Functional imaging of the kidney in pediatric patients is typically performed using contrast-enhanced MR urography (MRU) or nuclear scintigraphy, both of which require either gadolinium-based contrast agents or ionizing radiation. Furosemide, a loop diuretic routinely used in both modalities to stimulate urinary flow, acutely increases tubular fluid volume. These changes in renal water content can be detected by MRI-based quantitative T2 mapping, which may provide a contrast- and radiation-free alternative for evaluating kidney function. To assess renal T2 relaxation time changes following intravenous furosemide administration as a surrogate marker for differential renal function (DRF) in pediatric MRU. In this prospective single-center study (June 2024 to March 2025), pediatric patients undergoing clinically indicated MRU received additional dynamic T2 mapping during furosemide administration using a respiratory-triggered gradient-and-spin-echo (GraSE) sequence. Two readers independently assessed T2 relaxation time changes. DRF was derived from the slope of the T2 increase (SlopeDRF) as well as from pre-T2 to post-T2 differences, expressed as each kidney's relative contribution to total function. These measures were compared with contrast-enhanced, Patlak-derived DRF (pDRF) using Pearson correlation and Bland-Altman analysis. Interreader agreement was assessed with the intraclass correlation coefficient (ICC). Thirty-two patients (16 males; median age: 7y, IQR: 0 to 11) were included. Renal parenchymal T2 relaxation times increased significantly after furosemide administration (pre: 118.4ms, IQR: 110.8 to 124.4; post: 134.8ms, IQR: 126.9 to 141.3; P < 0.001). SlopeDRF correlated strongly with pDRF (r = 0.81), and T2-difference DRF also demonstrated strong correlation with pDRF (r = 0.80). Interreader agreement for DRF was excellent (ICC = 0.94). Dynamic renal T2 mapping after intravenous furosemide administration shows strong correlation with Patlak-derived DRF from contrast-enhanced MRU and may provide a noninvasive, contrast- and radiation-free method for quantifying differential renal function in children.

Antenatal hydronephrosis (ANH) is a common prenatal finding with a heterogeneous postnatal course. This study aims to describe an institutional experience and protocol adherence regarding the clinical course, intervention timing, and surgical outcomes of severe ANH secondary to ureteropelvic junction obstruction (UPJO) and its rare coexistence with ureterovesical junction obstruction (UVJO). We retrospectively reviewed the records of infants referred to our tertiary center with severe prenatal urinary tract dilation (UTD A2-3 / high risk). Out of 400 initially screened patients, 80 infants who completed a standardized 1-year postnatal follow-up protocol were included, representing a highly selected completer cohort. Postnatal evaluation included serial ultrasounds (USG) and mercatoacetyltriglycine 3 (MAG-3) renography. Surgical intervention (dismembered pyeloplasty) was indicated based on standardized empirical consensus criteria: anterior-posterior renal pelvic diameter (APRPD) ≥ 19mm, parenchymal thickness ≤ 5mm, or split differential renal function (DRF) ≤ 40% with obstructive clearance patterns. Postoperative complications were graded using the Clavien-Dindo classification. The final analysis included 80 infants. Isolated UPJO was diagnosed in 12 patients (15.0%), transient/physiological hydronephrosis in 35 (43.75%), vesicoureteral reflux (VUR) in 29 (36.25%), and coexisting UPJO and UVJO in 4 patients (5.0%). Pyeloplasty was performed in all 12 isolated UPJO patients and 4 coexisting UPJO+UVJO patients (total n = 16 surgical cases) at a median age of 3 months. Postnatal USG at 12 months demonstrated a significant reduction in pelvic dilatation and marked parenchymal thickening. No deterioration in renal function was observed during follow-up, and no postoperative complications were recorded in this cohort. Adherence to a strict, conservative management protocol with standardized surgical thresholds was associated with favorable outcomes in high-risk ANH patients. Given the single-center descriptive nature and substantial loss-to-follow-up within this completer cohort, these findings represent descriptive institutional experiences rather than statistically validated threshold models.

Long-term renal outcomes after pediatric pyeloplasty: Defining optimal imaging intervals and predictors of functional recovery.

