Normal ranges of renal function parameters for 99mTc-EC renal scintigraphy.

BACKGROUND: Dynamic renal scintigraphy remains the recognized method for evaluation of kidney function and perfusion. Although there is an extensive body of knowledge about the use of technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3), much less has been written about renal technetium-99m-ethylenedicysteine (99mTc-EC) scintigraphy. The aim of this study was to determine the normal value of renal function parameters in 99mTc-EC dynamic renal scintigraphy: Tmax and T1/2. The effects of age, left or right side in the retroperitoneal space, and sex on those parameters were examined. MATERIAL AND METHODS: The research was conducted on 123 patients (F/M: 70/53; aged 2-71; averaging 14.8 years of age) with at least one normal kidney. A total of 194 healthy kidneys were examined, including pediatric kidneys. RESULTS: According to this study, the normal value of Tmax is 2.85 min (± 1.16) and T1/2 is 8.7 min (± 3.61). Values calculated for pediatric studies are Tmax is 2.81 (± 1.16) and T1/2 is 8.63 (± 3.71). CONCLUSIONS: The normal value of secretory and excretory renal function parameters was calculated. Although the value is slightly lower for children, this is not statistically significant, as globally there are no differences between the kidney-location sides and sexes for any parameter.

Glomerular filtration rate: comparison of simultaneous plasma clearance of 99mTc-DTPA and 51Cr-EDTA revisited.

The issue of whether 99mTc-DTPA can replace 51Cr-EDTA for measurement of plasma clearance as a surrogate for glomerular filtration rate (GFR) is of great relevance to daily clinical practice. Prompted by the shortage of 51Cr-EDTA we conducted a head-to-head comparison in patients attending our department for GFR determination. The two tracers (3.7 MBq of 51Cr-EDTA and 8 MBq of 99mTc-DTPA) were administered intravenously immediately after each other, and the standard number of blood samples were drawn. Fifty-four patients were enrolled. In 51 of these, single-sample measurement was performed with the following results: GFREDTA was 84.6 ± 23.3 mL/min, GFRDTPA was 84.2 ± 24.7 mL/min. The mean difference was 0.4 ± 2.8 mL/min, p = 0.32, and results based on the two tracers were highly correlated (r = 0.995). GFRDTPA exceeded GFREDTA at high GFR values (difference < 0 at GFREDTA >91.4 mL/min) and vice versa (difference > 0 at GFREDTA < 91.4 mL/min). However, differences fell within few GFR units that most often will have no clinical consequence. We therefore conclude that 99mTc-DTPA can replace 51Cr-EDTA for single-sample determination of GFR in a clinical setting.

Comparison of simultaneous plasma clearance of 99mTc-DTPA and 51Cr-EDTA: can one tracer replace the other?

Both 99mTc-DTPA and 51Cr-EDTA are widely used to determine glomerular filtration rate (GFR), but few direct comparative studies exist. The shortage of 51Cr-EDTA makes a direct comparison highly relevant. The aim of the study was to investigate if there is any clinically relevant difference between plasma clearance of 99mTc-DTPA and 51Cr-EDTA. Patients ≥18 years of age referred for routine GFR measurement by 51Cr-EDTA were prospectively enrolled. The two tracers (10 MBq 99mTc-DTPA (CaNa3-DTPA) and 2.5 MBq 51Cr-EDTA) were intravenously injected at time zero. A standard 4-sample technique was applied with samples collected at 180, 200, 220 and 240 min, if the estimated GFR (eGFR) was ≥30 mL/min. A comparison of single-sample GFR based on the 200 min sample was also conducted. Fifty-six patients were enrolled in the study. All patients had an estimated GFR >30 mL/min/1.73 m2. No patients suffered from ascites or significant oedema. The mean 51Cr-EDTA plasma clearance was 82 mL/min (range 16-226). The plasma clearances determined by the two methods were highly correlated (r = 0.993). The plasma clearance was significantly higher when measured by 99mTc-DTPA than by 51Cr-EDTA (p = 0.01), but the numerical difference was minimal (mean difference 1.4 mL/min; 95% limits of agreement (LOA) -6.6 to 9.4). The difference between the two methods was independent of the level of renal function. Similar results were found for one-sample GFR. No clinically relevant differences were found between the plasma clearance of 99mTc-DTPA and that of 51Cr-EDTA. Therefore, 99mTc-DTPA can replace 51Cr-EDTA when needed.

