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Competing Interests: The authors declare that they have no conflict of interest.

After therapeutic pelvic radiation for malignancy such as prostate cancer, patients are at greater risk for spontaneous ureteral rupture. Bladder outlet obstruction and other more proximal causes of obstruction also exacerbate this vulnerability. Here we present a case of spontaneous ureteral rupture during a 99m Tc-mercaptoacetyltriglycine nuclear renal scan secondary to Foley catheter obstruction in a 73-y-old man with a prior ureteral reimplantation procedure. Prompt detection of Foley catheter malfunction could potentially prevent such adverse events., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Introduction: Diuretic renography is crucial in evaluation of paediatric hydronephrosis. Furosemide is conventionally given 15-20 min after radiolabelled tracer (F+15/F+20 protocol), however this is equivocal in around 15% of patients. Giving furosemide 15 min prior to tracer (F-15 MAG3 protocol) has been suggested as an additional tool in the investigation of patients with suspected upper urinary tract obstruction. However, the role of this method in assessment and management of paediatric hydronephrosis is not widely reported., Objective: To investigate utility of F-15 renograms in children with hydronephrosis being assessed for Pelvi-Ureteric Junction Obstruction (PUJO)., Study Design: Retrospective review of patients <16 years old undergoing F-15 MAG3 renogram between 2018 and 2021 in our tertiary paediatric surgical centre. Data collected included patient demographics, mode of presentation, investigations, management and outcomes., Results: Eighteen patients were included. Median age at F-15 renogram was 7.3 years. Eleven patients presented with antenatal hydronephrosis, 5 with symptoms in childhood and 2 with incidental hydronephrosis on trauma imaging. Fourteen patients were symptomatic. Ten had a prior non-obstructed F+20 renogram but persisting symptoms suggestive of PUJO. Seven had previous equivocal F+20 renograms. One symptomatic patient directly underwent an F-15 renogram. A conclusive result was obtained in 16/18 (89%); 11 patients had obstructed curves and 5 non-obstructed. Two asymptomatic patients' scans were inconclusive. All symptomatic patients had conclusive scans. Of 11 patients with an obstructed F-15, 9 have undergone pyeloplasty to date. All have had post-operative resolution in symptoms and static or improved post-operative ultrasound. One patient with an inconclusive scan underwent pyeloplasty due to persisting hydronephrosis and parent preference. Three patients with non-obstructed F-15 renograms have been discharged. One symptomatic patient with a non-obstructive F-15 had a ureteric stent inserted due to persistent flank pain; 1 continues under surveillance., Discussion: It is known that conventional F+20 MAG3 renograms can give equivocal results. Published experience suggests that F-15 renograms are conclusive in the majority of patients. Routine primary use is, however, discouraged as they can 'over diagnose' obstruction and limit the study of tracer transit under physiological flow rates. This study indicates that the F-15 renogram is a useful adjunct in the assessment of patients with symptoms suggestive of PUJO who have previously had an equivocal or a non-obstructed F+20 renogram., Conclusion: F-15 renogram was conclusive in 89% of patients. We recommend using F-15 renograms to aid surgical decision-making in children with equivocal F+20 renograms, especially in the presence of symptoms., Competing Interests: Conflict of interest None., (Copyright © 2024 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Objective: The aim of this study is to develop a noninvasive technique for measuring tissue tracer extraction efficiency ( E ) and illustrate it for Tc-99m-mercaptoacetyltriglycine (MAG3) and kidney., Methods: E was measured in 10 patients with normal MAG3 renography. E is the ratio of tissue clearance-to-blood flow ( Ki/F ). For single-photon tracers, attenuation constants are unknown, so Ki and F cannot be separately measured. However, by deriving attenuation-uncorrected Ki' and F' from the same regions of interests (ROIs), these constants cancel out, giving E . Using a lung ROI for blood activity, F was measured from first-pass and Ki' from Gjedde-Patlak-Rutland (GPR) analysis up to 130 s. Because of interference from right ventricle, a left ventricular ROI (LV) is unsuitable for F' but was used in GPR analysis, making an adjustment for the ratio of respective blood pool signals arising from lung and LV ROIs in early frames (60-90 s)., Results: A lung ROI underestimates F' by 4% at normal LV function. Chest wall interstitial activity ( I ), which does not affect F' , amounted to 53 and 30% of the lung and LV signals at 20 min, and 12 and 6% at 130 s, resulting in underestimations of Ki of 4 and 2%, respectively. Ignoring these opposing errors, E based on lung ROI for left and right kidneys was 43.5 (SD 8)% and 47.3 (9)%, and based on LV ROI for GPR analysis was 44.5 (10.9)% and 48.3 (10.6)%., Conclusion: E can be measured by combining blood flow from first-pass with clearance from GPR analysis, and has potential value both clinically and in clinical research., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

