Utility of F-15 diuretic MAG3 renography in assessment of paediatric hydronephrosis.

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.

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 ±â€…1.29E04 MBq.s in male infants, which was nearly half of the 1.94 E04 ±â€…1.80E04 MBq.s ( P  = 0.15) in female infants. However, the absorbed doses for testes in male infants were 7.37E-01 ±â€…8.50E-01 mGy, which was approximately 10 times the 6.38E-02 ±â€…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.

Assessment of Individual Renal Function Using 99mTc-MAG3 Renography.

BACKGROUND/AIM: This study performed 99mTc-MAG3 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 99mTc-MAG3 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 99mTc-MAG3 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: 99mTc-MAG3 renal scintigraphy provides the kidney shape and size and can identify potential obstructive and non-obstructive kidneys in rabbits.

177Lu-PSMA-617 Therapy in Mice, with or without the Antioxidant α1-Microglobulin (A1M), Including Kidney Damage Assessment Using 99mTc-MAG3 Imaging.

Anti-prostate specific membrane antigen (PSMA) radioligand therapy is promising but not curative in castration resistant prostate cancer. One way to broaden the therapeutic index could be to administer higher doses in combination with radioprotectors, since administered radioactivity is kept low today in order to avoid side-effects from a high absorbed dose to healthy tissue. Here, we investigated the human radical scavenger α1-microglobulin (A1M) together with 177-Lutetium (177Lu) labeled PSMA-617 in preclinical models with respect to therapeutic efficacy and kidney toxicity. Nude mice with subcutaneous LNCaP xenografts were injected with 50 or 100 MBq of [177Lu]Lu-PSMA-617, with or without injections of recombinant A1M (rA1M) (at T = 0 and T = 24 h). Kidney absorbed dose was calculated to 7.36 Gy at 4 days post a 100 MBq injection. Activity distribution was imaged with Single-Photon Emission Computed Tomography (SPECT) at 24 h. Tumor volumes were measured continuously, and kidneys and blood were collected at termination (3-4 days and 3-4 weeks after injections). In a parallel set of experiments, mice were given [177Lu]Lu-PSMA-617 and rA1M as above and dynamic technetium-99m mercaptoacetyltriglycine ([99mTc]Tc-MAG3) SPECT imaging was performed prior to injection, and 3- and 6-months post injection. Blood and urine were continuously sampled. At termination (6 months) the kidneys were resected. Biomarkers of kidney function, expression of stress genes and kidney histopathology were analyzed. [177Lu]Lu-PSMA-617 uptake, in tumors and kidneys, as well as treatment efficacy did not differ between rA1M and vehicle groups. In mice given rA1M, [99mTc]Tc-MAG3 imaging revealed a significantly higher slope of initial uptake at three months compared to mice co-injected with [177Lu]Lu-PSMA-617 and vehicle. Little or no change compared to control was seen in urine albumin, serum/plasma urea levels, RT-qPCR analysis of stress response genes and in the kidney histopathological evaluation. In conclusion, [99mTc]Tc-MAG3 imaging presented itself as a sensitive tool to detect changes in kidney function revealing that administration of rA1M has a potentially positive effect on kidney perfusion and tubular function when combined with [177Lu]Lu-PSMA-617 therapy. Furthermore, we could show that rA1M did not affect anti-PSMA radioligand therapy efficacy.

Body morphometry appropriate computational phantoms for dose and risk optimization in pediatric renal imaging with Tc-99m DMSA and Tc-99m MAG3.

