99mTc-MAG3 diuresis renography in differentiating renal obstruction: Using statistical parameters as new quantifiable indices.

OBJECTIVE: The aim of this study was to research, develop and assess the feasibility of using basic statistical parameters derived from renogram, "mean count value (MeanCV) and "median count value (MedianCV)", as novel indices in the diagnosis of renal obstruction through diuresis renography. SUBJECTS AND METHODS: First, we re-digitalized and normalized 132 renograms from 74 patients in order to derive the MeanCV and MedianCV. To improve the performance of the parameters, we extrapolated renograms by a two-compartmental modeling. After that, the cutoff points for diagnosis using each modified parameter were set and the sensitivity and specificity were calculated in order to determine the best variants of MeanCV and MedianCV that could differentiate renal obstruction status into 3 distinct classes - i) unobstructed, ii) slightly obstructed, and iii) heavily obstructed. RESULTS: The modified MeanCV and MedianCV derived from extended renograms predicted the severity of the renal obstruction. The most appropriate variants of MeanCV and MedianCV were found to be the MeanCV50 and the MedianCV60. The cutoff points of MeanCV50 in separating unobstructed and obstructed classes as well as slightly and heavily obstructed classes were 0.50 and 0.72, respectively. The cutoff points of MedianCV60 in separating unobstructed and obstructed classes as well as slightly and heavily obstructed classes were 0.35 and 0.69, respectively. Notably, MeanCV50 and MedianCV60 were not significantly influenced by either age or gender. CONCLUSIONS: The MeanCV50 and the MedianCV60 derived from a renogram could be incorporated with other quantifiable parameters to form a system that could provide a highly accurate diagnosis of renal obstructions.

Time-Dependent Effects of Cryoablation for Renal Tumor on Overall and Split Renal Function.

PURPOSE: To evaluate the influence of percutaneous cryoablation for renal cell carcinoma on function of the affected kidney. MATERIALS AND METHODS: Between June 2016 and September 2017 at our institution, 12 inoperable patients underwent 15 cryoablation sessions for 17 small renal tumors. Of these, 9 patients who underwent 11 sessions of cryoablation were the focus of this study. For those patients, time-dependent changes in postoperative renal function were investigated by a retrospective review of clinical records. Evaluated were the estimated glomerular filtration rate (eGFR) and scintigraphy using 99m technetium-mercaptoacetyltriglycine (99mTc-MAG3) before and 1 week, 1-2 months, and more than 6 months after cryoablation. RESULTS: Mean baseline eGFR was 76.88 ± 29.82 mL/min/1.73 m2 (mean ± standard deviation; range, 23.4-112.5). Mean eGFR 1 week, 1-2 months, and more than 6 months after cryoablation were 74.56 ± 26.68 mL/min/1.73 m2 (21.0-101.1), 69.5 ± 25.28 mL/min/1.73 m2 (24.1-105.6), and 75.08 ± 26.25 mL/min/1.73 m2 (29.0-107.3), respectively. Changes were statistically insignificant (P = .6044, P = .6699, and P = .9038, respectively). Regarding split renal function, the mean baseline contribution of the affected kidney determined by 99mTc-MAG3 was 47.27% ± 6.14 (38.8%-57.0%). Mean contributions of the affected kidney 1 week after, 1-2 months after, and more than 6 months after cryoablation were 44.40% ± 5.37 (38.3%-53.6%), 44.57% ± 6.52 (34.35%-55.0%), and 45.41% ± 7.77 (34.4%-56.5%), respectively. Differences from baseline were significant for the earliest 2 periods (P = .0473 and P = .0334, respectively) but not the later period (P = .2532). CONCLUSIONS: Results suggested that total renal function does not worsen after cryoablation; however, function of the affected kidney worsened after cryoablation but later partially recovered.

Effect of Verapamil on Kidney Function Using Radionuclide Imaging.