Successful paediatric renography does not require sedation.

INTRODUCTION: Sedation is often used to optimise ren-ography in children < 3 years, but it requires continuous monitoring. METHODS: We discontinued routine use of chloral hydrate sedation of patients undergoing renography, and introduced that children < 2 years were placed in a child immobiliser for nuclear examinations at the Department of Paediatrics before being transported for renography. In addition, children < 3 years were offered melatonin, which is not a sedative. Chloral hydrate was given only if parents wanted sedation. We analysed the results from a consecutive series of patients undergoing renography from August 2010 to December 2015 and compared data from those who had been administered choral hydrate sedation with those who had received no sedation. RESULTS: Renography was unaccomplished in 10% (3/30) of the choral hydrated sedated children and in 11% (54/512) of the non-sedated children (p = 0.83). Uncooperative children resulted in failed renography in 0% (0/3) and 39% (21/54) of cases, respectively (p = 0.46). Patients placed in a child immobiliser at the Department of Paediatrics had the greatest probability of achieving successful renography (p = 0.0013), the shortest renography procedure duration irrespective of melatonin use (p = 0.0001) and the lowest risk of a procedure duration > 60 minutes (p = 0.0004). CONCLUSIONS: Renography can be performed without sedation. We recommend that children < 2 years be placed in a child immobiliser at the Department of Paediatrics before being transported for renography. Additional studies are needed to investigate the effects of melatonin. FUNDING: none. TRIAL REGISTRATION: not relevant.

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.

Reference Ranges in [(99m)Tc]Mercaptoacetyltriglycerine Renography: Comparison of a Semi-automated (Xeleris, GE) and Manual (Picker, Odyssey) Processing Software.

PURPOSE: The purpose of the study was to define reference ranges for quantitative parameters in [(99m)Tc]mercaptoacetyltriglycerine ([(99m)Tc]MAG3) renography to assist interpretation in a semi-automated (Xeleris, GE) compared to a manual (Picker, Odyssey) software package. PROCEDURES: Forty-eight subjects approved for renal donation were evaluated with [(99m)Tc]MAG3 renography using both the Xeleris and the Picker software. RESULTS: Reference ranges for the two software were comparable regarding the relative function of the two kidneys (the split function, SF) and the residual activities (RA). The time to peak whole-kidney activities (T max whole-kidney) was more dependent on the type of software. Using Bland-Altman limits, we found good and acceptable agreement between the two methods. CONCLUSIONS: We found good correlation between renography results using the Xeleris and Picker software packages. However, software-specific reference ranges are needed.

Preliminary assessment of interand intraobserver reproducibility, and normative values of renal mean transit time (MTT) and parenchymal transit time (PTT) for 99mTc-etylenodicysteine.

BACKGROUND: The clinical significance of MTT and PTT, determined by deconvolution of renographic curves, is arguable. Their usefulness in diagnosis of obstructive uro- and nephropathy, renovascular hypertension and monitoring of transplanted kidneys is pointed out, but susceptibility of deconvolution methods to errors resulting from "statistical noise" is also stressed. So far there are no reports on normative MTT values for 99mTc-EC, although such values were already determined for ¹³¹I-OIH, 99mTc-DTPA and 99mTc-MAG3. The aim of this study is an assessment of inter- and intraobserver reproducibility of MTT and PTT for 99mTc-EC, and determination of normative values for these parameters. MATERIALS AND METHODS: 31 patients (17 women and 14 men aged 19-75, average 44 years) referred for dynamic renal scintigraphy with: unilateral flow impairment (11), unilateral nephrolithiasis (2), control after unilateral lithotripsy (4), moderate hypertension (demographically with > 99% probability of primary hypertension) (4), suspected cirrhosis of one kidney (3), future kidney donors (3), control after abdominal injuries (3), incontinence (1). 42 functionally efficient kidneys were included in the study. Criteria for recognition of a kidney as functionally efficient were: - no earlier history of renal disease, signs of renal damage in basic blood and urine tests, or abnormalities in ultrasonography; - normal result of dynamic renal scintigraphy (in terms of sequential images and renographic curve). MTT and PTT values were determined independently by two operators, using a matrix method for deconvolution of renographic curves. RESULTS: Differences between mean MTT and PTT from two studies by one operator were insignificant and those values were closely correlated (r = 0.99 and r = 0.97, respectively). Differences of values obtained by both operators were practically insignificant for MTT (r = 0.93), and significant for PTT (r = 0.81 and p < 0.001). These differences do not disqualify that processing method. The upper limits of normative values of MTT and PTT were based on the results from first study performed by more experienced operator - 200 s and 170 s, respectively. CONCLUSIONS: The procedure of processing dynamic renal scintigraphy used in this study is reproducible. Normative values of MTT and PTT for 99mTc-EC were established as 200 s and 170 s, respectively. An attempt to optimize and standardize the technique of determining parenchymal ROI in a matrix deconvolution method, followed by an evaluation of clinical usefulness of these parameters in the diagnosis of chosen renal function impairments would be a logical continuation of this initial research.

