Male Pelvic Imaging

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Male Pelvic Anatomy & Modalities - Pixel Perfect Pelvis

  • Key Structures & Zones:
    • Prostate: Peripheral (PZ - commonest cancer site), Central (CZ), Transitional (TZ - BPH site).
    • Seminal Vesicles (SVs), Vas Deferens, Ejaculatory Ducts.
    • Bladder, Urethra, Rectum. Sagittal T2 MRI of male pelvis anatomy
  • Primary Imaging Modalities:
    • USG: TRUS for prostate (biopsy, volume); TAUS for bladder.
    • MRI: Best soft tissue. Multiplanar.
      • Prostate: T2WI (zonal anatomy), DWI (malignancy), DCE (vascularity). PI-RADS (1-5).
      • Local staging: prostate, rectal, bladder cancers.
    • CT: Trauma, bony pelvis, calcifications, gross nodal/distant mets.
    • Fluoroscopy: RGU/VCUG for urethral strictures, VUR.

⭐ On T2-MRI, prostate cancer in PZ often appears as a low signal intensity focus.

Prostate Gland Imaging - Gland Central Station

  • Modalities:
    • Transrectal Ultrasound (TRUS): Biopsy guidance, initial assessment.
    • Multiparametric MRI (mpMRI): Gold standard for detection, staging, and active surveillance of prostate cancer. Sequences: T2W, DWI, DCE.
    • CT: Limited for primary tumor; useful for nodal/metastatic disease.
  • Zonal Anatomy (T2W MRI):
    • Peripheral Zone (PZ): ~70% cancers. High T2 signal.
    • Transition Zone (TZ): BPH origin. Heterogeneous T2 signal.
    • Central Zone (CZ): Low T2 signal.
    • Anterior Fibromuscular Stroma (AFMS): Very low T2 signal. Prostate MRI T2W zonal anatomy
  • Prostate Cancer on mpMRI:
    • PZ: T2 hypointense, restricted diffusion (low ADC), early enhancement.
    • TZ: More challenging; ill-defined, homogenous, T2 hypointense, lenticular.
  • PI-RADS (Prostate Imaging Reporting and Data System):
    • Standardized reporting for cancer risk (Score 1-5).
    • Dominant sequence: PZ (DWI), TZ (T2W).

⭐ Most prostate cancers (~70-80%) arise in the Peripheral Zone (PZ).

Testicular & Scrotal Imaging - Testicular Tales

  • Ultrasound (USG): Primary modality. High-frequency linear probe (7.5-12 MHz).
    • Normal Testis: Homogeneous, mid-grey. Size: 3-5 cm (L). Volume: ~20 ml.
    • Color Doppler: Crucial for vascularity.
  • Key Conditions:
    • Testicular Torsion:
      • Acute pain.
      • USG: Enlarged, hypoechoic testis. ↓/absent Doppler flow. Whirlpool sign of cord.
      • ⚠️ Surgical emergency: salvage ↓ after 6 hrs.
    • Epididymo-orchitis:
      • Pain, fever.
      • USG: Enlarged epididymis &/or testis. ↑ Doppler flow. Reactive hydrocele.
    • Varicocele:
      • Dilated pampiniform veins (>2-3 mm), ↑ with Valsalva. Usually left.
    • Hydrocele:
      • Anechoic fluid in tunica vaginalis.
    • Testicular Tumors:
      • Seminoma: Hypoechoic, homogeneous.
      • NSGCT: Heterogeneous.
      • Markers: AFP, β-hCG.

Testicular Ultrasound: Torsion vs Epididymo-orchitis

⭐ "Bell-clapper" deformity, where the tunica vaginalis has an abnormally high attachment to the spermatic cord, is a major predisposing factor for testicular torsion.

Penile & Urethral Pathologies - Pointing Out Problems

  • Penile Pathologies:
    • Peyronie's Disease: Fibrous plaques (tunica albuginea) → penile curvature. USG: calcified plaques.
    • Priapism: Erection >4 hrs. Doppler USG: Ischemic (low flow) vs. Non-ischemic (high flow).
    • Penile Fracture: Tunica albuginea rupture. "Eggplant deformity". USG/MRI. RGU if urethral injury suspected.
    • Penile Cancer (SCC): MRI for local staging, inguinal node assessment. Penile Cancer T-Staging Diagram
  • Urethral Pathologies:
    • Urethral Strictures: Fibrotic narrowing. RGU/VCUG (MCU) for diagnosis, location, length.
    • Urethral Trauma:
      • Anterior: Straddle injury. RGU.
      • Posterior: Pelvic fracture. 📌 "High-riding prostate".
    • Urethral Diverticula: Outpouching. VCUG/RGU, MRI.
    • Urethral Cancer (SCC): Rare. RGU, MRI for staging.

⭐ Posterior urethral injury (pelvic fracture): "High-riding prostate" on imaging due to hematoma. RGU often deferred or performed with caution after initial stabilization (e.g., suprapubic catheter).

High‑Yield Points - ⚡ Biggest Takeaways

  • MRI is gold standard for prostate cancer staging (TNM) and local recurrence detection.
  • TRUS is key for prostate biopsy guidance and evaluating male infertility (e.g., ejaculatory duct obstruction).
  • Testicular torsion: Color Doppler US shows absent testicular blood flow - a surgical emergency.
  • Varicocele: Ultrasound with Valsalva identifies dilated pampiniform plexus veins (>2-3mm).
  • Zinner syndrome: Triad of seminal vesicle cyst, ejaculatory duct obstruction, ipsilateral renal agenesis.
  • RGU/MCU are crucial for evaluating urethral injuries, especially post-trauma.

Practice Questions: Male Pelvic Imaging

Test your understanding with these related questions

Bell clapper deformity (abnormal testicular fixation) predisposes to which of the following conditions?

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Flashcards: Male Pelvic Imaging

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Investigation of choice in renal cell carcinoma to evaluate IVC and renal vein involvement is _____.

TAP TO REVEAL ANSWER

Investigation of choice in renal cell carcinoma to evaluate IVC and renal vein involvement is _____.

MRI

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