BACKGROUND AND OBJECTIVE: Calcium channel blockers (CCBs) are among the most widely used prescribed drugs for the treatment of cardiovascular diseases. The present study investigates the effect of verapamil, which is most commonly used as a CCB, on kidney function using radionuclide imaging. METHODS: Ten New Zealand white rabbits were used in vitro (4) and in vivo (6) studies. Isometric tensions were recorded for isolated renal artery ring segments, while renographic studies were performed using Technetium-99m mercaptoacetyltriglycine and Gamma camera. Time to peak activity (Tmax) and time from peak to 50% activity (T1/2), were calculated from the renograms for control and treated rabbits with verapamil. RESULTS: In vitro, verapamil shifted the curve of phenylephrine concentration-dependent contraction on renal artery to the right, and decrease the highest contraction by 30 ± 3%. In vivo, the average values of Tmax for control and treated rabbits were 2.8 ± 0.1 and 2.2 ± 0.2 min respectively. The T1/2 for control and treated rabbits were 4.7 ± 0.05 and 4.2 ± 0.08 min respectively. The differences were statistically significant: p < 0.05. There is 30 ± 4% decrease in the 2 values. This indicates that there is a rapid renal uptake of the tracer and clearance of the radioactivity after verapamil. CONCLUSION: Verapamil dilates the renal artery and accelerates both the Tmax and T1/2 in the renogram. It increases renal blood perfusion and protects kidney function and therefore improves its work. However, verapamil should not be used while performing renograms to avoid misleading results.

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.

99mTc-MAG3: Image Wisely.

Purpose To determine if commonly administered doses of technetium 99m (99mTc) mertiatide (MAG3) in the range of 300-370 MBq (approximately 8-10 mCi) contribute to image interpretation and justify the resulting radiation exposure. Materials and Methods The respective institutional review boards approved this HIPAA-compliant study and waived informed consent. Baseline and furosemide 99mTc-MAG3 imaging examinations in 50 patients suspected of having renal obstruction and 48 patients suspected of having renovascular hypertension (RVH) were randomly selected from archived databases and were independently scored by three experienced readers without access to 2-second flow images. Readers were blinded to their original scores, and then they rescored each examination with access to high-activity 2-second flow images. Relative renal function was determined after a low activity (62.9 MBq ± 40.7) baseline acquisition for RVH and a high activity (303.4 MBq ± 48.1) acquisition after administration of enalaprilat. Data were analyzed by using random effects analysis of variance and mean and standard error of the mean for the difference between sets of scores and the difference between relative function measurements. Results There was no significant difference in the scores without flow images compared with blinded scores with high-activity flow images for patients suspected of having obstruction (P = .80) or RVH (P = .24). Moreover, there was no significant difference in the relative uptake measurements after administration of low and high activities (P > .99). Conclusion Administered doses of 99mTc-MAG3 in the range of 300-370 MBq (approximately 8-10 mCi) do not affect the relative function measurements or contribute to interpretation of images in patients suspected of having RVH or obstruction compared with administration of lower doses; unnecessary radiation exposure can be avoided by administering doses in the range of 37-185 MBq as recommended incurrent guidelines. © RSNA, 2017.

The role of dynamic renal scintigraphy on clinical decision making in hydronephrotic children.

Hydronephrosis may be related to an obstructive cause, ureteropelvic/uretero-vesical junction obstruction or nonobstructive [vesicoureteral reflux (VUR)]. When an obstructive pathology is considered, dynamic renal scintigraphy may help to predict whether it is a true obstruction or not. In this study, we aimed to determine the contribution of dynamic renal scintigraphy with [99] mTc-MAG-3 to the clinical decision-making for surgery in hydronephrotic children. Files of the patients evaluated by MAG-3 scintigraphy for antenatal (AH)/postnatal (PH) hydronephrosis between 1992 and 2014 were reviewed. Gender, age, hydronephrosis (HN) grade by ultrasound (US), presence of VUR, MAG-3 result (obstructive vs. nonobstructive), ultimate diagnosis, and need for surgery were assessed. Cases with double collecting system and neurogenic bladder were excluded from the study. All of the patients had normal serum creatinine and eGFR. There were a total of 178 patients with 218 hydronephrotic renal units (mean age 34.7 ± 52.7 months; male/ female = 121/57, AH of 62%). MAG-3 was nonobstructive in 134 and obstructive in 84 hydronephrotic renal units. MAG-3 was obstructive in 47 of 121 (39%) males and 30 of 57 (53%) females (P = 0.058, odds ratio (OR) for obstruction was 1.9 for girls). MAG-3 was obstructive in 47 of 135 (35%) units with AH and 37 of 83 (45%) units with PH (P = 0.137). In 81 units with the society of fetal urology-4 HN by US, MAG-3 was obstructive in 55 (68%), and surgery was required in 52 of 55 (95%). Surgery was required for only two (7%) of the remaining 26 units with nonobstructive dilatation (P <0.001, sensitivity 96%, specificity 89%, OR 208). Antero-posterior diameter >16.5 mm was the best cutoff level for predicting obstruction by MAG-3 (sensitivity 75.2%; specificity 71%; OR 3.8). MAG-3 significantly affects clinical decision for surgery in HN. Hydronephrotic girls have more risk in terms of true obstruction. Combining MAG-3 with US improves the discrimination of true obstruction during follow-up.

