IVIM DW-MRI of autoimmune pancreatitis: therapy monitoring and differentiation from pancreatic cancer

To evaluate IVIM DW-MRI for changes in IVIM-derived parameters during steroid treatment of autoimmune pancreatitis (AIP) and for the differentiation from pancreatic cancer (PC). Fifteen AIP-patients, 11 healthy patients and 20 PC-patients were examined with DWI-MRI using eight b-values (50, 100, 150, 200, 300, 400, 600, 800). 12 AIP-patients underwent follow-up examinations during treatment. IVIM-parameters and ADC₈₀₀-values were tested for significant differences and an ROC analysis was performed. The perfusion fraction f was significantly lower in patients with AIP at the time of diagnosis (10.5 ± 4.3 %) than in patients without AIP (20.7 ± 4.3 %). In AIP follow-up, f increased significantly to 17.1 ± 7.0 % in the first and 21.0 ± 4.1 % in the second follow up. In PC, the f-values were lower (8.2 ± 4.0 %, n.s.) compared to initial AIP and were significantly lower compared to first and second follow-up examination. In the ROC-analysis AUC-values for f were 0.63, 0.88 and 0.98 for differentiation of PC from initial, first and second follow up AIP-examination. The found differences in f between AIP, AIP during steroid treatment and pancreatic cancer suggest that IVIM-diffusion MRI could serve as imaging biomarker during treatment in AIP-patients and as a helpful tool for differentiation between PC and AIP. (orig.)