Search

Abstract: 99m Tc-MAG3 diuresis renography is a noninvasive functional imaging technique used to assess clearance of radiotracer in a dilated urinary tract under high diuresis. It is commonly performed in patients to diagnose functionally significant urinary tract obstruction. In some pediatric patients, sedation is required to enable imaging. However, propofol, a commonly used IV sedative agent, is associated with altered renal hemodynamics. We report a case series of 3 pediatric patients at our institution who received propofol sedation to enable 99m Tc-MAG3 diuresis renography using a F+0 protocol, outlining that some "abnormal" studies were in fact assessed to be nondiagnostic., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

The dose to kidneys of newborns and 1-year old children was calculated using the MIRD methodology. In order to perform renal studies radiopharmaceutical like 99m Tc-DTPA, 99m Tc-MAG3 and 99m Tc-DMSA are used. Here, besides the anatomic and structure information of kidneys another data are provided in benefit of patient, however during the radioisotope decay emitted radiations delivers, totally or partially, their energy. Therefore is important to estimate the internal radiation dose of the organs. The largest dose to kidneys comes from the self-dose and it is due to the charged particles emitted during 99m Tc decay. From the three radiopharmaceutical here used the largest dose to kidneys is due to 99m Tc-DMSA, and the smaller dose is due to 99m Tc-MAG3., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objective: To determine the clinical value of visually assessed renal tissue transit time (TTT) in 99m Tc-mercaptoacetyltriglycine ( 99m Tc-MAG3) renography for patients undergoing pyeloplasty., Materials and Methods: Medical records of 164 patients who underwent dismembered pyeloplasty were retrospectively reviewed. Baseline and postoperative renal ultrasonography and 99m Tc-MAG3 renography were performed. Two urologists blinded to clinical data evaluated the renography and classified TTT as timely or delayed based on visualization of the tracer in the kidney pelvis between 2 and 10 minutes. Renal functional change after pyeloplasty was compared between patients in the timely and delayed groups., Results: A total of 126 patients (median age, 9 months) were evaluated after excluding patients with bilateral ureteropelvic junction obstruction, a single functioning kidney, duplicated ureter, or <3 months of follow-up. There were no differences between 89 patients with timely TTT and 37 patients with delayed TTT in mean preoperative hydronephrosis grade (3.7 vs 3.8) and pelvic diameter (3.1 cm vs 3.4 cm). Although the pre- and postoperative mean values of differential renal function (DRF) were significantly higher in the timely group than in the delayed group (47.2% vs 38.3% and 47.9% vs 44.6%), DRF change was greater in the delayed group (6.3% vs 0.6%). In multivariate analysis, delayed TTT was the only significant predictor of >5% improvement in renal function after pyeloplasty., Conclusion: Delayed TTT in 99m Tc-MAG3 renography was a significant predictor of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction. Because substantial improvement of renal function is anticipated, we recommend immediate pyeloplasty in patients with delayed TTT and decreased DRF., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: This study aims to evaluate interobserver agreement on visual analysis of technetium-99m mercaptoacetyltriglycine (Tc-MAG3) renal tissue transit used for the evaluation of antenatal hydronephrosis., Materials and Methods: Thirty-eight Tc-MAG3 diuretic renograms were retrospectively collected between 1 and 31 December 2015. The 1-min reframed images were presented to four nuclear medicine consultants and to two nuclear medicine residents, one in the first year of the training program and the others in their fourth and final year. These observers were asked to classify the radiotracer cortical transit (normal/delayed) based solely on visual assessment of the images. For the interobserver agreement, modified Fleiss' kappa (κ) analysis for multiple raters was carried out. For both groups, percentages of agreement were also calculated., Results: A total of 69 kidneys were evaluated. All four nuclear medicine consultants agreed on the classification of 88.4% of the kidneys. When the agreement of at least three of the four observers was considered, the percentage of agreement reached 98.6%. The two nuclear medicine residents agreed on the classification of 69.6% of the kidneys. The modified Fleiss' κ-value was 0.88 (95% confidence interval: 0.79-0.95) for the group of nuclear medicine consultants, indicating almost perfect agreement. For the residents, it was 0.39 (95% confidence interval: 0.16-0.59), suggesting fair agreement., Conclusion: Our results seem to indicate that there is an almost perfect agreement in the qualitative identification of delayed cortical transit among physicians with experience at observing renographic images.

