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.

Harmonisation of imaging protocols, radiation doses and image quality in gastrointestinal fluoroscopy examinations - multicentre study

BACKGROUND

Paediatric gastrointestinal fluoroscopy examinations can impart varying amounts of radiation for the same patient size and exam type.

OBJECTIVE

To investigate the variability of imaging protocol, radiation dose and image quality in paediatric fluoroscopy examinations in order to provide recommendations for the harmonisation and optimisation of local practices.

MATERIALS AND METHODS

Five paediatric radiology departments performing fluoroscopically-guided contrast enema, micturating cystourethrography and upper gastrointestinal tract examinations participated in this study. Information on imaging protocols and radiation doses was retrospectively collected for more than 2,400 examinations. Image quality was analysed on clinical and phantom images.

RESULTS

Patient doses showed great variability among centers with up to a factor of 5 for similar fluoroscopy times. The five departments had imaging protocols with major differences in fluoroscopy dose regulation curves and additional filtration. Image quality analysis on phantoms and patients images showed no major improvement in contrast, spatial resolution or noise when increasing the radiation dose. Age-based diagnostic reference levels using both dose area product and fluoroscopy time were proposed per procedure type.

CONCLUSION

Disparities between centers and no correlation of radiation dose with image quality criteria create margins for optimisation. These results highlight the need for guidelines on fluoroscopy image quality and dose reference levels in paediatric gastrointestinal examinations to harmonise practices and optimise patient dose.

Radiation exposure to infants undergoing voiding cystourethrography: The importance of the digital imaging technology

PURPOSE

To determine the radiation burden to infants undergoing voiding cystourethrography (VCUG) in a single institution and investigate the effect of shifting from analogue to digital imaging that allowed the use of a radiography-free examination protocol.

METHODS

Anthropometric and exposure data were prospectively collected for 35 consecutive infants undergoing VCUG on a digital system with a standardized examination protocol not including radiographs. Thermoluminescent dosimeters were used to determine entrance-skin dose. Monte Carlo simulations and patient-specific anthropomorphic phantoms were employed to determine organ/tissue doses and effective dose (ED). The associated theoretical risk of radiation-induced cancer was determined and compared to the nominal risk of cancer induction. The radiation burden from VCUG on a modern digital system with a contemporary examination protocol was compared to corresponding data reported previously for an analogue system in the same institution.

RESULTS

The median ED from VCUG was found 47 μSv. The associated total life attributable risk of radiation-induced cancer was found 10x10^-6 and 13x10^-6 for boys and girls, respectively. VCUG was found to increase the nominal risk of cancer by a factor of 1.000025 in boys and 1.000034 in girls. Shifting from analogue to digital imaging system resulted in 89% reduction of the radiation burden from VCUG.

CONCLUSION

The theoretical radiation risks for infants undergoing VCUG using a modern digital imaging system and a radiography-free protocol were found to be minor. The transition from analogue to digital equipment resulted in considerable reduction of the radiation burden from VCUG.

Radiation dose monitoring in pediatric fluoroscopy: comparison of fluoroscopy time and dose-area product thresholds for identifying high-exposure cases

BACKGROUND

Fluoroscopy time has been used as a surrogate for radiation dose monitoring in pediatric fluoroscopy; however it does not account for factors such as magnification or collimation. Dose-area product (DAP) is a more accurate measure of radiation exposure but its dependence on patient weight and body-part thickness is a challenge in children of varying ages.

OBJECTIVE

To determine whether fluoroscopy time and DAP produce concurrent results when they are used to identify high-exposure cases, and to establish radiation dose thresholds for our institution.

MATERIALS AND METHODS

During a 2-year period we prospectively monitored pediatric fluoroscopy studies performed at the Children's Hospital at Montefiore. We recorded study type, fluoroscopy time, DAP, patient age, weight and height. We then calculated 90th percentile fluoroscopy time and DAP thresholds for weight and age.