Preoperative urinary tract obstruction in scoliosis patients.

BACKGROUND: While the association between scoliosis and cardiac and respiratory function impairments has been well characterized in clinical practice and research, the potential effect of scoliosis on urinary tract structure and renal function has received little attention. Therefore, the purpose of this study was to evaluate the preoperative clinical characteristics of urinary tract structure and renal function in pediatric patients with idiopathic scoliosis, using a combination of blood tests, urinalysis, and imaging. METHODS: Preoperative measures of urinary tract structure and renal function were obtained for 16 patients, 13-17 years old, scheduled for corrective surgery for idiopathic scoliosis. Preoperative assessment included blood test and urinalysis, combined with structural imaging on ultrasound (US), magnetic resonance imaging (MRI), magnetic resonance urography (MRU), and radioisotope tracing (RI), using technetium-99 m mercaptoacetyltriglycine (99m Tc-MAG3). Differences in blood and urine tests between patients with and without urinary tract obstruction (UTO) were evaluated for significance using Mann-Whitney U test. RESULTS: For all 16 patients, blood tests and MRU were within normal limits. Dilatation of the renal pelvis was identified on US in eight patients (50.0%). UTO was identified on RI in six patients (37.5%). UTO was associated with elevated ß2-microglobulin concentration. Urinary ß2-microglobulin concentration >0.7 µg/mg Cr differentiated patients with UTO from those without UTO, with a sensitivity of 100% and specificity of 70%. CONCLUSIONS: ß2-Microglobulin concentration may be a useful marker to screen for asymptomatic UTO in patients with idiopathic scoliosis.

Measurement of Renal Depth in Dynamic Renal Scintigraphy Using Ultralow-Dose CT.

PURPOSE: Renal depths predicted using predefined formulas are commonly used for camera-based evaluation of renal function. We investigated the feasibility and utility of renal depth measurement using ultralow-dose CT images acquired in conjunction with dynamic renal scintigraphy. METHODS: Dynamic renal scintigraphy with Tc-MAG3 was performed in 117 patients (225 kidneys) using a SPECT/CT scanner, and ultralow-dose CT (estimated effective dose of 0.17 mSv) was performed during free breathing immediately before tracer injection. The clarity of the renal contour on the CT images was evaluated visually. The renal depths were measured by 2 methods and compared with depths predicted by 2 previously reported methods. The accuracy of camera-based clearance using predicted and measured depths was evaluated using a single-sample method as a standard. RESULTS: The clarity of the renal contour was poor in 18 of 225 kidneys, and 12 of 117 patients were considered ineligible for depth measurement. The measurement for eligible patients showed excellent intraobserver and interobserver repeatabilities. Although mean depths were similar among the 2 CT measurement methods and 2 prediction methods, absolute differences of more than 1 cm were observed in approximately 20% of kidneys between CT measurement and prediction. CT measurement of renal depth failed to improve the accuracy of camera-based clearance evaluation. CONCLUSION: Ultralow-dose CT allowed measurement of renal depth in most patients. Substantial differences in renal depth between prediction and CT measurement indicated potential usefulness of CT measurement, although no actual improvement in the accuracy of clearance estimation was demonstrated in this study.

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.

Pharmacokinetic alteration of (99m)Tc-MAG3 using serum protein binding displacement method.