Background:Measuring differential renal function (DRF) is critical for managing children with congenital and acquired urological diseases. MAG-3 renal scintigraphy is the most widely used clinical technique; dynamic contrast-enhanced MRI (DCE-MRI) provides a radiation-free and high-resolution alternative method for assessing DRF.Objective:To evaluate the agreement between DRF values derived from DCE-MRI and MAG-3 scintigraphy-derived DRF in pediatric patients.Materials and Methods:This retrospective study included 23 pediatric patients (age range: 3 months-20 years; mean ± SD: 8.3±7.4 years) who underwent DCE-MRI embedded in MR urography (MRU) protocol and MAG-3 studies within 6 months. DCE-MRI was performed using a golden-angle radial dynamic stack of stars acquisition with golden-angle sparse parallel (GRASP) reconstruction, and analyzed renal filtration rate with a 2-compartment tracer kinetic model. DRF values from DCE-MRI were compared with those from MAG-3, using both default (n=23) and C-shaped background regions for MAG-3 analysis, where raw data were available (n=16). Agreement was evaluated using Bland–Altman analysis, Pearson and concordance correlations, and paired statistical tests.Results:With default MAG-3 background analysis (n=23), mean DRF difference (MAG-3 minus DCE-MRI) was 0.4% (95% CI: −3.3% to 4.2%), with 95% limits of agreement of −16.7% to +17.5%. Concordance correlation coefficient (CCC) was 0.870 (95% CI: 0.718–0.942). Within the pre-defined clinically acceptable margin of ±10%, 78.3% (18/23) of cases fell, with a mean absolute difference of 6.1%. With C-shaped background subtraction in the subset with available raw MAG-3 data (n=16), mean difference was −2.3% (95% CI: −6.7% to 2.0%), limits of agreement −18.3% to +13.6%, and CCC 0.845 (95% CI: 0.614–0.943). Pearson correlation was strong in both analyses (n=23: r=0.872, 95% CI: 0.719–0.945; n=16: r=0.866, 95% CI: 0.648–0.953; both p<0.001). No clinically significant systematic or proportional bias was detected in either analysis.Conclusion:DCE-MRI demonstrates strong linear association and concordance with MAG-3 scintigraphy for pediatric differential renal function assessment with no clinically significant systematic bias, though the observed measurement variability indicates caution is warranted when comparing values near surgical decision thresholds. C-shaped background correction is recommended for MAG-3 in hydronephrotic kidneys to optimize inter-modality agreement.

Adults with repaired bladder exstrophy may develop late upper urinary tract obstruction and stone disease due to complex reconstructed anatomy. Obstructive acute pyelonephritis is a urological emergency requiring urgent drainage and antimicrobial therapy, followed by delayed definitive stone treatment once infection is controlled. We report the case of a 31-year-old man with a history of bladder exstrophy reconstruction, including bilateral ureteral reimplantation in infancy and a Mitrofanoff catheterizable channel, who presented with febrile right flank pain. Computed tomography demonstrated right hydronephrosis caused by a large distal ureteral stone [30 × 13 mm; 1200 HU] at the iliac segment, associated with severe stenosis at the reimplanted ureteral orifice. He received intravenous antibiotics and urgent right percutaneous nephrostomy drainage. Renal scintigraphy performed after infection resolution showed reduced right differential renal function [22%]. Definitive surgery was performed via a right iliac approach. The stone was extracted through ureterotomy; double-J stent placement was initially impossible due to tight terminal ureteral stenosis. The ureter was transected proximal to the stenosis, a double-J stent was placed, and redo ureteroneocystostomy was completed after bladder identification by filling through the Mitrofanoff channel. Postoperative recovery was uncomplicated, with drain removal on postoperative day 2, nephrostomy removal intraoperatively, and discharge after 5 days. The ureteral stent was removed 1 month later. Follow-up to date is favorable, with no dilation on imaging and serum creatinine improving to 9 mg/L.

A clinical nomogram for predicting postoperative renal function improvement in children with UPJO.

