Table 2 Cross-sectional imaging features and differential diagnoses of complicated urinary infections affecting the lower tract and male genital organs
Infectious conditions | Cross-sectional imaging signs | Key differential diagnoses |
|---|---|---|
Acute infectious cystitis | Diffuse mural bladder thickening, particularly if: - marked (≥1 cm thick) - hypoenhancing - oedematous at T2-weighted MRI - increased compared to previous studies Urothelial hyperenhancement - minimally thickened - uniform, circumferential Perivesical fat inflammatory changes | Urinary bladder carcinoma Nephrogenic adenoma, malacoplakia Urinary tuberculosis Schistosomiasis w/o superimposed squamocellular carcinoma Post-chemotherapy Radiation cystitis Uncommon: cystitis cystica, cystitis glandularis, eosinophilic cystitis |
Mural bladder abscess | Intramural / exophytic collection - internally hypoattenuating (10–15 HU) non-enhancing - irregular, often thick peripheral enhancement - usual site: upper bladder aspect | Infected bladder diverticulum Urinary bladder carcinoma with perivesical invasion |
Emphysematous cystitis | Gas-attenuation linear changes along the bladder wall | Intraluminal air from catheterisation Enterovesical fistulisation (particularly from colonic diverticulosis or Crohn’s disease) |
Prostatic abscess | Single or multifocal collection - peripheral or septal enhancement - centrally non-enhancing fluid-like Variable prostatic enlargement, urethral displacement Possible extraprostatic extension | Acute bacterial prostatitis Prostate carcinoma (particularly after treatment) |
Seminal vesicle abscess | Uni- or bilateral seminal vesicle enlargement - thick irregular enhancing walls and septa - internally hypoattenuating, non-enhancing Adjacent fat inflammatory changes | Chronic infection Urinary tuberculosis Congenital cysts Metastases, rare primary tumours |
Acute urethritis | Thickened penile urethra and surrounding tissues - increased T2 MRI signal intensity - corresponding increased contrast enhancement | |
Periurethral abscess | Periurethral collection - internally fluid or purulent - peripheral enhancement - typical site: ventral, communicating with penile urethra Thickened, oedematous corpus spongiosum Possible further inferior extension to perineum and scrotum Possible development of necrotizing fasciitis (Fournier’s gangrene) | Urethral diverticulum |
Funiculitis, epididymitis | Unilateral spermatic cord thickening - with engorged enhancing vessels Variable epididymal enlargement - increased T2 MRI signal intensity - hyperenhancing epididymis | Tuberculosis Varicocele Inguino-crural hernia Spermatocele/sperm granuloma Rare epididymal tumours, e.g. neurofibroma, metastasis |
Orchitis, scrotal abscess | Unilateral testicular enlargement - decreased T1, increased T2 MRI signal intensity - increased vascularity (diffuse or “tiger skin” appearance) - loss of contrast enhancement when necrosis occurs Funiculitis and epididymitis commonly associated Abscess/pyocele: - fluid-like collections - enhancing periphery - surrounded by hypervascularised testicular parenchyma | Testicular torsion Testicular tumours, e.g. lymphoma, seminoma, germ cell tumours Necrotizing fasciitis (Fournier’s gangrene) from non-urinary source Hidradenitis suppurativa |