RESULTS

We evaluated 1,011 cases (453 upper gastrointestinal [UGI] series, 266 voiding cystourethrograms [VCUGs], 120 contrast enemas, 108 speech studies, and 64 esophagrams). Fluoroscopy time demonstrated moderate correlation with DAP (r_s=0.45, P<0.001, Spearman rank). DAP strongly correlated with patient weight (r_s=0.71, P<0.001) and age (r_s=0.70, P<0.001). Concordance of cases exceeding 90th percentile thresholds for fluoroscopy time and DAP were κ=0.27 for UGI series and κ=0.49 for VCUG for weight-based cutoffs, and κ=0.36 for UGI series and κ=0.40 for VCUG for age-based cutoffs.

CONCLUSION

The limited correlation of fluoroscopy time with DAP suggests these methods are not equivalent for dose monitoring. However, the strong correlation of DAP with patient weight and age presents a challenge for establishing DAP thresholds in children, who range widely in size. Despite controlling for weight or age, there was limited overlap of cases exceeding the 90th percentile threshold for fluoroscopy time and DAP. This further reinforces the non-overlapping outcome of these two methods and indicates that fluoroscopy time might be inadequate for dose monitoring.

Effect of Reader and Patient Parameters on the Performance of Last-Image-Hold for Fluoroscopic Grading of Vesicoureteric Reflux

OBJECTIVE. The purpose of this study is to determine the effect of different reader and patient parameters on the degree of agreement and the rate of misclassification of vesicoureteric reflux grading on last-image-hold frames in relation to spot-exposed frames from voiding cystourethrography (VCUG) as well as to determine the nature of reflux misclassification on last-image-hold frames. MATERIALS AND METHODS. Blinded readers conducted a retrospective evaluation of last-image-hold and spot-exposed frames of the renal fossae from 191 sequential VCUG examinations performed during a five-year period. Kappa tests were used to determine the agreement between reflux gradings and to assess the impact of reader and patient parameters. Pearson product-moment correlations were used to evaluate the effect of patient parameters on reader level of certainty regarding reflux grading. RESULTS. We measured almost perfect overall agreement for more experienced readers and substantial overall agreement for less experienced readers. Point estimates of overall misclassification were less than 2% for more experienced readers and less than 4% for less experienced readers. The readers' level of certainty about reflux grading had a positive impact on agreement values and misclassification rates. Experienced readers' most common misclassification was assigning reflux a grade of 3 on a spot-exposed frame and a grade of 2 on an equivalent last-image-hold frame. Inexperienced readers' most common misclassification involved missing reflux altogether. CONCLUSION. Instances of grade 2 reflux on last-image-hold frames may warrant supplemental evaluation with spot-exposed frames. Otherwise, a reader's level of certainty regarding reflux grading on a last-image-hold frame may help determine whether a supplemental spot-exposed frame would be beneficial.

Pediatric voiding cystourethrography: An essential examination for urologists but a terrible experience for children

Voiding cystourethrography is the most important fluoroscopic examination in pediatric urology for the investigation of lower urogenital tract diseases, such as vesicoureteral reflux or urethral stricture. However, this invasive procedure imposes a significant burden on children and their parents, and recently there has been a paradigm shift in the diagnosis and treatment of vesicoureteral reflux. In the 2011 revision, the American Academy of Pediatrics guidelines on urinary tract infection recommended abandoning routine voiding cystourethrography after the first febrile urinary tract infection. In 2014, the randomized intervention for children with vesicoureteral reflux study recommended discontinuation of routine continuous antibiotic prophylaxis for vesicoureteral reflux. The time is now ripe to radically reconsider indications for voiding cystourethrography and the procedure itself.

Systematic Radiation Dose Reduction in Cervical Spine CT of Human Cadaveric Specimens: How Low Can We Go?

BACKGROUND AND PURPOSE

While the use of cervical spine CT in trauma settings has increased, the balance between image quality and dose reduction remains a concern. The purpose of our study was to compare the image quality of CT of the cervical spine of cadaveric specimens at different radiation dose levels.

