Evaluating Neoadjuvant Immunochemotherapeutic Response for Bladder Carcinoma Using Amide Proton Transfer-Weighted MRI

Abstract

Rationale and Objectives

To investigate the feasibility of amide proton transfer-weighted (APTw) and diffusion-weighted MRI in evaluating the response of bladder cancer (BCa) to neoadjuvant immunochemotherapy.

Materials and Methods

From June 2021 to July 2023, participants with pathologically confirmed BCa were prospectively recruited to undergo MRI examinations, including APTw and diffusion-weighted MRI before and after neoadjuvant immunochemotherapy. Histogram analysis features (mean, median, and entropy) were extracted from pre- and post-treatment APTw and apparent diffusion coefficient (ADC) maps, respectively. Participants were categorized into pCR (pathological complete response, no residual tumor) and non-pCR groups based on histologic evaluation of post-treatment cystectomy specimens. The diagnostic efficacy of parameters in predicting tumor responsiveness was evaluated by calculating the area under receiver operating characteristic curve (AUC).

Results

Significant differences were found in several imaging biomarkers derived from pre-treatment APTw and diffusion-weighted MRI (P < 0.05 for all). The baseline APTw mean values yielded the highest diagnostic performance, with an AUC of 0.85 (AUC: 0.75–0.93), for evaluating tumor responsiveness. For the pCR group, APTw values markedly decreased while ADC values noticeably increased at post-treatment MRI (P < 0.05 for all). However, the parameter changes in non-pCR group were not significant (P > 0.05 for all).

Conclusion

MRI parametrics derived from APTw and diffusion-weighted MRI can both serve as valuable noninvasive imaging biomarkers for evaluating the efficacy of immunochemotherapy and may be used to guide personalized precision therapy.