By analysing diverse risk factors, the role of pathological grading is essential to better recurrence and prognosis in a small hepatacellular carcinoma.^[1]This study is designed to investigate whether ADC values of lipid-containing small HCC with different pathological grading are the same as well as the correlation of ADC values with the pathological differentiate degree.

Inclusion criteria: ① the lesions contained fat, which was diagnosed and conformed by two intermediate diagnosticians before surgery; ② the tumor was first discovered without any anti-tumor therapy; ③ the maximum diameter of the single lesion was not more than 3cm or the sum of diameters of two lesions was no more than 3cm.Finally 78 cases were retrospectively collected with pathology confirmed hepatocellular carcinoma. These cases were divided into low-grade group, moderate-grade group and high-grade group according to postoperative pathology. ADC values were measured.Statistical analysis was performed by using SPSS 17.0. Quantitative data of single group with normal distribution and homogeneity of variance was performed by analysis of variance (ANOVA). Independent samples t-test was applied to pairwise comparisons, while Spearman rank correlation analysis was used to assess the correlation of ADC values with HCC differentiation. P <0.05 was considered statistically significant.

All patients were examined by diffusion-weighted imaging (DWI) scan, MR plan scan, MR dynamic enhancement scan at a clinical GE signa HDxt 3.0T 8-channel MR scanner. DWI scan: MR body surface coil was adopted. Scanning sequence and parameters were SE-EPI sequence, and TR 1500 ms, TE 47ms, b = 0,800s/mm2 respectively; the acquisition thickness was 7mm and the interval was 1mm. As for each scan, the longest breath holding time was limited within 24s for the completion of DWI signal acquisition, and 4-6 time scan was conducted for the whole liver. Horizontal surface fat-suppressed respiratory triggered rapid recovery spin echo sequence (TR 7000 ms, TE 85 ms) was used for T2WI, while breath-hold dual echo spoiled gradient echo sequence (TR 160ms, TE 4.5ms) was used for T1WI. Liver acquisition with volume acceleration flexible (LAVA Flex) acquisition sequence:(TE 1.7 ms, TR 3.7 ms),0.2 ml/kg contrast agent Gd. DTPA was injected with high-pressure syringe in flow rate of 2.5 ml/s by hand vein for enhancement scan, and then 20 ml of normal saline was injected for rinsing tube.The ADC value of lipid-containing small HCC in low-grade, moderate-grade and high-grade group was (0.96 ± 0.03) x 10^-3mm/s, (1.14± 0.09) x 10^-3mm/s, (1.43± 0.04) x 10^-3mm/s respectively. There was significant difference between low-grade group and moderate-grade group, as well as between low-grade group and high-grade group (P <0.05), while there was abviously significant difference between moderate-grade and high-grade group (p <0.05). Meanwhile, there was moderately positive correlation between ADC value and pathological grading of lipid-containing small HCC (P=0.002, r=0.419) and the coefficient of association was 0.95. ADC value can distinguish different pathological grading of lipid-containing small HCC, and there is moderately positive correlation between them. This may due to that cancer cells are closely arranged and the diffusion of water molecules are severely restricted in low-grade lipid-containing small HCC, while cancer cells are relatively neatly arranged in a regular and the diffusion of water molecules are less restricted in lipid-containing high-grade small HCC.