Background Living donor renal transplantation is the most common treatment for end-stage renal disease, and correct donor evaluation is mandatory to ensure safety and improve outcomes. Multidetector computed tomography angiography offers high-resolution anatomical assessment and potential functional evaluation within a single imaging session. Aims and objectives The aim and objectives of the study were to analyse multidetector computed tomography accuracy in delineating renal vascular anatomy against surgical findings and compare multidetector computed tomography-derived differential renal function with technetium-99m DTPA (Tc-99m DTPA) scintigraphy. Material and methods Sixty-four living renal donors underwent multidetector computed tomography angiography using a triple-bolus contrast protocol, followed by Tc-99m DTPA renal scintigraphy. Renal arterial and venous anatomy, vascular variants, and collecting system abnormalities were evaluated on multidetector computed tomography. Surgical findings were used as the reference standard for vascular anatomy. Differential renal function calculated from computed tomography was compared with scintigraphy using Pearson correlation and Bland-Altman analysis. Results Multidetector computed tomography angiography correctly identified renal arteries in 98.44% (63/64) of donors and renal veins in 100% (64) of donors. Sensitivity and specificity for arterial variants were 98% and 100%, respectively, and 100% for venous variants. Multidetector computed tomography-derived differential renal function correlated significantly with scintigraphy-derived differential renal function (right kidney: r=0.59, p<0.01; left kidney: r=0.55, p<0.01) with a mean difference of 0.10% and 95% limits of agreement within ±6% for both kidneys. Conclusion Multidetector computed tomography angiography provides the best anatomical detail and shows a moderate agreement with scintigraphy for differential renal function. It is a reliable, comprehensive modality for living donor evaluation in appropriately selected candidates.

Assessing inter-rater reliability of objective renal sonographic measurements for identification of clinically significant ureteropelvic junction obstruction.

Being born small for gestational age is an independent risk factor for failure of endoscopic treatment in vesicoureteral reflux.

Clinical prediction modeling of baseline differential renal function based on ultrasound in congenital unilateral ureteropelvic junction obstruction.

Introduction: Neonatal autosomal recessive polycystic kidney disease (ARPKD) can be complicated by respiratory failure, refractory hypertension, and feeding intolerance due to renal failure and mass effect from the kidneys. Current recommendations lack consensus regarding the benefit of unilateral versus bilateral nephrectomy. Description: We describe our experience with a neonate with prenatally diagnosed ARPKD and associated pulmonary hypoplasia. The patient initially required intubation at birth but tolerated weaning, extubation, and a 9 week period of minimal non-invasive respiratory support. During this period, she developed severe hypertension refractory to high doses of anti-hypertensives, including amlodipine, diuretics, labetalol, minoxidil, clonidine, and parenteral drips. She also had rapid cystic kidney growth and developed respiratory failure secondary to mechanical thoracoabdominal competition requiring re-intubation and a positive-end expiratory pressure of at least 12 cm H2O to maintain lung expansion. Due to respiratory failure and inadequate blood pressure control, the decision was made to undergo nephrectomy via a staged approach. Prior to surgery, renal scintigraphy showed differential renal function of 30% on the left and 70% on the right. She had an uncomplicated total left nephrectomy on DOL 96. Euvolemia was maintained post-operatively through a combination of peritoneal dialysis ultra-filtration and robust urine output from the remaining kidney. Post-nephrectomy, her hypertension was adequately treated with enteral medications and a single anti-hypertensive infusion. Tolerance of enteral feeds also improved. She continued to require mechanical ventilation but was successfully supported on a conventional ventilator. Discussion: Palliative unilateral nephrectomy is an effective tool for blood pressure control and temporizing of thoracoabdominal competition, allowing time for growth until renal transplant is feasible. Delaying eventual bilateral nephrectomy is beneficial given concerns surrounding effective dialysis in an anuric neonate.

Functional outcomes of pyeloplasty in children with reduced preoperative renal function: A multicenter study.

