Predictive value of cortical transit time on MAG3 for surgery in antenatally detected unilateral hydronephrosis caused by ureteropelvic junction stenosis

doi:10.1016/j.jpurol.2017.08.009

Journal of Pediatric Urology

Volume 14, Issue 1, February 2018, Pages 55.e1-55.e6

https://doi.org/10.1016/j.jpurol.2017.08.009 Get rights and content

Summary

Background

In children with antenatally detected hydronephrosis caused by ureteropelvic junction (UPJ) stenosis, the main challenge is preserving renal function by identifying children who require early surgical intervention from those for whom watchful waiting may be appropriate because of the potential for spontaneous resolution without a significant loss of renal function.

Objective

To assess the impact of initial cortical transit time (CTT) on technetium-99m mercaptoacetyltriglycerine (MAG3) diuretic renogram on the need for surgery in children with antenatally detected unilateral hydronephrosis caused by UPJ stenosis.

Study design

We retrospectively reviewed the medical records of 33 patients with antenatally detected unilateral hydronephrosis caused by UPJ stenosis who were managed at our institution between 2006 and 2014. Delayed CTT was defined as the absence of activity in the subcortical structures within 3 min of tracer injection on a MAG3 scan. The surgical indication includes symptomatic UPJ stenosis, seriously deteriorating hydronephrosis with parenchymal thinning on serial USG, split renal function <40%, or progressive deterioration of split renal function (>5%) on a MAG3 scan. This study analyzed and compared the initial level of Society for Fetal Urology grade, anteroposterior diameter (APD), split renal function, drainage pattern on a diuretic renogram, and CTT with the need for surgery.

Results

Of the 33 children, 16 were classified into the delayed CTT group and 17 were placed in the normal CTT group. During the follow-up period (mean 31.8 months), surgery was needed in 75.0% (12/16) of patients in the delayed CTT group and in 5.9% (1/17) of those in the normal CTT group. Multivariate analysis showed that delayed CTT on initial MAG3 scan and APD on initial ultrasonography were independent predictive factors of the need for surgery.

Discussion

In this era of conservative management of antenatally detected hydronephrosis caused by UPJ stenosis, it is critical to identify which measurement on an image study is the most reliable for predicting the need for surgery by reflecting functional deterioration. In this study, multivariate analysis revealed that CTT on the initial MAG3 scan was an independent predictive factor of the need for surgery. In addition, CTT showed high negative predictive value for surgical need in children with antenatally detected unilateral hydronephrosis caused by UPJ stenosis.

Conclusion

CTT on an initial MAG3 scan may be a useful predictor of the need for surgery in children with antenatally detected unilateral hydronephrosis caused by UPJ stenosis.

Introduction

The postnatal course of antenatally detected hydronephrosis (ANH) caused by ureteropelvic junction (UPJ) stenosis varies from spontaneous resolution to the progressive deterioration of renal function, and a not inconsiderable number of children with UPJ stenosis can have serious long-term consequences such as loss of renal function [1]. Although the management paradigm has shifted gradually from early surgery to a more conservative approach consisting of active surveillance and selective surgery, postnatal management of ANH caused by UPJ stenosis remains controversial [2], [3], [4]. The main challenge of its management is preserving renal function by identifying children who require early surgical intervention from those for whom watchful waiting may be appropriate because of the potential for spontaneous resolution without a significant loss of renal function [5], [6]. Although many studies have examined the predictive factors of functional deterioration [4], different criteria for surgical intervention and the variable use of diagnostic tools to assess renal function have contributed to the controversy in the management of ANH caused by UPJ stenosis.

A few recent studies showed that cortical transit time (CTT) on a technetium-99m mercaptoacetyltriglycerine (MAG3) diuretic renogram could successfully predict functional deterioration in children with UPJ stenosis [7], [8], [9], [10]. These studies showed a significant correlation between CTT and the clinical outcomes of children with UPJ stenosis. However, the true advantage of CTT as a prognostic factor of the clinical course of ANH caused by UPJ stenosis remains questionable. Therefore, we assessed the impact of initial CTT on a MAG3 scan for surgical need in children with unilateral ANH caused by UPJ stenosis.

