Radiological Outcome of Subcentimeter Arterially Enhancing Nodules Detected during Surveillance for Hepatocellular Carcinoma- A Cohort Study

Abstract

Introduction: Hepatocellular Carcinoma (HCC) is the sixth most diagnosed cancer and the fourth leading cause of cancerrelated death globally. The male: female ratio for HCC in India is 4:1 with age of presentation ranging from 40 to 70 years. There is limited clinical information on the course of SubcentimeterSized Nodules (SCSNs) detected during surveillance for HCC. Aim: To evaluate the serial outcome of subcentimeter arterially enhancing nodules evolving into HCC and henceforth, to identify specific radiological features which can prognosticate and, if possible, predict which SCSNs will turn into HCC. Materials and Methods: A prospective cohort study was conducted in a tertiary care center in Delhi NCR, in the Department of Radiodiagnosis between 1st May 2018 and 30th April 2019. Total of 72 lesions in 59 patients were evaluated during the study period of one year, which included images spanning over a mean duration of three years (range 2-6.5 years). Dynamic contrast enhanced imaging was done as per Liver Imaging Reporting and Data System version 2018 (LI-RADS version 2018) using either Magnetic Resonance Imaging (MRI) or Computed Tomography (CT). The gold standard for HCC diagnosis was LR 5 lesion. Size cut-off, rate of growth, enhancement features were studied and calculated. Student’s t-test was used for comparison of quantitative outcome parameters. Results: A total of 59 patients were analysed with mean age 53±12 years, of which 85% were males. The cumulative HCC development rate was 47.5%. A 60.9% of the SCSNs which turned into HCCs showed an increase in size, 31.6% of the non HCC-SCSN lesions also showed an increase in size. Upon baseline comparison, the growth difference was more in the HCC group (8.2±12.24 mm) than in the non HCC group (3.37±7.39 mm). The optimal cut-off points after which the likelihood of an arterially enhancing lesion turning into HCC increased significantly was 8.5 mm on CT and 10.5 mm on MRI. Conclusion: Around 47.5% of arterially enhancing SCSN converted into HCC; this percentage is much higher than quoted literature. A six monthly follow-up may be considered as 52.2 percent of lesions turned into HCC in a span of 1 year. The optimal cut-off points after which the likelihood of an arterially enhancing lesion turning into HCC increases can be taken as 8.55 mm on CT and 10.5 mm on MRI. Among the lesions showing washout, 80.8 % on CT and 91.3% nodules on MRI changed into HCC.