Aim: The sulfonamide group is widely used for bacterial diseases including kidney and urinary tract infections. The present study investigates the effect of a sulfa drug on kidney function and renography studies by using a radionuclide., Methods: Renography studies were performed on New Zealand white rabbits. Each rabbit was injected with 48.1 MBq technetium-99m mercaptoacetyltriglycine ((99m) Tc-MAG-3). Dynamic images were acquired using a gamma camera. Radioactivity time curves were generated from the regions of interest, time to peak activity (Tmax ) and time from peak to 50% activity (T1/2 ). Each rabbit served as its own control. The sulfa drug was given to these rabbits for 7 days (i.v injection 130 mg/kg daily in two divided doses; i.e. the single dose is 65 mg/kg), then dynamic images were acquired., Results: Treatment with sulfa shifted the experimental curves to the right of the control curves. This result showed that there was a delayed renal uptake of (99m) Tc-MAG-3 and its clearance. Calculated averages of Tmax were 2.2 ± 0.3 and 5.9 ± 0.5 min; while for T1/2 were 3.1 ± 0.3 and 8.4 ± 0.6 min for control and sulfa-treated rabbits, respectively (n = 20; P < 0.05)., Conclusion: Our results indicate that sulfa drug induced pharmacokinetic changes because of delaying both the Tmax and T1/2 . Sulfa drug has an effect on the reabsorption from the renal tubules and the excretion process of (99m) Tc-MAG-3 which is excreted almost exclusively by the renal tubules. Therefore, sulfa drug causes a deterioration in kidney function and an alteration on radionuclide renography., (© 2014 Asian Pacific Society of Nephrology.)

Several single sample methods for determination of (99m)Tc-mercaptoacetyltriglycine (MAG3) clearance are being used clinically. Kabasakal et al. proposed a similar formula for (99m)Tc-ethylenedicysteine (EC). This study was performed to compare his method with Bubeck et al. formula for (99m)Tc-MAG3 already in use. Twenty-eight subjects divided in two groups were registered which included 22 patients with various renal diseases (group-I) and six normal volunteers (group II). All subjects were studied twice using both the radiopharmaceuticals. The images and renogram parameters, that is TMAX and T1/2 of both the agents, were similar in all the subjects. The clearance of the (99m)Tc-EC was however considerably higher than (99m)Tc-MAG3 in both the groups (mean ± SEM =279 ± 14 ml min(-1)/1.73 m(2) versus 177 ± 15 ml min(-1)/1.73 m(2) in group-I and 377 ± 11.90 ml min(-1)/1.73 m(2) versus 238 ± 8.23 ml min(-1)/1.73 m(2) in group II). This difference was more pronounced in cases with reduced renal functions. Among the Effective Renal Plasma Flow (ERPF) values determined from EC and MAG3 clearances in six normal volunteers, four cases only in MAG3 had ERPF below the lower limit. This study has demonstrated superiority of single sample method for (99 m)Tc-EC clearance over its analogous method for (99m)Tc-MAG3., (© 2013 The Authors Clinical Physiology and Functional Imaging © 2013 Scandinavian Society of Clinical Physiology and Nuclear Medicine.)

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.

Purpose: To establish camera-based methods for estimating Tc-99m mercaptoacetyltriglycine (MAG3) clearance without blood sampling., Materials and Methods: 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., Results: 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., Conclusion: The camera-based methods determined in the present study allow the estimation of MAG3 clearance with acceptable accuracy.

