Imaging features of malignant vs stone-induced biliary obstruction: Aspects to consider

Abstract

Radiological studies play a crucial role in the evaluation of patients with biliary duct obstruction, allowing for the guidance of clinical diagnosis towards a malignant or stone-induced etiology through the recognition of relevant imaging features, which must be continuously revisited given their prognostic significance. This article aims to emphasize the importance of recognizing crucial imaging aspects of malignant and stone-induced biliary obstruction.

Key Words: Malignant biliary obstruction; Choledocholithiasis; Dilated bile ducts; Magnetic resonance; Multidetector computed tomography

Core Tip: Recognizing the radiological aspects of biliary obstruction is crucial for distinguishing between lithiasis and malignant origins, thereby facilitating the diagnosis and management of this pathology.

TO THE EDITOR

I read with great interest the letter written by Aydin and Irgul[1]. In their article, they aim to highlight some imaging findings for distinguishing between malignant biliary obstruction and common stone biliary obstruction.

I agree with Aydin and Irgul[1] that imaging studies play an invaluable role in the evaluation of patients with biliary tract obstruction. In the same line, I intend to contribute to the article highlighting some crucial imaging features of biliary obstruction that we should consider.

Obstruction of the biliary tree can occur as a result of gallstones disease[2] (Figure 1), as well as multiple types of cancers, including primary tumors originated from bile duct cells as well as those originating from adjacent organs that could cause extrinsic compression of the common bile duct (CBD), such as cholangiocarcinoma and pancreatic cancer respectively[3].

Figure 1 Distal choledocholithiasis in a 53-year-old man with acute secondary cholangitis. A: Axial magnetic resonance T2-weighted images depicts intra- and extrahepatic biliary ductal dilatation; B: Multiple void signal images within the lumen of the common bile duct.

As expected, patients with biliary obstruction of malignant origin have a significantly worse clinical course compared to those with lithiasic obstruction of the bile duct, present a higher incidence of severe acute cholangitis, greater admission to critical care units, and 30-d mortality, as recently reported by Tsou et al[4], which underscores the importance of being able to differentiate the origin of biliary obstruction during the imaging study.

For instance, initial imaging evaluation of patients with biliary obstruction may depict dilatation of the CBD and common hepatic duct associated with heterogeneous sizeable non-encapsulated heterogeneous mass of irregular contour, accompanied by hepatic capsular retraction and dilated peripheral bile ducts, with progressive enhancement in delayed phases and slight-to high signal intensity on T2-weighted images (T2WI), and low signal intensity on T1-weighted images (T1WI), which is highly suggestive of primary bile duct carcinomas[3,5] (Figure 2).

Figure 2 69-years-old woman with biliary obstruction secondary to intrahepatic mass-forming type cholangiocarcinoma with tumoral involvement of the biliary ducts confluence. A: Axial late computed tomography arterial phase depicts a soft-tissue mass in left hepatic lobe, with delayed phase enhancement; B: Dilatation of intrahepatic ducts; C: Axial magnetic resonance images demonstrate a T2-weighted images slightly hyperintense; D: T1-weighted images hypointense heterogeneous mass occluding the confluence of the hepatic ducts with moderate dilatation of left lobar intrahepatic bile ducts, and tumoral involvement of the left intrahepatic biliary branches.

In addition, CBD dilation may also be associated with the presence of a heterogeneous enhancing mass dependent on the pancreatic head, with iso- to slightly hyperintense signal on T2WI, and hypointense signal on T1WI, which generates extrinsic compression of the CBD, which may produce secondary cholangitis[6] (Figure 3).

Figure 3 Pancreatic ductal adenocarcinoma in a 72-years-old man with obstructive jaundice. A: Axial contrast-enhanced computed tomography image shows a well-circumscribed exophytic tumor in the pancreatic head with heterogeneuos enhancement in delayed arterial; B: Portovenous phase; C: Axial magnetic resonance fat suppression T2-weighted images image showing a mildly hyperdense irregular mass in the head of the pancreas; D: T1-weighted images with hypointense signal.

In both cases, the additional finding of focal hypovascular liver lesions with a peripheral halo and perihilar and retroperitoneal lymphadenopathy further support the diagnosis of biliary obstruction towards a malignant origin[7,8].

In summary, when conducting radiological evaluations of patients with bile duct obstruction, comprehensive consideration should be given to various imaging findings, with a focus on analyzing important imaging information. Considering the clinical implication of these diseases, I hope the discussion on the interesting articles by Tsou et al[4]. and Aydin and Irgul[1] will promote the permanent ongoing review of the imaging features of malignant and stone-induced bile duct obstruction to further improve the early recognition and appropriate management of these patients.