Current guidelines for administered activity (AA) in pediatric nuclear medicine imaging studies are based on a 2016 harmonization of the 2010 North American Consensus guidelines and the 2007 European Association of Nuclear Medicine pediatric dosage card. These guidelines assign AA scaled to patient body mass, with further constraints on maximum and minimum values of radiopharmaceutical activity. These guidelines, however, are not formulated based upon a rigor-ous evaluation of diagnostic image quality. In a recent study of the renal cortex imaging agent 99mTc-DMSA (Li Y et al 2019), body mass-based dosing guidelines were shown to not give the same level of image quality for patients of differing body mass. Their data suggest that patient girth at the level of the kidneys may be a better morphometric parameter to consider when selecting AA for renal nuclear medicine imaging. The objective of the present work was thus to develop a dedicated series of computational phantoms to support image quality and organ dose studies in pediatric renal imaging using 99mTc-DMSA or 99mTc-MAG3. The final library consists of 50 male and female phantoms of ages 0 to 15 years, with percentile variations (5th to 95th) in waist circumference (WC) at each age. For each phantom, nominal values of kidney volume, length, and depth were incorporated into the phantom design. Organ absorbed doses, detriment-weighted doses, and stochastic risks were assessed using ICRP reference biokinetic models for both agents. In Monte Carlo radiation transport simulations, organ doses for these agents yielded detriment-weighted dose coefficients (mSv/MBq) that were in general larger than current ICRP values of the effective dose coefficients (age and WC-averaged ratios of eDW/e were 1.40 for the male phantoms and 1.49 for the female phantoms). Values of risk index (ratio of radiation-induced to natural background cancer incidence risk x 100) varied between 0.062 (newborns) to 0.108 (15-year-olds) for 99mTc-DMSA and between 0.026 (newborns) to 0.122 (15-year-olds) for 99mTc-MAG3. Using tallies of photon exit fluence as a rough surrogate for uniform image quality, our study demonstrated that through body region-of-interest optimization of AA, there is the potential for further dose and risk reductions of between factors of 1.5 to 3.0 beyond simple weight-based dosing guidance.

Utility of MAG3 scintigraphy with the use of a 2 min uptake parameter in the assessment of postsurgical renal transplant complications.

OBJECTIVE: Major complications including acute tubular necrosis or rejection may occur after renal transplantation. We use a semiquantitative parameter, 2 min uptake (2MU), as part of Tc mercaptoacetyltriglycine (MAG3) scintigraphy for transplant evaluation. The aim of this study were (a) to examine the utility of Tc MAG3 scintigraphy in the assessment of postsurgical complications using the renal biopsy as the gold standard and (b) examine for any correlation with 2MU with serum creatinine (sCr) at 3 and 12 months. MATERIALS AND METHODS: We retrospectively reviewed all Tc MAG3 studies at our institution between July 2015 and June 2016, alongside available renal ultrasound, biopsy, and sCr results. RESULTS: A total of 105 patients fulfilled the inclusion criteria. 30/105 patients underwent biopsy less than 7 days of the Tc MAG3 study. Within this 7 day cohort, the negative predictive value for rejection with normal perfusion on Tc MAG3 study was 79% and the positive predictive value for rejection with abnormal Tc MAG3 perfusion was 9%. There was a weak negative correlation between 2MU and 3-month sCr (R=-0.358, P<0.001), and 2MU and 12-month sCr (R=-0.348, P<0.001). CONCLUSION: Although normal perfusion on Tc MAG3 scintigraphy study has a reasonable negative predictive value for rejection, abnormal Tc MAG3 perfusion is not useful in the differentiation of rejection from moderate to severe acute tubular necrosis. The 2MU parameter showed no additional benefit in the identification of rejection, but appeared to have a weak negative correlation with the 3-month and 12-month sCr, and may thus play a role in the prediction of longer term graft function.

Assessment of the relationship between renal volume and renal function after minimally-invasive partial nephrectomy: the role of computed tomography and nuclear renal scan.