Multicenter evaluation of renography with an automated physical phantom.

PURPOSE: The diversity of the dynamic radionuclide renal imaging (renography) study protocols sets challenges for the overall study quality, therefore raising a need for national quality control. The aim of this study was to encourage the standardization of renography in Finland and to evaluate the development after a previous study performed in 1997. METHODS: The new Heikkinen phantom was imaged in each of the 20 participating nuclear medicine laboratories. The results were interpreted in the manner of a regular patient study, and reconstructions and printouts were made according to the clinical routines of each laboratory. Four quantitative parameters were calculated and compared between laboratories. The reports were also assessed in a blind test. RESULTS: The average error in T(max) values ranged from -5 to 7% (-29 to +18% in 1997), in T(1/2) from 0 to 35% (-43 to +66%), in RCA20 from -20 to +28% (-50 to +82%) and in relative uptake from -3 to 5%. The difference from average in relative uptake ranged from -4 to 5% (-21 to +36%). CONCLUSION: The results showed that the errors in T(max) and relative uptake were generally within quite acceptable margins, and the variation in quantitative parameters between laboratories was shown to be smaller than 14 years earlier. The reason might be the use of new software packages as well as increased efforts to improve the quality of the studies.

Revised guidelines on management of antenatal hydronephrosis.

Widespread antenatal screening has resulted in increased detection of anomalies of the kidneys and urinary tract. The present guidelines update the recommendations published in 2000. Antenatal hydronephrosis (ANH) is transient and resolves by the third trimester in almost one-half cases. The presence of oligohydramnios and additional renal or extrarenal anomalies suggests significant pathology. All patients with ANH should undergo postnatal ultrasonography; the intensity of subsequent evaluation depends on anteroposterior diameter (APD) of the renal pelvis and/or Society for Fetal Urology (SFU) grading. Patients with postnatal APD exceeding 10 mm and/or SFU grade 3-4 should be screened for upper or lower urinary tract obstruction and vesicoureteric reflux. Infants with vesicoureteric reflux should receive antibiotic prophylaxis through the first year of life, and their parents counseled regarding the risk of urinary tract infections. The management of patients with pelviureteric junction or vesicoureteric junction obstruction depends on clinical features and results of sequential ultrasonography and radionuclide renography. Surgery is considered in patients with increasing renal pelvic APD and/or an obstructed renogram with differential renal function <35-40% or its subsequent decline. Further studies are necessary to clarify the role of prenatal intervention, frequency of follow up investigations and indications for surgery in these patients.

Guidance document for structured reporting of diuresis renography.