INTRODUCTION: When a radiopharmaceutical is simultaneously administered with a medicine that has high affinity for the same plasma protein, the radiopharmaceutical is released at higher concentrations in blood, leading to enhanced transfer into target tissues. This is known as the serum protein binding displacement method. In this study, we investigated the pharmacokinetic alteration of technetium-99m-labeled mercaptoacetylglycylglycylglycine ((99m)Tc-MAG3) using the serum protein binding displacement method. METHODS: Rat and human serum protein binding rates of (99m)Tc-MAG3 were measured by ultrafiltration with or without displacers of human serum albumin (HSA) binding sites I and II (200µM and 400µM loading). Male Wistar rats were injected with (99m)Tc-MAG3 (740kBq/0.3mL saline) via the tail vein, and biodistribution was assessed at 2, 5, 10 and 15min. Dynamic whole-body images were obtained for (99m)Tc-MAG3 (11.1MBq/0.3mL saline)-injected rats, with or without HSA displacers. RESULTS: (99m)Tc-MAG3 strongly bound to HSA (87.37%±2.13%). Using HSA site I displacers, the free fraction of (99m)Tc-MAG3 increased significantly (1.20 to 1.47 times) when compared with controls. For biodistribution and imaging, rapid blood clearance was observed with bucolome (BCL) loading, which is an HSA site I displacer. With BCL loading, peak times for rat renograms were respectively shifted from 240s to 110s, and from 170s to 120s. CONCLUSIONS: We found that (99m)Tc-MAG3 bound to the HSA binding site I. It was confirmed that pharmacokinetic distribution of (99m)Tc-MAG3 is altered by presence of BCL, which leads to increases in the free fraction of (99m)Tc-MAG3, and BCL produced rapid blood clearance and fast peak times on rat renograms. The serum protein binding displacement method using (99m)Tc-MAG3 and BCL, a safe displacer for humans, may be applicable to clinical study and lead to better diagnostic images with shorter waiting times and lower radiation doses for patients.

Sonographic measurement of diuretic-induced renal length changes: are they correlated with renal function?

OBJECTIVES: The purposes of this study were to prospectively identify diuretic-induced renal length changes and to determine whether the percentages of the renal length changes allow estimation of the differential renal function. METHODS: Twenty-three children (14 boys and 9 girls; mean age, 7.83 years) who were undergoing technetium Tc 99m diethylenetriamine pentaacetic acid or technetium Tc 99m mercaptoacetyltriglycine diuretic renography were included in this study. Renal lengths were measured by sonography just before and 15 to 20 minutes after diuretic injection. The Spearman test was used to assess the correlation between renal length increases due to diuretic injection and the differential renal function. RESULTS: The mean renal lengths ± SD measured before and after diuretic administration were 91.52 ± 20.87 and 95.38 ± 21.46 mm, respectively. The increase in renal length after diuretic administration was statistically significant (P < .001). There was a positive correlation between the renal length change and functional status (P = .006). CONCLUSIONS: Renal length may change after diuretic injection according to the functional status, and the sonographic measurements of these changes may be used as an alternative to other imaging methods in estimation of renal function.

Reduction in radiation dose in mercaptoacetyltriglycerine renography with enhanced planar processing.

PURPOSE: To determine the minimum dose of technetium 99m ((99m)Tc) mercaptoacetyltriglycerine (MAG3) needed to perform dynamic renal scintigraphy in the pediatric population without loss of diagnostic quality or accurate quantification of renal function and to investigate whether adaptive noise reduction could help further reduce the minimum dose required. MATERIALS AND METHODS: Approval for this retrospective study was obtained from the institutional review board, with waiver of informed consent. A retrospective review was conducted in 33 pediatric patients consecutively referred for a (99m)Tc-MAG3 study. In each patient, a 20-minute dynamic study was performed after administration of 7.4 MBq/kg. Binomial subsampling was used to simulate studies performed with 50%, 30%, 20%, and 10% of the administered dose. Four nuclear medicine physicians independently reviewed the original and subsampled images, with and without noise reduction, for image quality. Two observers independently performed a quantitative analysis of renal function. Subjective rater confidence was analyzed by using a logistic regression model, and the quantitative analysis was performed by using the paired Student t test. RESULTS: Reducing the administered dose to 30% did not substantially affect image quality, with or without noise reduction. When the dose was reduced to 20%, there was a slight but significant decrease (P = .0074) in image quality, which resolved with noise reduction. Reducing the dose to 10% caused a decrease in image quality (P = .0003) that was not corrected with noise reduction. However, the dose could be reduced to 10% without a substantial change in the quantitative evaluation of renal function independent of the application of noise reduction. CONCLUSION: Decreasing the dose of (99m)Tc-MAG3 from 7.4 to 2.2 MBq/kg did not compromise image quality. With noise reduction, the dose can be reduced to 1.5 MBq/kg without subjective loss in image quality. The quantitative evaluation of renal function was not substantially altered, even with a theoretical dose as low as 0.74 MBq/kg.

