Vesicoureteral reflux by contrast ultrasound, comparison with voiding and retrograde urethrocystography: A prospective accuracy study.

INTRODUCTION: Diagnosis of vesicoureteral reflux (VUR) plays an important role in the management and follow-up of children presenting with urinary tract infection. This study compared voiding uronosography (VUS) as a diagnostic method for the diagnosis of VUR with the "gold standard", voiding or micturating cystourethrography (MCU). The objective of the study is not only to compare the effectiveness of both methods, but also to assess the feasibility of implementing VUS technically and economically in a large tertiary radiology center in South America. MATERIALS AND METHOD: This was a prospective accuracy study that include 41 patients (a total of 85 ureteral units) aged between 1 month and 16 years. VUS was performed in an alternative form as regular MCU, by injecting microbubble contrast solution (SonoVue©) into the bladder through an intermittent catheter and evaluating the presence of reflux with ultrasound. MCU was always performed immediately after VUS. One pediatric radiologist evaluated all VUS exams, while a second independent pediatric radiologist evaluated all MCU exams, with both blinded to each other's assessments. RESULTS: Comparing VUS with MCU in the diagnosis of VUR, we observed a sensitivity of 92.3 % (95 % CI 74.9-99.1 %), specificity of 98.3 % (95 % CI 90.9-100 %), positive predictive value of 96.0 % (95 % CI 79.6-99.9 %), negative predictive value of 96.7 % (95 % CI 88.5-99.6 %) and a Kappa of 0.916 (0.822-1.000). When comparing the VUR grading between VUS and MCU the agreement between the two methods was high with a Kendall's Tau-b > 0.9. VUS failed to diagnose two grade 1 VUR reflux cases in teenagers while diagnosing one grade 4 VUR in a very dilated kidney-ureter unit, which was missed on MCU. VUS and MCU had similar costs when considering the price of the ultrasound contrast agent. DISCUSSION: VUS is a reliable alternative method to MCU for the diagnosis of VUR with the advantages of not exposing the child to ionizing radiation and potentially being more accessible due to the greater availability of ultrasound equipment. Limitations to this study include the usage of a single ultrasound equipment, which limits its generalizability and not evaluating the interobserver variability. CONCLUSION: Consideration should be given to implementing VUS for the diagnosis of VUR, particularly in centers without fluoroscopy equipment available, since the exam's performance and cost are comparable to those of the MCU.

Does preoperative screening VCUG affect the outcomes and complications of pyeloplasty in patients with ureteropelvic junction obstruction?

INTRODUCTION: The role of voiding cystourethrogram (VCUG) in evaluating vesicoureteral reflux (VUR) in patients with known ureteropelvic junction obstruction (UPJO) remains unclear. While VCUG is frequently performed, the incidence of concomitant VUR and UPJO is low, and VUR is often low-grade with high rates of spontaneous regression. OBJECTIVE: To analyze the clinical relevance of VCUG in patients with UPJO by determining its incidence and studying the difference in clinical outcomes between patients with known, unknown, and negative VUR. STUDY DESIGN: Retrospective review of patients with UPJO who underwent pyeloplasty from 2012 to 2020 with <18 years-old, unilateral UPJO, postoperative follow-up of ≥2 months and had at least 1 renal ultrasound (US) after pyeloplasty. Results were compared among 3 groups: patients who underwent VCUG before pyeloplasty and were found to have VUR (group 1), patients who underwent VCUG before pyeloplasty without VUR (group 2), and patients who did not have a VCUG before pyeloplasty (group 3). RESULTS: A total of 275 patients met the inclusion criteria, of which 21 patients were classified in group 1, 166 patients in group 2, and 88 patients in group 3 (Table). The age at preoperative VCUG was 14.7 ± 32.9 months in group 1 and 15.17 ± 35.8 months in group 2 (p = 0.960). Overall, the incidence of concomitant UPJO and VUR was 11.2%. In group 1 the initial VUR grade was 5 in 2 patients, 4 in 3, 3 in 5, 2 in 7, and 1 in 4 patients. Of these, only 1 patient required ureteral reimplantation after pyeloplasty. Post-pyeloplasty, no significant differences were observed in complications (p = 0.7436), length of follow up (p = 0.3212), SFU grade 4 hydronephrosis (p = 0.2247), postoperative UTIs (p = 0.1047) and pyeloplasty success rate (p = 0.4206) among the 3 groups. Despite the use of antibiotic prophylaxis being significantly different amongst the three groups (p < 0.001), it was not associated with a lower incidence of postoperative UTIs (group 1 p = 0.068, group 2 p = 0.486, group 3 p = 1). In patients with reflux, an increase in age was associated with a decrease in the rates of complications (p = 0.019). CONCLUSION: We found no significant difference in the outcomes in patients who had a preoperative VCUG as compared to those who did not. The preoperative diagnosis of VUR by VCUG changed the management in less than 1% of the study population and thus its role in patients with UPJO should be reevaluated.