In preclinical single-photon emission computed tomography (SPECT) system development the primary objective has been to improve spatial resolution by using novel parallel-hole or multi-pinhole collimator geometries. However, such high-resolution systems have relatively poor sensitivity (typically 0.01-0.1%). In contrast, a system that does not use collimators can achieve very high-sensitivity. Here we present a high-sensitivity un-collimated detector single-photon imaging (UCD-SPI) system for the imaging of both small animals and plants. This scanner consists of two thin, closely spaced, pixelated scintillator detectors that use NaI(Tl), CsI(Na), or BGO. The performance of the system has been characterized by measuring sensitivity, spatial resolution, linearity, detection limits, and uniformity. With (99m)Tc (140 keV) at the center of the field of view (20 mm scintillator separation), the sensitivity was measured to be 31.8% using the NaI(Tl) detectors and 40.2% with CsI(Na). The best spatial resolution (FWHM when the image formed as the geometric mean of the two detector heads, 20 mm scintillator separation) was 19.0 mm for NaI(Tl) and 11.9 mm for CsI(Na) at 140 keV, and 19.5 mm for BGO at 1116 keV, which is somewhat degraded compared to the cm-scale resolution obtained with only one detector head and a close source. The quantitative accuracy of the system's linearity is better than 2% with detection down to activity levels of 100 nCi. Two in vivo animal studies (a renal scan using (99m)Tc MAG-3 and a thyroid scan with (123)I) and one plant study (a (99m)TcO4(-) xylem transport study) highlight the unique capabilities of this UCD-SPI system. From the renal scan, we observe approximately a one thousand-fold increase in sensitivity compared to the Siemens Inveon SPECT/CT scanner. UCD-SPI is useful for many imaging tasks that do not require excellent spatial resolution, such as high-throughput screening applications, simple radiotracer uptake studies in tumor xenografts, dynamic studies where very good temporal resolution is critical, or in planta imaging of radioisotopes at low concentrations.

Study Design: Retrospective cohort study., Objective: To investigate the potential of technetium-99m-mercaptoacetyltriglycine (99mTc-MAG-3) renal scintigraphy for predicting maximal detrusor pressure in the early stages of spinal cord injury (SCI)., Setting: Tertiary rehabilitation facility., Methods: Medical records of individuals with SCI admitted between January 2020 and April 2023 who underwent both 99mTc-MAG-3 renal scintigraphy and urodynamic study within 90 days of SCI onset were retrospectively reviewed. Pearson's coefficient analysis was performed to determine the relationship between 99mTc-MAG-3 renal scintigraphy findings and urodynamic study findings. A multivariate linear regression analysis was performed to determine the best predictors of maximal detrusor pressure. A multivariate logistic regression analysis was performed to determine risk factors for high detrusor pressure., Results: Ninety-four participants were enrolled in this study. Pearson's correlation analysis showed that effective renal plasma flow (ERPF) and ERPF (% predicted) were significantly correlated with maximal detrusor pressure. The multivariate linear regression analysis demonstrated that ERPF (% predicted) was a significant predictor of maximal detrusor pressure. The multivariate logistic regression analysis showed that ERPF (% predicted) was significantly associated with high detrusor pressure. The receiver operating characteristic curve demonstrated that the predictive model had an area under the curve of 0.725, with an ERPF (% predicted) cut-off of 64.05%, sensitivity 1.000, and specificity 0.429., Conclusions: These results suggest that 99mTc-MAG-3 renal scintigraphy may be useful for predicting high detrusor pressure in early SCI and may guide the timing of urodynamic studies in individuals with early SCI for appropriate management of neurogenic lower urinary tract dysfunction., (© 2024. The Author(s), under exclusive licence to International Spinal Cord Society.)