BACKGROUND: To evaluate the correlation between the loss of renal function as assessed by Tc99MAG-3 renal scan and the loss of renal volume as calculated by volumetric assessment on CT-scan in patients who underwent minimally-invasive partial nephrectomy (PN). METHODS: PN prospectively-maintained database was retrospectively queried for patients who underwent minimally-invasive PN (2012-2017) for renal mass ≤cT2 and had complete data on renal scan and contrast-enhanced CT-scan (both performed in our Institution) both at preoperative assessment and at the third postoperative month follow-up. Tc99MAG-3 renal scan was performed to get renal functional data; renal volume was calculated by dedicated software from CT-scan with a semiautomated method. Statistical analysis aimed to identify relationships between loss of renal volume and loss of renal function and other patients' and surgical variables, particularly regarding lesion complexity (assessed by PADUA Score). RESULTS: Fifty-seven patients were analyzed. Both at univariate and multivariate analysis, the percentage of loss of renal function was significantly correlated to the loss of renal volume (P<0.001). Warm ischemia significantly correlated with the loss of renal volume (P=0.003). After stratification according to PADUA score categories, higher surgical complexity renal masses had stronger correlation between the loss of renal volume and the loss of renal function. CONCLUSIONS: The use of the semiautomated method for the 3D segmentation of the kidney to get the volumetric assessment could be a valid tool to support the future use of CT-scan as the tool to pair the oncological and the functional follow-up after PN.

Preliminary Human Radiation Dose Estimates of PET Renal Agents, Para-18F-Fluorohippuric Acid and Ortho-124I-Iodohippuric Acid from Rat Biodistribution Data.

BACKGROUND: Para-18F-fluorohippuric acid (18F-PFH) and ortho-124I-iodohippuric acid (124IOIH) were recently identified as potential radiotracers suitable for conducting renography using positron emission tomography (PET). The aim of this work was to estimate preliminary human-equivalent internal radiation dose of 18F-PFH and 124I-OIH using the biodistribution data reported in healthy rats. The results were compared with the absorbed dose data of technetium-99m-mercaptoacetyltriglycine (99mTc- MAG3) as documented in the International Commission on Radiological Protection (ICRP) publication 80. METHODS: The medical internal radiation dose (MIRD) formula was applied to extrapolate data from rats to human and to project the absorbed radiation dose for various organs in humans. S factor was calculated by Monte-Carlo N-particle (MCNP) simulation. RESULTS: Our dose prediction shows that an injection of 18F-PFH or 124I-OIH in humans would result in an estimated effective absorbed dose of 0.09 or 0.17 µSv/MBq respectively for whole body, which is about 135 or 73 times respectively lower than that obtained with an injection of 99mTc-MAG3. All organs except kidneys would receive an estimated effective absorbed dose of <0.1 µSv/MBq for 18F-PFH or 124I-OIH. Kidneys would receive a dose of 0.83 or 0.77 µSv/MBq respectively for 18F-PFH or 124I-OIH. CONCLUSIONS: Our results indicate that 18F-PFH and 124I-OIH would deliver much safer levels and lower radiation doses to the patients compared to 99mTc-MAG3 and warrants a clinical trial to estimate the radiation doses more accurately.

The assessment of renal cortex and parenchymal volume using automated CT volumetry for predicting renal function after donor nephrectomy.

BACKGROUND: Contrast-enhanced CT is necessary before donor nephrectomy and is usually combined with a Tc-99m-mercapto-acetyltriglycine (MAG3) scan to check split renal function (SRF). However, all transplant programs do not use MAG3 because of its high cost and exposure to radiation. We examined whether CT volumetry of the kidney can be a new tool for evaluating SRF. METHODS: Sixty-three patients underwent live donor nephrectomy. Patients without a 1.0 mm slice CT or follow-up for <12 months were excluded leaving 34 patients' data being analyzed. SRF was measured by MAG3. Split renal volume (SRV) was calculated automatically using volume analyzer software. The correlation between SRF and SRV was examined. The association between the donor's postoperative estimated glomerular filtration rate (eGFR) and predicted eGFR calculated by MAG3 or CT volumetry was analyzed at 1, 3, and 12 months post nephrectomy. RESULTS: Strong correlations were observed preoperatively in a Bland-Altman plot between SRF measured by MAG3 and either CT cortex or parenchymal volumetry. In addition, eGFR after donation correlated with SRF measured by MAG3 or CT volumetry. The correlation coefficients (R) for eGFR Mag3 split were 0.755, 0.615, and 0.763 at 1, 3 and 12 months, respectively. The corresponding R values for cortex volume split were 0.679, 0.638, and 0.747. Those for parenchymal volume split were 0.806, 0.592, and 0.764. CONCLUSION: Measuring kidney by CT volumetry is a cost-effective alternative to MAG3 for evaluating SRF and predicting postoperative donor renal function. Both cortex and parenchymal volumetry were similarly effective.

