The SNMMI and EANM Procedural Guidelines for Diuresis Renography in Infants and Children

Objective sonographic measurements of renal pelvic diameter and renal parenchymal thickness can identify renal hypofunction and poor drainage in patients with antenatally detected unilateral ureteropelvic junction obstruction

INTRODUCTION

Hydronephrosis grading systems risk stratify patients with potential ureteropelvic junction obstruction, but only some criteria are measured objectively. Most notably, there is no consensus definition of renal parenchymal thinning.

OBJECTIVES

The objective of this study was to assess the association between sonographic measures of renal length, renal pelvic diameter, and renal parenchymal thickness and the outcomes of a)renal hypofunction(differential renal function{DRF} <40%) and b)high-risk renal drainage(T1/2 > 40 min).

STUDY DESIGN

An institutional database of patients who had diuretic renograms(DR) for unilateral hydronephrosis was reviewed. Only infants with Society for Fetal Urology(SFU) grades 3/4 hydronephrosis without hydroureter on postnatal sonogram and had a DR within 120 days were included. The following measurement variables were analyzed: anterior posterior renal pelvic diameter(APRPD), renal length(RL), renal parenchymal thickness(PT), minimal renal parenchymal thickness(MPT = shortest distance from mid-pole calyx to parenchymal edge), and renal pyramidal thickness(PyrT). RL, PT, MPT, PyrT measurements were expressed as ratios (hydronephrotic kidney/contralateral kidney). Multivariate logistic regression was performed for each outcome by comparing three separate renal measurement models. Model 1: RLR, APRPD, MPTR; Model 2: RLR, APRPD, PTR, Model 3: RLR, APRPD, PyrTR. Individual performance of variables from the best performing model were assessed via ROC curve analysis.

RESULTS

196 patients were included (107 with SFU grade 3, 89 with SFU grade 4) hydronephrosis. Median patient age was 29[IQR 16,47.2] days. 10% had hypofunction, and 20% had T1/2 > 40 min 90% with hypofunction and 87% with high-risk drainage had SFU4 hydronephrosis. Model 1 exhibited the best performance, but on multivariate analysis, only APRPD and MPTR were independently associated with both outcomes. No other measure of parenchymal thickness reached statistical significance. The odds of hypofunction and high-risk drainage increase 10% per 1 mm increase in APRPD(aOR 1.1 [CI 1.03-1.2], p = 0.005; aOR 1.1 [CI 1.03-1.2], p = 0.003). For every 0.1unit increase in MPTR the odds of hypofunction decrease by 40%(aOR 0.6 [CI 0.4-0.9], p = 0.019); and the odds of high-risk drainage decrease by 30%(aOR 0.7 [CI 0.5-0.9], p = 0.011). Optimal statistical cut-points of APRPD >16 mm and/or MPTR <0.36 identified patients at risk for obstructive parameters on DR.

DISCUSSION AND CONCLUSION

Of the sonographic hydronephrosis measurement variables analyzed, only APRPD and MPTR were independently associated with objective definitions of obstruction based on renal function and drainage categories. Patients who maintain APRPD <16 mm and/or MPTR >0.36 can potentially be monitored with renal sonograms as there is >90% chance that they will not have DRF<40% or T1/2 > 40 min.

A fully automatic deep learning-based method for segmenting regions of interest and predicting renal function in pediatric dynamic renal scintigraphy

OBJECTIVE

Accurate delineation of renal regions of interest (ROIs) is critical for the assessment of renal function in pediatric dynamic renal scintigraphy (DRS). The purpose of this study was to develop and evaluate a deep learning (DL) model that can fully automatically delineate renal ROIs and calculate renal function in pediatric 99mTechnetium-ethylenedicysteine (99mTc-EC) DRS.

METHODS

This study retrospectively analyzed 1,283 pediatric DRS data at a single center from January to December 2018. These patients were divided into training set (n = 1027), validation set (n = 128), and testing set (n = 128). A fully automatic segmentation of ROIs (FASR) model was developed and evaluated. The pixel values of the automatically segmented ROIs were calculated to predict renal blood perfusion rate (BPR) and differential renal function (DRF). Precision, recall rate, intersection over union (IOU), and Dice similarity coefficient (DSC) were used to evaluate the performance of FASR model. Intraclass correlation (ICC) and Pearson correlation analysis were used to compare the consistency of automatic and manual method in assessing the renal function parameters in the testing set.