This Guidance Document for structured reporting of diuresis renography in adults was developed by the International Scientific Committee of Radionuclides in Nephro-urology (ISCORN; http://www.iscorn.org). ISCORN chose diuresis renography for its first structured report Guidance Document because suspected obstruction is the most common reason for referral, most radionuclide renal studies are conducted at institutions that perform fewer than 3 studies per week, and a large percentage of studies are interpreted by physicians with limited training in nuclear medicine. Ten panelists were asked to categorize specific reporting elements as essential, recommended, optional (without sufficient data to support a higher ranking), and unnecessary (does not contribute to scan interpretation or quality assurance). The final document was developed through an iterative series of comments and questionnaires with a majority vote required to place an element in a specific category. The Guidance Document recommends a reporting structure organized into indications, clinical history, study procedure, findings and impression and specifies the elements considered essential or recommended in each category. The Guidance Document is not intended to be restrictive but, rather, to provide a basic structure and rationale so that the diuresis renography report will: (1) communicate the results to the referring physician in a clear and concise manner designed to optimize patient care; (2) contain the essential elements required to evaluate and interpret the study; (3) clearly document the technical components of the study necessary for accountability, quality assurance and reimbursement; and (4) encourage clinical research by facilitating better comparison and extrapolation of results between institutions.

Renogram comparison of p-[(18)F]fluorohippurate with o-[(125)I]iodohippurate and [(99m)Tc]MAG3 in normal rats.

OBJECTIVE: We recently identified p-[(18)F]fluorohippurate ([(18)F]PFH) as a potential positron emission tomography (PET) renal agent. The objective of this study was to compare renogram parameters of [(18)F]PFH with o-[(125)I]iodohippurate ([(125)I]OIH) as a surrogate for the renal imaging gold standard (131)I-OIH and with a clinically used agent [(99m)Tc]MAG3. METHODS: Normal Sprague-Dawley rats (n=4) were sequentially imaged on days 1, 2, and 3 using [(99m)Tc]MAG3 (18.1-19.1 MBq, dynamic planar), [(18)F]PFH (2.6-4.1 MBq, dynamic PET), and [(125)I]OIH (7.7-13.5 MBq, dynamic planar), respectively. The PET data were binned into frames of 30 s each, whereas the planar images were acquired as 30 s per frame. Regions of interest were drawn on both kidneys, and decay-corrected renograms were generated for each imaging modality. RESULTS: The PET-derived [(18)F]PFH renograms revealed an average time-to-peak (T(max)) of 4.8±2.4 min, which was comparable to the T(max) of 3.6±1.7 min and 4.3±1.7 min for [(125)I]OIH and [(99m)Tc]MAG3 renograms, respectively. The average time-to-half-maximal activity was found to be 16.6±6.6 min, 8.3±2.4 min, and more than 20 min with [(18)F]PFH, [(125)I]OIH, and [(99m)Tc]MAG3, respectively. CONCLUSIONS: Compared with [(99m)Tc]MAG3, the renogram parameters of [(18)F]PFH seem to be closer to those obtained from [(125)I]OIH. The quality of the renogram and the images obtained with the dynamic [(18)F]PFH PET study were remarkably better than those obtained with the [(99m)Tc]MAG3 dynamic planar imaging study.

Guidelines for standard and diuretic renogram in children.

Special consideration needs to be given to children who undergo dynamic renography. The Paediatric Committee of the European Association of Nuclear Medicine has updated the previous guidelines. Details are provided on how to manage the child, the equipment, and the acquisition and processing protocols. The pitfalls, difficulties and controversies that are encountered are also discussed, as well as the interpretation of the results.

Advantages of standardized criteria for the interpretation of angiotensin-converting enzyme inhibition renography.

BACKGROUND: The aim of this study was to evaluate the efficiency of captopril renography to detect renovascular hypertension (RVH) using the standardized test criteria established at the consensus conference in Santa Fe 1995. The evaluation was made prospectively and in a clinical situation. METHODS: Renal scintigraphy was performed with Tc-MAG3 according to a 2-day protocol in patients receiving 25 mg captopril 1 h before the test. A baseline study was added only in patients showing abnormal findings in the captopril-stimulated study. All tests were re-evaluated according to the consensus criteria by two nuclear medicine specialists who were unaware of the original evaluation that was made by different doctors on duty at the nuclear medicine section at the time. RESULTS: Using a 12-month clinical follow-up as a reference, 16 patients in a group of 164 hypertensive patients had RVH, that is, a prevalence of 10%. The re-evaluation and original evaluation indicated a sensitivity of 94 versus 100%, specificity of 97 versus 88%, accuracy of 97 versus 89%, positive predictive value of 83 versus 47%, and negative predictive value of 99 versus 100%. In 15 studies, results from the two evaluations were discordant and in 14 of these studies an originally false positive or intermediate study was re-evaluated as negative. The test result was highly decisive in the future management of patients, minimizing the number of renal angiograms that had to be performed and initiating a search for other causes of secondary hypertension. CONCLUSION: Captopril renography is a useful and reliable test in patients with suspicion of RVH. Strict adherence to the diagnostic criteria and recommendations from the 1995 consensus conference further improved the performance of the test compared with clinical follow-up.