A 25-y-old man with horseshoe kidney was referred for diuretic-augmented renal scintigraphy. Single-detector dynamic posterior imaging was performed and revealed asymmetric retention of radiotracer in the left collecting system. Renal scintigraphy was repeated with a modified protocol. Dynamic imaging was performed this time using dual-detector acquisition of both anterior and posterior data. Thereafter, pregravity and subsequently postgravity static images were obtained in both anterior and posterior projections. This second study showed near-complete emptying of the left collecting system. This case illustrates the utility of using simultaneous anterior and posterior imaging and geometric mean calculations for functional analysis and also highlights the value of physiologic maneuvers to augment the traditional diuretic challenge.

Objective: Specific quantitative measurements have been recommended to assist in the interpretation of technetium-99m mercaptoacetyltriglycine (MAG3) renal studies. Our objective was to define the sex- and age-specific normal ranges for these recommended parameters., Materials and Methods: Data were obtained from a retrospective analysis of 106 subjects who were evaluated for kidney donation. The MAG3 clearance was calculated using a common camera-based method. The relative uptake, prevoid/postvoid and postvoid/maximum count ratios were determined using whole-kidney regions of interest (ROIs). Time to peak, time to half-peak, 20 min/maximum and 20 min/2-3 min count ratios were determined for cortical and whole-kidney ROIs. Residual urine volume was calculated on the basis of the pre- and postvoid bladder counts and voided urine volume., Results: The mean camera-based MAG3 clearance was 321 +/- 69 mL/min/1.73 m2, essentially the same as the mean plasma sample MAG3 clearance in comparable populations. The percentages of relative uptake in the right and left kidneys were 49% and 51% +/- 4%, respectively; no difference was seen between men and women. Cortical values were lower than the whole-kidney values (p < 0.001); the mean cortical 20 min/maximum count ratio was 0.19 (SD, 0.07 and 0.04 for right and left kidneys, respectively). The mean postvoid/maximum whole-kidney count ratio was < 0.1, and the mean postvoid residual bladder volume was < 30 mL., Conclusion: Normal limits adjusted for age and sex have been established. Applying normal ranges to quantitative MAG3 parameters may assist in the interpretation of MAG3 scintigraphy and facilitate appropriate patient management.

Rationale and Objectives: The purpose of this study was to evaluate the influence of hydration status upon renogram patterns and renal physiological parameters and clarify the differences between DTPA and MAG3 studies in normal volunteers., Material and Methods: The study populations were 22 kidneys of 11 volunteers with no history of hypertension or renal disease with normal serum creatinine levels. They were 6 men and 5 women aged from 24 to 48 yrs (mean age: 33.4 yrs). Renal scintigraphies with both 185 MBq (5 mCi) of Tc-99m DTPA and Tc-99m MAG3 were performed after dehydration (urine specific gravity > 1.025) and adequate hydration (urine specific gravity < 1.010) in each subject at least with a 5-7-day interval. Renograms were generated from the whole kidney and cortical ROIs. We analyzed the clearance, renogram pattern, mean transit time, time to maximum activity, time from maximum activity to half activity, and residual cortical activity. Paired t-test and Wilcoxon signed rank test were used as statistical analysis methods. Statistical analysis was considered significant at p < 0.05., Results: In the dehydrated state, with Tc-99m DTPA and whole kidney ROI, parameters such as time to maximum activity, time from maximum activity to half activity, residual cortical activity, and mean transit time were delayed as compared to parameters in the adequately hydrated state, but the clearance was not changed. With the cortical ROI, the changes of parameters due to dehydration were partially offset. There were insignificant differences between most parameters of Tc-99m DTPA and Tc-99m MAG3 with the whole kidney and cortical ROIs., Conclusions: Dehydration may bring about a false positive curve pattern on renograms which can be prevented or minimized by using the cortical ROI. There were insignificant differences between most parameters of Tc-99m DTPA and Tc-99m MAG3.