RESULTS

The FASR model achieved a precision of 0.88, recall rate of 0.94, IOU of 0.83, and DSC of 0.91. In the testing set, the r values of BPR and DRF calculated by the two methods were 0.94 (P < 0.01) and 0.97 (P < 0.01), and the ICCs (95% confidence interval CI) were 0.94 (0.90-0.96) and 0.94 (0.91-0.96).

CONCLUSION

We propose a reliable and stable DL model that can fully automatically segment ROIs and accurately predict renal function in pediatric 99mTc-EC DRS.

Non-contrast-enhanced magnetic resonance urography for measuring split kidney function in pediatric patients with hydronephrosis: comparison with renal scintigraphy

BACKGROUND

Split kidney function (SKF) is critical for treatment decision in pediatric patients with hydronephrosis and is commonly measured using renal scintigraphy (RS). Non-contrast-enhanced magnetic resonance urography (NCE-MRU) is increasingly used in clinical practice. This study aimed to investigate the feasibility of using NCE-MRU as an alternative to estimate SKF in pediatric patients with hydronephrosis, compared to RS.

METHODS

Seventy-five pediatric patients with hydronephrosis were included in this retrospective study. All patients underwent NCE-MRU and RS within 2 weeks. Kidney parenchyma volume (KPV) and texture analysis parameters were obtained from T2-weighted (T2WI) in NCE-MRU. The calculated split KPV (SKPV) percent and texture analysis parameters percent of left kidney were compared with the RS-determined SKF.

RESULTS

SKPV showed a significant positive correlation with SKF (r = 0.88, p < 0.001), while inhomogeneity was negatively correlated with SKF (r =  - 0.68, p < 0.001). The uncorrected and corrected prediction models of SKF were established using simple and multiple linear regression. Bland-Altman plots demonstrated good agreement of both predictive models. The residual sum of squares of the corrected prediction model was lower than that of the uncorrected model (0.283 vs. 0.314) but not statistically significant (p = 0.662). Subgroup analysis based on different MR machines showed correlation coefficients of 0.85, 0.95, and 0.94 between SKF and SKPV for three different scanners, respectively (p < 0.05 for all).

CONCLUSIONS

NCE-MRU can be used as an alternative method for estimating SKF in pediatric patients with hydronephrosis when comparing with RS. Specifically, SKPV proves to be a simple and universally applicable indicator for predicting SKF.

Hydronephrotic lower moiety of duplex systems: Observations using diuresis renography

PURPOSE

The purpose of this study is to characterize the prevalence and behavior of hydronephrosis of non-refluxing lower moiety of duplex kidneys using MAG-3 diuresis renography. We compare our data to previous case series and ureteropelvic junction obstruction of single systems.

MATERIALS AND METHODS

An IRB-approved database of over 5000 diuresis renograms performed in 2025 patients was queried to identify cases of hydronephrosis of lower moiety of duplex kidneys suspicious for ureteropelvic obstruction, excluding those with hydroureter or reflux. Kidney function and post-furosemide drainage parameters on initial and follow-up diuresis renograms were recorded. Medical records and patient outcomes were reviewed.

RESULTS

In total, 19 renal units were identified in 18 patients (11 male, 7 female), age range 0.5 months to 17.8 years, including one patient with bilateral lower moiety hydronephrosis. Initial diuresis renograms in 12 asymptomatic patients (13 renal units) with antenatal hydronephrosis demonstrated varying drainage patterns from normal to obstructed. Follow-up studies showed worsening drainage in 3 patients, who all underwent surgery. Drainage improved in 4 patients and remained unchanged in 5 patients (6 renal units). Of the 6 patients presenting with Dietl's crisis, 5 showed obstructive drainage on initial diuresis renogram, 2/5 with decreased function. All 5 obstructed patients underwent surgery.

CONCLUSION

Hydronephrosis of the lower moiety of a duplex system is rare and behaves similarly to single systems. The majority are diagnosed antenatally, display a dynamic nature, and may present with acute obstruction. Diuresis renography is a valuable tool in its evaluation and management.