[Voiding cystourethrography : Indications, fluoroscopy technique and radiation protection]. / Miktionszysturethrographie : Indikationen, Durchleuchtungstechnik und Strahlenschutz.

BACKGROUND: Voiding cystourethrography continues to be the gold standard in the diagnostics of a wide range of diseases of the urinary tract in children. MATERIAL AND METHODS: Indications, implementation of voiding cystourethrography in terms of preparation, materials used, dealing with the child and the parents as well as the standardized examination technique are presented. In particular, the technical aspects of fluoroscopy devices and criteria for good image quality are discussed. Case studies are used to illustrate the problems of frequent urological diseases. DISCUSSION: The three standard examinations for the detection of vesicoureteral reflux (VUR), radionuclide cystography, contrast-enhanced voiding urosonography and voiding cystourethrography are compared. Their potential for detecting VUR and additional urological pathologies is discussed in detail. Furthermore, the optimized examination technique of voiding cystourethrography is presented. The applicability of the current dose reference values of the German Federal Office for Radiation Protection (BfS) in the daily routine is discussed and the feasibility of the dose reference values is explained.

Sources of error in direct radionuclide cystography in children and the need for a standardized, manometric apparatus.

Direct radionuclide cystography (DRC) is a safe and reliable method for the detection and follow-up of vesico-ureteral reflux (VUR). Since the first DRC was performed, during the early 60s, the method has undergone many refinements. Themanometric approach, which was first introduced in 1984, provides a correlation between the bladder pressure and VUR visualization. In this study the sources of error that may alter the results of DRC are discussed and a novel, standardized low costmanometric apparatus is suggested.

Conflicting views of physicians and surgeons concerning pediatric urinary tract infection: a comparative review.

BACKGROUND: A first febrile urinary tract infection (UTI) is a common condition in children, and pathways of management have evolved over time. OBJECTIVE: To determine the extent to which pediatricians and surgeons differ in their investigation and management of a first febrile UTI, and to evaluate the justifications for any divergence of approach. MATERIALS AND METHODS: A literature search was conducted for papers addressing investigation and/or management following a first febrile UTI in children published between 2011 and 2021. Searches were conducted on Medline, Embase, and the Cochrane Controlled Trials Register. To be eligible for inclusion, a paper was required to provide recommendations on one or more of the following: ultrasound (US) and voiding cystourethrogram (VCUG), the need for continuous antibiotic prophylaxis and surgery when vesicoureteral reflux (VUR) was detected. The authorship required at least one pediatrician or surgeon. Authorship was categorized as medical, surgical, or combined. RESULTS: Pediatricians advocated less imaging and intervention and were more inclined to adopt a "watchful-waiting" approach, confident that any significant abnormality, grades IV-V VUR in particular, should be detected following a second febrile UTI. In contrast, surgeons were more likely to recommend imaging to detect VUR (p<0.00001), and antibiotic prophylaxis (p<0.001) and/or surgical correction (p=0.004) if it was detected, concerned that any delay in diagnosis and treatment could place the child at risk of kidney damage. Papers with combined authorship displayed intermediate results. CONCLUSION: There are two distinct directions in the literature regarding the investigation of an uncomplicated first febrile UTI in a child. In general, when presented with a first febrile UTI in a child, physicians recommend fewer investigations and less treatment, in contrast to surgeons who advocate extensive investigation and aggressive intervention in the event that imaging detects an abnormality. This has the potential to confuse the carers of affected children.

