Dynamic enhancement patterns of small-diameter mass-forming intrahepatic cholangiocarcinomas on contrast-enhanced magnetic resonance imaging: Challenges faced by the radiologist

Contrast-enhanced magnetic resonance imaging (MRI) characteristics of small-diameter mass-forming intrahepatic cholangiocarcinomas (ICCs) (diameter ≤3 cm) are still unclear. This study focused on imaging findings of small mass-forming ICCs. The MRI findings for small-diameter mass-forming ICCs were summarized, and the enhancement features of small ICC nodules with different diameters [2 groups were defined: a smaller nodule group (ICC diameter <2 cm) and a larger nodule group (ICC diameter >2 cm)] were compared on contrast-enhanced MRI. In our study, there were 41 small ICC nodules in 41 patients, including 30 men and 11 women (average age, 56 years). The nodules were characterized by peripheral hyperintense in the arterial phase on contrast-enhanced MRI. In the different diameter groups, peripheral hyperintense was the most common in the larger nodule group (56% vs 12%, P < .05) and hypointense was more common in the smaller nodule group (25% vs 0%, P < .05) in the arterial phase on contrast-enhanced MRI. Smaller nodules mainly showed progressive enhancement, whereas larger nodules mainly showed peripheral continuous enhancement (56% vs 6%, P < .05). The small-diameter mass-forming ICC nodules mainly show peripheral continuous enhancement on contrast-enhanced MRI; however, those with diameters <2 cm commonly show progressive enhancement.