Tc-99m Mercaptoacetyltriglycine Research Articles

The role of nuclear medicine techniques; Tc-99m-labeled dimercaptosuccinic acid, diethylenetriaminepentaacetic acid, and mercaptoacetyltriglycine scintigraphies in pediatric surgery

The purpose of this review is to highlight the pivotal role of nuclear medicine in pediatric surgery, specifically in the diagnosis and management of nephro-urological conditions. This review focuses on the applications and advantages of three key nuclear medicine techniques: Tc-99m dimercaptosuccinic acid (DMSA), Tc-99m diethylenetriaminepentaacetic acid (DTPA), and Tc-99m mercaptoacetyltriglycine (MAG3) scintigraphies. These imaging modalities are crucial for providing detailed anatomical and functional information with minimal invasiveness, essential for evaluating congenital anomalies, urinary tract infections, and obstructive uropathies in children. DMSA Scintigraphy is established as the gold standard for detecting renal cortical scarring and assessing functional renal parenchymal damage. It offers superior sensitivity and specificity compared to other imaging techniques, making it indispensable for identifying renal scars from recurrent urinary tract infections or pyelonephritis. DTPA Scintigraphy is critical for measuring glomerular filtration rate (GFR) and analyzing renogram curves, providing quantitative assessments of renal function. It effectively evaluates renal perfusion and identifies perfusion defects and renal ischemia, essential for managing conditions like renal artery stenosis and unilateral kidney disease. MAG3 Scintigraphy excels in dynamic renal scintigraphy, particularly in patients with impaired renal function. It provides high-quality images and superior diagnostic capability, making it invaluable for assessing ureteropelvic junction obstruction and other obstructive uropathies in pediatric patients. The review concludes by emphasizing the integration of these scintigraphy techniques with SPECT/CT, enhancing diagnostic accuracy and providing comprehensive anatomical and functional insights. Despite concerns regarding radiation exposure, measures such as dose optimization and advanced imaging techniques ensure safety and efficacy in pediatric applications.

Differential renal length index: useful measure in management of isolated unilateral hydronephrosis?

To explore the usefulness of the 'differential renal length index' (iDRL) before and after pyeloplasty, as the anteroposterior diameter is commonly used to quantify hydronephrosis but inaccuracies arise due to interobserver variability, hydration status and pure intra-renal dilatation. Prospectively collected data, from two centres, of all children undergoing pyeloplasty for isolated unilateral pelvi-ureteric junction obstruction (PUJO) (2015-2021) were analysed. Subgroup analysis was undertaken: Group A - differential renal function (DRF) ≥40%, Group B - subnormal DRF (20-39%), and Group C - symptomatic. Children with structural anomalies of upper and lower urinary tract, bilateral involvement, and subnormal DRF (<20%) were excluded. All the children had a pre- and postoperative ultrasound scan and Tc99m mercapto-acetyltriglycine (MAG3) renograms. The iDRL was calculated as follows: iDRL = ([a - b]/b) × 100, where 'a' is the length of hydronephrotic kidney (cm) and 'b' is the length of contralateral normal kidney (cm). The mean difference and standard error of mean (SEM) between the pre- and postoperative iDRL was evaluated using the paired Student's t-test, with P < 0.05 considered statistically significant. A total of 119 children with 1-year follow-up were included. For the entire cohort, the mean (SEM) preoperative iDRL was 27.7 (1.4) and postoperatively was 12.5 (1.1), with a mean (range) DRF improvement of 54% (44-66%) (P < 0.001). In Group A (n = 97), the mean (SEM) preoperative iDRL was 26.6 (1.5) and postoperatively was 13.1 (1.2), with a mean (range) DRF improvement of 50% (38-63%) (P < 0.001). In Group B (n = 22), the mean (SEM) preoperative iDRL was 32.6 (3.5) and postoperatively was 10.0 (2.8), with a mean (range) DRF improvement of 69% (49-89%) (P < 0.001). In Group C (n = 28), the mean (SEM) preoperative iDRL was 19.9 (2.3) and postoperatively was 7.7 (1.9), with a mean (range) DRF improvement of 61% (38-85%) (P < 0.001). Our study identifies the iDRL as a useful measure of improvement following successful pyeloplasty. In the subgroup with DRF of >39% minimum improvement was >37%. Similar minimum DRF improvement was also noted (>37%) in hypo-functioning kidneys and symptomatic PUJO.