PIC cystography in occult vesicoureteral reflux: A systematic review highlighting its utility in children with recurrent urinary tract infections and normal VCUG.

BACKGROUND: Vesicoureteral reflux (VUR) affects 1-2% of children, predisposing them to pyelonephritis, renal scarring, and reflux nephropathy. Treatment aims to prevent febrile urinary tract infections (f-UTI) and long-term sequelae. While guidelines differ, the current consensus proposes individual risk-stratification and subsequent management strategies. Here, we systematically analyzed the current literature on Positional Instillation of Contrast Cystography (PIC) for individualized diagnostics in patients with recurrent f-UTIs. OBJECTIVE: We present a comprehensive qualitative and quantitative synthesis. Outcomes were: 1. the ability of PIC to predict VUR in patients with negative voiding cystographies (VCUG), 2. the ability of PIC to predict occult contralateral VUR, 3. the correlation of occult VUR in PIC with dimercaptosuccinic acid (DMSA) scan findings, and 4. the incidence of postoperative f-UTI in children treated for occult VUR picked up on PIC. STUDY DESIGN: We conducted a systematic review following the PRISMA guidelines, applying the following inclusion criteria: Children with occult VUR in PIC with negative VCUG. RESULTS: We included nine studies with 496 symptomatic patients with a mean age of 6.8 years, published between 2003 and 2021. PIC detected VUR in 73% of patients. Out of them, 81% had low-grade and 19% high-grade VUR. Occult contralateral VUR was present in 41% children. The presence of renal scars on DMSA scan was 1.39 times more likely with occult VUR on PIC. 85% of patients did not experience recurrent f-UTIs after PIC and subsequent treatment. DISCUSSION: PIC can detect occult VUR in patients with recurrent f-UTIs in whom VCUG is negative. However, we recommend a cautious approach in the use of PIC in clinical practice until further prospective studies confirm the validity of our outcome measures. CONCLUSION: Identification, risk stratification, and prompt action are central in managing VUR. PIC can be helpful in identifying VUR in patients with recurrent f-UTI.

Rapid gastric emptying during pregnancy in a rat model.

BACKGROUND/AIMS: The effect of pregnancy on gastric emptying has not been established, although the predominant clinical assumption is that gastric emptying is delayed during pregnancy. We hypothesized that the rate of emptying of nutrients during pregnancy is not delayed, but is actually more rapid when compared to the non-pregnant state. The rate of gastric emptying is a major determinant of postprandial glucose elevations. MATERIALS AND METHODS: 24 female and 4 male Spague-Dawley rats were used. Female rats were randomly divided into two groups: eight rats for the control group and sixteen rats for the pregnant group. Using physiologic, non-traumatic nuclear medicine scintigraphy imaging methodology, the authors studied gastric emptying of a liquid mixed meal in pregnant rats and non-pregnant controls. Body weights, daily food ingestion, and the rate of nutrient gastric emptying were recorded in both groups at pre-pregnancy, early pregnancy, and late pregnancy. RESULTS: The authors found that pregnancy in this rat model is associated with a 37-43% increased rate of nutrient gastric emptying from the stomach in late pregnancy as compared to non-pregnant control rats and pre-pregnancy rats. CONCLUSION: These findings contradict the current clinical assumption that gastric emptying is delayed in pregnancy. If further studies confirm a more rapid gastric emptying rate during human pregnancy, new therapies aimed at slowing the rate of nutrient absorption should be considered for the prevention and treatment of pregnancy-associated nausea, gestational diabetes, and other insulin-resistant pregnancy-associated states such as pre-eclampsia.

