MRI-DTI Assessment of Urethral Internal Sphincter Ring and Prostate Base Morphology

This is a single-center, observational imaging study designed to evaluate the in vivo morphology of the male urethral internal sphincter ring using magnetic resonance diffusion tensor imaging (MRI-DTI) fiber tracking and to investigate its relationship with prostate base morphology. Male participants undergoing clinically indicated pelvic, seminal vesicle, or prostate-related MRI-DTI examinations will be included. The study population may include patients with benign prostatic enlargement, younger men undergoing MRI for suspected cryptorchidism or suspected seminal vesiculitis, and patients with prostate cancer scheduled to receive androgen deprivation therapy (ADT). All participants will undergo T2-weighted imaging and DTI. T2WI-DTI image registration, dual-region-of-interest fiber tracking, and three-dimensional reconstruction will be used to visualize ring-like muscle fiber structures in the bladder neck, prostate base, and proximal urethral region. The cross-sectional imaging cohort will be used to assess the associations between prostate-side morphological parameters, including prostate volume, prostate base diameter or area, and intravesical prostatic protrusion, and sphincter-ring parameters, including ring inner diameter and ring area. The ADT paired cohort will undergo MRI-DTI before treatment and during follow-up after ADT to evaluate whether reduction in prostate volume and prostate base morphology is accompanied by corresponding changes in the urethral internal sphincter ring. This study will not alter the participants' existing clinical diagnostic or treatment pathways. Imaging data will be analyzed using standardized post-processing and quantitative measurement procedures. The results may provide in vivo imaging evidence for age- and prostate-related displacement and morphological remodeling of the male urethral internal sphincter and may inform future surgical strategies for identifying, preserving, or reconstructing proximal urinary continence-related structures.