Introduction: It has been suggested that renal retention function can be estimated by differentiation of the Patlak-Rutland plot., Aim: To evaluate the error resulting from this method., Methods: A total of 5800 renograms were generated by convolving real input functions with artificial retention functions. Ten bi-exponential plasma disappearance curves of Tc mercaptoacetyltriglycine (Tc-MAG3) with varying renal clearances served as input functions and 580 retention functions with mean transit time between 3 and 60 min, and variable ratios of minimal to mean transit time served as original retention functions. The retention function was estimated by differentiation of the Patlak-Rutland plot of each renogram. A variant of this retention function was calculated by setting negative values to zero., Results: Minimal transit time was estimated correctly in all cases but the recovered retention function systematically underestimated the original, and negative values were observed. Mean transit time was underestimated with a difference ranging from -22.05 to -0.06 min. By setting the negative values to zero, a less important underestimation was observed which ranged from -13.37 to 0.00 min. Maximal transit time was underestimated systematically with a difference ranging from -22.05 to 0.00 min. All differences were influenced by mean transit time, renal clearance and ratio of minimal to mean transit time., Conclusion: Estimation of the renal retention function by differentiation of the Patlak-Rutland plot results in systematic and sometimes important underestimations. By setting the negative values of the recovered retention function equal to zero, important but still partial improvement can be obtained.

Unlabelled: One of the potential limitations in the usefulness of both renal output efficiency (ROE) and normalized residual activity (NORA) is their residual dependence on total renal function. The purpose of this study was to present and examine a new quantitative method whereby the effects of this dependence may be removed., Methods: The analytic method involves the determination of a retention function using an unconstrained matrix algorithm deconvolution technique followed by reconvolution with a chosen standard input function to yield a new secondary renal activity time (A/T) curve from which normalized values of ROE and NORA, denoted as N&#95;ROE and N&#95;NORA, respectively, can then be obtained using conventional definitions. The method has been applied in a series of 50 patient studies, which had been acquired using (99m)Tc-mercaptoacetyltriglycine (99(m)Tc-MAG3) and a standard F+18 furosemide protocol, with values of the ratio of plasma clearance to plasma volume (C/V) in the range 0.013-0.242 min(-1)., Results: Pre- and postnormalization values of NORA, calculated at 30 min after injection, showed a significant difference in mean values (paired t test; P < 0.001), with a maximum observed difference, DeltaNORA(30), of -4.82 (-482%) and with a SD on the paired differences, DeltaNORA(30), of 0.56 (56%) or 0.63 (63%) if background subtraction on the input function (BSIF) had been performed. In contrast, corresponding values of ROE showed a nonsignificant difference in means (P > 0.05) and a SD on the paired differences, DeltaROE(30), of 3.7% or 3.2% with and without BSIF, respectively. The normalized parameters N&#95;ROE and N&#95;NORA were found to be strongly linearly correlated (r = -0.99; P < 0.001), in agreement with theoretical predictions., Conclusion: These results suggest that renal function affects NORA significantly more than ROE. The effects can be corrected by our normalization technique, resulting in equivalent values of normalized ROE and normalized NORA.

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.

The aim of this study was to evaluate Rutland's method for the recovery of renal retention function without deconvolution. Renograms (n=5800) were generated by convolving 10 real input functions with 580 artificially created retention functions. Their ratios of minimal to mean transit time ranged from 0.1 to 1.0, and for mean transit time ranged from 3 to 60 min. The retention function was recovered from each renogram and its associated input function by calculating the first derivative of the residence time of the tracer in the kidney. Minimal, mean, and maximal transit time of the recovered retention function were calculated and compared with the original values. Qualitatively, the recovered retention function differed little from the original one. Quantitatively, values for recovered minimal transit time equalled original minimal transit time in all cases, whilst recovered mean transit time and maximal transit time equalled, respectively, the original mean transit time and maximal transit time if the original minimal to mean transit time ratio equalled 1. If this ratio was less than 1, recovered mean transit time was higher than original mean transit time and recovered maximal transit time was lower than original maximal transit time. For values of mean and maximal transit time, the differences from the original value increased with increasing original mean and maximal transit time, respectively, and with increasing renal clearance and decreasing minimal to mean transit time ratio. It is confirmed that Rutland's method is a particularly interesting alternative to deconvolution analysis. The errors that occur when recovering the retention function are relatively small.

