Fat- and iron-corrected ADC to assess liver fibrosis in patients with chronic hepatitis B.

Purpose: We aimed to evaluate the diagnostic performance of apparent diffusion coefficient (ADC) in assessing liver fibrosis after correcting for the effects of hepatic steatosis or iron deposition.

Methods: Seventy-three patients with chronic hepatitis B (CHB) were included in this retrospective study. The aspartate aminotransferase-to-platelet ratio index (APRI) was calculated for classification of the fibrosis grade. Significant fibrosis and cirrhosis were diagnosed with the APRI. The proton density fat fraction (PDFF), R2*, and ADC values were measured. The impact of the PDFF and R2* on the ADC was analyzed. The PDFF- and R2*-corrected ADC values (ADCPDFF and ADCR2*) were calculated according to linear regression equations. The diagnostic performance of uncorrected ADC (ADCu), ADCPDFF and ADCR2* in predicting significant fibrosis and cirrhosis was assessed, and the area under the curve (AUC) values were compared.

Results: Among the 73 patients in this study, the mean ADC was 0.866 ± 0.084×10-3 mm2/s, the mean R2* was 60.24 (42.77, 85.37) 1/s, and the mean PDFF was 2.90% (1.60%- 4.80%). The ADC was negatively correlated with the PDFF (r= -0.298, P = .010) and R2* (r = -0.457, P < .001). Linear regression analysis showed that the PDFF and R2* were independent factors of the ADC (β= -0.315, P = .007, R2= 0.099 and β= -0.493, P < .001, R2= 0.243, respectively). Compared with the uncorrected ADC (r= -0.307, P = .022), the correlation between the ADCPDFF and fibrosis grade increased (r= -0.513, P < .001), and the correlation between the ADCR2* and fibrosis grade decreased (r=-0.168, P = .215). The AUC of the ADCPDFF was significantly larger than that of the ADCu in the diagnosis of significant fibrosis and cirrhosis, which increased from 0.68 to 0.81 (P = .003) for predicting significant fibrosis and from 0.75 to 0.84 (P = .009) for predicting cirrhosis. The AUCs for the ADCR2* in the diagnosis of significant fibrosis and cirrhosis were both lower than that for the uncorrected ADC (P = .206 and P = .109, respectively).

Conclusion: After correcting for the effects of steatosis, the diagnostic performance of the ADC for signifi-cant fibrosis and cirrhosis increased. The ADC corrected for the effects of steatosis may be more reliable for identifying liver fibrosis.