Diffusion-weighted MRI in liver fibrosis staging: Added value of normalized ADC using spleen and renal cortex as reference organs

AbstractAimTo evaluate the potential value of the spleen and renal cortex as a reference organ to improve the performance of DWI in the assessment of liver fibrosis.Material and methods44 subjects were included: 30 patients with chronic viral hepatitis and 14 age matched volunteers. They were subjected to diffusion weighted MRI (DWI). Liver ADC, normalized ADC (ratio between ADC of liver to spleen (S-ADC) and renal cortex (R-ADC)) was calculated. Data was analyzed and ROC was used to evaluate the performance of ADC, S-ADC and R-ADC.ResultsNo significant difference between spleen ADC and renal ADC values between patient group and control group or in-betweens different fibrosis stages. The mean liver ADC was significantly lower in cirrhotic patients than control group (1.59±0.024 versus 1.55±0.036×10−3mm2/s, P=0.009) with some overlap in different fibrosis grades.With exception to stage 1 fibrosis, the mean S-ADC value was significantly lower in patients with different hepatic fibrosis stages in comparison to control group (P 0.02–<0.001). Significant negative correlation was noted between S-ADC value and fibrosis stage (r=−0.75, p<0.001). It had significant difference between stage 0 compared to stage 2, 3, and 4 as well as between stage 4 in comparison to stage 1, 2 and 3. S-ADC had a significant ability to differentiate between stages 0–1 Vs stage 2–4, stage 0–2 Vs stage 3–4 as well as stage 0–3 Vs stage 4.Significant negative correlation was noted between R-ADC value and fibrosis stage (r=−0.68, p<0.001). The mean R-ADC value was lower in patients with liver fibrosis compared to volunteers with significant difference between stage 0 and 3 and between stage 0 and 4 (P<0.001). It had significant difference between stage 0 compared to stage 3, and 4 as well as in stage 4 in comparison to stage 1 and 2. R-ADC has a significant ability to differentiate between stages 0–1 Vs stage 2–4, stage 0–2 Vs stage 3–4 as well as stage 0–3 Vs stage 4.ROC analysis showed higher performance using S-ADC in comparison to liver ADC and R-ADC while R-ADC had higher performance in comparison to liver ADC. The AUC, sensitivity, specificity, PPV, NPV and k-value for detection of fibrotic stages ⩾2 (0.85, 95.8%, 60%, 74%, 92% and 0.85 for S-ADC Vs 0.68, 66.7%, 60%, 66%, 60% and 0.28 for ADC and 0.85, 95.8%, 50%, 69%, 91% and 0.47 for R-ADC). and in detection of fibrotic stages ⩾3 was (0.86, 100%, 52%, 61%, 100% and 0.48 for S-ADC Vs 0.63, 63%, 52%, 50%, 65% and 0.14 for ADC and 0.88, 100%, 44%, 57%, 100% and 0.40 for R-ADC) while for fibrosis stage 4, the corresponding values was (1, 100%, 100%, 100%, 100% and 1 for S-ADC Vs 0.7, 81%, 54%, 37%, 90% and 0.26 for ADC and 0.65, 100%, 65%, 45%, 100% and 0.43 for R-ADC) respectively.ConclusionNormalized liver ADC using the spleen and kidney increases the performance of ADC in the evaluation of liver fibrosis which is highest in spleen normalized ADC