Comparative analysis of amide proton transfer and diffusion-weighted imaging for assessing Ki-67, p53 and PD-L1 expression in bladder cancer.

Rationale And Objectives: To evaluate amide proton transfer (APT) imaging for assessing Ki-67, p53 and PD-L1 status in bladder cancer (BC) and compare its diagnostic efficacy with that of diffusion-weighted imaging (DWI).

Materials And Methods: Consecutive patients suspected of BC were recruited for preoperative multiparametric MRI. APT signal was quantified by asymmetric magnetization transfer ratio (MTR). MTR and apparent diffusion coefficient (ADC) were measured by two radiologists, with interobserver agreement assessed. Spearman's correlation analyzed MTR values and molecular markers. The Whitney U test evaluated MTR and ADC variation based on molecular marker status. Optimal cutoff points were determined using area under the curve (AUC) analysis.

Results: 88 patients (72 ± 10 years; 77 men) with BC were studied. MTR values were significantly correlated with Ki-67, p53 and PD-L1 levels (P < 0.05). Higher MTR values were found in high Ki-67 expression BCs (1.89% [0.73%] vs. 1.23% ± 0.26%; P < 0.001), high p53 expression BCs (1.63% [0.56%] vs. 1.24% [0.56%]; P < 0.001) and positive PD-L1 expression BCs (2.02% [0.81%] vs. 1.48% [0.38%]; P < 0.001). Lower ADCs were found in high Ki-67 expression BCs (1.06 ×10 mm/s [0.32 ×10 mm/s] vs. 1.38 ×10 mm/s [0.39 ×10 mm/s]; P < 0.001). For p53 status, an MTR threshold of 1.27% had 95% sensitivity, 60% specificity, and AUC of 0.781. For PD-L1 status, a 1.90% threshold had 88% sensitivity, 92% specificity, and AUC of 0.859.

Conclusion: APT may significantly enhance the preoperative assessment of BC aggressiveness and inform targeted immunotherapy decisions, with performance superior to DWI.