Pre-operative ADC predicts early recurrence of HCC after curative resection

Abstract

OBJECTIVES: To assess a correlation between the preoperative diffusion-weighted imaging (DWI) and early recurrence (<2 years) and to determine the best DWI parameters as the risk factor of early recurrence after surgery in single hepatocellular carcinoma (HCC).

METHODS: The study included 114 patients with surgically resected single HCC (≤5 cm) who underwent preoperative magnetic resonance imaging (MRI) with DWI. Radiologists evaluated the diffusion restriction of the tumours using qualitative assessment and the mean and minimum apparent diffusion coefficient values (ADCmean and ADCmin) of the tumours using quantitative measurement. Clinical and laboratory findings and DWI parameters as a risk factor for early recurrence were identified by using Cox proportional hazards model.

RESULTS: No significant difference was observed in early recurrence rates of HCCs between those with and those without diffusion restriction (p = 0.484). Early recurrence rates of HCCs with ADCmean and ADCmin values lower than the optimal cut-offs (1.023 and 0.773 × 10-3 mm2/s, respectively) were significantly higher compared with those with values higher than the optimal cut-offs (p = 0.001 and p < 0.001, respectively). In the multivariable analysis, tumour size [hazard ratio (HR) per centimetre, 2.011; 95% CI, 1.304-3.102; p = 0.002] and ADCmin ≤0.773 × 10-3 mm2/s (HR, 13.339; 95% CI, 4.422-40.240; p < 0.001) were independent risk factors for early HCC recurrence.

CONCLUSIONS: DWI is a promising imaging tool for early recurrence of HCC. Among qualitative and quantitative assessments of DWI, ADCmin is a significant risk factor for early recurrence after surgery in single HCC.

KEY POINTS: • The performance of minimum apparent diffusion coefficient (ADCmin) is significantly better than that of mean apparent diffusion coefficient (ADCmean) for identifying early recurrence. • ADCmin is a significantly independent risk factor of early HCC recurrence after surgery. • ADCmin correlates with early recurrence after curative resection of single HCC, reflecting histopathological features of the tumours including histological grade and microvascular invasion.