Background: Large field of view CZT SPECT cameras with a ring geometry are available for some years now. Thanks to their good sensitivity and high temporal resolution, general dynamic SPECT imaging may be performed more easily, without resorting to dedicated systems. To evaluate the dynamic SPECT imaging by such cameras, we have performed an in vivo pilot study to analyze the kidney function of a pig and compare the results to standard dynamic planar imaging by a conventional gamma camera., Methods: A 7-week-old (12 kg) female Landrace pig was injected with [ 99m Tc]Tc-MAG3 and a 30 min dynamic SPECT acquisition of the kidneys was performed on a CZT ring camera. A fast SPECT/CT was acquired with the same camera immediately after the dynamic SPECT, without moving the pig, and used for attenuation correction and drawing regions of interest. The next day the same pig underwent a dynamic planar imaging of the kidneys by a conventional 2-head gamma camera. The dynamic SPECT acquisition was reconstructed using a MLEM algorithm with up to 20 iterations, with and without attenuation correction. Time-activity curves of the total counts of each kidney were extracted from 2D and 3D dynamic images. An adapted 2-compartment model was derived to fit the data points and extract physiological parameters. Comparison of these parameters was performed between the different reconstructions and acquisitions., Results: Time-activity curves were nicely fitted with the 2-compartment model taking into account the anesthesia and bladder filling. Kidney physiological parameters were found in agreement with literature values. Good agreement of these parameters was obtained for the right kidney between dynamic SPECT and planar imaging. Regional analysis of the kidneys can be performed in the case of the dynamic SPECT imaging and provided good agreement with the whole kidney results., Conclusions: Dynamic SPECT imaging is feasible with CZT swiveling-detector ring cameras and provides results in agreement with dynamic planar imaging by conventional gamma cameras. Regional analysis of organs uptake and clearance becomes possible. Further studies are required regarding the optimization of acquisition and reconstruction parameters to improve image quality and enable absolute quantification., (© 2024. The Author(s).)