Renal functional outcomes after robot-assisted partial nephrectomy and percutaneous cryoablation of clinical T1 renal cell carcinoma - A prospective study.

The objective of this study was to investigate renal function after robot-assisted partial nephrectomy (RAPN) and percutaneous cryoablation (PCA) in clinical stage T1 (cT1) renal cell carcinoma (RCC) and evaluate the relationship between baseline renal function and renal functional outcome. Patients with cT1 RCC treated with RAPN or PCA were prospectively enrolled between June 2019 and January 2021. Renal function was evaluated using estimated glomerular filtration rate, Tc-99m diethylenetriamine-pentaacetate plasma clearance, Tc-99m mercaptoacetyltriglycine renography, and renal volume at baseline and 6 months after treatment. Fifty-six patients were included (18 RAPN, 38 PCA). PCA patients had a significantly higher age (68.5 years; P = 0.019) and Charlson comorbidity index (3.0; P = 0.007). Tumor characteristics did not differ significantly between RAPN and PCA. Total renal volume decreased significantly after PCA (-18.2 cm3; P = 0.001). Baseline chronic disease stage IIIb-IV leads to a greater reduction in renal volume (-31.8 cm3; P = 0.003) but not other renal function measures. Renal function declined significantly after either treatment without significant differences between RAPN and PCA. This study found a small, similar decrease in renal function 6 months after RAPN or PCA, despite significant differences in baseline patient characteristics. Reduced renal function at baseline did not lead to a worse renal functional outcome.

Comparing the role of renal ultrasound vs MAG3 renal scans for evaluation of neurogenic bladder after spinal cord injury.

Compare ability of renal ultrasound and Tc-99m mercaptoacetyltriglycine (MAG3) renal scan to identify upper urinary tract stasis. Retrospective chart review. Outpatient Neuro-urology clinic serving a large SCI population. One hundred and sixty-five individuals with spinal cord injury, presenting for annual evaluation. Renal ultrasound, MAG3 renal scan. Radiologic evidence of upper urinary tract stasis as reviewed by independent radiologist. For renal ultrasounds, this included: mild hydronephrosis, dilation of collecting systems, pelviectasis, or caliectasis. For MAG3 renal scans, this included evidence of slow drainage of radioisotope, dilation of collecting systems, or reverse peristalsis. Forty-five individuals with spinal cord injury demonstrated upper tract stasis, with 12 identified by renal ultrasound and 43 identified by MAG3 renal scan. There was a strong relative correlation between test results (Yule's Q = 0.90), though MAG3 renal scan identified a significantly higher rate of upper tract stasis within the same patients (P < 0.0001). The odds ratio of improved identification using MAG3 renal scan was 16.5 (95% CI 3.96-68.76). While renal ultrasound is more effective at evaluating renal anatomy, MAG3 renal scan identifies significantly more upper urinary tract stasis than renal ultrasound and should be considered for SCI individuals with risk factors of upper tract injury.

Effect of Ursodeoxycholic Acid on the Biodistribution and Excretion of Technetium-99m Radiopharmaceuticals in Rat: A Potential Image Quality Enhancer.

PurposeThis study aimed to investigate the effect of ursodeoxycholic acid (UDCA) on the biodistribution and excretion of technetium-99m (Tc-99m)-labeled radiopharmaceuticals.Materials and MethodsTc-99m hydroxy-methylene-diphosphonate (HDP), Tc-99m pertechnetate, and Tc-99m dimercaptosuccinic acid (DMSA) were injected via the tail vein of rats. After 30 min, the control group was administered saline, and the UDCA group was given UDCA orally. Scintigraphy images were acquired after 30 min and 1, 2, 3, and 4 h. Radioactivity and rate of change were compared. Tc-99m mercaptoacetyltriglycine (MAG3) imaging was also performed.ResultsIn image analysis of Tc-99m HDP, radioactivity of the buttock was lower in the UDCA group at 4 h. Rates of change in the buttock were significantly different at 3 h–30 min and 4 h–30 min, and buttock radioactivity in the UDCA group had decreased more. In analysis of Tc-99m pertechnetate, radioactivity of the buttock was higher in the control group. Rates of change in the thyroid gland and buttock were different at 1 h–30 min, 3 h–30 min, and 4 h–30 min, with radioactivity in the UDCA group decreasing more. In the analysis of Tc-99m DMSA, while the radioactivity of the kidneys in the control group showed little decrease at 1 h–30 min, that in the UDCA group increased. In the analysis of Tc-99m MAG3 images, radioactivity and radioactivity/total body radioactivity (TBA) values for the kidneys were higher in the UDCA group at 2 min. At 5 and 10 min, radioactivity/TBA values for soft tissue in the UDCA group were lower than those in the control group.ConclusionThis study demonstrated that administration of UDCA increases renal excretion and soft tissue clearance of radiopharmaceuticals. This investigation could contribute to the broadening of applications of UDCA.

