Value of diffusion kurtosis MR imaging and conventional diffusion weighed imaging for evaluating response to first-line chemotherapy in unresectable pancreatic cancer.

Objective: To investigate the diagnostic value of diffusion kurtosis magnetic resonance imaging (DKI) and conventional diffusion-weighted imaging (DWI) for evaluating the response to first-line chemotherapy in unresectable pancreatic cancer.

Materials and methods: We retrospectively analyzed 21 patients with clinically and pathologically confirmed unresected pancreatic cancer who received palliative chemotherapy. Three-tesla MRI examinations containing DWI sequences with b values of 0, 100, 700, 1400, and 2100 s/mm² were performed before and after chemotherapy. Parameters included the apparent diffusion coefficient (ADC), mean diffusion coefficient (MD), and mean diffusional kurtosis (MK). The performances of the DWI and DKI parameters in distinguishing the response to chemotherapy were evaluated by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve. Overall survival (OS) was calculated from the date of first treatment to the date of death or the latest follow-up date.

Results: The ADC_change and MD_change were significantly higher in the responding group (PR group) than in the nonresponding group (non-PR group) (ADC_change: 0.21 ± 0.05 vs. 0.11 ± 0.09, P = 0.02; MD_change: 0.37 ± 0.24 vs. 0.10 ± 0.12, P = 0.002). No statistical significance was shown when comparing ADC_pre, ADC_post, MK_pre, MK_post, MK_change, MD_pre, and MD_post between the PR and non-PR groups. The ROC curve analysis indicated that MD_change (AUC = 0.898, cutoff value = 0.7143) performed better than ADC_change (AUC = 0.806, cutoff value = 0.1369) in predicting the response to chemotherapy.

Conclusion: The ADC_change and MD_change demonstrated strong potential for evaluating the response to chemotherapy in unresectable pancreatic cancer. The MD_change showed higher specificity in the classification of PR and non-PR than the ADC_change. Other parameters, including ADC_pre, ADC_post, MK_pre, MK_post, MK_change, MD_pre, and MD_post, are not suitable for response evaluation. The combined model SUM_change demonstrated superior performance compared to the individual DWI and DKI models. Further experiments are needed to evaluate the potential of DWI and DKI parameters in predicting the prognosis of patients with unresectable pancreatic cancer.