Nuclear medicine and pediatric nephro-urology: a long-lasting successful partnership

Congenital anomalies of the kidney and urinary tract, as well as urinary infections, are very frequent in children. After the clinical and laboratory evaluation, the first imaging procedure to be done is a renal and bladder ultrasound, but afterwards, a main contribution comes from nuclear medicine. Through minimally invasive and sedation-free procedures, nuclear medicine allows the evaluation of the functional anatomy of the urinary tract, and the quantification of renal function and drainage. If pediatric dosage cards provided by scientific societies are used, radiation exposure can also be low. In the pediatric conditions previously mentioned, nuclear medicine is used both for initial diagnosis and follow-up, mostly in cases of suspicion of ureteropelvic or ureterovesical junction syndromes, as well as vesicoureteral reflux or renal scars of febrile infectious episodes. Pediatric nephro-urology constitutes a significant workload of pediatric nuclear medicine departments. The following paragraphs are a revision of the renal radiopharmaceuticals, as well as the nuclear nephro-urology procedures - dynamic and static renal scintigraphy, and direct and indirect radionuclide cystography. A summary of the techniques, main indications, interpretation criteria and pitfalls will be provided. Some future directions for the field are also pointed out, among which the most relevant is the need for nuclear medicine professionals to use standardized protocols and integrate multidisciplinary teams with other pediatric and adult health professionals that manage these life-long pediatric pathologies, which are recognized as an important cause of adult chronic kidney disease.

Assessment of infant gonadal dose irradiated from urine-contaminated diapers during diuretic renal scintigraphy

OBJECTIVE

To estimate the gonadal doses irradiated from urine- contaminated diapers during diuretic renal scintigraphy.

METHODS

Images of 31 patients (18 males and 13 females) with urine-contaminated diapers during 99m Tc-MAG3 renal scintigraphy were analyzed. The count rate of the diapers was converted into a time-activity curve based on the calibrated factor of the gamma camera system. The cumulative activity was determined from the area under the curve. By incorporating dose per unit cumulative activity pre-calculated from Monte Carlo simulation with 0-year phantom, the gonadal dose irradiated from diaper was calculated. To assess the degree of this additionally introduced dose from diapers, the calculated gonadal dose was compared to the internal gonadal dose from injected radiotracer activity.

RESULTS

The cumulative activities irradiated from urine-contaminated diapers were 1.12 E04 ± 1.29E04 MBq.s in male infants, which was nearly half of the 1.94 E04 ± 1.80E04 MBq.s ( P  = 0.15) in female infants. However, the absorbed doses for testes in male infants were 7.37E-01 ± 8.50E-01 mGy, which was approximately 10 times the 6.38E-02 ± 5.94E-02 mGy for ovaries in female infants ( P  < 0.01). The diaper-introduced dose for testes and ovaries was 91.7% and 3.9% of the gonadal doses from the injected activity in patients with normal renal function, and 99.0% and 4.3% of those in patients with abnormal renal function.

CONCLUSION

Urine-contaminated diapers introduced additional radiation doses to infant patients during 99m Tc-MAG3 renal scintigraphy. The gonadal doses were of significance in male infants who had nearly double the absorbed dose for the testes.

EANM procedural recommendations for managing the paediatric patient in diagnostic nuclear medicine

PURPOSE

The manuscript aims to characterize the principles of best practice in performing nuclear medicine procedures in paediatric patients. The paper describes all necessary technical skills that should be developed by the healthcare professionals to ensure the best possible care in paediatric patients, as it is particularly challenging due to psychological and physical conditions of children.

METHODS

We performed a comprehensive literature review to establish the most relevant elements of nuclear medicine studies in paediatric patients. We focused the attention to the technical aspects of the study, such as patient preparation, imaging protocols, and immobilization techniques, that adhere to best practice principles. Furthermore, we considered the psychological elements of working with children, including comforting and distraction strategies.

RESULTS

The extensive literature review combined with practical conclusions and recommendations presented and explained by the authors summarizes the most important principles of the care for paediatric patient in the nuclear medicine field.

CONCLUSION

Nuclear medicine applied to the paediatric patient is a very special and challenging area, requiring proper education and experience in order to be performed at the highest level and with the maximum safety for the child.

Influence of foetal position on the degree of isolated antenatal hydronephrosis

BACKGROUNDS

The effect of foetal position on the degree of antenatal hydronephrosis (ANH) is unknown. We hypothesized that foetal position is an important contextual factor in ANH, with consequences on prenatal counselling and postnatal management. The current study aimed to investigate the effect of foetal position on the degree of ANH.