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., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Patients with high grade hydronephrosis (HN) and non-obstructive drainage on mercaptoacetyltriglycine (MAG-3) diuretic renography (renal scans) can pose a dilemma for clinicians. Some patients may progress and require pyeloplasty; however, more clarity is needed on outcomes among these patients., Objective: Our primary objective was to predict which patients with high-grade HN and non-obstructive renal scan, (defined as T ½ time <20 min) would experience resolution of HN. Our secondary objective was to determine predictors for surgical intervention., Study Design: Patients with prenatally detected HN were prospectively enrolled from 7 centers from 2007 to 2022. Included patients had a renal scan with T ½<20 min and Society for Fetal Urology (SFU) grade 3 or 4 at last ultrasound (RBUS) prior to renal scan. Primary outcome was resolution of HN defined as SFU grade 1 and anterior posterior diameter of the renal pelvis (APD) < 10 mm on follow-up RBUS. Secondary outcome was pyeloplasty, comparing patients undergoing pyeloplasty with patients followed with serial imaging without resolution. Multivariable logistic regression was used for analysis., Results: Of the total 2228 patients, 1311 had isolated HN, 338 patients had a renal scan and 129 met inclusion criteria. Median age at renal scan was 3.1 months, 77% were male and median follow-up was 35 months (IQR 20-49). We found that 22% (29/129) resolved, 42% of patients had pyeloplasty (54/129) and 36% had persistent HN that required follow-up (46/129). Univariate predictors of resolution were age≥3 months at time of renal scan (p = 0.05), T ½ time≤5 min (p = 0.09), SFU grade 3 (p = 0.0009), and APD<20 mm (p = 0.005). Upon multivariable analysis, SFU grade 3 (OR = 4.14, 95% CI: 1.30-13.4, p = 0.02) and APD<20 mm (OR = 6.62, 95% CI: 1.41-31.0, p = 0.02) were significant predictors of resolution. In the analysis of decision for pyeloplasty, SFU grade 4 (OR = 2.40, 95% CI: 1.01-5.71, p = 0.04) and T ½ time on subsequent renal scan of ≥20 min (OR = 5.14, 95% CI: 1.54-17.1, p = 0.008) were the significant predictors., Conclusions: Patients with high grade HN and reassuring renal scan can pose a significant challenge to clinical management. Our results help identify a specific candidate for observation with little risk for progression: the patient with SFU grade 3, APD under 20 mm, T ½ of 5 min or less who was 3 months or older at the time of renal scan. However, many patients may progress to surgery or do not fully resolve and require continued follow-up., Competing Interests: Conflicts of interest There is no financial or perceived conflict of interest for those involved in this work., (Copyright © 2024 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Introduction: 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., Objective: 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., Study Design: 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., Results: 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)., Discussion: 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., Conclusion: 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., Competing Interests: Conflict of interest None, (Copyright © 2023 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Objective: iRENEX is a software module that incorporates scintigraphic and clinical data to interpret 99m Tc- mercaptoacetyltriglycine (MAG3) diuretic studies and provide reasons for their conclusions. Our objectives were to compare iRENEX interpretations with those of expert physicians, use iRENEX to evaluate resident performance and determine if iRENEX could improve the diagnostic accuracy of experienced residents., Methods: Baseline and furosemide 99m Tc-MAG3 acquisitions of 50 patients with suspected obstruction (mean age ± SD, 58.7 ± 15.8 years, 60% female) were randomly selected from an archived database and independently interpreted by iRENEX, three expert readers and four nuclear medicine residents with one full year of residency. All raters had access to scintigraphic data and a text file containing clinical information and scored each kidney on a scale from +1.0 to -1.0. Scores ≥0.20 represented obstruction with higher scores indicating greater confidence. Scores +0.19 to -0.19 were indeterminate; scores ≤-0.20 indicated no obstruction. Several months later, residents reinterpreted the studies with access to iRENEX. Receiver operating characteristic (ROC) analysis and concordance correlation coefficient (CCC) quantified agreement., Results: The CCC among experts was higher than that among residents, 0.84, versus 0.39, respectively, P  < 0.001. When residents reinterpreted the studies with iRENEX, their CCC improved from 0.39 to 0.73, P  < 0.001. ROC analysis showed significant improvement in the ability of residents to distinguish between obstructed and non-obstructed kidneys using iRENEX ( P  = 0.036)., Conclusion: iRENEX interpretations were comparable to those of experts. iRENEX reduced interobserver variability among experienced residents and led to better agreement between resident and expert interpretations., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc.)

PURPOSE: To evaluate the effect of sildenafil, administered prior to renal ischemia/reperfusion (I/R), by scintigraphy and histopathological evaluation in rats. METHODS: Twenty-four rats were divided randomly into two groups. They received 0.1 ml of 99mTechnetium-etilenodicisteine intravenous, and a baseline (initial) renal scintigraphy was performed. The rats underwent 60 minutes of ischemia by left renal artery clamping. The right kidney was not manipulated. The sildenafil group (n=12) received orally 1 mg/kg of sildenafil suspension 60 minutes before ischemia. Treatment with saline 0.9% in the control group (n=12). Half of the rats was assessed after 24 hours and half after seven days I/R, with new renal scintigraphy to study differential function. After euthanasia, kidneys were removed and subjected to histopathological examination. For statistical evaluation, Student t and Mann-Whitney tests were used. RESULTS: In the control group rats, the left kidneys had significant functional deficit, seven days after I/R, whose scintigraphic pattern was consistent with acute tubular necrosis, compared with the initial scintigraphy (pOBJETIVO: Estudar o efeito do sildenafil, administrado previamente à isquemia/reperfusão (I/R) renal, em avaliações cintilográficas e histopatológicas em ratos. MÉTODOS: Vinte e quatro ratos Wistar foram aleatoriamente distribuídos em dois grupos. Os animais receberam 0,1 ml IV de 99mTecnécio-Etilenodicisteína, foram submetidos à cintilografia renal inicial e em seguida submetidos a isquemia no rim esquerdo, com oclusão da artéria renal, durante 60 minutos, com posterior reperfusão. O grupo sildenafil (n=12) recebeu previamente 1mg/kg de sildenafil em suspensão 60 minutos antes da isquemia. Solução salina 0,9% foi administrada no grupo controle (n=12). Metade dos animais de cada grupo foi avaliada após 24 horas e a outra metade após sete dias de reperfusão, com nova cintilografia renal. Após eutanásia, os rins foram retirados e submetidos a exame histopatológico. Na avaliação estatística foram empregados os testes t de Student e de Mann-Whitney. RESULTADOS: Foi observado no rim esquerdo (submetido a I/R) do grupo controle déficit funcional diferencial nas imagens cintilográficas após sete dias, com padrão de necrose tubular aguda, quando comparado com a cintilografia inicial (p

