Abdominal MR: liver and pancreas

Following the introduction of rapid, high-quality scan techniques and the d evelopment of new. tissue-specific contrast agents, the applications of MRI for abdominal imaging are experiencing unprecedented growth. This article examines the current status of liver and pancreatic MRT, highlighting techn ical I and methodological approach, use of contrast agents, and main clinic al applications, The MRI technique appears to be the ideal diagnostic tool for detection and characterization of benign and malignant liver neo-plasms . and for evaluating tumor response after nonsurgical treatments. Dynamic i maging after bolus injection of a gadolinium chelate is currently a fundame ntal component of an MRI examination of the liver in many instances. Optima l dynamic scanning depends on the use of a multisection spoiled gradient-ec ho technique that allows one to image the entire region of interest during a single suspended respiration. Images are obtained during four phases rela tive to the injection of the contrast agent: precontrast, arterial (pre-sin usoidal), portal (sinusoidal), and delayed (extracellular) phase. Liver-spe cific contrast agents, including hepatobiliary agents and reticuloendotheli al system-targeted iron oxide particles, however, may offer advantages over gadolinium chelates in some clinical settings. Computed tomography is stil l preferred to MRI for imaging the pancreas. However, stale-of-the-art MRI may currently be at least as accurate as spiral C-T for depiction of inflam matory and neoplastic pancreatic diseases. Moreover, MRI has the advantage of allowing simultaneous investigation of the biliary tree, owing to cholan giopancreatography techniques. Hence, a comprehensive assessment of most pa ncreatic diseases can be achieved with a single examination.