Novel single-stage preputial spiral graft for panurethral stricture: a step-by-step description of the technique.

PURPOSE: To report the 12-month results of a novel urethroplasty technique relying on a spiral preputial graft for panurethral stricture disease. MATERIALS AND METHODS: Twenty consecutive patients were treated between May and October 2021 at our center. A spiral preputial mucocutaneous graft is a foreskin-based graft, developed from a 5-cm-wide preputial skin, which is harvested using a helicoidal shape and can reach up to 20 cm in length. Stricture characteristics were assessed through preoperative retrograde and voiding cystourethrogram and maximum uroflowmetry data (Qmax). Complications were collected up to 30 days after surgery and graded using the Clavien-Dindo (C-D) classification. The patients were followed up to 12 months. RESULTS: Preoperative median Qmax was 6.5 ml/s [interquartile range (IQR): 4.0-8.7]. After a median follow-up of 12 months (IQR 12-13), six patients experienced at least one complication. Of them, two patients had grade 2 C-D complications, while only one developed a grade 3a C-D complication. The median postoperative Qmax was 16 ml/s (IQR: 13-18). Only one patient had early urethral stricture recurrence treated with dilatation after catheter removal. At one-year follow-up, no other patients had urethral stricture recurrence with an overall median Qmax of 15.1 ml/s (IQR 13.5-16.4). CONCLUSIONS: Our novel single-stage spiral preputial graft urethroplasty for panurethral stricture treatment appears to be safe and could be used as a valid alternative to two-stage procedures or even to single-stage buccal mucosa graft augmentation.

Utility of Positional Instillation of Contrast Cystography for Diagnosing Occult Vesicoureteral Reflux in Children: A Report of Two Cases.

Positional instillation of contrast (PIC) cystography is effective for detecting occult vesicoureteral reflux (VUR), which can not be revealed by standard voiding cystourethrography (VCUG). We experienced two cases of young female patients; one had repeated urinary tract infection with a negative VUR on standard VCUG, and the other had findings suggestive of reflux hydronephrosis and intolerance of standard VCUG. They underwent PIC cystography, and occult VUR was detected in both cases. Both were successfully treated with simultaneous endoscopic injection therapy with dextranomer/hyaluronic acid. PIC cystography is useful for detecting occult VUR in children with negative VUR findings on standard VCUG or who are unable to tolerate standard VCUG.

Viability of contrast-enhanced voiding urosonography as an alternative to fluoroscopy during video urodynamics.

Pediatric urodynamic studies are performed to evaluate bladder function, commonly in conjunction with a voiding cystourethrogram (VCUG). Contrast-enhanced voiding urosonography (CeVUS) has been approved in the evaluation of vesicoureteral reflux and has been shown to have equal or superior diagnostic value to VCUG. In this technical innovation, we have shown that ultrasound contrast agent microbubbles are compatible with the equipment used for urodynamic evaluation. We have also shown that it is feasible to use contrast ultrasound in pediatric urodynamic examinations. The purpose of our study was to assess the technical feasibility of CeVUS during urodynamics with an in vitro test followed by a vivo evaluation. This single-center prospective study enrolled 25 patients aged 0-18 years who underwent CeVUS instead of VCUG at their regularly scheduled appointment. During the in vitro saline experiment, the radiologic and urologic equipment were found to be compatible. Microbubbles were observed at flow rates of 10 and 20 ml/min.

Inter-rater reliability of retrograde urethrograms.