Assessment of the scatter correction procedures in single photon emission computed tomography imaging using simulation and clinical study.

BACKGROUND: Compton-scattered photons transfer incorrect spatial information. These photons are detected in used photo-peak energy window. In this study, three scatter correction procedures including dual-energy window (DEW), three energy window (TEW), and new approach were evaluated, and then the best procedure based on simulation and clinical conditions introduced. MATERIALS AND METHODS: In this study, simulation projections and three-dimensional nonuniform rational B-spline-based Cardiac-Torso phantoms were produced by GEANT4 application for emission tomography simulation code. For clinical study, 2-day stress/rest myocardial perfusion imaging (MPI) protocol was performed with 99m Tc-sestamibi for 46 patients. Image quality parameters including contrast, signal-to-noise ratio (SNR), and relative noise of the background (RNB) were evaluated. RESULTS: The simulation results showed that contrast values for DEW, TEW, and new approach were (0.45 ± 0.07, 0.5 ± 0.08, and 0.63 ± 0.09), SNR values (4.74 ± 0.94, 5.58 ± 1.08, and 6.56 ± 1.24), and RNB values (0.33 ± 0.06, 0.33 ± 0.07, and 0.33 ± 0.05), respectively. In clinical study, the contrast values for DEW, TEW, and new approach were 0.53 ± 0.03, 0.57 ± 0.07, and 0.62 ± 0.04 in rest MPI and were 0.52 ± 0.04, 0.57 ± 0.06, and 0.6 ± 0.05 in stress MPI, respectively. Moreover, for the rest images, the SNR values were 7.65 ± 1.9, 9.08 ± 2.2, and 10.2 ± 1.75 and for stress images were 7.76 ± 1.99, 9.12 ± 2.25, and 10.17 ± 2.04, respectively. Finally, RNB values for rest and stress images were 0.12 ± 0.03, 0.13 ± 0.03, and 0.13 ± 0.03, respectively. CONCLUSION: The simulation and the clinical studies showed that the new approach could be better performance than DEW, TEW methods, according to values of the contrast, and the SNR for scatter correction.

Cost-Savings Analysis of Renal Scintigraphy, Stratified by Renal Function Thresholds: Mercaptoacetyltriglycine Versus Diethylene Triamine Penta-Acetic Acid.

PURPOSE: To determine the financial implications of switching technetium (Tc)-99m mercaptoacetyltriglycine (MAG-3) to Tc-99m diethylene triamine penta-acetic acid (DTPA) at certain renal function thresholds before renal scintigraphy. METHODS: Institutional review board approval was obtained, and informed consent was waived for this HIPAA-compliant, retrospective, cohort study. Consecutive adult subjects (27 inpatients; 124 outpatients) who underwent MAG-3 renal scintigraphy, in the period from July 1, 2012 to June 30, 2013, were stratified retrospectively by hypothetical serum creatinine and estimated glomerular filtration rate (eGFR) thresholds, based on pre-procedure renal function. Thresholds were used to estimate the financial effects of using MAG-3 when renal function was at or worse than a given cutoff value, and DTPA otherwise. Cost analysis was performed with consideration of raw material and preparation costs, with radiotracer costs estimated by both vendor list pricing and proprietary institutional pricing. The primary outcome was a comparison of each hypothetical threshold to the clinical reality in which all subjects received MAG-3, and the results were supported by univariate sensitivity analysis. RESULTS: Annual cost savings by serum creatinine threshold were as follows (threshold given in mg/dL): $17,319 if ≥1.0; $33,015 if ≥1.5; and $35,180 if ≥2.0. Annual cost savings by eGFR threshold were as follows (threshold given in mL/min/1.73 m(2)): $21,649 if ≤60; $28,414 if ≤45; and $32,744 if ≤30. Cost-savings inflection points were approximately 1.25 mg/dL (serum creatinine) and 60 mL/min/1.73m(2) (eGFR). Secondary analysis by proprietary institutional pricing revealed similar trends, and cost savings of similar magnitude. Sensitivity analysis confirmed cost savings at all tested thresholds. CONCLUSIONS: Reserving MAG-3 utilization for patients who have impaired renal function can impart substantial annual cost savings to a radiology department.