Interobserver reproducibility of mercaptoacetyltriglicine renography in children and adults with suspected obstruction: parameters of drainage and function calculated by International Atomic Energy Agency software.

The aim of this study was to estimate interobserver reproducibility of Tc-99m mercaptoacetyltriglycine renography in children and adults by assessing the parameters of the International Atomic Energy Agency (IAEA) software for the analysis of dynamic renal studies. The renograms of 65 children and 65 adults covered a wide age range, different quality of drainage, overall function and differential renal function (DRF). Three observers were processing parameters of the IAEA software. Normalized residual activity at 20 min (NORA20), NORA on the postmicturition acquisition (NORApm), PM to maximum renal count ratio (PM/max), output efficiency at 20 min (OE20), OE 20 min after diuretic stimulation (OEF + 20), whole kidney mean transit time (MTT) and DRF by integral and Rutland-Patlak were calculated by observers. The overall agreement between three observers was almost perfect [the average intraclass correlation coefficient (ICC) above 0.99] in children and adults, with no significant difference between the parameters of renal drainage, transit and DRF. ICCs for all parameters were higher than 0.980 in children under 12 months, even slightly greater for PM/max and OEF+20. In children with poor/incomplete drainage and DRF below 40%, ICCs were above 0.98. In the subgroup of adults with impaired overall tubular extraction rate, level of reproducibility was almost perfect. Slightly lower but still insignificant values of ICC were presented in adults with poor/incomplete drainage. Our results indicate an excellent interobserver reproducibility for all quantitative parameters of IAEA software in both pediatric and adult patients.

Retroperitoneal Approach for Ureteropelvic Junction Obstruction: Encouraging Preliminary Results With Robot-Assisted Laparoscopic Repair.

Introduction stating the aim of the study: Robot-assisted laparoscopic pyeloplasty (RALP) is gaining acceptance among pediatric urologists. Few studies have evaluated the retroperitoneal approach for RALP. We share our experience from the first 2 years of a multidisciplinary pediatric robotic program in our center.Patients (or Materials) and Methods: We performed a retrospective analysis of prospectively collected data of children undergoing RALP for ureteropelvic junction obstruction (n = 50). Diagnosis was confirmed by ultrasound and Tc-99m mercaptoacetyltriglycine renal scan or MRI; the same criteria were used to evaluate outcome. Surgical approach was chosen according to a specific algorithm. Transperitoneal approach (n = 13) was reserved for horseshoe kidney, ectopic kidney, and redo surgery. We analyzed the 37 cases performed by a lateral retroperitoneal approach. Dismembered pyeloplasty was done for all cases and anastomosis was performed using a running monofilament 6/0 absorbable suture. All were drained by double J stent. Patient data, operating room parameters and postoperative course were recorded.Results: The median age was 7.9 years (5.1–13.8); the youngest was 2 years old. The median weight was 23 kg (17–41) with the smallest weighing 12.4 kg. Aberrant crossing vessels were present in 18 children. Median set-up time, from skin incision until the end of the 4-port insertion, was 33 min (29–48). Median surgeon's console time was 151 min (136–182). No conversion to an open procedure was necessary. The postoperative course was free of complications, except urinary tract infection in 6 children. All but 4 patients were discharged on day one. Median follow-up was 9 months (5–13). Redo pyeloplasty was not required. Practical training of other colleagues was possible after 10 cases performed by the same surgeon.Conclusion: These preliminary results suggest that retroperitoneal RALP in children is feasible, safe and effective. It is an excellent option with ideal anatomical exposure. Longer term results as well as continued practice will identify and overcome any challenges and enable surgical mastery of this procedure which is still evolving.