PURPOSE: Reliability of pre-operative testing is important for adequate surgical planning. For urethral stricture disease, preoperative planning frequently includes retrograde urethrogram (RUG). The radiographic interpretation of RUGs is often done by urologists themselves. We aimed to evaluate the reliability of RUG interpretation by urologists at our institution. METHODS: We examined the RUGs of 193 patients. These were deidentified and interpreted by three urologists, two general urologists and one reconstructive urologist. These interpretations were compared in 2 ways. Each of the general urologists was compared to the "gold standard" reconstructive urologist interpretation, and the general urologists were additionally compared to each other. We used intraclass correlation coefficient (ICC) for numerical variables and Fleiss' Kappa or Cohen's Kappa statistic (κ) for categorical variables to rate inter-interpreter reliability and agreement among interpretations with regards to the quantitative variables of stricture length and caliber. RESULTS: Level of agreement ranged from poor to moderate across all variables interpreted. Comparing general urologists to the gold standard yielded no better than moderate agreement, with the majority being poor to fair. Similarly, agreement amongst the general urologists did not reach above moderate, with the majority being poor to slight. CONCLUSION: To our knowledge, this is the first analysis of inter-rater reliability of RUGs among practicing urologists. Our analysis showed clinically unacceptable reliability with regards to stricture length, location, caliber, and indicated procedures. This study suggests a need for standardized interpretation of RUGs and poses an opportunity for actionable improvement in management of strictures.

Pediatric magnetic resonance angiography: to contrast or not to contrast.

Magnetic resonance (MR) angiography and MR venography imaging with contrast and non-contrast techniques are widely used for pediatric vascular imaging. However, as with any MRI examination, imaging the pediatric population can be challenging because of patient motion, which sometimes requires sedation. There are multiple benefits of non-contrast MR angiographic techniques, including the ability to repeat sequences if motion is present, the decreased need for sedation, and avoidance of potential risks associated with gadolinium administration and radiation exposure. Thus, MR angiography is an attractive alternative to CT or conventional catheter-based angiography in pediatric populations. Contrast-enhanced MR angiographic techniques have the advantage of increased signal to noise. Blood pool imaging allows long imaging times that result in high-spatial-resolution imaging, and thus high-quality diagnostic images. This article outlines the technique details, indications, benefits and downsides of non-contrast-enhanced and contrast-enhanced MR angiographic techniques to assist in protocol decision-making.

Omitting routine cystography after RARP: Analysis of complications and readmission rates in suprapubic and transurethral drained patients.

OBJECTIVES: Robot-assisted radical prostatectomy (RARP) has become the therapy of choice for local treatment of prostate cancer. Postoperatively, urologists perform cystography before removing urinary catheters due to concerns about the integrity of the vesicourethral anastomosis. This study aims to evaluate the safety of waiving cystography before early catheter removal after RARP. METHODS: A total of 514 patients from two tertiary referral centers who underwent RARP were retrospectively included. Patients received postoperative urinary drainage by transurethral (TUC) or suprapubic catheter (SPC). During the first year, both centers performed routine cystography before removing TUC or SPC on postoperative day 5. In the following year, management changed and catheters were removed without cystography unless indicated by the surgeon. Demographic and perioperative data were analyzed. Postoperative complications and readmission rates were compared between standard cystography (StCG), no cystography (NCG), and selective cystography (SCG). RESULTS: Groups were comparable regarding demographic and oncological parameters. Analysis showed no significant difference regarding major complications and readmission rates between standard and no cystography (p = 0.155 and 0.998 respectively). Omitting routine cystography did not lead to inferior postoperative courses regardless of both urinary drainage used and tumor stage. Subgroup analysis showed an increase of major complications in SCG patients when compared with NCG (p = 0.003) while readmissions remained comparable (p = 0.554). CONCLUSION: Waiving routine cystography before early catheter removal after RARP appears to be safe and feasible regardless of urinary drainage. However, the selective cystogram at the surgeon's request still plays a role in monitoring patients with an elevated risk profile.

The accuracy of cystography under general anesthesia in children with vesicoureteral reflux.