The dimethyl ester of diethylene triamine penta-acetic acid (DMDTPA) (I) can be easily and efficiently labelled with 99mTc. This method can be readily adapted for kit formulations to produce a highly stable and very pure chelate, as shown by paper electrophoresis and reverse-phase high performance liquid chromatography experiments. In mice, this chelate was excreted unchanged in the urine, and the amount of renal excretion was much higher than that of 99mTc-DTPA and comparable with that of 99mTc-mercaptoacetyl triglycine (99mTc-MAG(3)) at two different time points. The renal excretion of co-injected 131I-ortho-iodohippurate (131I-OIH), however, was significantly greater than that of the 99mTc chelates. The renal clearance values of 99mTc-DMDTPA and 99mTc-MAG(3) were also similar and exceeded the corresponding value for 99mTc-DTPA, but were only half that of the 131I-OIH value in the rat. The renograms for 99mTc-DMDTPA and 99mTc-MAG(3) showed overall similarity in a dog model. The diethyl ester (III) and monoethyl ester (II) of DTPA, after labelling with 99mTc, produced the same chelate, as shown by analytical results and biological data, indicating that one of the ester groups in the DTPA diester is dealkylated during the chelation procedure. To confirm this, two more ligands, diethylene triamine 1,4,7,7-tetra-acetic acid (IV) and diethylene triamine 1,4,7-triacetic acid (V), were synthesized, resembling DTPA monoalkyl ester (II) and dialkyl ester (I, III), respectively, in the arrangement of the donor atoms. Ligand IV but not ligand V, on 99mTc chelation, can generate the specific pharmacophore for renal tubular transport that is also present in the ester chelates 99mTc-I, 99mTc-II and 99mTc-III, as shown by their decreased renal excretion in mice pretreated with a renal tubular transport inhibitor such as probenecid.

Objective: Since the approval of mercaptoacetyltriglycine (MAG3) for routine clinical use, reports have appeared about hepatobiliary excretion deleteriously affecting available diagnostic and quantitative information. The purpose of this study was to evaluate gallbladder (GB) uptake of MAG3 in the clinical setting and its effect on the evaluation of relative renal function and imaging., Methods: Sixty patients with varying degrees of renal impairment were studied. Routine renal function imaging was followed with anterior and right lateral 3-min abdominal images. Factors such as photolytic degradation, reconstitution steps, (99m)Tc O(4) solution, age, and concentration are discussed. In addition, patient fasting state and radiochemical purity are evaluated. The GB uptake was determined as a percentage of the injected dose., Results: The MAG3 quality control ranged from 90.9% to 99.0%. The GB uptake ranged from 0.0% (not visualized) to 0.71%. The effective renal plasma flow ranged from 88 to 743 mL/min. There was no correlation between the QC and the percentage of GB uptake (r = 0.12). The majority of patients in the nonfasting state showed minimal or reduced GB uptake when compared with the majority of patients in the fasting state., Conclusion: Our data suggest that GB uptake of MAG3 is minimal, with no adverse effects on the diagnostic and quantitative analysis of renal function.

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., (Copyright 2002 Elsevier Science Inc.)