Section snippets

Material and methods

We retrospectively reviewed the medical records of the children with unilateral ANH caused by UPJ stenosis who were managed at our institution between January 2006 and December 2014. Ninety-nine children with significant unilateral hydronephrosis (maximal anteroposterior diameter [APD] of the renal pelvis >10 mm) on an initial postnatal ultrasonography (USG) conducted 1–2 weeks after birth were consecutively included in this study. Patients were excluded if they had ipsilateral or contralateral

Results

Thirty-three children with unilateral ANH caused by UPJ stenosis were identified in this study. The mean follow-up duration was 31.8 months. The male to female ratio was 25:8 and the left to right ratio was 27:6. The mean APD on initial USG was 17.7 mm and the SFU grade of hydronephrosis on initial USG was grade I in 0 (0%), grade II in nine (27.3%), grade III in eight (24.2%), and grade IV in 16 (48.5%) patients. The initial SRF of the affected kidney was 50.7% and the drainage pattern was

Discussion

Many factors have been suggested as predictors related to the future deterioration of renal function in children with unilateral ANH caused by UPJ stenosis [1], [11], [12], [13], [14]. However, the main obstacle in this conservative era is that none of these parameters measured by conventional tools including USG, a diuretic renogram, magnetic resonance imaging, or even biological markers, has given us a reliable predictive value [12], [14]. Therefore, it is critical to identify which

Conclusions

In this study, we observed that CTT on the initial MAG3 scan is an independent predictor of surgical need in children with unilateral ANH caused by UPJ stenosis. CTT as a promising predictor in UPJ stenosis may help clinicians to decide whether to pursue surgical treatment before significant renal deterioration occurs, to plan follow-up duration and frequency, and to counsel families.

Conflict of interest

None declared.

Funding

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2015R1D1A3A03020378).

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Cited by (18)