PURPOSE: To examine the accuracy of cystography under general anesthesia in children with vesicoureteral reflux (VUR). MATERIALS AND METHODS: A prospective study of children who had VUR on cystography without general anesthesia (i.e., the gold-standard), and who are candidates for endoscopic VUR repair surgery. All children subsequently underwent a cystography under general anesthesia before injection using standardized method, which was compared to the gold-standard cystography. χ2 and Mann-Whitney U tests were used to compare proportions and medians between groups. RESULTS: Between 2017 and 2021, 126 renal units in 13 boys and 50 girls were included. Median age was 3.4 years (interquartile range [IQR] 1.5-6.5). Median time from cystography without to cystography with general anesthesia was 3.8 months (IQR 2.7-6). Of the 126 renal units, 96 had VUR on cystography without general anesthesia. On dichotomous analysis (no VUR vs. any VUR) sensitivity, specificity, negative and positive predictive values of cystography under general anesthesia were 47% (45/96), 87% (26/30), 34% (26/77) and 92% (45/49), respectively. Accuracy was 56.3%; Cohen's Kappa coefficient was 0.22, indicating poor agreement. In subgroup analysis, the sensitivity of cystography under general anesthesia was significantly lower in primary VUR (20% vs. 55% in secondary VUR, p = 0.01) and active VUR (14% vs. 52% in passive VUR, p = 0.008). CONCLUSION: Cystography under general anesthesia was poorly correlated to cystography performed while the child was awake or lightly sedated. Clinical decision relying on this cystography is questionable.

Contrast-enhanced voiding urosonography (CEVUS) as a safe alternate means of assessing vesicoureteral reflux in pediatric kidney transplant patients.

BACKGROUND: Although voiding cystourethrogram (VCUG) is currently the gold standard in VUR evaluation, there is ionizing radiation exposure. Contrast-enhanced voiding urosonography (CEVUS) uses ultrasound contrast agents to visualize the urinary tract and has been reported to be safe and effective in VUR evaluation in children. CEVUS application has yet to be specifically described in VUR evaluation in the pediatric kidney transplant population. The purpose of this study was to report the use of CEVUS and VCUG in evaluating and managing VUR in pediatric renal transplant patients. METHODS: Retrospective review was conducted for pediatric kidney transplant patients (18 years and younger) who underwent VCUG or CEVUS to assess for transplant VUR from July 2019 through June 2021. Demographic information, reason for VUR evaluation, fluoroscopy time, and postimaging complications were evaluated. Costs of imaging modalities were also considered. RESULTS: Eight patients were evaluated for transplant VUR during the study period. Of the 3 patients who underwent VCUG, all 3 had VUR (median grade 3). Median fluoroscopy time was 18 s and dose-area product was 18.7 uGy*m2 . Of the 5 patients who underwent CEVUS, 4 had VUR (median grade 4). There were no complications for either modality. Based on clinical and radiographic findings, patients were recommended no intervention, behavioral modification, or ureteral reimplantation. The total cost of CEVUS was $800 less than that of VCUG. CONCLUSION: CEVUS can provide an alternate means of safely evaluating VUR in kidney transplant patients with similar outcomes, potentially lower costs, and no exposure to ionizing radiation.

Accuracy of contrast-enhanced voiding urosonography using Optison™ for diagnosis of vesicoureteral reflux in children.