[Validation of the renogram with immediate diuretic stimulus]. / Validación del renograma con estímulo diurético inmediato.

OBJECTIVE: The aim of this study is to determine the diagnostic reliability of the renogram with diuretic stimulus simultaneously at the administration of the dose, comparing two groups of 59 patients each one (F0 and F+10), to select patients for surgery. MATERIAL AND METHODS: This is an retrospective study about two groups of 59 patients to whom the diuretic renogram was carried out by stimulus (furosemide), by suspicion of ureteropelvic or vesicoureteral obstruction, using (99m)Tc-Mercaptoacetylglicine. In the first one, the study was conducted applying the diuretic stimulus 600 seconds after the administration of the dose of the radiotracer (F+10). In the second one it was carried out simultaneously to the administration (F0). For the interpretation there was used the visual analysis, the parameters of the curves and the percentage of elimination after modification by the severity and micturition. Statistical analysis of the information was made. RESULTS: The F+10 renogram shows a sensitivity of 96,7%, specificity of 96,1%, positive predictive value of 90,6%, and a negative predictive value of 98,6%. The F0 renogram shows a sensitivity of 95,2%, specificity of 98,9%, positive predictive value of 95,2%, and a negative predictive value of 98,9%. CONCLUSION: The performance of renogram by means of the administration of diuretic stimulus at the same time as the administration of the radiotracer is a useful and comfortable method in paediatric patients, not supposing a significant wastage in the parameters of efficiency of the test in the patients selection for surgery.

A renal protocol for all ages and all indications: mercapto-acetyl-triglycine (MAG3) with simultaneous injection of furosemide (MAG3-F0): a 17-year experience.

Current clinical requirements mandate the existence of a renal diuretic protocol, which is fast and easy, applicable in all ages and for all indications, convenient for both the patient and the technologist, and provides diagnostic as well as prognostic information. Seventeen years ago a 25-minute protocol, after oral hydration, with no bladder catheterization, and simultaneous injection of mercapto-acetyl-triglycine (MAG(3)) and furosemide (MAG(3)-F(0)), was initiated. It initially was used for the evaluation of drainage and emerged as a protocol to also evaluate the renal parenchyma. Results of this protocol have been published individually, per clinical application. MAG(3)-F(0) was instrumental in the evaluation and prognosis of congenital disorders. For obstruction, in the newborn, an increasing renogram mandates intervention, whereas a downsloping one predicts spontaneous resolution. In children or adults, preoperatively or postoperatively, when the cortex was visualized and drained normally, there was no obstruction, even if urine was retained within a dilated collecting system or an extrarenal pelvis. For diseases of the renal parenchyma, the protocol enabled the diagnosis of acute pyelonephritis (APN) revealing the "regional parenchymal dysfunction," diagnostic of APN. Diffuse parenchymal diseases were characterized by increased residual cortical activity (RCA), and their progression was manifested as a deterioration of RCA. End-stage renal disease was characterized by lack of accumulation and retention. Trauma and leaks were identified with specific patterns. In renovascular hypertension (RVH), an increase in RCA after angiotension-converting enzyme inhibitors is diagnostic of RVH and prognostic of the beneficial effect of angioplasty on hypertension. In renal colic, stratification was possible into (1) complete or severe obstruction requiring immediate intervention, (2) mild obstruction allowing waiting, (3) spontaneous decompression (stunned kidney), and (4) no recent obstruction. In transplants, it enabled differentiation of acute tubular necrosis, acute or chronic rejection and nephrotoxicity, and identified infarcts, RVH, leaks and obstruction. Finally, this method allows for a quick semiquantification of renal function. The clinical usefulness of the MAG(3)-F(0) protocol in most congenital or acquired renal problems is proven through long-term clinical experience and has resulted in a substantial utilization of the test at our Center.