Determination of tissue tracer transit of Technetium-99m-mercaptoacetyltriglycine diuretic renography in infants with suspected ureteropelvic junction obstruction - A multicenter prospective observational study
2023, Journal of Pediatric Urology
There is an ongoing controversy regarding management of ureteropelvic junction obstruction in infants, with a shift towards a non-operative approach. However, precise predictors of outcome are lacking. Recent studies postulated a high prognostic value of Technetium-99m-mercaptoacetyltriglycine tissue tracer transit with regard to the development of an impaired differential renal function and its potential improvement following pyeloplasty.
To evaluate the prognostic value of Technetium-99m-mercaptoacetyltriglycine tissue tracer transit for the occurrence of changes in differential renal function in infants with suspected unilateral ureteropelvic junction obstruction in a prospective observational multicenter study.
Infants below 3 months of age with a unilateral isolated hydronephrosis ≥ grade 3 received ultrasound and Technetium-99m-mercaptoacetyltriglycine diuretic renography at two different time points (timepoint 1 and timepoint 2). Data were analyzed at local centers and at the study center and were collected in an internet-based database system. Tissue tracer transit was determined for each diuretic renography, inter-observer variation for tissue tracer transit and standard parameters for judgement of differential renal function development were assessed.
Thirty-seven patients were analyzed. Median age was 11 weeks (7–15) at timepoint 1 and 26 weeks (19–33) at timepoint 2. A delayed tissue tracer transit at timepoint 1 was not associated with deterioration of differential renal function at timepoint 2 in both, locally (10/37 cases) and centrally (4/37) analyzed cases. However, sensitivity and specificity were poor. The intraclass correlation coefficient comparing local and central findings of tissue tracer transit and renal drainage demonstrated poor or fair agreement. Analysis of standard parameters for differential renal function development revealed a prognostic value only for the dichotomized anteroposterior renal pelvic diameter (APD, p = 0.03, 95%-CI 1.2–22.2).
Regarding the primary endpoint of our study, we could not confirm the hypothesis that delayed tissue tracer transit reliably predicts a subsequent decline in differential renal function in the cohort of patients studied. Whether the low age of the patients, technical problems in the correct assessment of tissue tracer transit by the investigator in early infancy, the study design, or the parameter itself played a role is debated.
In the presented setting tissue tracer transit was not useful as a predictive parameter for deterioration of differential renal function in infants with suspected unilateral ureteropelvic junction obstruction. Sensitivity and specificity of tissue tracer transit were not sufficient for risk stratification. Improved utility of tissue tracer transit as a marker might be achieved using a different study setting.
Deep learning of renal scans in children with antenatal hydronephrosis
2023, Journal of Pediatric Urology
Antenatal hydronephrosis (ANH) is one of the most common anomalies identified on prenatal ultrasound, found in up to 4.5% of all pregnancies. Children with ANH are surveilled with repeated renal ultrasound and when there is high suspicion for a ureteropelvic junction obstruction on renal ultrasound, a mercaptuacetyltriglycerine (MAG3) Lasix renal scan is performed to evaluate for obstruction. However, the challenging interpretation of MAG3 renal scans places patients at risk of misdiagnosis.
Our objective was to analyze MAG3 renal scans using machine learning to predict renal complications. We hypothesized that our deep learning model would extract features from MAG3 renal scans that can predict renal complications in children with ANH.
We performed a case-control study of MAG3 studies drawn from a population of children with ANH concerning for ureteropelvic junction obstruction evaluated at our institution from January 2009 until June of 2021. The outcome was renal complications that occur ≥6 months after an equivocal MAG-3 renal scan. We created two machine learning models: a deep learning model using the radiotracer concentration versus time data from the kidney of interest and a random forest model created using clinical data. The performance of the models was assessed using measures of diagnostic accuracy.
We identified 152 eligible patients with available images of which 62 were cases and 90 were controls. The deep learning model predicted future renal complications with an overall accuracy of 73% (95% confidence inteveral [CI] 68–76%) and an AUC of 0.78 (95% CI 0.7, 0.84). The random forest model had an accuracy of 62% (95% CI 60–66%) and an AUC of 0.67 (95% CI. 0 64, 0.72)
Our deep learning model predicted patients at high risk of developing renal complications following an equivocal renal scan and discriminate those at low risk with moderately high accuracy (73%). The deep learning model outperformed the clinical model built from clinical features classically used by urologists for surgical decision making.
Our models have the potential to influence clinical decision making by providing supplemental analytical data from MAG3 scans that would not otherwise be available to urologists. Future multi-institutional retrospective and prospective trials are needed to validate our model.
Cortical transit time: understanding utility and pitfalls in children with pelviureteric junction obstruction
2020, Journal of Pediatric Urology
Citation Excerpt :
The low incidence of antenatally detected hydronephrosis is due to inadequate coverage of antenatal care in India, which is approximately 11.6%. Cortical transit time on the MAG3 renal scan has been recently used in identifying children who are more likely to benefit by surgery [5–8,18]. The premise behind this association is that, owing to PUJO, the intrapelvic pressure rises.