Objectives: Technetium-99m mercapto-acetyl-triglycine ([ 99m Tc]Tc-MAG3) is a radiopharmaceutical diagnostic agent used in nuclear medicine intended for the exploration of nephrological and urological disorders. Patient safety and reliability of this imaging procedure especially depend on the radiochemical purity (RCP) of the [ 99m Tc]Tc-MAG3 preparation. Recently, the Summary of Product Characteristics (SPC) of NephroMAG, a kit dedicated to [ 99m Tc]Tc-MAG3 preparation, proposed a two-strip thin layer chromatography (TLC) based quality control (QC) method. Also, Straub et al recently proposed another TLC based QC method. We sought to evaluate the transferability of these QC methods in our hospital radiopharmacy and compared them to our currently employed TLC method and radio-HPLC (high-pressure liquid chromatography) to select the most appropriate in the context of hospital radiopharmacy., Methods: Ten consecutive [ 99m Tc]Tc-MAG3 preparations were controlled using: HPLC combined with a radiodetector (radio-HPLC), a single strip TLC method (method 1) in current use in our centre, a two-strip TLC method described in the SPC (method SPC) and a two-strip TLC method (method 2) described by Straub et al . Quantitative results for the four tested QC methods were measured and compared in terms of RCP (%), sodium pertechnetate ([ 99m Tc]TcO 4 - ) (%) and duration of analysis (min)., Results: RCP was significantly different between method SPC and radio-HPLC (p<0.001) and method 2 (p<0.001). Also, the percentage of [ 99m Tc]TcO 4 - was statistically different between the radio-HPLC and the method SPC (p<0.001), but not with the method 1 and method 2 group (p>0.05). The duration of analysis (min) was significantly different between the four QC procedures (p<0.001) with method 2 and method SPC being the quickest., Conclusions: Our study showed it is possible to transfer and select a quick and reliable QC method for the preparation of NephroMAG kits in our centre. We therefore advise the widespread use of the method from Straub et al in hospital radiopharmacies., Competing Interests: Competing interests: None declared., (© European Association of Hospital Pharmacists 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose Renal function following percutaneous nephrolithotomy has long been a concern to urologists, especially in the setting of multi-tract access. We determined whether the risk of renal injury after multi-tract percutaneous nephrolithotomy was greater than after a single access approach. Materials and Methods We retrospectively reviewed the records of 307 consecutive patients treated with percutaneous nephrolithotomy from 2011 to 2012 at Wake Forest Health. Perioperative 99m Tc-mercaptoacetyltriglycine nuclear renogram parameters along with serum creatinine values were assessed within 1 year of the procedure. Patients were stratified by single access vs multi-access (2 or more). Results We identified 110 cases in which renography was done before and after percutaneous nephrolithotomy. A total of 74 patients (67.3%) underwent single access percutaneous nephrolithotomy while 36 (32.7%) underwent multi-access percutaneous nephrolithotomy. Serum creatinine did not significantly differ between the 2 cohorts postoperatively (p = 0.09). There was a significant 2.28% decrease in renal function based on mercaptoacetyltriglycine nuclear renogram results after percutaneous nephrolithotomy of the affected kidney in patients with multiple accesses (p <0.01). This relationship was not observed when patients were stratified by multiple comorbidities associated with nephrolithiasis. Conclusions Multi-access percutaneous nephrolithotomy is associated with a small reduction in the function of the targeted kidney compared to a single access approach. [ABSTRACT FROM AUTHOR]