Effectiveness and renal tolerance of multidetector helical CT with gadobutrol: results of a comparative porcine study.

PURPOSE: To prospectively evaluate the safety and effectiveness of high doses of 1 mol/L gadobutrol as a contrast agent for computed tomography (CT). MATERIALS AND METHODS: Experiments were performed according to guidelines for care of laboratory animals. The local animal care committee approved the study protocol. Unenhanced and contrast material-enhanced CT images of the chest and abdomen were obtained randomly in nine domestic pigs. Gadobutrol was injected (1, 2, or 3 mL per kilogram of body weight; three pigs for each dose). Attenuation was measured in different vascular and parenchymal structures. Changes in blood chemistry and hematologic parameters were monitored before and 1, 2, 3, and 7 days after gadobutrol administration. Urine samples were evaluated before and 7 days after gadobutrol administration. Technetium 99m mertiatide renal scintigraphy was performed before and 7 days after contrast medium injection. Animals were sacrificed 7 days after contrast medium administration, and one kidney was removed from each animal for examination with light microscopy. No serious adverse events occurred. A mixed-model nested analysis of variance was used for statistical evaluation. RESULTS: Mean attenuations for the 1, 2, and 3 mL/kg gadobutrol doses, respectively, were 148 HU +/- 20 (standard deviation), 282 HU +/- 18, and 289 HU +/- 20 in the thoracic aorta; 99 HU +/- 11, 166 HU +/- 9, and 153 HU +/- 18 in the kidneys; and 106 HU +/- 7, 186 HU +/- 18, and 224 HU +/- 24 in the inferior vena cava. No clinically relevant changes in hematologic, blood chemistry, or urine analysis results were detected. Markers for glomerular filtration and tubular function were unaffected in all groups. Scintigraphy revealed no differences between unenhanced and contrast-enhanced results. No morphologic changes of the renal parenchyma were found at histologic analysis. CONCLUSION: Contrast-enhanced CT with a 2 or 3 mmol/kg dose of 1 mol/L gadobutrol resulted in excellent vascular and parenchymal enhancement. A gadobutrol dose of up to 3 mL/kg did not affect renal function.

Preliminary evaluation of 99mTechnetium diethylenetriamine pentaacetic acid, 99mTechnetium dimercaptosuccinic acid, and 99mTechnetium mercaptoacetyltriglycine for renal scintigraphy in corn snakes (Elaphe guttata guttata).

The efficacy of three radiopharmaceuticals, 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA), 99mTc-dimercaptosuccinic acid (99mTc-DMSA), and 99mTc-mercaptoacetyltriglycine (99mTc-MAG3), for renal imaging was examined in 16 corn snakes (Elaphe guttata guttata). All snakes received the radiopharmaceutical via an intracardiac injection. The kidneys could not be visualized in the three snakes that received 99mTc-DTPA or in the three snakes that received 99mTc-DMSA, but were well delineated in all 10 snakes receiving 99mTc-MAG3. These snakes were anesthetized and a dynamic frame mode acquisition was obtained for 30 min immediately following injection. A 60 s single static frame mode image was then obtained with the snake in a curled position. Two of the 10 snakes that received 99mTc-MAG3 were removed from further analysis because of suspected pericardial injections. Of the remaining eight snakes, the mean (+/- SD) renal uptake was 25 +/- 9.8% or 24 +/- 9.7%, with or without correction for residual injection site activity, respectively. Correction for remaining radioactivity in the heart does not appear to be necessary if it is less than 10% of the total dose. 99mTc-MAG3 provided consistently high quality images of the kidneys and further studies are warranted to evaluate its sensitivity for detecting decreased function in snakes with renal disease.

Administered activity optimization in 99mTc-MAG3 renography for adults.