Pelviureteric junction obstruction (PUJO) is the most common cause of pediatric hydronephrosis; however, distinguishing obstructive and non-obstructive dilatation remains challenging. Existing diagnostic modalities are limited by the lack of validation against objective measures of renal injury. Preoperative imaging is critical for guiding surgical decision-making; however, its correlation with histopathologic renal damage has not been fully elucidated. To evaluate the association between preoperative sonographic and nuclear scintigraphy parameters and intraoperative renal histopathology in children with congenital PUJO and to identify imaging predictors of significant renal parenchymal damage. A prospective observational study was conducted on 60 children (< 16years) with unilateral PUJO who underwent Anderson-Hynes pyeloplasty. Preoperative ultrasound parameters, including Society for Fetal Urology (SFU) grade, anterior-posterior pelvic diameter (APD), cortical thickness, and Doppler resistive index (RI), as well as nuclear scintigraphy parameters, including differential renal function (DRF), drainage half-time (T½), and renogram curve were recorded. Renal lower pole cortical biopsies were graded using Elder's histopathology scoring system, with significant histologic damage defined as moderate-to-severe injury (score of ≥ 6). Statistical correlations and receiver operating characteristic analyses were performed to assess the predictive value of imaging parameters for histologic injury. High-grade hydronephrosis (SFU grade III-IV) was observed in 70.0% of patients, an anteroposterior diameter (APD) ≥ 20mm in 66.7%, and an elevated Doppler resistive index (RI ≥ 0.70) in 45.0%. Nuclear scan parameters demonstrated reduced differential renal function (DRF < 40%) in 48.3% of patients and prolonged drainage half-time (T½ ≥ 20min) in 56.7% of patients. Histopathological examination revealed significant renal damage in 73.3% of kidneys. Significant associations, with histologic injury were observed for APD ≥ 20mm (p = 0.017), SFU grade ≥ III (p = 0.018), RI ≥ 0.70 (p = 0.030), DRF < 40% (p = 0.008), and T½ ≥ 20min (p = 0.021). Receiver operating characteristic analysis demonstrated fair predictive accuracy across parameters, with area under the curve (AUC) values of 0.707 for SFU grade, 0.697 for RI, 0.640 for APD, 0.702 for DRF, and 0.673 for T½. SFU grade ≥ III showed the highest sensitivity (79.5%) but moderate specificity (56.2%), while DRF < 40% demonstrated the highest specificity (81.2%) and positive predictive value (89.7%). Doppler RI ≥ 0.68 and T½ ≥ 20min exhibited balanced diagnostic performance, with sensitivities of 70.5% and 65.9% and specificities of 68.8% each. Negative predictive values were modest across all parameters (41.9-50.0%). Ultrasonographic and nuclear imaging parameters correlate significantly with histopathologic injury in pediatric PUJO and serve as practical, noninvasive predictors of renal parenchymal damage. While ultrasonography provides higher sensitivity, nuclear scan indices offer greater specificity and predictive value, supporting a combined imaging approach for optimal evidence-based decision-making to preserve renal function in affected children.

Anderson-Hynes dismembered pyeloplasty remains the gold standard surgical treatment for pelviureteric junction obstruction (PUJO). However, the extent of renal functional recovery following pyeloplasty continues to be debated. Numerous clinical and sradiological parameters have been proposed to predict postoperative renal function improvesment, yet with inconsistent outcomes. This study aimed to evaluate the degree of histopathological alterations in obstructed renal parenchyma and determine their predictive value for functional recovery after pyeloplasty. In this prospective observational study, renal biopsies were obtained intraoperatively during pyeloplasty from sixteen pediatric and adult patients diagnosed with PUJO. Histopathological changes were graded from I to III based on severity. Differential renal function (DRF), assessed by diethylene triamine pentaacetic acid (DTPA) renal scintigraphy was recorded preoperatively and at 6 months postoperatively. Associations between histological grade and functional outcomes were analyzed using Fisher’s exact test for categorical variables and Wilcoxon signed-rank test for continuous variables. A significant correlation was observed between the severity of histopathological damage and postoperative renal functional recovery. Thirteen patients (81.3%) with mild to moderate changes (Grade I-II) demonstrated significant improvement in DRF at 6 months following pyeloplasty (P0.05). Overall, postoperative DRF improved in 13 patients, while 3 patients experienced a decline. No significant association was found between preoperative DRF and histopathological grade. The severity of PUJO-related histopathological alterations in renal parenchyma serves as a valuable predictor of renal functional recovery after pyeloplasty. Patients with mild to moderate renal biopsy changes are more likely to achieve meaningful postoperative improvement, whereas severe histological damage may indicate limited functional reversibility.