Purpose To discriminate pathological from physiological hydronephrosis 99m Tc-mercaptoacetyltriglycine (MAG3) diuretic renography is a fundamental imaging modality. Initial asymmetrical differential function or decreasing function on serial MAG3 scans is a classic surgical indication. However, prognostic evidence supporting this is limited. Therefore, we examined the association between initial function and outcomes. We hypothesized that patients with initially asymmetrical function would have higher odds of functional decline, and experience symptoms and surgical intervention compared to patients with initially symmetrical scans. Materials and Methods We retrospectively reviewed the charts of 1,124 pediatric patients with hydronephrosis seen at Stollery Children’s Hospital from 2000 to 2014. A total of 387 cases of unilateral ureteropelvic junction obstruction were grouped by initial postnatal differential function with asymmetrical defined as a greater than 10% difference in relative function. Postnatal surveillance, followup MAG3 results, pyeloplasty rates and post-pyeloplasty outcomes were compared. Results Of 387 patients 143 (37%) had initially asymmetrical function. Of those undergoing MAG3 scan surveillance 17% experienced a 10% or greater decline in ipsilateral differential function vs a 6% rate of function loss in the initially symmetrical group (OR 3.2, 95% CI 1.6–6.4, p = 0.0008). The overall pyeloplasty rate in patients with asymmetrical and symmetrical function was 27% and 16%, respectively (OR 1.9, 95% CI 1.1–3.2, p = 0.013). Patients with initially asymmetrical function had an increased rate of pyeloplasty secondary to symptoms compared to those with initially symmetrical function (16% vs 8%, OR 2.1, 95% CI 1.1–4.0, p = 0.019). Mean time to functional decline and pyeloplasty was 19 and 17 months, respectively. Conclusions Patients with initially asymmetrical differential function had increased ORs for subsequent renal decline, symptom onset and pyeloplasty. [ABSTRACT FROM AUTHOR]

Purpose We define sonographic biomarkers for hydronephrotic renal units that can predict the necessity of diuretic nuclear renography. Materials and Methods We selected a cohort of 50 consecutive patients with hydronephrosis of varying severity in whom 2-dimensional sonography and diuretic mercaptoacetyltriglycine renography had been performed. A total of 131 morphological parameters were computed using quantitative image analysis algorithms. Machine learning techniques were then applied to identify ultrasound based safety thresholds that agreed with the t½ for washout. A best fit model was then derived for each threshold level of t½ that would be clinically relevant at 20, 30 and 40 minutes. Receiver operating characteristic curve analysis was performed. Sensitivity, specificity and area under the receiver operating characteristic curve were determined. Improvement obtained by the quantitative imaging method compared to the Society for Fetal Urology grading system and the hydronephrosis index was statistically verified. Results For the 3 thresholds considered and at 100% sensitivity the specificities of the quantitative imaging method were 94%, 70% and 74%, respectively. Corresponding area under the receiver operating characteristic curve values were 0.98, 0.94 and 0.94, respectively. Improvement obtained by the quantitative imaging method over the Society for Fetal Urology grade and hydronephrosis index was statistically significant (p <0.05 in all cases). Conclusions Quantitative imaging analysis of renal sonograms in children with hydronephrosis can identify thresholds of clinically significant washout times with 100% sensitivity to decrease the number of diuretic renograms in up to 62% of children. [ABSTRACT FROM AUTHOR]

