular lesions of the liver and gastrointestinal tract.

In the liver, imaging can show lesions of large and medium-sized vessels, perfusion disorders related to vascular lesions, and parenchymal lesions including infarcts, regenerative nodules, and focal nodular hyperplasia. In the gastrointestinal tract, vascular lesions often result in bowel ischemia. Imaging can be used to show the vascular lesions and bowel wall abnormalities, including mural thickening, lack of perfusion, and pneumatosis. Doppler sonography, multislice helical computed tomography (CT), magnetic resonance (MR) imaging, and angiography are useful to demonstrate vascular lesions. Doppler sonography offers high spatial and temporal resolution. Information about blood flow and velocity can be obtained. However, the visualization of retroperitoneal vessels is often limited because of intestinal gas. A global view of the abdominal vasculature can be observed by using helical CT. High spatial and temporal resolution are obtained, especially when new multislice CT scanners are used. MR imaging has a better contrast resolution than CT, but its spatial resolution is lower. MR imaging can also be used to measure flow with phase contrast methods. The role of arteriography in the diagnosis of vascular lesions is decreasing. However, its role remains important to definitively demonstrate obstruction of the hepatic artery and to show arterial lesions in acute mesenteric ischemia. In addition, it is used as a problem-solving method to detect lesions in medium-sized vessels and to guide intravascular treatment.