Imaging modality in Hepatobiliary Diseases
Rustam Effendi YS
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Symptoms, clinical findings, chemical laboratories, serological test, immunological investigations and imaging examinations are necessary to clarify the etiology and the stage of hepatobiliary disease. Several imaging modalities are used to investigate the liver and biliary tract, and as an important part of the diagnosis and follow-up to therapy of hepatobiliary disease. The commonest is ultrasonography (US), which is safe, cheap and readily available. It is often used as a screening modality. Computed tomography (CT) or magnetic resonance imaging (MRI) or both are often the next modalities of choice, and are used to explore any unusual findings detected on ultrasound. CT has a central role for emergency imaging, cancer diagnosis and staging, and assessment of treatment response. MRI is excellent for investigating the liver parenchyma, and is the modality of choice for characterizing a focal liver lesion and non-invasive investigation of the biliary tree. A recent advance with the development of MRI is magnetic resonance cholangio-pancreatography (MRCP). The addition of hepatobiliary contrast agents and diffusion-weighted imaging has further improved accuracy. Fluoroscopic imaging procedures, such as percutaneous transhepatic cholangiography (PTS) and endoscopic retrograde cholangiopancreatography (ERCP), are often used when intervension is required, usually for therapeutic reasons. Endoscopic ultrasound (EUS) uses an aquiptment that combine endoscope and ultrasonography. It has evolved from a diagnostic to a useful therapeutic tool. In this article, we describe the role of the each of these imaging modalities in benign and malignant hepatobiliary disease, summarize their use in commonly encountered conditions, such as gallstones, cirrhosis, and focal liver lesions, and delineate their advantages and disadvantages. Often, a combination of different modalities is required to reach the final diagnosis. We also describe the complementary role of other less commonly used modalities.