The accuracy of quantitative parameters in (99m) Tc-MAG3 dynamic renography: a national audit based on virtual image data.

Assessment of image analysis methods and computer software used in (99m) Tc-MAG3 dynamic renography is important to ensure reliable study results and ultimately the best possible care for patients. In this work, we present a national multicentre study of the quantification accuracy in (99m) Tc-MAG3 renography, utilizing virtual dynamic scintigraphic data obtained by Monte Carlo-simulated scintillation camera imaging of digital phantoms with time-varying activity distributions. Three digital phantom studies were distributed to the participating departments, and quantitative evaluation was performed with standard clinical software according to local routines. The differential renal function (DRF) and time to maximum renal activity (Tmax ) were reported by 21 of the 28 Swedish departments performing (99m) Tc-MAG3 studies as of 2012. The reported DRF estimates showed a significantly lower precision for the phantom with impaired renal uptake than for the phantom with normal uptake. The Tmax estimates showed a similar trend, but the difference was only significant for the right kidney. There was a significant bias in the measured DRF for all phantoms caused by different positions of the left and right kidney in the anterior-posterior direction. In conclusion, this study shows that virtual scintigraphic studies are applicable for quality assurance and that there is a considerable uncertainty associated with standard quantitative parameters in dynamic (99m) Tc-MAG3 renography, especially for patients with impaired renal function.

Ipsilateral renal function preservation after robot-assisted partial nephrectomy (RAPN): an objective analysis using mercapto-acetyltriglycine (MAG3) renal scan data and volumetric assessment.

OBJECTIVE: To objectively assess ipsilateral renal function (IRF) preservation and factors influencing it after robot-assisted partial nephrectomy (RAPN). PATIENTS AND METHODS: Our database was queried to identify patients who had undergone RAPN from 2007 to 2013 and had complete pre- and postoperative mercapto-acetyltriglycine (MAG3) renal scan assessment. The estimated glomerular filtration rate (eGFR) for the operated kidney was calculated by multiplying the percentage of contribution from the renal scan by the total eGFR. IRF preservation was defined as a ratio of the postoperative eGFR for the operated kidney to the preoperative eGFR for the operated kidney. The percentage of total eGFR preservation was calculated in the same manner (postoperative eGFR/preoperative eGFR × 100). The amount of healthy rim of renal parenchyma removed was assessed by deducting the volume of tumour from the volume of the PN specimen assessed on pathology. Multivariable linear regression was used for analysis. RESULTS: In all, 99 patients were included in the analysis. The overall median (interquartile range) total eGFR preservation and IRF preservation for the operated kidney was 83.83 (75.2-94.1)% and 72 (60.3-81)%, respectively (P < 0.01). On multivariable analysis, volume of healthy rim of renal parenchyma removed, warm ischaemia time (WIT) > 30 min, body mass index (BMI) and operated kidney preoperative eGFR were predictive of IRF preservation. CONCLUSIONS: Using total eGFR tends to overestimate the degree of renal function preservation after RAPN. This is particularly relevant when studying factors affecting functional outcomes after nephron-sparing surgery. IRF may be a more precise assessment method in this setting. Operated kidney baseline renal function, BMI, WIT >30 min, and amount of resected healthy renal parenchyma represent the factors with a significant impact on the IRF preservation. RAPN provides significant preservation of renal function as shown by objective assessment criteria.

Renal ultrasound volume in children with primary vesicoureteral reflux allows functional assessment.