We compared single-sample methods, proposed by Russell et al. and Bubeck et al., and camera-based methods in calculating 99mTc-MAG3 clearance, and determined camera-based methods that provide estimates comparable to those measured by the Russell method. Twenty-one patients underwent 99mTc-MAG3 renal scintigraphy, and clearance was measured by the Russell method and Bubeck method. Various renogram parameters were determined based on the slope of the renogram and area under the renogram, and correlated with the clearance measured by the Russell method. Camera-based clearance was calculated with the obtained regression equations and with equations determined previously using the Bubeck method as a standard. The Bubeck method provided lower measures than the Russell method in high renal function. Clearance measured by the Russell method was well correlated with renogram parameters, and clearance calculated with the obtained regression equation was comparable to that measured by the Russell method. When camera-based clearance was predicted with the previous equation, it was lower than the result obtained by the Russell method in high function. In conclusion, there are systematic differences in 99mTc-MAG3 clearance calculated by different methods. The camera-based methods obtained in this study appear to facilitate comparison of results obtained by the Russell method and camera-based method.

Unlabelled: Preliminary data suggest that aspirin renography is more sensitive than captopril renography for indicating renal artery stenosis (RAS). Considering that aspirin, compared with captopril, reduces renal blood flow and, thus, tubular tracer delivery in poststenotic kidneys, aspirin renography is expected to be more useful, particularly if tubular tracers are used., Methods: We prospectively compared aspirin renography (20 mg/kg orally) and captopril renography (25 mg orally) with 99mTc-mercaptoacetyltriglycine in 75 consecutive patients suspected of having RAS., Results: RAS, diagnosed as stenosis of more than 50% on angiography, was found unilaterally in 34 patients and bilaterally in 17 patients. RAS was absent in 24 patients. The sensitivities for unilateral RAS or bilateral RAS (i.e., stenosis that was at least unilateral) were, respectively, 88% and 88% for captopril renography and 82% and 94% for aspirin renography (not significant). The overall specificity was 75% for captopril renography and 83% for aspirin renography (not significant). Tracer uptake ratios, time to peak activity, and percentage of 20-min tracer retention were also not significantly different for captopril and aspirin renography. Subgroup analysis of modest (50-75%) and severe (> or =75%) RAS, or of plasma creatinine greater than 120 micromol/L, also showed no difference between captopril and aspirin renography., Conclusion: We conclude that for identification of RAS, the usefulness of aspirin renography equals, but does not surpass, that of captopril renography.

Unlabelled: Angiotensin-converting enzyme inhibition by captopril decreases renal (131)I-o-iodohippurate sodium or iothalamate extraction in patients with renal artery stenosis (RAS). This study investigated the effect of captopril on another renal radiopharmaceutical, (99m)Tc-mercaptoacetyltriglycine (MAG3), in particular its plasma clearance., Methods: Three groups of patients were studied. Group I contained 22 patients with hypertension but a low likelihood of RAS according to negative captopril renography results, confirmed by angiography in 5. Group II contained 22 hypertensive patients with RAS documented by angiography and positive captopril and plasma renin response. Group III contained 10 patients after successful percutaneous transluminal renal angioplasty (PTRA) with negative captopril renography results. The 60-min, single-sample technique was used for measurement of the plasma clearance of MAG3 during baseline and captopril renography., Results: In 18 of 22 group I patients, clearance increased (P < 0.01) during captopril renography compared with baseline conditions, whereas in 18 of 22 group II patients, clearance decreased (P< 0.01). In group III patients, clearance was not significantly altered. The clearance decrease in group II did not correlate with the blood pressure decrease or plasma renin activity increase during captopril renography., Conclusion: Renal function assessed by MAG3 plasma clearance decreases in hypertensive patients with RAS but increases in patients without RAS. MAG3 clearance measurements during baseline and captopril renography can thus serve as additional diagnostic information when investigating patients with hypertension for the possibility of an RAS.