METHODS

A retrospective study was carried out on consecutive pregnancies with isolated ANH over a 10-year period. Gestational age, foetal presentation (cephalic vs. breech), and degree of ANH (as measured by the AP diameter) were retrieved. Foetuses with other ultrasound findings of the renal tract (renal parenchymal abnormality, ureteric dilatation, or bladder abnormalities) were excluded. Logistic regression analysis was conducted to examine the relationship between the anterior-posterior diameter (APD) and the mode of presentation (cephalic or breech). A P-value of <0.05 was considered significant.

RESULTS

Initially 745 scans were identified, with 436 included in the final analysis. Overall, there was an association between foetal presentation and APD regardless of trimester, with cephalic presentations having a greater APD (OR 1.07, 95% CI 1.02-1.11, P = 0.04).

CONCLUSION

Cephalic presentations are associated with a significantly greater APD indicating that foetal position should be considered when stratifying ANH. Furthermore, foetal position may be a contributing factor in the mechanism of 'physiological' hydronephrosis.

Can we improve the usefulness of the diuretic renogram in the diagnosis of ureteropelvic junction obstruction (UPJO) in children? Introduction of mercaptoacetyltriglycine-suspected obstruction scoring system (MAG-SOS)

INTRODUCTION

Mercaptoacetyltriglycine (MAG-3) renogram is one of the gold standard diagnostic tools of ureteropelvic junction obstruction (UPJO); however, there is no widely agreed indications of pyeloplasty based on MAG-3 findings. In this study, we introduce a renogram scoring system that can help improve the prognostic value of MAG-3 renogram and in the decision making of pyeloplasty.

PATIENTS AND METHODS

We retrospectively reviewed consecutive pyeloplasties for antenatal hydronephrosis from 2010 to 2020. A control group was included of non-operatively managed SFU grade 3 and 4. The initial renal ultrasound and preoperative MAG-3 Lasix renogram were reviewed for differential renal function (DRF), type of renogram curve and tracer washout half-time (T1/2). A ROC curve was used to evaluate the cut-off points that can be associated with obstruction. A multivariate linear regression model was used to assess the best renogram parameter that can predict surgical intervention.

RESULTS

We included 188 patients with 209 renal units. The median age for pyeloplasty was 5.4 months. The mercaptoacetyltriglycine-Suspected Obstruction Scoring System (MAG-SOS) was associated with pyeloplasty (AUC = 0.97, P < 0.001) (Figure A). A score of 5 is 100% specific for obstruction. 78% of units required surgical intervention had a MAG-SOS score of≥5 while all units of the control group had a range of score 0-4. Using the multivariate analysis, the MAG-SOS system showed to the only independent predictor for pyeloplasty (HR = 0.03, p < 0.001).

DISCUSSION

This study has some limitations. Firstly, the retrospective nature of the cohort; however, all patients were reviewed by one investigator who was blinded to the line of management. This is a single institutional study; therefor, this MAG-SOS should be evaluated by other centers to ensure its efficiency. Lastly, the pyeloplasty decision was taken by 3 different urologists; nevertheless, all of them adopt the same indications which are similar to those of the Society for Pediatric Urology and the Canadian Urological Association guidelines.

CONCLUSION

The MAG-SOS system showed to be a useful tool that can predict pyeloplasty. A score of 5 has 100% specificity for patients having a pyeloplasty performed. Prospective studies are required to confirm the usefulness of this novel tool.

Quantitative assessment of renal functions using 68Ga-EDTA dynamic PET imaging in renal injury in mice of different origins

Background

Early detection of kidney diseases can be challenging as conventional methods such as blood tests or imaging techniques (computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonography) may be insufficient to assess renal function. A single-photon emission CT (SPECT) renal scan provides a means of measuring glomerular filtration rates (GFRs), but its diagnostic accuracy is limited due to its planar imaging modality and semi-quantification property. In this study, we aimed to improve the accuracy of GFR measurement by preparing a positron emission tonometry (PET) tracer 68Ga-Ethylenediaminetetraacetic acid (68Ga-EDTA) and comprehensively evaluating its performance in healthy mice and murine models of renal dysfunction.

Methods

Dynamic PET scans were performed in healthy C57BL/6 mice and in models of renal injury, including acute kidney injury (AKI) and unilateral ureter obstruction (UUO) using 68Ga-EDTA. In a 30-min dynamic scan, PET images and time-activity curves (TACs) were acquired. Renal function and GFR values were measured using renograms and validated through serum renal function parameters, biodistribution results, and pathological staining.