Nuclear Imaging in Pediatric Kidney Diseases

Renal scintigraphy is a useful tool in diagnosis and management of various nephro-urological conditions. Tc-99m dimercaptosuccinic acid renal scintigraphy (Tc-99m-DMSA), Tc-99m mercaptoacetyltriglycine (Tc-99m-MAG3) or Tc-99m diethylenetriaminepentaacetic acid (Tc-99m-DTPA) dynamic renal scintigraphy, and Radionuclide micturating cystography are the common scans used in children with kidney diseases. These studies are minimally invasive, easily available, and offer both anatomic details and functional information required for thorough evaluation. At the same time, it is essential to have appropriate knowledge to interpret these studies and be aware of their limitations and pitfalls. The advent of Positron emission tomography-computed tomography/magnetic resonance imaging (PET-CT/MRI) has broadened the scope of nuclear medicine. This article focuses on the technique, interpretation, indication and recent practice guidelines of renal scintigraphy in children with kidney diseases.

Long-term Outcomes of Robot-assisted Laparoscopic Pyeloplasty for Ureteropelvic Junction Obstruction

To describe the long-term outcomes of robot-assisted laparoscopic pyeloplasty (RALP) for the correction of ureteropelvic junction (UPJ) obstruction. A retrospective electronic medical record review of RALPs from October 2002 to July 2014 was performed, with additional follow-up for patients released from regular urological care obtained by phone. RALP success was defined as resolution of symptoms of UPJ obstruction, improved hydronephrosis radiographically, or resolution of obstruction on follow-up Tc-99m mercaptoacetyltriglycine renal scan, intravenous pyelogram, or Whitaker test. RALP failure was defined as persistence of symptoms with obstruction demonstrated on functional imaging or requirement for a subsequent UPJ procedure. A total of 129 cases were identified, with an average patient age of 34.3 years. Stented RALP was performed in 80.6% of cases whereas 19.4% of patients underwent stentless RALP. A dismembered technique was performed in 90.7% of pyeloplasties, whereas 9.3% were nondismembered Fenger, Y-V, or flap pyeloplasties. Five intraoperative complications and 18 postoperative complications (Clavien I-IIIb) were described. One hundred twenty-nine patients received follow-up for a mean of 33.8 months (range 1-147 months). RALP was successful in 125/129 (96.9%), with an 8-year failure-free survival of 91.5%. When considering only stented pyeloplasties, the 8-year failure-free survival was 96.3%. RALP is a safe and effective minimally invasive method for correction of UPJ obstruction, resulting in lasting improvement in symptoms and resolution of obstruction for most patients.

Studies on Catalase-Like Activity of Some Tc-99m Radiopharmaceuticals

Studies on Catalase-Like Activity of Some Tc-99m Radiopharmaceuticals E. C ceka,∗ and B. Dede Faculty of Science and Art, Mehmet Akif Ersoy University, Burdur, Turkey Faculty of Science and Art, Suleyman Demirel University, Isparta, Turkey Hydrogen peroxide is an ubiquitous metabolite in living systems, produced at increased levels in a variety of pathological situations. Therefore suppressing or at least controlling H2O2 production is important. Catalase enzymes can convert hydrogen peroxide into water and dioxygen and a similar role can be played by transition metal ions or some radiopharmaceuticals. (1) TcO4 , (2) Tc-99m mercaptoacetyltriglycine (MAG3) and (3) Tc-99m methoxyisobutylisonitrile (MIBI) were each tested for their ability to catalyse the disproportionation of hydrogen peroxide in the presence of the added base imidazole. It was found that (2) and (3) exhibit acceptable catalase-like activity compared to the Tc-99m pertechnetate.

639 EVALUATION OF THE ISCHEMIC RENAL INJURY AFTER NEPHRON-SPARING SURGERY USING DYNAMIC RENAL SCINTIGRAPHY AND L-TYPE FATTY ACID BINDING PROTEIN

