The role of diffusion weighted imaging in diagnosis and follow-up of liver masses alongside conventional MRI findings

Purpose: The aim of this study is to investigate the efficiancy of quantitative ADC (apperent diffusion coefficient) data in the diagnosis and follow-up of liver lesions detected in MRI (magnetic resonance imaging). Material-Method: 524 out of 948 patients who had solid and/or cystic hepatic lesions detected in MRI between december 2014-2017 and aged 18 and over, were included in the study. One lesion was measured at each examination. Two MRIs of 40 patients who were under follow-up and one MRI for each another patient. (564 examinations; 564 measurements). The location, size, margin-border and T1-T2 signal characteristic of the lesion were evaluated with 1.5 Tesla MRI device. Quantitative ADC measurements (minimum, maximum, mean) and lesion enhancement pattern were identified through the licensed image analysis software program. Statistical analysis (SPSS v22, MedCalc v18) p<0.05 was considered significant. Results: Out of 524 (242 male, 282 female) cases 350 (67%) were benign and 174 (33%) were malignant. The mean age of the patients was 60 (±12/21-88). The mean size was 30 (±20/10-125) mm in benign lesions and 52 (±40/10-200) mm in malignant lesions. Statistically significant difference was found for the minimum, maximum and mean ADC values of benign-malignant lesion groups (p <0.001, Mann-Whitney U). When the mean ADC value which used commonly in routine practice taken 1.72 x10-3mm2/s as cut-off value for the differentiation of benign-malignant lesions, sensitivity was 83%, specificity was 98%, negative predictive value was 99% and positive predictive value was found 74% respectively (ROC analyse, MedCalc). Statistically significant difference was found between the good, moderate and poor differentiation types of hepatocellular carcinomas (HCC) for minimum ADC (p <0.001/One-Way ANOVA). According to the Li-RADS classification, there was no significant difference between the L3-L4-L5 groups in ADC values (p: 0.698). The increase in ADC values in malign lesions which showed dimensional regression under treatment, were significant. (p <0.001/Wilcoxon T test). Conclusion: In addition to conventional MRI sequences, quantitative ADC measurements were found to be useful in the differentiation of benign-malign lesions, in the differentiation histological grading of HCC and in the correct evaluation of treatment response. Keywords: Liver Lesions, Magnetic Resonance Imaging (MRI), Diffusion-Weighted Imaging (DWI), ADC (Apperent Diffusion Coefficient) Contact Address: Adnan Menderes University Faculty of Medicine, Department of Radiology, AYDIN / E-mail: dr.a.tanyeri@gmail.com