Results

68Ga-EDTA dynamic PET imaging quantitatively captured the tracer elimination process. The calculated GFR values were 0.25 ± 0.02 ml/min in healthy mice, 0.01 ± 0.00 ml/min in AKI mice, and 0.25 ± 0.04, 0.29 ± 0.03 and 0.24 ± 0.01 ml/min in UUO mice, respectively. Furthermore, 68Ga-EDTA dynamic PET imaging and GFRPET were able to differentiate mild renal impairment before serum parameters indicated any changes.

Conclusions

Our findings demonstrate that 68Ga-EDTA dynamic PET provides a reliable and precise means of evaluating renal function in two murine models of renal injury. These results hold promise for the widespread clinical application of 68Ga-EDTA dynamic PET in the near future.

Protective effect of spore oil-functionalized nano-selenium system on cisplatin-induced nephrotoxicity by regulating oxidative stress-mediated pathways and activating immune response

In clinical practice, cisplatin is the most commonly used chemotherapy drug to treat a range of malignancies. Severe ROS-regulated nephrotoxicity, however, restricts its applicability. Currently, the main mechanisms leading to cisplatin-induced nephrotoxicity in clinical settings involve hydration or diuresis. However, not all patients can be treated with massive hydration or diuretics. Therefore, it is crucial to develop a treatment modality that can effectively reduce nephrotoxicity through a foodborne route. Selenium has been reported to have strong antioxidant as well as anticancer effects when administered as spore oil. Herein, we established cellular and animal models of cisplatin-induced nephrotoxicity and synthesized spore oil-functionalized nano-selenium (GLSO@SeNPs). We found that GLSO@SeNPs inhibit the mitochondrial apoptotic pathway by maintaining oxidative homeostasis and regulating related signaling pathways (the MAPK, caspase, and AKT signaling pathways). In vivo, GLSO@SeNPs could effectively improve cisplatin-induced renal impairment, effectively maintaining oxidative homeostasis in renal tissues and thus inhibiting the process of renal injury. In addition, GLSO@SeNPs were converted into selenocysteine (SeCys2), which may exert protective effects. Furthermore, GLSO@SeNPs could effectively modulate the ratio of immune cells in kidneys and spleen, reducing the proportions of CD3⁺CD4⁺ T cells, CD3⁺CD8⁺ T cells, and M1 phenotype macrophages and increasing the proportion of anti-inflammatory regulatory T cells. In summary, in this study, we synthesized food-derived spore oil-functionalized nanomaterials, and we explored the mechanisms by which GLSO@SeNPs inhibit cisplatin-induced nephrotoxicity. Our study provides a basis and rationale for the inhibition of cisplatin-induced nephrotoxicity by food-derived nutrients.

Initial observational management of hydronephrosis in infants with reduced differential renal function and non-obstructive drainage parameters

INTRODUCTION

Hydronephrosis secondary to ureteropelvic junction (UPJ) obstruction is a common finding in infants with prenatally-diagnosed hydronephrosis and often results in pyeloplasty due to obstructive drainage parameters and/or renal function compromise. However, little is known regarding the natural history of hydronephrosis with reduced differential renal function (DRF) but non-obstructive drainage.

OBJECTIVE

We sought to explore our experience with initial observational management of these patients.

STUDY DESIGN

A retrospective review of our institutional database of all diuretic MAG-3 renal scans obtained between 2000 and 2016 was performed. We included patients with antenatally-detected unilateral hydronephrosis ≥ SFU grade 2, first MAG-3 scan prior to 18months of age, DRF <40% and post-furosemide half-time (T1/2) <20 min. Exclusion criteria were: hydroureter, VUR, solitary kidney, duplication anomalies. Outcomes of interest were a progression of T1/2 ≥ 20 min and/or further decline in DRF >5%.

