[Clinical digitalization of visual manifestations of late radiation cystitis (pilot study)]

Late radiation cystitis is an irreversible and progressively deteriorating disease that affects not only the mucous membrane but all layers of the bladder wall. Current methods for visualizing biopsy specimens are complex and lack sufficient informativeness, as the changes occurring in the deep layers of the bladder wall and the criteria for their assessment at the ultrastructural level remain insufficiently understood.

To investigate the potential for clinical digitalization of the visual manifestations of late radiation cystitis by correlating data from scanning electron microscopy (SEM) of biopsy specimens and combined positron emission tomography and computed tomography (PET/CT) of the bladder wall.

This pilot study presents four clinical cases involving the digitalization of visual manifestations of late radiation cystitis. Clinical symptoms developed 12 to 24 months following external beam radiation therapy for stage II cervical cancer. Bladder wall biopsies were obtained during cystoscopy and processed for SEM. Whole-body PET/CT scanning was performed using C-choline, and the standardized uptake value (SUVmax) within the bladder wall was assessed. Clinical digitalization, encompassing 3D reconstruction of the cystoscopic image and the ultrastructure of all bladder wall components as an integrated unit, was conducted based on the SUVmax parameter using proprietary software.

A comprehensive analysis revealed that the cystoscopic and ultrastructural manifestations of late radiation cystitis correspond with the visual patterns of 11C-choline uptake on PET/CT imaging of the bladder wall. An increase in the SUVmax was associated with progressive worsening of cystoscopic and ultrastructural alterations within the bladder wall. For each clinical case, a predictive 3D cystoscopic model and a 3D ultrastructural reconstruction of all bladder wall layers (urothelium, lamina propria, muscular layer, intercellular spaces) were generated as a single block.

The study demonstrates a correlation between the digital parameter of C-choline uptake (SUVmax) in the bladder wall and the cystoscopic and ultrastructural manifestations of late radiation cystitis, presented in a format conducive for clinical interpretation. PET/CT with C-choline may serve as an adjunctive tool for objectively assessing the severity of late radiation cystitis.