OBJECTIVE: Renal scintigraphy represents the current diagnostic standard to assess split kidney function. We tested the hypothesis that the relative renal volume assessed by ultrasound provides an equally reliable but less invasive tool for assessment of kidney function as compared to renal scintigraphy in patients with primary vesicoureteral reflux. METHODS: Renal ultrasound and renal scintigraphy were performed in 85 patients (median age 4.5 years, range 0.25-7.7) and repeated in 74 patients after 2-13 months (mean 7) of the primary investigation. Renal size was measured by ultrasound, and relative renal volume was calculated for each kidney by using the formula of a prolate ellipsoid. Renal function was estimated for each side (split renal function) by scintigraphy with (99m)Tc MAG3. RESULTS: The mean difference between relative renal volume measured by ultrasound and split renal function determined by renal scintigraphy was 2.8% (standard deviation ± 4.1%; 95% confidence interval 10.8/-5.2%). There was a statistically significant correlation between relative renal volume estimated by ultrasound and split renal function estimated by renal scintigraphy at first examination (r = 0.98; p < 0.001) and at follow-up (r = 0.91; p < 0.001). CONCLUSION: We conclude that ultrasound measurement of relative renal volume is capable of assessing split renal function in children with primary vesicoureteral reflux and, thus, should be considered instead of the more invasive MAG3 scintigraphy.

Dynamic (99m)Tc-MAG3 renography: images for quality control obtained by combining pharmacokinetic modelling, an anthropomorphic computer phantom and Monte Carlo simulated scintillation camera imaging.

In dynamic renal scintigraphy, the main interest is the radiopharmaceutical redistribution as a function of time. Quality control (QC) of renal procedures often relies on phantom experiments to compare image-based results with the measurement setup. A phantom with a realistic anatomy and time-varying activity distribution is therefore desirable. This work describes a pharmacokinetic (PK) compartment model for (99m)Tc-MAG3, used for defining a dynamic whole-body activity distribution within a digital phantom (XCAT) for accurate Monte Carlo (MC)-based images for QC. Each phantom structure is assigned a time-activity curve provided by the PK model, employing parameter values consistent with MAG3 pharmacokinetics. This approach ensures that the total amount of tracer in the phantom is preserved between time points, and it allows for modifications of the pharmacokinetics in a controlled fashion. By adjusting parameter values in the PK model, different clinically realistic scenarios can be mimicked, regarding, e.g., the relative renal uptake and renal transit time. Using the MC code SIMIND, a complete set of renography images including effects of photon attenuation, scattering, limited spatial resolution and noise, are simulated. The obtained image data can be used to evaluate quantitative techniques and computer software in clinical renography.

Assessment of renal function in mice with unilateral ureteral obstruction using 99mTc-MAG3 dynamic scintigraphy.

BACKGROUND: Renal scintigraphy using 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) is widely used for the assessment of renal function in humans. However, the application of this method to animal models of renal disease is currently limited, especially in rodents. Here, we have applied 99mTc-MAG3 renal scintigraphy to a mouse model of unilateral ureteral obstruction (UUO) and evaluated its utility in studying obstructive renal disease. METHODS: UUO mice were generated by complete ligation of the left ureter. Sham-operated mice were used as a control. Renal function was investigated on days 0, 1, 3, and 6 post-surgery using dynamic planar imaging of 99mTc-MAG3 activity following retro-orbital injection. Time-activity curves (TACs) were produced for individual kidneys and renal function was assessed by 1) the slope of initial 99mTc-MAG3 uptake (SIU), which is related to renal perfusion; 2) peak activity; and 3) the time-to-peak (TTP). The parameters of tubular excretion were not evaluated in this study as 99mTc-MAG3 is not excreted from UUO kidneys. RESULTS: Compared to sham-operated mice, SIU was remarkably (>60%) reduced in UUO kidneys at day 1 post surgery and the TACs plateaued, indicating that 99mTc-MAG3 is not excreted in these kidneys. The plateau activity in UUO kidneys was relatively low (~40% of sham kidney's peak activity) as early as day1 post surgery, demonstrating that uptake of 99mTc-MAG3 is rapidly reduced in UUO kidneys. The time to plateau in UUO kidneys exceeded 200 sec, suggesting that 99mTc-MAG3 is slowly up-taken in these kidneys. These changes advanced as the disease progressed. SIU, peak activity and TTPs were minimally changed in contra-lateral kidneys during the study period. CONCLUSIONS: Our data demonstrate that renal uptake of 99mTc-MAG3 is remarkably and rapidly reduced in UUO kidneys, while the changes are minimal in contra-lateral kidneys. The parametric analysis of TACs suggested that renal perfusion as well as tubular uptake is reduced in UUO kidneys. This imaging technique should allow non-invasive assessments of UUO renal injury and enable a more rapid interrogation of novel therapeutic agents and protocols.