Unlabelled: In patients with ischemic cardiomyopathy (CM), abnormal renograms may result not only from circulatory failure (which should reverse after transplantation) but also from intrinsic renal disease (which contraindicates heart transplantation). Here, the outcome of heart transplantation was related to preoperative renograms, and the differentiating and prognostic value of renography was analyzed., Methods: The study population consisted of 50 patients with ischemic CM expecting heart transplantation. Anatomical renal pathology was excluded in all patients. Dynamic renal scintigraphy was performed with 99mTc-mercaptoacetyltriglycine. Background-subtracted renograms were inspected visually and characterized numerically. Mean parenchymal transit time (mPTT), renal tracer content at 15 min (RTC15) and retention index (RI) were determined. The parametric renogram values were related to a normal reference group of 64 patients. The preoperative renograms were matched with the postoperative outcome., Results: Three characteristic types of symmetrical findings in the kidneys were found: no pathological findings, mildly delayed peak and excretion phase and severely delayed peak and excretion phase. Pathological renograms were observed in 36 of 50 (72%) patients. The mean parametric renogram values in ischemic CM were as follows: Group A (normal kidney function), mPTT = 142+/-26.6 sec, RTC15 = 22.3%+/-4.6% and RI = 24.7+/-11.9; Group B (mild dysfunction), mPTT = 210+/-44.0 sec, RTC15 = 42.6%+/-10.3% and RI = 101.4+/-50.5; Group C (severe dysfunction), mPTT = 320+/-94.2 sec, RTC15 = 79.6%+/-15.9% and RI = 347.7+/-194.7; and reference patients (normal kidney function), mPTT = 137+/-31.1 sec, RTC15 = 22.8%+/-3.8% and RI = 24.6+/-7.9. Postoperative serum creatinine levels were <1.5 mg/dl in all Group A patients, between 1.5 and 2.5 mg/dl in 78% of Group B patients and >2.5 mg/dl in 75% of Group C patients., Conclusion: Renography revealed abnormal kidney function when structural pathology was excluded. The renographic abnormalities in ischemic CM did not reflect simply the circulatory failure. The numerical grading of renograms allowed patient stratification, suggestive of possible renal insufficiency after cardiac transplantation and immunosuppressive therapy. With further experience, renography may become a useful tool for predicting postoperative outcome in ischemic CM.

Three consensus reports entitled "renal clearance," "ACE inhibitor renography for detecting renovascular hypertension," and "diuresis renography for investigating the dilated upper urinary tract" were published in The Journal of Nuclear Medicine in 1996. Although nuclear nephrology is useful technique to evaluate renal function, there were wide variations of technical procedure and their interpretations among different centers. Minimal standardization by these consensus reports may help to raise the level of practice of renal nuclear medicine. The introduction of 99mTc-MAG3 (MAG3) enhanced the utility of renal nuclear medicine because of the rapid clearance and suitable gamma-ray energy for imaging by gamma camera. In this chapter, the principle, procedures, and interpretations of renal nuclear medicine examinations using MAG3 regarding renal clearance measurements, ACE inhibitor renography, and diuresis renography are explained and discussed.

Our objective was to assess mean transit time (MTT) and initial uptake, both parameters derived from the renal retention function (RRF), in the study of renal function in patients with diabetic nephropathy. We studied 25 patients, 7 with type I diabetes mellitus and 18 with type II diabetes mellitus, all of whom fulfilled the criteria for diabetic nephropathy with proteinuria and/or retinopathy. We found a statistically significant correlation between initial uptake and the other biochemical and renographic parameters studied except proteinuria: serum creatinine (r = 0.66, P < 0.002), creatinine clearance (r = 0.61, P < 0.003), glomerular filtration rate (r = 0.74, P < 0.003) and effective renal plasma flow (r = 0.66, P < 0.003). The other renographic parameters studied (maximal activity of the conventional renogram and MTT of the deconvoluted renogram) did not show any correlation. Initial uptake is a semi-quantitative renographic parameter that can provide complementary information to biochemical data and it may be useful in the management of diabetic nephropathy, especially in patients with high serum creatinine or creatinine clearance.