You have accessJournal of UrologyKidney Cancer: Evaluation & Staging (I)1 Apr 2013639 EVALUATION OF THE ISCHEMIC RENAL INJURY AFTER NEPHRON-SPARING SURGERY USING DYNAMIC RENAL SCINTIGRAPHY AND L-TYPE FATTY ACID BINDING PROTEIN Shun Takai, Tokunori Yamamoto, Yoshihisa Matsukawa, and Momokazu Gotoh Shun TakaiShun Takai Nagoya, Japan More articles by this author , Tokunori YamamotoTokunori Yamamoto Nagoya, Japan More articles by this author , Yoshihisa MatsukawaYoshihisa Matsukawa Nagoya, Japan More articles by this author , and Momokazu GotohMomokazu Gotoh Nagoya, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.191AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Renal scintigraphy is an established method to quantitatively assess split renal function. L-type fatty acid binding protein (L-FABP) is a novel urinary biomarker to reflect acute kidney injury and may play a role in predicting the extent of ischemic renal injury following nephron-sparing surgery. We evaluated the ischemic renal injury after nephron-sparing surgery using dynamic renal scintigraphy and urine level of L-FABP in treated kidney. METHODS We performed open and laparoscopic nephron-sparing surgery for 9 patients with small renal mass and inserted ureteral catheter to the treated renal pelvis. Ischemic renal injury of the treated kidney was evaluated by comparing effective renal plasma flow (ERPF) estimated by radionuclide technetium Tc 99m-mercaptoacetyltriglycine (99mTc-MAG-3) renal scintigraphy before and 1 week after the operation. We calculated a previously described variable called baseline weighted differential (b-WD) of ERPF that represent the percentage of loss of kidney function, considering the baseline value with b-WD of ERPF= (1 week Postoperative ERPF- baseline ERPF)/ baseline ERPF. Urine was obtained from the ureteral catheter 4 hours and 24 hours after de-clamping of the renal artery. We defined induction rate of L-FABP by dividing 24 hours level by 4 hours level. The correlation between b-WD of ERPF and induction rate of L-FABP obtained from the ureteral catheter was assessed. RESULTS There was a strong correlation between b-WD of ERPF and the logarithm of induction rate of L-FABP. CONCLUSIONS The results of the present study show that L-FABP is an effective urinary biomarker to predict the extent of ischemic renal injury following nephron-sparing surgery. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e261 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shun Takai Nagoya, Japan More articles by this author Tokunori Yamamoto Nagoya, Japan More articles by this author Yoshihisa Matsukawa Nagoya, Japan More articles by this author Momokazu Gotoh Nagoya, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Use of Early Postoperative MAG3 Renal Scan To Predict Long-Term Outcomes of Renal Transplants

A Tc-99m mercaptoacetyltriglycine renal scan has been used to evaluate perfusion and excretory function of renal allografts. A Tc-99m mercaptoacetyltriglycine renal scan has been reported to correlate with early allograft outcomes. This study was done to determine whether a Tc-99m mercaptoacetyltriglycine renal scan has any relation with long-term renal transplant outcomes. A total of 311 consecutive kidney transplant recipients were included in the study. All had Tc-99m mercaptoacetyltriglycine renal scans on posttransplant days 3 and 7. Patterns of the renography curve was graded as follows: 0=normal perfusion and excretion; 1=normal perfusion, reduced excretion; 2=normal perfusion, flat excretion; and 3=reduced perfusion and rising curve. Early postoperative Tc-99m mercaptoacetyltriglycine scintigraphy findings were correlated with serum creatinine values, acute rejection episodes, and long-term graft survival. A Tc-99m mercaptoacetyltriglycine renography of a deceased-donor kidney transplant showed a significantly higher grade on both days 3 and 7 than did live-donor kidney transplant (P < .001). Serum creatinine was positively correlated with the renography grades on days 3 and 7. The acute rejection rate was higher in the renography on days 3 and 7. Grade 2 renography on day 3 showed a significantly higher graft failure rate compared with the other grades (8.8% vs 8.6% vs 31.6% vs 7.3%; P = .014). Also, the renography showed the worst 5-year graft survival rate (95.9% vs 93.3% vs 89.5% vs 94.1%; P = .019). There were no differences in the graft failure rate or in graft survival rate according to the Tc-99m mercaptoacetyltriglycine renography grades on day 7. Our data show that a Tc-99m mercaptoacetyltriglycine renography grade correlate not only with early postoperative kidney function and incidence of acute rejection, but also with long-term outcomes of a renal allograft. A grade 2 renography pattern, with normal uptake and flat excretion, indicates a dismal prognosis for the long-term allograft survival.