Effect of warm ischemia on renal function during partial nephrectomy: assessment with new 99mTc-mercaptoacetyltriglycine scintigraphy parameter.

OBJECTIVE: A decrease in renal function after partial nephrectomy caused by ischemic damage or nephron loss cannot be distinguished by conventional methods. We quantified renal function using a new 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) renal scintigraphy parameter. MATERIAL AND METHODS: We included 32 patients with a normally functioning contralateral kidney who received open partial nephrectomy with average warm ischemic time of 26.0 (range 14-46) min in this study. Effective renal plasma flow (ERPF) was calculated from 99mTc-MAG3 renal scintigraphy before and at 1 week and 6 months after surgery. We also analyzed regional 99mTc-MAG3 uptake in the surgically nonaffected parts. RESULTS: One week after surgery, average ERPF in the operated kidney decreased to 66.4% from baseline (from 177.8 to 116.9 mL/min/1.73 m2) and regional 99mTc-MAG3 uptake decreased to 83.4%. A stronger correlation was found between ischemic time and the decrease in regional 99mTc-MAG3 uptake (P<.001) compared with ERPF (P=.029). The decrease in regional 99mTc-MAG3 uptake remained at 6 months in the group with ischemic time≥25 minutes, whereas it recovered when ischemic time was <25 minutes. CONCLUSION: This new parameter quantified ischemic renal damage better than the conventional split functional evaluation. When warm ischemic time was ≥25 minutes, irreversible diffuse damage was seen in surgically preserved nephrons.

[(99m)Tc-MAG3 diuretic renography in assessment of obstructive uropathy. The new test F+10SP: a step ahead in the differential diagnosis]. / Scintigrafia renale sequenziale con diuretico (99m)Tc-MAG3, nella valutazione della uropatia ostruttiva. La nuova procedura F+10SP: un passo avanti nella diagnosi differenziale.

BACKGROUND: Dilation of the renal pelvis is a problem Urologists have often to deal with. One of the key aspects is to clear if the dilation is the consequence of an obstruction to the outflow or a simple anatomic variant. Aim of this study was to compare two diuretic renographic procedures, F-15 vs the new procedure F+10SP (Seated Position) in a group of hydronephrotic patients, in order to increase the accuracy in the differential diagnosis between non-obstructive and obstructive dilation. MATERIALS AND METHODS: 34 Patients (14 male, 20 female, 18-71 yrs range), 27 pts having an unilateral hydronephrosis and 7 pts a bilateral hydronephrosis diagnosed by ultrasound, were enclosed in the study. They were subjected to two 99mTc-MAG3 diuretic renography with furosemide consecutively, with different modalities: 1) 40 mg of furosemide were administered IV to patient in supine position 15 minutes before tracer injection (Test F-15, by English); 2) the new procedure: 20 mg of furosemide were administered IV to patient in Seated Position (SP), 10 minutes after tracer injection during dynamic acquisition (Test F+10 SP). The average interval between the two tests was 7 days. Two different physicians analyzed all the tests. The results were classified as: non-obstruction (only F+10SP can distinguish between normal and dilated without obstruction), obstruction, equivocal and not applicable. RESULTS: Among the 68 renal units (RU) included in the analysis, the F+10SP test showed normal findings in 21 RU (30,8%), dilation without obstruction in 21 RU (30,8%), obstruction in 25 RU (36.8%) and equivocal result in 1 RU. The F-15 renography showed non-obstructive results in 35 RU (51.5%), obstruction in 20 RU (29.4%) and equivocal findings in 11 RU (16.1%); the test was not applicable in 2 RU (2.9%) due to insufficient renal function. Side effects reported for the F-15 renogram were hypotension in 1 patient, renal colic in 3 patients, bladder filling in 13 patients, disruption because of voiding in 4 patients. No complications were observed during or after the F+10SP renography. The 20 RU diagnosed with obstruction at the F-15 test were considered obstructed also at the F+10SP test. CONCLUSIONS: The "equivocal" test rate lowered from 16% for the F-15 test to less than 1.5% for the new F+10 SP test. The F+10SP procedure is easy, well tolerated, time saving and seems to be a more reliable tool in assessment of obstructive uropathy in adults.