BACKGROUND: There is limited quality of evidence regarding the accuracy of contrast-enhanced voiding urosonography (ceVUS) for diagnosis of vesicoureteral reflux (VUR) compared to fluoroscopic voiding cystourethrography (VCUG), and minimal data on the use of the ultrasound contrast agent Optison™ for this purpose. OBJECTIVE: To compare the accuracy of ceVUS using Optison™ to VCUG, and to assess inter-rater agreement regarding presence and grading of VUR. STUDY DESIGN: In this retrospective investigation, all sequential ceVUS with Optison™ and VCUG studies performed in children between 2014 and 2017 were reviewed. Two raters independently graded all ceVUS studies using a 5-point scale. CeVUS sensitivity and specificity were estimated separately for each rater using the VCUG report as the ground truth for presence and degree of VUR. Logistic and ordinary linear regression models assessed rater-report agreement and inter-rater agreement for each kidney, Optison™ dose, and referral diagnosis. RESULTS: 97 children (51 females) with 101 paired studies were included. Sensitivity and specificity of ceVUS for VUR detection were identical for both raters: right kidney 75%/90.9%; left kidney 85.7%/78.9% (Figure). There was no statistically significant difference in disagreement between raters and the VCUG report for the right or left kidney. Inter-rater agreement on ceVUS grading was 90% and 88% for right and left kidneys, respectively. There was a significant negative association between fetal hydronephrosis vs urinary tract infection and disagreement between Rater 2 and the VCUG report for the left kidney. There were no other significant associations with respect to either kidney, Optison™ dose, or referral diagnosis. DISCUSSION: Our study showed that detection of VUR with ceVUS and Optison™ is comparable to fluoroscopic VCUG. Based on the VCUG reports, the incidence of VUR in our patient population was substantially lower than in the meta-analysis of Chua et al. and in the study of Kim et al. The explanation for the large discrepancy in VUR incidence may reflect differences in the patient populations, and in our reporting of VUR with respect to kidney number rather than to pelviureteral units. Study limitations include its retrospective nature and potential bias in terms of patient selection. Since VUR is an intermittent phenomenon, sequential rather than simultaneous performance of the ceVUS and fluoroscopic studies might have influenced VUR detection. CONCLUSION: A blinded comparison of ceVUS performed with Optison™ to fluoroscopic VCUG showed moderate-good sensitivity and specificity for diagnosis of VUR.

Identifying urethral strictures using machine learning: a proof-of-concept evaluation of convolutional neural network model.

INTRODUCTION: To evaluate urethral strictures and to determine appropriate surgical reconstructive options, retrograde urethrograms (RUG) are used. Herein, we develop a convolutional neural network (CNN)-based machine learning algorithm to characterize RUG images between those with urethral strictures and those without urethral strictures. METHODS: Following approval from institutional REB from participating institutions (The Hospital for Sick Children [Toronto, Canada], St. Luke's Medical Centre [Quezon City, Philippines], East Virginia Medical School [Norfolk, United States of America]), retrograde urethrogram images were collected and anonymized. Additional RUG images were downloaded online using web scraping method through Selenium and Python 3.8.2. A CNN with three convolutional layers and three pooling layers were built (Fig. 1). Data augmentation was applied with zoom, contrast, horizontal flip, and translation. The data were split into 90% training and 10% testing set. The model was trained with one hundred epochs. RESULTS: A total of 242 RUG images were identified. 196 were identified as strictures and 46 as normal. Following training, our model achieved accuracy of up to 92.2% with its training data set in characterizing RUG images to stricture and normal images. The validation accuracy using our testing set images showed that it was able to characterize 88.5% of the images correctly. CONCLUSION: It is feasible to use a machine learning algorithm to accurately differentiate between a stricture and normal RUG. Further development of the model with additional RUGs may allow characterization of stricture location and length to suggest optimal operative approach for repair.

Radiation Dose Reduction Opportunities in Vascular Imaging.

Computed tomography angiography (CTA) has been the gold standard imaging modality for vascular imaging due to a variety of factors, including the widespread availability of computed tomography (CT) scanners, the ease and speed of image acquisition, and the high sensitivity of CTA for vascular pathology. However, the radiation dose experienced by the patient during imaging has long been a concern of this image acquisition method. Advancements in CT image acquisition techniques in combination with advancements in non-ionizing radiation imaging techniques including magnetic resonance angiography (MRA) and contrast-enhanced ultrasound (CEUS) present growing opportunities to reduce total radiation dose to patients. This review provides an overview of advancements in imaging technology and acquisition techniques that are helping to minimize radiation dose associated with vascular imaging.