Hepatobiliary imaging: imaging modalities.

Imaging modalities are a major part of the diagnosis and follow-up to therapy of hepatobiliary disease. Changes of the liver, spleen, gallbladder and pancreas can be assessed by a variety of highly technical and evolving methods. The purpose of this paper is to review briefly some diseases of the hepatobiliary tree and pancreas and how they may be diagnosed through imaging modalities. Hepatic diseases may include those that affect the parenchyma, biliary tree, or gallbladder. The spleen is often altered in size secondary to liver disease. Pancreatic diseases present particular difficulties in diagnosis as they relate to clinical chemistry tests, tumor markers or imaging. Imaging modalities for hepatobiliary disease include x-ray studies with or without contrast, and with or without computerized tomographic enhancements. Some of the x-ray procedures are done in association with percutaneous or endoscopic retrograde approaches. Ultrasound is an excellent technique for evaluation of cholelithiasis and gives useful information for hepatic and splenic size. Radionuclide studies can be either anatomically or physiologically based. Magnetic resonance imaging is evolving as a very useful, specific and sensitive method of evaluating the liver, gallbladder, spleen and pancreas. There is a diverse armamentarium of imaging modalities available for the evaluation of hepatobiliary disease. Ultrasound is the first choice for cholelithiasis. Endoscopic retrograde cholecystography (ERCP) is a definitive method for evaluating the biliary tree. Radionuclide studies with the iminodiacetic acid (IDA) derivatives are very useful for functional disorders of the gallbladder. Computer assisted tomography and magnetic resonance imaging (MRI) provide optimal anatomic resolution for tumors, abscesses, and other metastatic lesions involving the liver and spleen.