Urinary incontinence is a s a major complication that reduces the quality of life in patients undergoing prostatectomy (PT) or radiotherapy (RT) in prostate cancer patients.
While the artificial urinary sphincter (AUS) stands as the preferred treatment, its efficacy and safety in irradiated patients is questioned due to challenging complications as cuff erosion that may result in urethral stenosis. 
Magnetic resonance imaging (MRI) provides a non-invasive method for assessing quantitatively the tissue quality pre-implantation to identify which patients will benefit from AUS, after radical PT and RT.

A single-center, retrospective, observational study was designed. Pre-implantation surgery MRI exams from prostate cancer patients acquired prior to AMS 800 AUS implantation, together with clinical data, were collected. A 3D manual segmentation of the urethral bulb was performed in the T2-weighted and Dynamic Contrast Enhanced (DCE) MRI sequences using the Quibim Precision® platform. In total, 106 radiomic features were extracted from all sequences. Welch's t-tests were employed to compare each independent variable across groups, irradiated/non-irradiated patients prior to AUS implantation and patients undergoing favorable vs. unfavorable progression after AUS implantation. Favorable progression denotes patients who have had good adaptation to the AUS, whereas unfavorable progression refers to those facing complications related to the device. To control the false discovery rate, the Benjamini-Hochberg correction was applied, thereby limiting the number of false positives

This study comprised a cohort of 31 prostate cancer patients who underwent PT followed by AUS implantation. The mean follow-up after AUS surgery was 58 months (range: 13-92).Among them, 45.2% of the patients were subjected to irradiation therapy. After AUS implantation, 58.1% of the total patients experienced a favorable progression. A pharmacokinetic perfusion analysis conducted on pre-surgery DCE sequences revealed that patients exhibiting a favorable progression demonstrated significantly different lower volume transfer constant between the blood plasma and the extravascular-extracellular space (Ktrans) and transfer constant between the extravascular-extracellular space and blood plasma (Kep) values in the urethral bulb compared to those with unfavorable progression. Conversely, irradiated patients exhibited a slight decrease in Ktrans values compared to non-irradiated patients, similar to those with unfavorable progression. 

Analysis of texture imaging biomarkers in T2-weighted MRI of the segmented urethral bulb revealed significant changes in 30 variables among patients experiencing favorable and non-favorable progression. Notably, 10th percentile, 90th percentile, range and median first order features and gray level co-occurrence matrix (GLCM) features, autocorrelation and joint average values, were increased in patients with a favorable progression after AUS implantation.

In contrast, the comparison between irradiated and non-irradiated patients showed slightly decreased values of the same first order features in irradiated patients. This was accompanied by a decrease in gray level run length matrix GLRLM features (run entropy value) and an increase in neighboring gray tone difference matrix (NGTDM) features (Coarseness) in the urethral bulb of irradiated patients.

To our knowledge, this is the first study   to identify radiomic features in the urethral bulb associated with long-term success of AUS. Radiomic analysis suggests that patients exhibiting a generalised increase in the heterogeneity of MRI intensities in the urethral bulb prior to AUS implantation may experience a more favorable adaptation to the device.

Additionally, our results suggest that radiation therapy not only jeopardizes the vascular permeability in the urethral bulb region but also impacts the structural tissue characteristics, leading to a more homogenous appearance. These findings align with the observation that 76.9% of patients experiencing complications related to AUS were previously subjected to RT.

Promising radiomic features potentially linked to tissue characteristics conducive to successful adaptation to AUS have been identified. Moreover, the study suggests that RT may negatively impact the success of AUS implantation due to alterations in the structural tissue characteristics of the urethral bulb and the associated vascular system. This study provides an opportunity to assess the clinical significance of combining the capabilities of MRI radiomics to identify patients at risk of complications after AUS implantation. Future research involving larger population sizes will enable a more comprehensive exploration of the potential of radiomics for the accurate evaluation of the urethra in prostate cancer patients undergoing AUS implantation

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Continence 12S (2024) 101484
DOI: 10.1016/j.cont.2024.101484