RESULTS

Of 704 patients with unilateral hydronephrosis, 91 had DRF≤40%, of which 29 (18 boys, 11 girls) met our inclusion criteria and were followed for a mean of 2.8 years (1.4 months-6.6 years). Mean age at first sonogram was 2.3 months. 2 patients had SFU grade 2, 16 had grade 3, and 9 had grade 4 hydronephrosis, and 2 unknown grade. Median half-time on initial MAG-3 scan across all patients was 10 min (3-20 min). Initial MAG3 scan was performed at a median of 2.3 months of age (0.3-17 months). 22/29 patients had >1 MAG3 scan. Of the 7 remaining, 5 were lost to follow-up and 2 demonstrated improvement in hydronephrosis. Worsening drainage occurred in 10/22(45%), median final T1/2 was 45.5 min 8 of these underwent pyeloplasty and 2 were lost to follow up. 4/22 patients (18%) had progressive decline in DRF (mean 8.3%, range 6-10%). 3/4 maintained non-obstructive drainage patterns and stable/improved hydronephrosis, and 1 underwent pyeloplasty. 13/18 remaining patients had stable DRF and 5 had improvement in DRF. 7(39%) of these underwent surgery for worsening drainage (Summary Figure). Overall, 7/29(24%) patients had sufficient resolution of hydronephrosis to be discharged from our care, 8(28%) are under continued observation, 9(31%) underwent pyeloplasty, and 5(17%) were lost to follow-up. In the observational group [median follow-up 4.5 years (3.7-6.6 years)], all 8 demonstrated improved non-obstructive drainage (T1/2 <20 minutes) and/or improvement in hydronephrosis. 4/10(40%) with DRF <35% underwent pyeloplasty versus 5/19(26%) with DRF 35-40%(p=0.67).

CONCLUSION

Initial observational management of unilateral hydronephrosis with reduced DRF and nonobstructive drainage is recommended as most kidneys maintain nonobstructive drainage and do not demonstrate further decline in DRF. Even when DRF decreases, the majority remain non-obstructive. Worsening drainage over time more often leads to the decision for pyeloplasty rather than change in DRF.

Utility of renal scintigraphy in diagnosis of multicystic dysplastic kidney

PURPOSE

To compare the prevalence of vesicoureteral reflux (VUR), febrile urinary tract infection (fUTI), and chronic kidney disease (CKD) among patients with multicystic dysplastic kidney (MCDK) diagnosed by renal scintigraphy (RS) versus follow-up renal ultrasound (RUS) alone.

METHODS

This was a retrospective review of patients seen at a tertiary care center from 2010 to 2020 with MCDK diagnosed by RS or follow-up RUS. Differences in the prevalence of VUR, fUTI, and CKD by cohort were assessed using logistic regression analysis, Pearson X² , and Fisher's Exact tests. Temporal trends in diagnostic methods used (RUS versus RUS + RS) were evaluated using the Cochran-Armitage trend test.

RESULTS

One-hundred seventy-two patients were included: 50% (n = 86) underwent RUS + RS and 50% (n = 86) underwent RUS alone to diagnose MCDK. Prevalence of VUR, fUTI, and CKD did not significantly vary between groups. Among patients who had a VCUG, 4.4% had contralateral VUR (1.7% RUS + RS group; 7.4% RUS group; p = 0.19) and 14.5% had at least one fUTI (16.3% RUS + RS group; 12.8% RUS group; p = 0.52). Females were significantly more likely to have at least one fUTI (p = 0.04). Four patients (2.3%) developed CKD, all in the RUS + RS cohort (p = 0.12). Diagnosis of MCDK by RUS versus RUS + RS did not significantly vary over time (p = 0.17).

CONCLUSION

Patients with unilateral MCDK confirmed by RS versus RUS alone do not significantly vary in the prevalence of VUR, fUTI, or CKD. Renal scintigraphy studies may not be necessary in unilateral MCDK diagnosis but continue to be used.

Pediatric Nephro-Urology: Overview and Updates in Diuretic Renal Scans and Renal Cortical Scintigraphy

Nuclear medicine offers several diagnostic scans for the evaluation of congenital and acquired conditions of the kidneys and urinary track in children. Tc-99m-MAG 3 diuretic renal scans are most commonly used in the evaluation and follow up of urinary track dilatations. They provide functional information on the differential renal function and on drainage quality which is allows distinction between obstructed and non-obstructed kidneys and the need for surgical correction vs conservative management in kidneys with impaired drainage. Standardized imaging and processing protocols are essential for correct interpretation and for meaningful comparisons between follow up scans. Different approaches and conceptions led to some contradicting recommendations between SNMMI and EANM guidelines on diuretic renography in children which caused confusion and to the emergence of self-made institutional protocols. In Late 2018 the two societies published joint procedural guidelines on diuretic renography in infants and children which hopefully will end the confusion. Tc-99m DMSA scans provide important information about the function of the renal cortex allowing detection of acute pyelonephritis, renal scars dysplasia and ectopy as well as accurate determination of the differential renal function. They are commonly used in the evaluation of children with urinary tract infections and affect clinical management. A standardized imaging and processing protocol improves the diagnostic accuracy of these studies. SPECT or pinhole images should be a routine part of the imaging protocol. This is one of the recommendations in the new EANM and SNMMI procedural guidelines for renal cortical scintigraphy in children available online on the SNMMI website and is under publication. This article provides an overview on the clinical role of diuretic renography and cortical scintigraphy in children and describes the imaging protocols focusing on the new recommendations in the procedural guidelines.

