Hepatic imaging: techniques and unique applications of magnetic resonance imaging.

The appropriate use of various MRI pulse sequences allows accurate detection and characterization of focal liver lesions. There are now a wide array of useful techniques for obtaining T1-weighted and T2-weighted images with or without suspended respiration. In the vast majority of cases, malignant liver lesions can be distinguished from hemangiomas or cysts, although contrast agents may be necessary. MRI can also definitively identify lipid and iron within hepatic parenchyma, increasing its usefulness for diagnosing and evaluating diffuse liver diseases. The expanded tissue contrast of MRI allows better differentiation of malignancies and "pseudotumors" due to diffuse liver disease. Appropriate two-dimensional time-of-flight techniques depict abdominal vessels clearly, allowing accurate detection or exclusion of hepatic vascular disorders. There is no other single method that can be used to examine the liver as comprehensively.