Delayed cortical transit time (CTT) has been recently studied and proposed as a parameter that can predict the need for surgery in children with pelviureteric junction obstruction (PUJO).
The aim of this study was to study the change in CTT, after surgery, in children with PUJO and to correlate CTT with intrapelvic pressure of the kidney.
A prospective study was performed, and all children who underwent pyeloplasty from January 2016 to December 2017 were included. Pre-operative and postoperative renal ultrasonography and Technetium-99m mercaptoacetyltriglycerine Tc-MAG3 renal scintigraphy were performed. Cortical transit time was measured by a visual method by two different observers. The renal intrapelvic pressure of the kidney was also measured during surgery after giving a diuretic to replicate the diuresis induced during the renal scan. The correlation was studied between the pre-operative CTT and intrapelvic pressures and between the pre-operative CTT and the renal function of the affected kidney.
Thirty-one children were included in the study. The median age of children who underwent surgery was 50 months (2–168). In 71% of patients, the CTT was prolonged before surgery, whereas only 22.5% had delayed CTT after surgery. The mean CTT before surgery was 226.1 ± 74.8 s and decreased to 165.4 ± 55.9 s after surgery (p= <0.001). The mean intrapelvic pressure was 21 ± 7.5 cm H₂O. There was no correlation noted between the intrapelvic pressure and the CTT. A significant negative correlation was noted between the CTT and the different renal function of the kidney.
This is the first prospective study that studies the changes in CTT after surgery. Only retrospective studies had been conducted to date which concluded that CTT was delayed in most of the patients who had been operated. It has been proposed that the prolonged CTT is due to raised pressure in the kidney secondary to obstruction. This study did not find any correlation between the pressure and CTT. The significant negative correlation between CTT and renal function also emphasizes the need to take the renal function into consideration before interpreting and using the absolute value of CTT for guiding treatment.
Cortical transit time assessment by the visual method is a useful parameter in the management of children with PUJO. There is a significant improvement in CTT after surgery.
Hydronephrosis After Pyeloplasty: “Will It Go Away?”
2018, Urology
Citation Excerpt :
We planned then to use this information to counsel families preoperatively and, thus, assuage stress postoperatively. In their respective cohorts of patients with antenatal hydronephrosis secondary to UPJO, Arora et al and Lee et al found increased APD and decreased function on diuretic renogram to be associated significantly with the need for surgical intervention, rather than conservative management.12,13 Similarly, Chertin et al found decreased function on nuclear study and higher grade of hydronephrosis to be statistically significant predictors of the need for surgery in their 343 children being followed for the same diagnosis.3
To identify attributes of pediatric patients with hydronephrosis due to ureteropelvic junction obstruction and of their surgical encounters which are predictive of resolution of dilatation in order to provide more effective counseling about expected outcomes. This study was inspired by the suggestion in recent literature that greater than 20% improvement in anteroposterior diameter (APD) of the renal pelvis after pyeloplasty is indicative of resolution of obstruction. The remaining dilatation, however, is often distressing to caregivers, and there are no data to guide clinicians in counseling about its likelihood to resolve.
We retrospectively reviewed children who underwent surgery at our institution for ureteropelvic junction obstruction between 1/01/2010 and 6/30/2017. APD of the pre- (preAPD) and postoperative (postAPD) renal pelves were documented. In children with more than 1 postoperative ultrasound, lastAPD was the measurement on their most recent study. Appropriate statistical tests examined the effects of clinical and surgical variables on hydronephrosis resolution.
PostAPD and lastAPD were obtained at medians of 3 months and 1.9 years after surgery, and were 0 cm in 12 of 105 (11.5%) and 9 of 65 (13.8%) patients, respectively. None of the variables analyzed significantly impacted complete resolution at either time point. Of those that did not resolve, 80.6% (75/93) showed greater than 20% improvement in APD; however, 3 of these children required reoperation due to secondary obstruction. In our study, no one with APD reduction greater than 43% required reintervention.
Complete resolution of hydronephrosis is uncommon and unpredictable. All caregivers should be counseled to expect dilatation to persist after obstruction is corrected.
Letter to the editor re: Malla et al. Management dilemma in pelvi-ureteric junction obstruction: is cortical transit time the answer?
2023, Pediatric Surgery International
Surgical intervention for pediatric ureteropelvic junction obstruction: When should this measure be considered?
2023, Monatsschrift fur Kinderheilkunde

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¹: Hyun Tae Kim and Sung Kwang Chung contributed equally to this work.

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Predictive value of cortical transit time on MAG3 for surgery in antenatally detected unilateral hydronephrosis caused by ureteropelvic junction stenosis

Summary

Background

Objective

Study design

Results

Discussion

Conclusion

Introduction

Section snippets

Material and methods

Results

Discussion

Conclusions

Conflict of interest

Funding

J Pediatr Urol

Urology

J Pediatr Urol

J Urol

Urology

J Pediatr Urol

J Urol

J Urol