OBJECTIVE: The objective of this work was to determine the minimum administered activity of (99m)Tc-mercaptoacetyltriglycine (MAG3) needed both to estimate effective renal plasma flow (ERPF) with adequate precision and to obtain good image quality. METHODS: Three groups of 10 patients each were injected with 45, 71, or 132 MBq of MAG3. Renograms and perfusion and clearance images were obtained. The age, sex, and weight of the patients; the labeling yield; the mean count and counting rate 2 min after injection; the kidney-to-background and cortex-to-background ratios; the uptake time from the renograms; the percentage of the injected activity 2 min after injection in the left and right kidneys (A2(LK) and A2(RK), respectively); and the ERPF for both kidneys were obtained and analyzed. Discriminant analysis of image quality was used to select the variables that most affected image quality. The selected variables were studied among activity groups to optimize the amount of activity administered in these studies. RESULTS: Precision in ERPF assessment did not significantly differ among administered activity levels (P = 0.824). The SDs of the ERPF were +/-1.5 for 132 MBq, +/-1.7 for 71 MBq, and +/-2.0 for 45 MBq. The labeling yield, the ratios of counts in the left and right kidneys to the background and in the left and right cortices to the background, and A2(LK) and A2(RK) were the only variables that provided a significant discriminant function for image quality. The only variable that significantly differed with the variation in administered activity was the ratio of counts in the right kidney to the background (P = 0.026), most likely because of the labeling yield. CONCLUSION: A 45-MBq activity is sufficient to guarantee good image quality and adequate precision in ERPF determination from the time-activity curve, provided the labeling yield is kept high.

Comparison of 99mTc-mercaptoacetyltriglycine and [131I]-o-iodohippurate elimination in perfused rat kidney.

Renal elimination of two renal radiodiagnostic agents, (99m)Tc-mercaptoacetyltriglycine ((99m)Tc-MAG3) and [(131)I]-o-iodohippurate (OIH) has been studied using the method of the perfused rat kidney. The experiments showed significant differences between renal handling of (99m)Tc-MAG3 and OIH in the perfused rat kidney. While the renal clearance for (99m)Tc-MAG3 was relatively stable, the renal clearance values of OIH rapidly decreased after the OIH administration in a bolus dose. The infusion administration of OIH resulted in stable clearance values during the perfusion. The OIH/(99m)Tc-MAG3 renal clearance ratio was 2.47. Both compounds were bound to proteins in the perfusate to a considerable extent. An analysis of renal handling showed that contribution of tubular secretion to the total excretion was 95% for OIH, and 97% for (99m)Tc-MAG3.

The choice of timing for diuresis renography: the F + 0 method.

OBJECTIVE: To investigate a method of diuresis renography where the radiopharmaceutical and frusemide (diuretic) are given simultaneously, in contrast to conventional renography which involves an intravenous injection with frusemide 20 min after administering the radiopharmaceutical (F + 20) or 15 min before (F - 15), with particular interest in the effect of this change on assessing split renal function and interpreting upper tract drainage dynamics. PATIENTS AND METHODS: In a prospective study, 29 patients (18 women and 11 men, mean age 47 years, range 21--86) were assessed. Each patient had two renograms taken over a 48-h period, either by the F + 20 or F - 15, and the F + 0 method: Data for split renal function and drainage curves were obtained in the usual way. Two independent assessments of the drainage curves were obtained and the results compared. RESULTS: The split function assessments were identical (< 5% variation) in all but two patients; 26 of 29 (90%) gave identical conclusions about the drainage curves. The three patients with discrepancies between the studies had either hugely dilated upper tracts or otherwise had multiple complicating factors, e.g. impaired renal function, neuropathic bladder. CONCLUSIONS: F + 0 renography has been used in paediatric urological practice before, but there are no comparative studies and no data on its use in adults. This prospective study confirmed that in investigating dilated upper tracts, the F + 0 technique gives similar results to the conventional techniques. The F + 0 method has the potential to reduce the time required to undertake standard F + 20 renography but it may not be useful in evaluating the grossly dilated upper tract, where the F-15 technique has the best record in terms of reducing equivocal results.

Use of 99mTc-mercaptoacetyltriglycine to evaluate renal function in horses.

Ten healthy horses were injected intravenously with 99mTc-MAG3 and the disappearance of radioactivity from the blood was measured. The total body clearance (Cl(B)) and elimination half-life (t1/2(beta)) were 7.9 +/- 1.5 ml/kg/minute and 32.8 +/- 4.1 minutes, respectively. The disappearance of 99mTc-MAG3 from the blood of 2 horses with compromised renal function was also measured. The data suggest that 99mTc-MAG3 is a useful and clinically applicable radiopharmaceutical for measurement of effective renal blood flow in the horse.