"Very early" intrahepatic cholangiocarcinoma (≤ 2.0 cm): MRI manifestation and prognostic potential.

ABSTRACT

AIMS: To explore the MRI characteristics and clinical outcome of the "very early" intrahepatic cholangiocarcinoma (iCCA) ≤2.0cm. MATERIALS AND METHODS: Totally 213 pathologically confirmed iCCAs (44 ≤ 2.0cm and 169 of 2.0-5.0cm) from two institutes were included. Forty-four matching non-iCCA malignancies ≤2.0cm were also enrolled. Recurrence-free survival (RFS) was estimated and compared between iCCAs ≤2.0cm and 2.0-5.0cm. MRI features were analyzed and compared between iCCAs ≤2.0cm and 2.0-5.0cm, as well as between iCCAs ≤2.0cm and non-iCCAs ≤2.0cm. Univariate and multivariate regression analyses were performed to identify independent imaging features for discrimination. An MRI-based diagnostic model for iCCA ≤2.0cm was constructed by incorporating the independent imaging features. RESULTS: ICCAs ≤2.0cm had a significantly longer RFS than those of 2.0-5.0cm (log rank P=0.014). Imaging features of homogeneous signal (odds ratio (OR) = 6.677, P<0.001) and lack of vessel invasion (OR=7.56, P<0.001) were more frequently displayed in iCCAs ≤2.0cm compared to iCCAs of 2.0-5.0cm independently. In the small lesions ≤2.0cm, imaging features of progressive or persistent enhancement pattern (OR=27.78, P=0.002) and rim diffusion restriction (OR=5.70, P=0.027) were independent imaging features suggestive of iCCA over non-iCCA malignancy; their combination yielded an area under the curve value of 0.824, with a sensitivity of 97.73%. CONCLUSION: The "very early" iCCA ≤2.0cm was associated with a favorable outcome after surgery, it displayed different and relatively atypical imaging manifestations compared with those of 2.0-5.0cm. Furthermore, in the small lesions ≤ 2.0cm, MRI can be served as a useful non-invasive diagnostic tool for iCCA in clinical screening with high sensitivity.