Contrast enhanced CT-scan to diagnose intrahepatic cholangiocarcinoma in patients with cirrhosis

Background & Aims

Contrast enhanced computed tomography (CT-scan) is a standard of care for the radiological diagnosis of hepatocellular carcinoma (HCC) in patients with cirrhosis. This technique, however, is not validated to exclude intrahepatic cholangiocarcinoma (ICC) which may develop in patients with cirrhosis, as well.

Methods

To assess the features of contrast CT-scan in the diagnosis of ICC, we reviewed all CT-scan films obtained in cirrhotic patients with a histologically documented ICC, taking in consideration the pattern and dynamics of the arterial, portal venous and delayed phases of contrast uptake.

Results

Thirty-two patients had 40 nodules of ICC (22 male; median age 62 years; 13 hepatitis C) that were identified either during surveillance with abdominal ultrasound (21 patients, 66%) or incidentally (11 patients, 34%). ICC was either multifocal or ⩾30 mm in 11 of the former and 10 of the latter group (52% vs. 91%, p <0.05). Two nodules (5%) escaped detection by CT-scan, while the remaining 38 showed a heterogeneous contrast enhancement pattern, being the arterial peripheral-rim enhancement present in 19 (50%) cases and a progressive homogeneous contrast uptake in 16 (42%) cases during the three vascular phases, with no relation to tumor size. Importantly, all nodules lacked the radiological hallmark of HCC, the only ICC nodule showing a homogeneous wash-in during the arterial phase followed by a wash-out in the delayed venous phase, however showing a homogeneous wash-in during the portal phase too.

Conclusions

ICC in cirrhotic patients displays distinct vascular patterns at CT-scan that allow for differentiation from HCC.

Introduction

Intrahepatic cholangiocarcinoma (ICC) stemming from biliary epithelial cells is the second most common primary cancer of the liver after hepatocellular carcinoma (HCC), partly reflecting an association with cirrhosis [1], [2], [3], [4]. In the face of its limited epidemiologic role (<5% of all de novo tumors detected in patients with cirrhosis), ICC has a relevant clinical importance, owing to its dismal prognosis with respect to HCC, a fact that calls for early diagnosis as the only approach to improve treatment outcome [5]. In this context, efforts have been put forward to optimize differential diagnosis between ICC and HCC in cirrhotic patients, using non-invasive radiological approaches, an area where the radiological criteria for diagnosis of HCC are adequately standardized [6], [7], [8], [9], [10], [11], [12], [13], [14]. Diagnosis of HCC, in fact, relies on contrast imaging techniques, demonstrating the hallmark of early global arterial enhancement (wash-in) followed by wash-out in the portal venous and delayed phases [13], [14]. According to both the American and European liver societies, the radiological diagnosis of HCC relies on either magnetic resonance imaging (MRI) or contrast enhanced computerized tomography (CT-scan) in the context of a sequential algorithm, which proved to identify up to 65% of small HCC nodules (<2 cm in size), with a negligible risk of false diagnoses [13], [14]. Meanwhile, contrast enhancement US has been withdrawn by both the American and European liver societies recommendations to diagnose HCC due to its inaccuracy in differentiating HCC from ICC in cirrhosis [7], [13], [14].

While MRI stands as a reliable imaging technique for the differential diagnosis between HCC and ICC in cirrhosis [6], [13], [14], yet robust studies on the diagnostic accuracy of contrast CT-scan for ICC in patients with cirrhosis are not available. In fact, the few studies of CT-scan in ICC patients either are underpowered or target patients with large tumors in a non-cirrhotic liver [10], [15], [16], [17]. We aimed at assessing the features of ICC during contrast enhanced CT-scan in the setting of cirrhosis in relation to the nodule size and enhancement pattern, with special emphasis on the differential diagnosis between ICC and HCC.