LAUSR

The “beaded” appearance is a characteristic imaging finding described for the endoscopic retrograde cholangiopancreatography (ERCP) or MRCP (magnetic resonance cholangiopancreatography) diagnosis of primary sclerosing cholangitis (PSC). It refers to the presence of multifocal intraand extra-hepatic bile duct strictures alternating with normal caliber or slightly dilated segments, resembling beads on a string (Fig. 1) [1]. PSC is an uncommon, idiopathic, chronic condition, due to a fibrosing inflammatory process involving the biliary tree. Histologically, it is characterized by submucosal periductal fibrosis and variable periportal inflammatory cell infiltration that can result in bile duct obliteration, cholestasis, and biliary cirrhosis [2]. Classically, PSC is associated with inflammatory bowel disease (in 60–80% of patients), especially ulcerative colitis, and other autoimmune diseases, such as retroperitoneal fibrosis, mediastinal fibrosis, and Sjögren syndrome [2, 3]. Traditionally, ERCP was widely used for the diagnosis of PSC, and it has generally been considered the gold standard imaging technique, because of its high spatial resolution for peripheral intrahepatic biliary tree detail (Fig. 2), and interventional capabilities such as mechanical dilation of obstructing strictures, stent placement, and biopsy. However, ERCP is an invasive method which can produce serious