Pretreatment diffusion-weighted imaging for prediction of relapsed and refractory primary central nervous system lymphoma.

Objectives: A subset of primary central nervous system lymphoma (PCNSL) has been shown to undergo an early relapsed/refractory (R/R) period after first-line chemotherapy. This study investigated the pretreatment clinical and MRI features to predict R/R in PCNSL, emphasizing the apparent diffusion coefficient (ADC) values in diffusion-weighted imaging (DWI).

Methods: This retrospective study investigated the pretreatment MRI features for predicting R/R in PCNSL. Only patients who had undergone complete preoperative and postoperative MRI follow-up studies were included. From January 2006 to December 2021, 52 patients from two medical institutions with a diagnosis of PCNSL were included (median follow-up time, 26.3 months). Among these, 24 (46.2%) had developed R/R (median time to relapse, 13 months). Cox proportional hazard regression analyses were performed to determine hazard ratios for all parameters.

Results: Significant predictors of R/R in PCNSL were female sex, complete response (CR) to first-line chemotherapy, and ADC value/ratio ( < 0.05). Cut-off points of ADC values and ADC ratios for prediction of R/R were 0.68 × 10 mm/s and 0.97, with AUCs of 0.78 and 0.77, respectively ( < 0.05). Multivariate Cox proportional hazards analysis showed that failure of CR to first-line chemotherapy and low ADC values (<0.68 × 10 mm/s) were significant risk factors for R/R, with hazard ratios of 5.22 and 14.45, respectively ( < 0.05). Kaplan-Meier analysis showed that lower ADC values and ratios predicted significantly shorter progression-free survival ( < 0.05).

Conclusion: Pretreatment ADC values in DWI offer quantitative valuable information for the treatment planning in PCNSL.