Validation of modified diuretic drainage times criteria in congenital hydronephrosis

INTRODUCTION AND OBJECTIVE

The value of diuretic renography drainage times in congenital hydronephrosis (AHN) decision making is controversial. Recently, a group suggested a modification to the classically described diuretic drainage time cut-off values. They found that a drainage half-time (T_1/2) < 5 min was normal whereas a T_1/2 exceeding 75 min predicted pyeloplasty. In addition, they reported on the benefit of a delayed drainage image obtained with gravity assistance. We sought to evaluate the ability of these modified T1/2 criteria to predict pyeloplasty, alone or in combination with a delayed drainage image referred to as Global Washout (GWO).

METHODS

We retrospectively reviewed 113 patients, including consecutive pyeloplasties for AHN from 2004 to 2018. Patients who underwent pyeloplasty due to low differential renal function (DRF) < 30% or infection were excluded. The control group comprised high grade AHN managed non-operatively. The initial renal ultrasound and MAG 3 Lasix renogram were reviewed for grade, differential renal function (DRF), T_1/2 and GWO. A ROC curve was used to evaluate the T_1/2 and GWO cut-off points that can predict pyeloplasty, using a p-value of less than 0.05.

RESULTS

The pyeloplasty group consisted of 62 patients and the control group consisted of 51 patients. Two patients (3%) in the pyeloplasty group had a T_1/2 < 5 min whereas 21 (34%) had T _1/2 > 75 min (p < 0.001). In the control group, 25 patients (49%) had T _1/2 < 5 min and none had T_1/2 >75 min (P < 0.001). The ROC curve for T_1/2 < 5 min demonstrated 94% sensitivity and 51% specificity whereas a T_1/2 >75 min demonstrated 100% specificity and 34% sensitivity. Analysis of the GWO using a ROC curve revealed that a cut-off of 50% GWO has 100% specificity and 52% sensitivity for pyeloplasty. Overall, a T1/2 > 75 min or GWO <50% predicted 53% of pyeloplasties (Fig A) and was absent in all conservatively managed cases.

DISCUSSION

The limitations of the present study include its retrospective nature. Secondly, the lack of a gold standard diagnostic test for uretero-pelvic junction obstruction hampers objective quantification of diagnostic test utility performance.

CONCLUSIONS

We confirm the utility of the modified diuretic half-time criteria and delayed gravity assisted imaging. A T1/2 > 75 min or GWO <50% are indicators of severity whereas a T1/2 of <5 min or GWO >90% is reassuring. Gravity assisted delayed imaging can be especially helpful in cases with indeterminate T 1/2 times and should be included in the standard assessment of hydronephrotic kidneys. These parameters can be used to tailor the frequency and invasiveness of imaging within observation protocols.

Renogram image characteristics and the reproducibility of differential renal function measurement

PURPOSE

Patient factors such as age and glomerular filtration rate (GFR), have been implicated as causes for poor reproducibility of differential renal function (DRF) estimates on 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) renography. This study aims to investigate factors associated with the reproducibility of DRF measurements.

METHODS

The association between age, GFR and imaged derived image characteristics and reproducibility of repeated DRF estimates calculated using the area under the curve method and the Rutland Patlak method was analysed for cohort 1 (n = 127). The association between these variables and reproducibility of DRF was tested with univariate linear regression. The univariate linear regression results were used to plan the multiple linear regression combinations.The associations between variables identified and reproducibility of DRF values were then tested in a second cohort (n = 227).