Purpose Traditionally a single posterior view is used to measure differential renal function during nuclear renal scintigraphy. Nevertheless, experimental data show important variation in this measurement in the setting of significant hydronephrosis. To date, the impact of degree of hydronephrosis on the accuracy of differential renal function determination has not been addressed. We evaluated the discrepancy between function measured by anterior and posterior views, and the relationship to varying degrees of hydronephrosis. Materials and Methods We retrospectively reviewed consecutive mercaptoacetyltriglycine renal scans from 2009 to 2011. Ultrasounds were reviewed and degree of hydronephrosis was recorded using anteroposterior pelvic diameter. Absolute percent difference in differential renal function between each view (anterior minus posterior) was calculated and correlated to anteroposterior pelvic diameter. Patients were stratified into 4 groups according to anteroposterior pelvic diameter, ie less than 10 mm, greater than 10 mm, greater than 15 mm and greater than 25 mm. Results A total of 519 scans with corresponding ultrasounds were analyzed. Median patient age was 2.26 years. Kidneys with a larger anteroposterior pelvic diameter had a greater discrepancy in function on anterior and posterior views. There was a meaningful discrepancy for anteroposterior pelvic diameter greater than 10 mm (p = 0.034) and greater than 25 mm (p = 0.032). Several statistical models were used to identify a meaningful cut point of 15 mm, where the discrepancy in anterior and posterior views became significant (p = 0.001). Conclusions The use of single views during nuclear renography for grossly hydronephrotic kidneys is often inaccurate. The discrepancy in differential renal function obtained on the anterior and posterior views is adversely impacted especially as anteroposterior pelvic diameter increases beyond 15 mm. Therefore, we suggest incorporation of conjugate views for estimating differential renal function in patients with hydronephrosis. [ABSTRACT FROM AUTHOR]

Background: Both the development of kidney function in healthy children and autoregulation ability of kidney function in patients with asymmetric kidneys are important in clinical diagnosis and treatment of kidney-related diseases, but there are however only limited studies. This study aimed to investigate development of kidney function in normal children with healthy symmetric kidneys and autoregulation of the healthy kidney compensating the functional loss of a diseased one in children with asymmetric kidneys., Methods: Two hundred thirty-seven children (156 male, 81 female) from 0 to 20y (average 4.6y ± 5.1) undergoing 99m Tc-MAG3 renography were included, comprising 134 with healthy symmetrically functioning kidneys and 103 with asymmetric kidneys. Clearance was calculated from kidney uptakes at 1-2 min. A developmental model between MAG3 clearance (CL) and patient age in normal group was identified (CL = 84.39Age 0.395  ml/min, r = 0.957, p < 0.001). The clearance autoregulation rate in abnormal group with asymmetric kidneys was defined as the ratio of the measured MAG3 clearance and the normal value predicted from the renal developmental model of normal group., Results: No significant difference of MAG3 clearance (p = 0.723) was found between independent abnormal group and normal group. The autoregulation rate of kidney clearance in abnormal group was 94.2% on average, and no significant differences were found between two age groups (p = 0.49), male and female (p = 0.39), and left kidney and right kidney (p = 0.92) but two different grades of asymmetric kidneys (p = 0.02)., Conclusions: The healthy kidney of two asymmetric kidneys can automatically regulate total kidney function up to 94% of two symmetric kidneys in normal children., (© 2022. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)

Competing Interests: C. Lamarche reports filed patents: PCT/CA2018/051167 and PCT/CA2018/051174. All remaining authors have nothing to disclose.

Purpose: Nuclear renal scan is currently the gold standard imaging study to determine differential renal function. We propose helical computerized tomography as a more efficient way to gain renal function information. Renal parenchymal volume is measured and percent total renal volume is used as a surrogate marker for differential renal function. Materials and Methods: Computerized tomography and diuretic enhanced nuclear renal scan were performed in 33 patients with chronic obstruction. Computerized tomography was contrast enhanced in 23 cases and nonenhanced in 10. Diagnoses included ureteropelvic junction obstruction, ureteral stricture and extrinsic compression. Using semiautomated boundary delineation with manual editing method the parenchymal volume of each kidney was measured and percent renal volume was calculated. Percent renal volume was compared with percent renal function, as determined by nuclear renal scan. Correlations between the 2 measures were evaluated using the Spearman or Pearson coefficient. Results: Strong correlations were observed between percent renal function and percent renal volume in all cases (r = 0.90, p <0.001), including the enhanced (r = 0.87, p <0.001) and nonenhanced (r = 0.95, p <0.001) groups. Moderately strong correlations were noted in the less than 40% (r = 0.76, p <0.001) and less than 30% (r = 0.64, p = 0.015) renal function subgroups. Conclusions: Differential renal volume measured from computerized tomography strongly correlates with differential renal function on nuclear renal scan for normal and chronically obstructed kidneys. Computerized tomography may serve as a single radiological diagnostic study for anatomical and functional assessment in patients in whom a poorly functioning kidney is suspected. [Copyright &y& Elsevier]

