Staging liver fibrosis in chronic hepatitis B with T1 relaxation time index on gadoxetic acid-enhanced MRI: Comparison with aspartate aminotransferase-to-platelet ratio index and FIB-4

PurposeTo assess the accuracy of the T-1 relaxation time index on gadoxetic acid-enhanced magnetic resonance imaging (MRI) for staging liver fibrosis in chronic hepatitis B (CHB), in comparison and combination with the aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 (FIB-4). Materials and MethodsA retrospective study of gadoxetic acid-enhanced T-1 mapping and serum biochemical tests was performed on 126 CHB patients who underwent gadoxetic acid-enhanced 1.5T MRI, and the histological score used as the gold standard. The reduction rate of T-1 relaxation time before and 20 minutes after gadoxetic acid injection (T-1, R1%), the contrast uptake rate (K-Hep), APRI, and FIB-4 were calculated. The diagnostic efficacy of T-1, R1%, K-Hep, APRI, and FIB-4 for predicting stage 2 or greater (S2), stage 3 or greater (S3), and stage 4 (S4) was compared. ResultsT(1) (r=-0.513, P < 0.001), R1% (r=-0.626, P < 0.001), K-Hep (r=-0.527, P < 0.001), APRI (r=0.519, P < 0.001), and FIB-4 (r=0.476, P < 0.001) correlated significantly with fibrosis stages. Areas under the curves (AUCs) of R1% for detecting S2, S3, and S4 were 0.849, 0.827, and 0.809, which were greater than that of APRI (0.763, 0.745, 0.787) and FIB-4 (0.727, 0.738, 0.772), but significant difference was found only in discriminating S2 between R1% and FIB-4 (P=0.027). The combination of all five indices performed best, with AUC, sensitivity, and specificity of 0.860, 87.21%, and 72.50% for diagnosing S2, 0.878, 82.81%, and 85.48% for S3, and 0.867, 80.00%, and 83.95% for S4. ConclusionThe gadoxetic acid-enhanced T-1 relaxation time index appears to be superior to APRI and FIB-4 for predicting hepatic fibrosis. The combined use of gadoxetic acid-enhanced T-1 mapping, APRI, and FIB-4 may be more reliable for staging liver fibrosis in CHB.