[Hepatobiliary phase image manifestation classification and pathological features of nodules in nodules accompanied...

Objective: To analyze the hepatobiliary phase (HBP) image manifestation classification and pathological features of nodules in nodules accompanied by hepatocellular carcinoma (NIN-HCC). Methods: Twenty-five cases cases (27 lesions) with cirrhosis who were confirmed as NIN-HCC by surgical pathology and underwent gadoxetate disodium-enhanced MRI examination before surgery at Nantong Third Hospital affiliated with Nantong University from July 2015 to November 2022 were retrospectively enrolled. The size, signal intensity, enhancement pattern, and pathological features of internal and external nodules were analyzed in NIN-HCC. The lesions score were recorded according to the 2018 version of the Liver Imaging Reporting and Data Systems (LI-RADS) classification criteria. NIN-HCCs were grouped and typed according to the different HBP signal intensities of the inner and outer nodules. The independent-samples t-test, Mann-Whitney U test or Fisher's exact probability method were used to compare the differences in imaging features and LI-RADS scores between the groups. The Spearman correlation coefficient was used to evaluate the correlation between the pathological differentiation degree of internal and external nodules and the HBP signal intensity. The Kaplan-Meier curve was used to analyze recurrence-free survival (RFS) following NIN-HCC surgery. Results: The internal nodules of the 27 NIN-HCCs showed altered hypervascularity with a maximum diameter of (13.2±5.5) mm during the arterial phase. 51.9% (14/27) and 48.1% (13/27) showed "fast in and fast out" and fast in and slow out"enhancement patterns. The external nodules showed altered hypovascularity with a maximum diameter of (25.7±7.3) mm, and 13 (48.1%) of them were accompanied to manifest during the arterial phase. NIN-HCC was divided into two groups according to the signal intensity of HBP of the outer nodules with the background liver parenchyma signal intensity as a reference: the hyposignal group (n=17, 63.0%) and the isosignal group (n=10, 37.0%). The hyposignal group and the isosignal group were divided into A~C type and D~F type, a total of six types, according to the hypo, iso, and hyper signals of the inner nodules and the signal intensity of the outer nodules as a reference. Within the hyposignal group, 7.4% (2/27) of the inner nodules showed hyposignal (type A), 37.0% (10/27) showed isosignal (type B), and 18.5% (5/27) showed hypersignal (type C). Within the isosignal group, 29.6% (8/27) of the inner nodules showed hyposignal (type D), 7.4% (2/27) showed isosignal (type E), and there was no hypersignal (type F). 40.7% (11/27) of the lesions were LR-4 in LI-RADS score, and 59.3% (16/27) were LR-5. There was no statistically significant difference (P>0.05) in the maximum diameter, enhancement pattern, and LI-RADS score of internal and external nodules between the hypo and iso signal group. Histologically, NIN-HCC showed fine trabecular/pseudoglandular duct type without microvascular invasion, among which the inner nodules were mainly moderately differentiated HCC, and the outer nodules were mainly well-differentiated HCC. The degree of differentiation between the inner and outer nodules and the HBP signal intensity had no statistically significant difference (r=0.290, P=0.143; r=0.079, P=0.697). The median RFS follow-up time after NIN-HCC radical resection was 31.7 months, and the cumulative RFS rates at 1, 3, and 5 years were 96.0%, 76.0%, and 64.0%, respectively. Conclusions: NIN-HCC can serve as a morphological marker for early-stage diagnosis of multi-step cancer evolution in HCC, with certain imaging and pathological features. HBP imaging classification is helpful to enhance the diagnostic recognition of this disease.