Comparison of nuclear renographic renal cortical transit time with diuretic drainage time parameters in congenital hydronephrosis.

PurposeRecent advances in deep learning have facilitated the exploration of mesh reconstruction techniques; however, these approaches have not yet been applied to mesh reconstruction of hydronephrosis lesions in pediatric patients. Three surgical strategies are currently available for robot-assisted pyeloplasty in children, but there remains no consensus on which yields superior clinical benefits.Materials and methodsA total of 36 patients received robot-assisted pyeloplasty were divided into three groups based on different surgical procedures: large anastomosis group (LAG), middle anastomosis group (MAG) and small anastomosis group (SAG).A deep learning network was utilized to reconstruct upper urinary tract models from patients’ magnetic resonance urography (MRU) images, followed by computational fluid dynamics (CFD) simulations to measure urine flow dynamics parameters in the reconstructed models. Statistical comparisons of parameters were performed among the three groups.ResultsStatistically significant differences were observed among the three groups in terms of improvement in differential renal function (DRF), reduction in postoperative anteroposterior diameter (APD) of the renal pelvis, postoperative pressure reduction, pressure gradient between the upper and lower planes, changes in urinary flow velocity, and alterations in wall eddy viscosity. DRF was significantly improved in both the MAG and LAG, whereas it was significantly decreased in the SAG. The MAG exhibited the most remarkable reduction in the anteroposterior diameter of the renal pelvis. Postoperative pressure reduction was more pronounced in the MAG when compared with the LAG and SAG. The median postoperative pressure gradient between the upper and lower planes was the highest in the LAG. Postoperative urinary flow velocity increased significantly in the LAG, only slightly in the MAG, but decreased in the SAG. Postoperative wall eddy viscosity increased significantly in the LAG, whereas it decreased in both the MAG and SAG.ConclusionsDeep learning-based upper urinary tract model reconstruction combined with CFD simulation constitutes a novel noninvasive method for measuring upper urinary tract urine flow dynamics parameters. Among the three robot-assisted pyeloplasty techniques, the middle anastomosis approach yields the optimal postoperative recovery.

To explore the therapeutic efficacy and technical characteristics of pneumovesical Cohen ureteral reimplantation (PCUR) versus laparoscopic dismembered Lich-Gregoir ureteral reimplantation (LLGR) in the treatment of primary obstructive megaureter (POM) in Paediatric Patients. A retrospective analysis was performed on 94 paediatric patients with unilateral POM who were admitted to the Department of Paediatric Surgery, The First Affiliated Hospital of Zhengzhou University between October 2017 and October 2023. Based on the surgical approach, patients were allocated into two groups: 51 cases underwent PCUR, constituting the PCUR group; the remaining 43 cases underwent LLGR, forming the LLGR group. Preoperative baseline characteristics, intraoperative metrics, and postoperative outcomes were compared between the cohorts. The study specifically evaluated the changes in the renal pelvis anteroposterior diameter (APD), the maximum distal ureteral diameter (MDUD), and differential renal function (DRF) on the affected side, comparing preoperative and postoperative values. No significant differences were observed in preoperative baseline characteristics between the PCUR and LLGR groups. Compared to the PCUR group, the LLGR group was associated with a significantly shorter operative time (Z=-1.473, P = 0.015) and a reduced duration of postoperative haematuria (Z = -4.843, P < 0.001). Preoperative and postoperative measurements of the affected-side APD, MDUD, DRF and RCT were comparable between the two groups, with no statistically significant differences identified. However, intragroup analysis demonstrated a significant postoperative improvement in all three parameters (APD, MDUD, DRF and RCT) within both surgical cohorts. Furthermore, the magnitude of improvement, defined as the delta (Δ) values for APD (ΔAPD; t = -0.310, P = 0.758), MDUD (ΔMDUD; t = -0.418, P = 0.678), DRF (ΔDRF; t = -1.526, P = 0.129), and RCT(△RC; t = -0.431, P = 0.668), did not differ significantly between the groups. Both PCUR and LLGR are safe and effective in treating paediatric POM. Compared with PCUR, LLGR offers advantages including shorter operative time, reduced duration of postoperative haematuria, broader age range applicability, more spacious surgical field, lower technical difficulty in ureteral tailoring, and no compromise to subsequent endoscopic interventions.

