Diffusion-weighted imaging of biliopancreatic disorders： Correlation with conventional magnetic resonance imaging

Diffusion-weighted magnetic resonance imaging （DWI） is a well established method for the evaluation of intra- cranial diseases, such as acute stroke. DWI for extra- cranial application is more difficult due to physiological motion artifacts and the heterogeneous composition of the organs. However, thanks to the newer technical de- velopment of DWI, DWI has become increasingly used over the past few years in extracranial organs including the abdomen and pelvis. Most previous studies of DWI have been limited to the evaluation of diffuse paren- chymal abnormalities and focal lesions in abdominal or- gans, whereas there are few studies about DWI for the evaluation of the biliopancreatic tract. Although further studies are needed to determine its performance in evaluating bile duct, gallbladder and pancreas diseases, DWI has potential in the assessment of the functional information on the biliopancreatic tract concerning the status of tissue cellularity, because increased cellularity is associated with impeded diffusion, as indicated by a reduction in the apparent diffusion coefficient. The detection of malignant lesions and their differentiation from benign tumor-like lesions in the biliopancreatic tract could be improved using DWI in conjunction with findings obtained with conventional magnetic reso- nance cholagiopancreatography. Additionally, DWI can be useful for the assessment of the biliopancreatic tract in patients with renal impairment because contrast-en- hanced computed tomography or magnetic resonance scans should be avoided in these patients.