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.

Sex

Male

Minimum age

15 Years

Maximum age

90 Years

Inclusion Criteria:

1. Male participants undergoing clinically indicated pelvic, seminal vesicle, or prostate-related MRI-DTI examination.
2. Participants with adequate T2-weighted MRI and DTI data for post-processing and quantitative assessment of the bladder neck, prostate base, and proximal urethral region.
3. Participants in the cross-sectional imaging cohort may include men undergoing MRI for suspected cryptorchidism, suspected seminal vesiculitis, benign prostatic enlargement, or other clinically indicated pelvic or prostate-related evaluations.
4. Participants in the ADT paired follow-up cohort must have prostate cancer and be scheduled to receive androgen deprivation therapy, with MRI-DTI planned before treatment and during follow-up after ADT.
5. Participants must be able to comply with MRI examination procedures.
6. Written informed consent will be obtained when required by the approved study protocol.

Exclusion Criteria:

1. Contraindications to MRI, including but not limited to incompatible metallic implants, severe claustrophobia, or other conditions preventing MRI examination.
2. Known neurogenic bladder dysfunction, including spinal cord injury, multiple sclerosis, Parkinson disease, or other neurological disorders that may significantly affect lower urinary tract function.
3. History of pelvic radiotherapy.
4. History of urethral reconstruction, sphincter surgery, or other prior surgery that substantially alters the bladder neck, proximal urethra, or prostate base anatomy.
5. Severe cardiopulmonary dysfunction, cognitive impairment, psychiatric disorder, or other conditions preventing cooperation with MRI examination or study procedures.
6. Use of medications or treatments within the previous 3 months that may substantially affect neuromuscular function of the lower urinary tract, as judged by the investigators.
7. Poor image quality or failed post-processing that prevents reliable visualization or measurement of the urethral internal sphincter ring.

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