Predicting Differential Renal Function in Children With Vesicoureteral Reflux Using Ultrasound.

This study aims to determine whether the calculation of the differential renal function (DRF) for renal scintigraphy using volumetric assessment is equivalent to conventional planar assessment using the geometric mean. Methods: A retrospective study was conducted with 108 patients referred for cortical renal scintigraphy. Forty-five patients were injected with 99mTc-dimercaptosuccinic acid (DMSA), and 63 patients were injected with 99mTc-glucoheptonate and furosemide, depending on which radiotracer was available at the time of the examination. DRF was measured using automatic 3-dimensional volume-of-interest delineation software on SPECT and 2-dimensional manual regions of interest on planar images, with geometric mean calculated for all patients. Images were reviewed by 2 independent masked observers. To assess intrarater reliability, a random sample of 20 images (10 with 99mTc-DMSA and 10 with 99mTc-glucoheptonate) was reprocessed by the same observers to after a minimum 2-wk interval to minimize recall bias. Values obtained by planar and SPECT methods were compared using a paired Student t test. Reproducibility was assessed through intraobserver and interobserver analyses using the intraclass correlation coefficient. Results: There was a significant difference in DRF values obtained by planar and SPECT methods with both 99mTc-glucoheptonate and 99mTc-DMSA (P < 0.05), with maximum absolute differences of 40.0% and 13.0%, respectively. High intrarater and interrater intraclass correlation coefficients were obtained for both methods and radiotracers (>0.9), indicating excellent reliability. Conclusion: The SPECT quantification method for the evaluation of DRF is reliable because of high intraobserver and interobserver agreement. Furthermore, it differs significantly from the planar quantification method, with more pronounced differences observed with 99mTc-glucoheptonate compared with 99mTc-DMSA.

Multicystic dysplastic kidney disease (MCDK) is a congenital kidney anomaly frequently misdiagnosed as hydronephrosis on antenatal ultrasound. Confirmatory nuclear imaging is seldom available in resource-limited settings. The study aimed to assess the diagnostic accuracy of kidney ultrasound (KUB scan) for detecting paediatric MCDK, using Mercaptoacetyltriglycine-3 scan ([99mTc]Tc-MAG3) differential renal function as the reference standard. A retrospective diagnostic accuracy analysis of consecutive children under 13years with suspected unilateral MCDK, who underwent both KUB and [99mTc]Tc-MAG3 scans within 6-8weeks of presentation at Red Cross War Memorial Children's Hospital between January 2014 and December 2023 was done. Diagnosis required characteristic MCDK features on KUB and absent function on [99mTc]Tc-MAG3 scans. Reporting adhered to the STARD guidelines. Of 793 eligible children, the [99mTc]Tc-MAG3 classified 101/101 (100.0%) kidneys as non-functional. The KUB scan accurately identified 97/98 and demonstrated a sensitivity of 99.0% (95% CI: 95.6-99.9%), specificity of 99.9% (95% CI: 99.4-100.0%), PPV of 99.0% (CI: 95.6-99.9%), NPV of 99.9% (99.4-100.0%) and overall accuracy of 99.7% in comparison to [99mTc]Tc-MAG3. Cohen's kappa indicated substantial agreement (0.988), with an AUC of 0.995 (95% CI: 0.983-1.000). Three missing KUB reports were excluded; sensitivity analysis accounting for missing data did not alter these findings. Postnatal kidney ultrasound scan performs excellently in diagnosing paediatric MCDK in the South African context and obviates the need for confirmatory nuclear imaging. This has clinical practice implications for paediatric nephro-urology and supports its use as a primary diagnostic tool both in resource-limited and resource-sufficient settings.