Steady-state captopril renography (SSCR) is an original technique for assessing the captopril-induced increase in technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) mean parenchymal transit time (MPTT) in kidneys affected with functional renal artery stenosis (RAS). The steady-state parenchymal activity achieved by constant infusion of 99mTc-MAG3 is directly linked to the MPTT of the radiopharmaceutical. This steady-state parenchymal activity was continuously monitored from 15 min before to 60 min after a single dose of captopril in order to detect possible disruption of the steady state. SSCR was performed in 11 hypertensive patients with unilateral RAS and in two with RAS of a solitary kidney before renal revascularization (RR). In four of these patients, an additional SSCR was performed after RR. Of the ten patients whose hypertension was cured or improved by RR, one presented an uninterpretable SSCR and six presented a positive SSCR on the affected side. Control SSCR performed in four of these six patients was bilaterally negative. SSCR was also bilaterally negative in the three patients who showed no blood pressure response to RR. These preliminary results tend to indicate that, in spite of the stability of pre- and post-captopril hydration and data acquisition conditions allowed by this steady-state technique, the sensitivity is lower than expected. However, the reason for the false-negative results does not seem to be inherent to SSCR.

In a study of gamma-camera renography, a digitized time-activity curve, or renogram, was standardized in terms of absolute renal uptake. The algorithm for standardization of the renogram was based on a gamma-camera uptake method employed by Gates and Schlegel et al. All count rates for the background-corrected renograms were converted to percent renal uptake per injected dose per minute (%RU). The maximum value for the scale on the y-axis was set at 20% RU. The renograms were generated from 66 kidneys in 35 patients (27 males, 8 females) aged 19-80 years. Using the newly developed computer program, the shape of the renograms was considered abnormal between 8/52 (15%) and 10/53 (19%) kidneys, depending on the observer, all of which were classified as normal when displayed conventionally. All the renograms for 4 patients with one poorly functioning kidney, and between 8 (28%) and 10 (32%) renograms for 31 patients with two poorly performing kidneys, exceeded the maximum g-axis value of 20% RU. Expression of the renograms based on absolute uptake is helpful in avoiding the potential problem of two poorly functioning kidneys, which may be considered near-normal in terms of count rate. The maximum value on the y-axis in 99Tcm-MAG3 renography should be fixed between 25 and 30% RU, while the actual amplitude of the standardized renogram may depend on the method used for quantification.

This study provides values of transit times obtained by 99Tcm- mercaptoacetyl triglycine (99Tcm-MAG3) renogram deconvolution for both normal subjects and kidney graft recipients. The analysis included 50 healthy kidney units from 25 volunteers and 28 normal functioning kidney grafts. The parameters calculated for the whole kidney (WK) and for the renal parenchyma (P) were: mean transit time (MTT) and times at 20% (T20) and 80% (T80) of renal retention function initial height. For healthy kidneys the WK MTT was 174 +/- 27 s and P MTT 148 +/- 22 s. The WK T20 values were 230 +/- 33 s and P T20 231 +/- 34 s. The WK T80 was 108 +/- 19 s and P T80 106 +/- 12 s. Whole kidney and parenchymal values of transit times for normal functioning kidney grafts do not present significant differences with respect to healthy kidneys.

Because of significant difficulties encountered in the manipulation of data from 99Tcm-DTPA and 99Tcm-mercaptoacetyltriglycine (MAG3) renogram studies, it was decided to try to improve the percentage dose of radioisotope injected and thus the number of counts obtained by using a minimum dose volume of 1 ml for all injections. This resulted in an improvement in the percentage dose injected. However, difficulties were still encountered in the younger children. 18.7% of children aged less than 3 months, received less than 50% of the injected dose, showing little or no improvement using the newer method. The difficulty of injecting small babies seems the most obvious reason. During the interpretation of the findings in paediatric radioisotope studies, it is important to remember that not all children may have received an adequate percentage dose to constitute a reliably diagnostic study.