Mercaptoacetyltriglycine renal scan for the differential diagnosis of acute tubular necrosis and interstitial nephritis associated to vancomycin

The differential diagnosis of vancomycin associated renal toxicity includes acute tubular necrosis and interstitial nephritis. We report a case of vancomycin induced renal toxicity shown by Tc-99m mercaptoacetyltriglycine renal scan. Nephrotoxicity was evolved secondary to vancomycin used for treating a patient with meningitis. Tc-99m mercaptoacetyltriglycine renal scan may play a role in differentiation between acute tubular necrosis and tubulointerstitial nephritis of vancomycin associated renal toxicity and can facilitate the clinical decision making.

Mercaptoacetyltriglycine renal scan for the differential diagnosis of acute tubular necrosis and interstitial nephritis associated to vancomycin

The differential diagnosis of vancomycin associated renal toxicity includes acute tubular necrosis and interstitial nephritis. We report a case of vancomycin induced renal toxicity shown by Tc-99m mercaptoacetyltriglycine renal scan. Nephrotoxicity was evolved secondary to vancomycin used for treating a patient with meningitis. Tc-99m mercaptoacetyltriglycine renal scan may play a role in differentiation between acute tubular necrosis and tubulointerstitial nephritis of vancomycin associated renal toxicity and can facilitate the clinical decision making.

Estimation of Tc-99m MAG3 Clearance Using Camera-Based Methods Without Blood Sampling

To establish camera-based methods for estimating Tc-99m mercaptoacetyltriglycine (MAG3) clearance without blood sampling. The results of renal scintigraphy with Tc-99m MAG3 obtained from 160 patients were analyzed retrospectively. Eight renogram parameters were calculated for each patient based on the area under the renogram (area method) and slope of the renogram (slope method) using different periods for analysis (1-2 and 1-2.5 minutes for the area method; 0.5-1.5 and 0.5-2 minutes for the slope method) and different backgrounds for subtraction (perirenal and subrenal backgrounds). The 8 parameters were then correlated with MAG3 clearance measured by the single-sample methods proposed by Russell et al and Bubeck et al to determine the equation for the conversion of renogram parameters to clearance. All 8 renogram parameters were highly correlated with clearance measured by the single-sample methods, and the obtained equations enabled the estimation of clearance from image data. Selection between the area and slope methods, between different periods for analysis, or between perirenal and subrenal backgrounds did not cause large differences in the estimation. The camera-based methods determined in the present study allow the estimation of MAG3 clearance with acceptable accuracy.

Is normalized residual activity a good marker of renal output efficiency?

Output efficiency (OE) and normalized residual activity (NORA) are two parameters that allow quantifying the renal drainage at any moment of renographic acquisition. Although OE is theoretically more accurate than NORA in case of a decreased overall renal function, both parameters present some weaknesses. To compare both parameters and to evaluate whether the clinical information provided by both parameters is identical. From a large database of Tc-99m mercaptoacetyltriglycine 3 renographic studies, 450 kidneys were selected covering a large range of ages, overall function, split function, and quality of drainage. NORA and OE were calculated at the end of the 20-min renogram, as well as on the late post erect postmicturition (PM) views. An inverse correlation was observed between NORA 20 and OE 20 (r=-0.926), as well as between NORA PM and OE PM (r=-0.936). Discrepancies were noted in approximately 10% of the kidneys, but main discrepancies, which would result in a different estimation of the quality of drainage, were only observed in 2% of the kidneys. There was no bias in the discordances; OE could reveal a better as well as a worse quality of drainage than NORA. It is likely therefore that imperfections of both parameters might be the cause of the divergences. The stratification of the kidneys according to age, overall renal function, split function, or quality of drainage did not modify the results. NORA, being much easier to program, can replace the output efficiency in the evaluation of renal drainage.

