AUA 2022 guidelines no longer recommend cystoscopy as a first line diagnostic screen for interstitial cystitis/ bladder pain syndrome (IC/BPS), which may have stemmed from  the wide variability in the subjective detection of cystoscopic abnormalities such as Hunner lesion and the absence of a standardized criteria for recording the spatial context of lesions after filling bladder via urethral catheter to maximum capacity at a pressure of 60–100 cmH2O.  In addition, the cystoscopic phenotyping of chronic cystitis from overlapping symptoms of non-neurogenic overactive bladder symptoms is hampered by a narrow field of view (FOV) and  trabeculations, defined by an irregular contour of hypertrophied muscle bundles- are detectable in nearly three-fourths of women with chronic cystitis (ref.1). Here, we report that unenhanced magnetic resonance (MR) urography by T2 weighted MRI can portray panoramic, 360 degree views of trabeculations and Hunner's lesion after naturalistic filling of bladder without catheterization for filling the bladder to maximum capacity and without the complications of invasive biopsy.

After signing informed consent, eight women with lower urinary tract symptoms (LUTS) were prospectively recruited from outpatient urology clinic of a major academic medical center for unenhanced MRI urography by Prisma 3T scanner with 4-channel flexible receiver coil centered on the pelvis. Only women with prior cystoscopy and a history of IC/BPS with or without Hunner’s lesion were enrolled   After rapidly locating the bladder, multi-slice 3mm thick 30-35 Turbo spin echo (TSE) T2-weighted slices were acquired for measuring bladder wall thickness (BWT),  lesions and trabeculations. Panoramic views of bladder were generated from stacked slices using Image J.

The evidence of focal bladder wall thickening in T2 weighted scans indexed Grade 1 trabeculations (T)- at least a single layer of muscle bundle on the mucosal and serosal side. T2 weighted scans are displayed in grey scale and the signal intensity is color coded for volumetric rendering of stacked slices and display trabeculations as thick contours of hypertrophied muscle bundles, visible on 
serosal and mucosal surface. Two of the enrolled women showed trabeculations together with periureterally located Hunner lesions. High water content of collagen makes the collagen rich foci to appear brighter than non-fibrotic tissue of post-menopausal IC/BPS patients without Hunner’s lesion.

While healthy bladder lining is uniformly thick with smooth appearance, the thickening of urothelium and Grade 1 trabeculations are the most common finding in adult women with lower urinary tract complaints. Our prospective MRI study reproduced the prevalence of trabeculations reported with invasive cystoscopy and biopsy. With the sensitivities of 68.1% for chronic cystitis, the absence of trabeculations on MRI can easily rule out chronic cystitis. Because there was no evidence of outlet obstruction in the enrolled subjects, the coincidence of trabeculations and BWT implicates inflammation initiating the cascade of events leading to BWT, which can be arrested by anti-inflammatory or anti-fibrotic drugs.  Multi-slice MRI acquisition in large FOV promises to reduce specialist burden in clinical work flow and render panoramic view without AI based image stitching algorithms needed for generating panoramic views from cystoscopic images taken by specialist.

Here, we report a non-invasive and a non-cystoscopic approach for detecting urothelial thickening, trabeculations and lesions in a large FOV without the discomfort of catheterization and involving specialist. MRI based detection of trabeculations and lesions can serve as a non-invasive patient screen for IC/BPS patients enrolled in clinical trials of anti-inflammatory and antifibrotic drugs and objectively measure the treatment response. Larger studies are warranted to confirm these preliminary findings.

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