Effects of radiofrequency ablation on individual renal function: assessment by technetium-99m mercaptoacetyltriglycine renal scintigraphy.

We quantitatively evaluated total and individual renal function by technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3) renal scintigraphy before and after radiofrequency ablation (RFA) of renal tumors. Eleven patients who underwent Tc-99m MAG3 renal scintigraphy 1 week before and after RFA were evaluated (7 men and 4 women; age range: 23-83 years; mean age: 60.6 years). Five patients had solitary kidneys, and five had normally or minimally functioning contralateral kidneys. One patient had a renal cell carcinoma in the contralateral kidney. One patient with a solitary kidney underwent RFA a second time for a residual tumor. In patients with a solitary kidney, MAG3 clearance decreased after 5 of 6 RFAs, and in patients with a normally functioning contralateral kidney, MAG3 clearance decreased after 4 of 5 RFAs, but no significant differences were observed between before and after treatments. In addition to the total MAG3 clearance, the split MAG3 clearance was evaluated in patients with a normally functioning contralateral kidney. MAG3 clearance decreased in 4 of 5 treated kidneys, while it adversely increased in the contralateral kidneys after 4 of 5 RFAs. No significant differences, however, were observed between before and after treatments. The results of our study revealed no significant differences in sCr, BUN, CCr, or MAG3 clearance between pre- and post-RFA values. These results support data regarding the functional impact and safety of renal RFA in published reports. We evaluated total and individual renal function quantitatively using Tc-99m MAG3 renal scintigraphy before and after treatment. This scintigraphy was very useful in assessing the effects of RFA on renal function.

Predicting postoperative renal insufficiency in patients undergoing nephrectomy for renal malignancy: assessment by renal scintigraphy using 99mtechnetium-mercaptoacetyltriglycine.

PURPOSE: We performed Tc-mercaptoacetyltriglycine (MAG3) renal scintigraphy in patients with renal malignancy to evaluate the function of each renal unit before and after nephrectomy to see if postoperative functional deterioration could be predicted based on scintigraphy results and creatinine clearance. MATERIALS AND METHODS: A total of 22 men and 13 women with renal malignancy, including 32 with renal cell carcinoma and 3 with urothelial cancer, were prospectively enrolled in this study. Average patient age was 64.3 years (median 65, range 43 to 88). All patients underwent MAG3 renal scintigraphy before and after unilateral nephrectomy. At the same time serum creatinine and endogenous creatinine clearance were determined. RESULTS: Mean serum creatinine was 0.93 mg/dl before and 1.31 after nephrectomy (p <0.0001). Preoperative endogenous creatinine clearance was 70.8 ml per minute per 1.73 m, which decreased to 49.0 ml per minute per 1.73 m after nephrectomy (p <0.0001). Mean MAG3 clearance of the remaining kidney increased 35.1% above baseline from 156.5 to 211.5 ml per minute per 1.73 m following nephrectomy. Spearman rank core analysis revealed that preoperative MAG3 clearance of the remaining kidney significantly correlated with postoperative creatinine clearance (r = 0.596, p = 0.0005). Preoperative MAG3 clearance of the remaining kidney more than 130 ml per minute per 1.73 m coincided with postoperative creatinine clearance above 40 ml per minute per 1.73 m. CONCLUSIONS: MAG3 renal scintigraphy may be useful for predicting renal insufficiency after nephrectomy. The findings in this study suggest that preoperative MAG3 clearance of the remaining kidney less than 130 ml per minute per 1.73 m is a risk factor for postoperative renal insufficiency.