ABSTRACT
Objective To summarize the MRI characteristics of fat-containing hepatocellular carcinoma (HCC).Methods The retrospective cross-sectional study was conducted.The clinicopathological data of 18 patients with fat-containing HCC who were admitted to the Eastern Hepatobiliary Surgery Hospital of the Second Military Medical University between January 2015 and April 2016 were collected.All patients underwent MRI examination.Observation indicators:(1) imaging examination;(2) pathological features;(3) treatment and follow-up.Follow-up using outpatient imaging examination was performed to detect tumor recurrence once at 1 month postoperatively and once every 3 months postoperatively up to December 2016.Measurement data with normal distribution were represented as-x±s.Results (1) Imaging examination:plain scans of MRI:of 18 patients,lesions of 9,7 and 2 patients were respectively located in left,right and caudate lobes of liver,and lesions were round-like,with a diameter of 1.6-9.0 cm.Tumors were single,and tumor thrombosis in the hepatic vein was seen in 1 patient.T2WI on fat-suppression of 15 and 3 patients showed respectively high signals and iso-signal;MRI examination showed that out-phase signal on T1WI was variously decreased than in-phase signal,showing focal or diffuse signal decreasing;lipid phase on T1WI showed diffuse distribution in 10 patients,patchy fat-containing regions were scattered within the peritumoral zone in 7 patients,and lipid of 1 patient was located in the central area.Dynamic contrast enhancement MRI showed that fast-in and fast-out,fast-in and slow-out,and slow-in and slow-out types were detected in 16,1 and 1 patients,respectively.Sixteen patients had capsule-like enhancement in delayed phase.Diffusion weighted imaging (DWI) showed high signals in 10 patients,slightly high signals in 6 patients and iso-signal in 2 patients.Apparent diffusion coefficient (ADC) value was (1.19± 0.20)×10-3 mm2/s,including (1.37±0.20) × 10-3 mm2/s in lipid-rich type,(1.17±0.13) × 10-3 mm2/s in clear cell type and (1.11±0.17)× 10-3 mm2/s in thick beam type.Of 18 patients,2 were preoperatively misdiagnosed as hepatic angiomyolipoma and 1 as hepatic adenoma.(2) Pathological features:pathological types of 18 patients with fat-containing HCC:5 and 13 patients were respectively in lipid-rich and non-lipid-rich types (4 in clear cell type and 9 in thick beam type);steatosis tumor cells,rich and translucent cytoplasms and large vacuolated lipid droplets were seen under the microscope;steatosis tumor cells were diffused or scattered within the lesions,some of which showed plaque-like performance of different sizes.Degree of microvascular invasion:grade M0,M1 and M2 were found in 12,3 (2 in thick beam type and 1 in clear cell type) and 3 (2 in thick beam type and 1 in lipid-rich type) patients,respectively.(3) Treatment and follow-up:18 patients underwent surgery and were followed up for 6-13 months,with a median time of 8 months.During the follow-up,5 patients in lipid-rich type and 4 in clear cell type had no recurrence;among 9 patients in thick beam type,1 of 4 with microvascular invasion had no recurrence,2 and 1 of 4 with microvascular invasion had respectively recurrence at 3 months postoperatively and 4 months postoperatively,and 5 without microvascular invasion had no recurrence.The lesions of 3 patients with recurrence is single,3 patients received local minimally invasive therapy and continuous follow-up.Conclusion MRI characteristics of fat-containing HCC include that decreased out-phase signal on T1WI compared with in-phase signal,high signal on DWI,low ADC value,fast-in and fast-out enhancement and capsule-like enhancement in delayed phase.