Correlation of PSMA-PET/CT standardized uptake value (SUV) and apparent diffusion coefficient (ADC) in MR-guided prostate radiotherapy

Motivation: Prostate cancer (PC) imaging utilizes PSMA-PET/CT and DWI for assessing tumor characteristics and treatment response, which should be useful in MR-guided radiotherapy (MRgRT). Goal(s): Investigate the correlation between PSMA-PET/CT SUVmax and ADC in PC patients undergoing MRgRT to understand their complementary roles. Approach: Retrospectively analyzed 17 PC patients who underwent pre-MRgRT PSMA-PET/CT and MR-simulation. Pearson's correlation between SUVmax and ADC was evaluated. Results: An weak inverse correlation between SUVmax and ADC (r=-0.30, p=0.08) was found in 34 lesions. The lack of significance may be primarily due to the androgen deprivation therapy administration between PSMA-PET/CT and MRI, affecting ADC but not SUVmax. Impact: This study underscores the intricate relationship between PSMA-PET/CT SUV and DWI-ADC in prostate MRgRT, significantly affected by the timing of androgen deprivation therapy administration, which may influence the scheduling and logistics of MRgRT imaging.