Abstract
Accurate evaluation of stent encrustation patterns, such as volume distribution, from different patient groups are valuable for clinical management and the development of better stents. This study quantitatively compares stent encrustation patterns from stone and kidney transplant patients. Twenty-seven double-J ureteral stents were collected from patients with stone disease or who underwent kidney transplantation. Encrustations on stent samples were quantified by means of micro−Computed Tomography and semantic segmentation using a Convolutional Neural Network model. Luminal encrustation volume per stent unit was derived to represent encrustation level, which did not differ between patient groups in the first six weeks. However, stone patients showed higher encrustation levels over prolonged indwelling times (p = 0.02). Along the stent shaft body, the stone group showed higher encrustation levels near the ureteropelvic junction compared to the ureterovesical junction (p = 0.013), whereas the transplant group showed no such difference. Possible explanations were discussed regarding vesicoureteral reflux. In both patient groups, stent pigtails were more susceptible to encrustations, and no difference between renal and bladder pigtail was identified. The segmentation method presented in this study is also applicable to other image analysis tasks in urology.
Highlights
Double-J ureteral stents are commonly used to bypass obstruction and alleviate pain in acute obstruction as well as in preparations prior to endoscopic stone treatment, or to stent the ureterovesical anastomosis after kidney transplantation to avoid obstruction due to edema in the early postoperative phase
Segmented images from stents at different indwelling times are shown in Figure 2 for each patient group
The amount of luminal encrustations in the stone group seems to increase over time, which is not observed in the transplant group
Summary
Double-J ureteral stents are commonly used to bypass obstruction and alleviate pain in acute obstruction as well as in preparations prior to endoscopic stone treatment, or to stent the ureterovesical anastomosis after kidney transplantation to avoid obstruction due to edema in the early postoperative phase. In spite of various material upgrades and design modifications, Quantitative Evaluation of Stent Encrustations encrustation remains a major problem causing stent associated complications with a significant impact on patients’ quality of life [1, 2]. For stone patients, indwelling times longer than six weeks have been associated with significantly higher encrustation rates [2,3,4]. For transplant patients, indwelling times from two to six weeks after transplantation have been recommended based on urinary tract infection (UTI) rates and stent-related complications such as pain, hematuria, encrustation and migration [5,6,7,8]
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