Predicting Preoperative Pathologic Grades of Bladder Cancer Using Intravoxel Incoherent Motion and Amide Proton Transfer-Weighted Imaging

Rationale and objectives: To investigate the predictive value of intravoxel incoherent motion (IVIM) combined with amide proton transfer-weighted (APTw) imaging for the preoperative grading of bladder cancer (BC).

Materials and methods: A total of 69 patients with histopathologically confirmed BC underwent diffusion-weighted imaging (DWI), IVIM, and APTw imaging at 3.0 T MRI. Two radiologists independently measured the mean apparent diffusion coefficient (ADC) in DWI, true diffusion coefficient (D), perfusion-related pseudo-diffusion coefficient (D*), and perfusion fraction (f) in IVIM, and APTw values, respectively. The areas under the receiver operating characteristic curves (AUCs) were utilized to compare the diagnostic efficacy of these single and combined quantitative parameters.

Results: ADC and D values of low-grade BC were significantly higher than those of high-grade BC ([1.42 ± 0.20 ×10^-3 mm²/s] vs. [1.09 ± 0.25 ×10^-3 mm²/s] and [1.24 ± 0.24 ×10^-3 mm²/s] vs. [0.89 ± 0.18 ×10^-3 mm²/s], respectively; all P < 0.001). Opposite patterns were found for APTw ( [1.53 ± 0.42]% vs. [2.38 ± 0.71]%, P < 0.001). The ROC curves indicated that the combination of D and APTw values could distinguish low- from high-grades of BC with the highest predictive efficacy (AUC = 0.96), as well as a significant difference compared to those by ADC, D, and APTw values separately (AUC = 0.84, 0.88, 0.85, respectively; all P < 0.05).

Conclusion: IVIM combined with APTw imaging significantly improved the predictive efficacy of assessing low- and high-grade BC compared to the individual parameters on their own, providing an effective non-invasive method for clinical preoperative prediction of BC grading.