Evaluation of Hydronephrosis With Tubeless Cutaneous Ureterostomy Using Tc-99m MAG3 Diuretic Renography

To assess hydronephrosis of tubeless cutaneous ureterostomy using Tc-99m mercaptoacetyltriglycine (MAG3) diuretic renogram. Cutaneous ureterostomy with a unilateral stomal creation was performed in 15 patients (27 renal units) with a minimum follow-up period of 6 months. Stomal obstruction was evaluated with Tc-99m MAG3 diuretic renography 3 months after the surgery. The data analyses were performed with half-times to tracer clearance (T1/2) after furosemide (0.5 mg/kg) administration. T1/2 means were 7.27 +/- 7.11, 5.69 +/- 4.63, and 8.96 +/- 8.37 minutes for total, ipsilateral, and contralateral kidneys, respectively, in side relationships between ureter and stoma. There were no statistical differences among the groups. Six months after the surgery, of 26 renal units (96.3%) that had achieved a tubeless condition, and 25 renal units (92.6%) had no hydronephrosis. T1/2 was within 20 minutes in these 25 renal units, and of 25 renal units 23 (92%) revealed less than 15 minutes in T1/2, suggesting that the upper limit of T1/2 for nonobstructed systems after construction of a cutaneous ureterostomy might be 15 minutes. Mild hydronephrosis without the need for intervention was present in 1 renal unit (T1/2, 31.70 minutes). Catheterization was performed in one renal unit (T1/2, 21.04 minutes) due to acute pyelonephritis and persistence of grade 2 hydronephrosis 5 months after the surgery. Only these 2 renal units showed more than 20 minutes in T1/2, resulting in an obstructive pattern on diuretic renography. Tc-99m MAG3 diuretic renography with T1/2 assessment is useful to evaluate stomal stenosis in tubeless cutaneous ureterostomy.

Comparative Evaluation of Tc-99m Cystine and Tc-99m MAG3 in Normals and Patients With Renal Functional Impairment

Tc-99m cystine has been proved to be a good renal agent in animals for morphologic as well as the functional status of the kidney. In this study, we compared Tc-99m cystine with Tc-99m mercaptoacetyltriglycine, which is used for evaluation of renal function in normal patients, and those with various degrees of renal functional impairment. The clearance values and static images are compared with Tc-99m mercaptoacetyltriglycine. The results show that Tc-99m cystine has good radiopharmaceutical characteristics suitable for evaluation of both renal function as well as morphology.

Perinephric Urinoma Secondary to Perforated UPJ Obstruction Diagnosed Using Tc-99m Mercaptoacetyltriglycine (MAG3) SPECT/CT

Abstract: An 80-year-old woman presented with a history of right flank pain and tenderness. Her white cell count and C-reactive protein were elevated at 12.3 × 109/L and 108 mg/L respectively. An ultrasound scan of the abdomen showed moderate right sided hydronephrosis without ureteric dilatation and a collection at the lower pole of the kidney. An isotope renogram was performed using Tc-99m mercaptoacetyltriglycine (MAG3) to assess the presence of renal obstruction and to look for evidence of a urinary leak. Planar images revealed partial obstruction of the right kidney and unusual accumulation of tracer inferior to the kidney. SPECT/CT was performed to further evaluate the location of the abnormal tracer accumulation. Fused images demonstrated a posterior perirenal urinoma due to rupture of the collecting system. The patient underwent retrograde ureteric stenting and made an uneventful recovery.

Use of Classification and Regression Trees in Diuresis Renography

Decision support systems have the capacity to improve diagnostic performance and reduce physician errors. The purpose of this study was to evaluate the use of classification and regression trees (CART) with bootstrap aggregation as a decision support system in the baseline plus furosemide (F + 20) diuresis renography protocol to determine when obstruction can be excluded without the furosemide acquisition and to identify the key parameters for making this determination. Patients with suspected ureteral obstruction were randomly assigned to a training set (80 patients, 157 kidneys) and a validation set (64 patients, 124 kidneys). Forty quantitative parameters (curve parameters, MAG3 clearance and voiding indices) were generated from each baseline Tc-99m mercaptoacetyltriglycine (MAG3) scan. Three expert readers independently evaluated each kidney regarding the need for furosemide and resolved differences by majority vote. CART with bootstrap aggregation was applied to the training set to generate prediction algorithms which were tested in the validation set. The algorithm agreed with the expert decision on the necessity of furosemide in 90% (111 of 124 kidneys), with misclassification rates of 10.0% and 10.9% for the left and right kidneys, respectively. The most important discriminators were the postvoid-to-maximum count ratio, the cortical 20-minute-to-maximum count ratio, and the postvoid-to-1-to-2-minute count ratio. CART can identify the key parameters for discriminating between nonobstruction and possible obstruction, has the potential to serve as a decision support tool to avoid unnecessary furosemide imaging, and can be applied to more complex imaging problems.