Abstract Introduction Intravoxel Incoherent Motion (IVIM) MRI quantifies microscopic diffusion and perfusion without contrast agents. Although widely used in oncologic and muscle physiology studies, its application to female sexual anatomy and radiation-related changes remains untested. Perfusion of the bulboclitoris, including the corpora cavernosa and spongiosa, is fundamental to sexual arousal physiology. IVIM may provide noninvasive, quantitative indices of erectile tissue vascularity and identify perfusion alterations after pelvic radiation therapy (RT), where off-target exposure can disrupt vascular and neural integrity affecting sexual function. Objective To demonstrate the feasibility of IVIM MRI for resolving perfusion-related parameters within female erectile tissues and integrating these measures with validated sexual function outcomes in healthy and post-RT participants. Methods A prospective pilot cohort included four sexually active females (mean age 35.3 ± 8.4 years): three healthy volunteers and one post-RT cervix cancer survivor. MRI was performed on a 3 T Siemens Prisma with a dedicated genitopelvic protocol: axial high-resolution T2-weighted and diffusion-weighted imaging (b-values: 0–1000 s/mm2). Regions of interest (ROIs) for corpora cavernosa, corpora spongiosa, and glans were manually delineated on T2 images and registered to IVIM maps. Voxelwise modeling estimated the perfusion fraction (f) and perfusion-related (pseudo-) diffusion coefficient (D*). Sexual function was assessed using calibrated T scores for PROMIS SexFS domains (clitoral discomfort, lubrication, orgasm-pleasure, orgasm-ability, global satisfaction). Clinically significant dysfunction was defined as deviation ≥ 3 T-score points from population means. Results All four participants completed imaging and PROMIS assessments without protocol deviations. Segmentation and registration were successful in all cases, yielding anatomically coherent f and D* maps. Mean ± SD perfusion fractions across the cohort were 0.102 ± 0.019 for the corpora cavernosa, 0.135 ± 0.041 for the corpora spongiosa, and 0.111 ± 0.044 for the glans. Corresponding mean D* values (×10-3 mm2/s) were 13.6 ± 4.4, 14.6 ± 6.4, and 15.5 ± 16.1, respectively. The post-RT participant demonstrated higher mean f in both corpora (cavernosa 0.129; spongiosa 0.19) compared with healthy controls (0.094 ± 0.007 and 0.117 ± 0.023, respectively), but lower D* in the cavernosa (8.2 vs 15.4 ± 3.2), consistent with potentially altered microvascular kinetics due to endothelial injury or fibrosis. PROMIS median T-scores indicated mild-to-moderate dysfunction in lubrication (47.5 43.4–51.3) and orgasm ability (49.0 39.6–58.4), with global satisfaction below population mean (44.0 41.5–47.9); dysfunction prevalence ranged 25–75% across domains. Exploratory stratification by orgasm-ability dysfunction showed lower f in both cavernosa (0.096 vs 0.109) and spongiosa (0.120 vs 0.150) groups, suggesting biologically plausible associations warranting further investigation. Conclusions Dedicated genitopelvic IVIM MRI is feasible in healthy and post-RT females, producing reproducible quantitative maps of erectile tissue perfusion. End-to-end implementation, from acquisition through ROI modeling and PRO integration, was successful in all participants. Observed inter-subject and post-RT parameter variation suggests potential physiologic sensitivity to vascular compromise. These findings justify test–retest reproducibility studies and expanded recruitment to validate IVIM as a biomarker of radiation-related sexual tissue injury that may inform safer, more targeted radiotherapy approaches that can preserve sexual function. Disclosure No
Castillo et al. (Mon,) studied this question.