RESULTS

The R2 values for goodness-to-fit for the multiple regression models ranged from 0.33 to 0.49 for cohort 1 and from 0.17 to 0.22 for cohort 2. Left kidney to background ratio (LKTBR) was significant in all the multiple linear regression combinations (P < 0.05). Right kidney to background ratio (RKTBR), right renal margins well defined, right renal margins poorly visualised, time visualisation right calyces and age were significant in most combinations. The reproducibility of DRF measurement was decreased when the kidney to background ratio (KTBR) was ≤2.

CONCLUSION

Only LKTBR, RKTBR, right renal margins well defined, time visualisation right calyces and age predicted reproducibility for the measurement of DRF on 99mTc-MAG3 renograms. The KTBR should be incorporated into the renal processing software as a quality control step. The DRF values should be interpreted with caution if the KTBR is ≤2.0.

Predicting the likelihood of prolongation of half-time among infants with initially indeterminate drainage values: A single-institution retrospective study of 535 patients with ureteropelvic junction obstruction

INTRODUCTION AND OBJECTIVE

Prior studies have shown a broad half time (T1/2) interval on MAG3 diuresis renography (DR) that is indeterminate for obstruction. We aimed to refine and sub-divide the indeterminate range and associate it with clinically meaningful outcomes: pyeloplasty and pyeloplasty-free survival.

METHODS

We identified patients <1.5 years-old at presentation with unilateral, isolated moderate to severe hydronephrosis who underwent DR from 2000 to 2016. A logistic regression model was created using T1/2 to predict surgery. An indeterminate range was defined based on patients with <90% probability of pyeloplasty or resolution. This group was sub-divided into three T1/2 intervals: 5-20, 21-40, and 41-60 min. Endpoints were pyeloplasty and pyeloplasty free survival. Indications for surgery were loss of differential renal function (DRF), worsening T1/2, family preference, and/or pain.

RESULTS

Among 2025 patients with DR, 704 met criteria (169 were lost to follow up). Of the remaining 535, 218 had pyeloplasties and 317 did not. The Pyeloplasty group had significantly worse DRF, T1/2 at initial DR, and exited the study earlier, at a median age 1.1years vs 2.3 years (p < 0.001). For all patients with antenatally detected unilateral UPJ obstruction, the odds of undergoing pyeloplasty at any time increased by 1.8 times (p < 0.001 [95% CI: 1.04, 1.08]) per 10 unit increase in T1/2 until T1/2 = 60. However, in patients with intermediate drainage, five year surgery-free survival probability for patients with T1/2 5-20, 21-40, and 41-60 min were 79.7%, 46.7% and 33.3% respectively (χ2 = 41.2, P = <0.001).

DISCUSSION

Previous efforts to define indeterminate drainage resulted in ranges for T1/2 that were too broad to be clinically useful. Within our endpoint-defined indeterminate range, our data show that there are significant step offs in 5-year surgery-free survival for patients with T1/2 < 20 min, 21-40 min, and 41-60 min. Although there is a steady decrease in surgery-free survival among patients with a T1/2 of 21-40 min over the first 5 years of life, half can be managed nonoperatively. These patients likely represent the true intermediate risk group and closer follow up is justified.

CONCLUSIONS

Initial T1/2 on DR is predictive of future surgery. When drainage is "indeterminate" for obstruction, sub-stratification allows for more accurate prognostication.

Diuresis renography in the evaluation and management of pediatric hydronephrosis: What have we learned?

Diuresis renography (DR) is widely used in the evaluation of hydronephrosis and hydroureter in infants and children. The goal of this provocative nuclear imaging examination should be to detect the hydronephrotic kidneys at risk for loss of function and development of pain, hematuria, and urinary tract infection. The reliability of DR is dependent on the acquisition and processing of the data as well as interpretation and utilization of the results. In this review, the key concepts of standardized DR and pitfalls to avoid are highlighted.

99mTc-LLEC Renal Dynamic Scan in a Patient With Pelvic Neuroblastoma

A 5-month-old boy with ultrasonography showing bilateral hydronephrosis, referred for renal scan. On Tc-L,L,ethylenedicysteine (Tc-LLEC) renal scan, tracer blush in flow images in the region of urinary bladder was seen and tumor mass was suspected. Contrast-enhanced CT showed a soft tissue mass in sacrococcygeal region. Histopathological examination of biopsy tissue revealed malignant round cell tumor and immunohistochemistry consistent with neuroblastoma. I-MIBG scan revealed uptake in the pelvic mass with no distant metastasis.