MATERIALS AND METHODS

The cervical spine of 4 human cadavers (mean body mass index; 30.5 ± 5.2 kg/m²; range, 24-36 kg/m²) was examined using different reference tube current-time products (45, 75, 105, 135, 150, 165, 195, 275, 355 mAs) and a tube voltage of 120 kV(peak). Data were reconstructed with filtered back-projection and iterative reconstruction. Qualitative image noise and morphologic characteristics of bony structures were quantified on a Likert scale. Quantitative image noise was measured. Statistics included analysis of variance and the Tukey test.

RESULTS

Compared with filtered back-projection, iterative reconstruction provided significantly lower qualitative (mean noise score: iterative reconstruction = 2.10/filtered back-projection = 2.18; P = .003) and quantitative (mean SD of Hounsfield units in air: iterative reconstruction = 30.2/filtered back-projection = 51.8; P < .001) image noise. Image noise increased as the radiation dose decreased. Qualitative image noise at levels C1-4 was rated as either "no noise" or as "acceptable noise." Any shoulder position was at level C5 and caused more artifacts at lower levels. When we analyzed all spinal levels, scores for morphologic characteristics revealed no significant differences between 105 and 355 mAs (P = .555), but they were worse in scans at 75 mAs (P = .025).

CONCLUSIONS

Clinically acceptable image quality of cervical spine CTs for evaluation of bony structures of cadaveric specimens with different body habitus can be achieved with a reference mAs of 105 at 120 kVp with iterative reconstruction. Pull-down of shoulders during acquisition could improve image quality but may not be feasible in trauma patients with unknown injuries.

Validation of the ureteral diameter ratio for predicting early spontaneous resolution of primary vesicoureteral reflux

INTRODUCTION AND OBJECTIVE

Management of primary vesicoureteral reflux (VUR) remains controversial, and reflux grade currently constitutes an important prognostic factor. Previous reports have demonstrated that distal ureteral diameter ratio (UDR) may be more predictive of outcome than vesicoureteral reflux (VUR) grade. We performed an external validation study in young children, evaluating early spontaneous resolution rates relative to reflux grade and UDR.

STUDY DESIGN

Voiding cystourethrograms (VCUGs) were reviewed. UDR was computed by measuring largest ureteral diameter within the pelvis and dividing by the distance between the L1 and L3 vertebral bodies (Figure). VUR grade and UDR were tested in univariate and multivariable analyses. Primary outcome was status of VUR at last clinical follow-up (i.e. resolution, persistence, or surgical intervention). Demographics, VUR timing, laterality, and imaging indication were also assessed.

RESULTS

One-hundred and forty-seven children (98 girls, 49 boys) were diagnosed with primary VUR at a mean age of 5.5 ± 4.7 months. Sixty-seven (45.6%) resolved spontaneously, 55 (37.4%) had persistent disease, and 25 (17%) were surgically corrected. Patients who spontaneously resolved had significantly lower VUR grade, refluxed later during bladder filling, and had significantly lower UDR. In a multivariable model, grade of VUR (p = 0.001), age <12 months (p = 0.008), ureteral diameter (p = 0.02), and UDR (p < 0.0001) achieved statistical significance. For every 0.1 unit increase in UDR, there was a 2.6 (95% CI 1.58-4.44) increased odds of persistent VUR, whereas a 1.6 (95% CI 0.9-3.0) increased odds was observed for every unit increase in grade.

DISCUSSION

Both grade of reflux and UDR were statistically significant in a multivariable model; however, UDR had a higher likelihood ratio and was more predictive of early spontaneous resolution than grade alone. Furthermore, unlike traditional VUR grading where children with grade 1-5 may outgrow reflux depending on other factors, there appears to be a consistent UDR cutoff whereby patients are unlikely to resolve. In the present study, no child with a UDR greater than 0.43 experienced early spontaneous resolution, and only three (4.5%) of those with spontaneous resolution had a UDR above 0.35.

CONCLUSIONS

UDR correlates with reflux grade, and is predictive of early resolution in children with primary VUR. UDR is an objective measurement of VUR, and provides valuable prognostic information about spontaneous resolution, facilitating more individualized patient care.