Intraprostatic Lesion Conspicuity Reproducibility Assessment of DWI in 1.5T MR-guided Radiotherapy: MRI-Simulator vs MR-Linac

Motivation: Diffusion-weighted imaging is crucial for identifying ILs in MRgRT. However, DWI quality varies between diagnostic scanners and MR-LINACs, potentially affecting its role in radiotherapy. Goal(s): To investigate IL conspicuity reproducibility using DWI at different b-values and ADC maps on 1.5T MR-simulator and MR-LINAC systems. Approach: Compared DW images from 19 prostate cancer patients on both systems. An expert rated lesion conspicuity on a 3-point scale, with statistical analysis performed to assess reproducibility and differences. Results: Moderate reproducibility between systems, with MR-simulator showing better IL visualization and b1400 images performed best. Findings of this study emphasize the need for improved DWI quality on MR-LINACs. Impact: This study reveals moderate reproducibility of intraprostatic lesion conspicuity between MR-simulator and MR-LINAC systems. Findings underscore the need for improved DWI quality and standardized protocols in MR-guided radiotherapy.