Purpose: Diethylenetriamine pentaacetic acid and mercaptoacetyltriglycine renal scans are commonly used to evaluate infants and children with hydronephrosis to assess for changes in kidney function and drainage. We evaluate the certified nuclear medicine technologist intraobserver and interobserver variability of data processing in diuretic renal scan interpretation of the percent differential function of the right kidney so that true physiological changes can be understood by the clinician. Materials and Methods: A total of 30 renal scans (diethylenetriamine pentaacetic acid in 20 patients and mercaptoacetyltriglycine in 10) were randomly selected for evaluation by 3 technologists who processed the scan data for each patient on 5 different occasions at least 1 week apart. Regions of interest were drawn and background areas were subtracted, and percent differential function of the right kidney was calculated. Technologists were blinded to patient identification and previous interpretation results. The data were then statistically analyzed. Results: The data focused on percent differential function of the right kidney. Confidence limits for the single scan interpretation at the 95% level showed ±5.8% differential function variation, although this scan was the same renal scan processed 1 week later. Conclusions: For differential function determined on diethylenetriamine pentaacetic acid or mercaptoacetyltriglycine diuretic renal scan the single scan 95% confidence limits were ±5.8% differential function. From one renal scan to the next the differential percent of kidney function must change ±11.6% differential function for a clinician to be 95% confident that a real change in kidney function has occurred. This uncertainty is substantial and is likely larger than is currently allowed for in clinical practice. [Copyright &y& Elsevier]

Purpose: We evaluated 99mtechnetium-mercaptoacetyltriglycine scintigraphy for detecting threshold bladder volume at which upper tract obstruction occurs in patients with bladder dysfunction. Materials and Methods: A total of 24 patients 19 to 74 years old with severe bladder dysfunction who underwent 99mtechnetium-mercaptoacetyltriglycine scintigraphy and videocystometrogram in a 4-year period were selected for retrospective study. 99mTechnetium-mercaptoacetyltriglycine scintigraphy was done with a full bladder with a mean instilled volume of more than 850 ml saline. In patients in whom an obstructed renal outflow pattern was observed saline was drained at a rate of 100 ml every 5 minutes while dynamic imaging was performed. If results were abnormal, the study was repeated with an empty bladder. Differential function, parenchymal transit time index and outflow efficiency were calculated. Results: Of the 24 patients 15 had an obstructed outflow pattern with a full bladder, which was relieved at a bladder volume of less than 390 ml (median 300, range 250 to 600). Only 2 of these 15 patients had a normal vesical end filling pressure of less than 20 cm H2O. There was no obstruction in 9 patients, of whom 5 had increased vesical end filling pressures. Followup in patients who had normal tracer outflow on a full bladder showed no decrease in renal function, while a small decrease was seen in patients who had obstructed outflow on a full bladder. Conclusion: This novel, full bladder 99mtechnetium-mercaptoacetyltriglycine scintigraphic technique provides the ability to detect bladder volumes at which obstructive outflow patterns develop in patients with severe bladder dysfunction. [Copyright &y& Elsevier]

Background/aim: This study performed 99m Tc-MAG 3 renal scintigraphy on rabbit kidneys and evaluated its ability to identify obstructive or non-obstructive kidneys., Materials and Methods: Renal function was assessed during a four-week post-obstruction period by obtaining planar images of 99m Tc-MAG 3 activity following an ear vein injection. The individual renal function was evaluated by renal scintigraphy in conjunction with histopathological and morphological examinations., Results: The renal perfusion of 99m Tc-MAG 3 in the right kidney with a ureteral obstruction decreased with time. The width, height, and cortical thickness of the obstructed right kidney were significantly larger than those of the left kidney. A histopathological examination four weeks after the ureteral obstruction revealed a typical pattern of urinary tract obstruction, including multiple tubules, enlargement of the interstitial area, and cytoplasmic vacuoles., Conclusion: 99m Tc-MAG 3 renal scintigraphy provides the kidney shape and size and can identify potential obstructive and non-obstructive kidneys in rabbits., (Copyright © 2022 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)