Estimation of renal function and its potential impact on carboplatin dosing in children with cancer.

Renal function-based carboplatin dosing is used routinely in paediatric oncology clinical practice. It is important that accurate assessments of renal function are carried out consistently across clinical centres, a view supported by recently published British Nuclear Medicine Society (BNMS) guidelines for measuring glomerular filtration rate (GFR). These guidelines recommend the use of a radioisotope method for GFR determination, with between two and five blood samples taken starting 2 h after radioisotope injection and application of the Brochner-Mortensen (BM) correction factor. To study the likely impact of these guidelines, we have investigated current practices of measuring GFR in all 21 Children's Cancer and Leukaemia Group (CCLG) paediatric oncology centres in the United Kingdom. This information was used to evaluate the potential impact on renal function-based carboplatin dosing using raw 51Cr-EDTA clearance data from 337 GFR tests carried out in children with cancer. A questionnaire survey revealed that between two and four samples were taken after isotope administration, with BM and Chantler corrections used in 38% (8/21) and 28% (6/21) of centres, respectively. A change from Chantler to BM correction, based on the BNMS guidelines, would result in a > 10% decrease in carboplatin dose in at least 15% of patients and a > 25% decrease in 2% of patients. A greater proportion of patients would have an alteration in carboplatin dose when centres not using any correction factor implement the BM correction. The increase in estimated 51Cr-EDTA half-life observed by omitting the I h sample decreases carboplatin dose by > 10% in 23-52% of patients and by > 25% in 3% of patients. This study highlights current variations in renal function measurement between clinical centres and the potential impact on carboplatin dosing. A standard methodology for estimating GFR should be followed to achieve uniform dosing in children with cancer.

International Scientific Committee of Radionuclides in Nephrourology (ISCORN) consensus on renal transit time measurements.

This report is the conclusion of the international consensus committee on renal transit time (subcommittee of the International Scientific Committee of Radionuclides in Nephrourology) and provides recommendations on measurement, normal values, and analysis of clinical utility. Transit time is the time that a tracer remains within the kidney or within a part of the kidney (eg, parenchymal transit time). It can be obtained from a dynamic renogram and a vascular input acquired in standardized conditions by a deconvolution process. Alternatively to transit time measurement, simpler indices were proposed, such as time of maximum, normalized residual activity or renal output efficiency. Transit time has been mainly used in urinary obstruction, renal artery stenosis, or renovascular hypertension and renal transplant. Despite a large amount of published data on obstruction, only the value of normal transit is established. The value of delayed transit remains controversial, probably due to lack of a gold standard for obstruction. Transit time measurements are useful to diagnose renovascular hypertension, as are some of the simpler indices. The committee recommends further collaborative trials.

Reference ranges for 51Cr-EDTA measurements of glomerular filtration rate in children.

BACKGROUND: 51Cr-Ethylenediaminetetraacetic acid (51Cr-EDTA) is widely used to measure the glomerular filtration rate (GFR) in children and adults. AIM: To produce paediatric reference data for use with the British Nuclear Medicine Society (BNMS) GFR guidelines. METHODS: This was a retrospective study of children and adolescents, aged 0-17 years, undergoing combined 99mTc-dimercaptosuccinic acid (99mTc-DMSA) scintigraphy and GFR examination. GFR was evaluated from Cr-EDTA plasma clearance using blood samples taken at 2, 3 and 4 h according to the methods set out in the BNMS GFR guidelines. 99mTc-DMSA images were reviewed to identify children with normal scans. RESULTS: Of the 45 children having a combined 99mTc-DMSA and GFR investigation, 27 (12 females, 15 males) had a normal scan result. The mean GFR (standard deviation) in the 24 subjects aged 2-17 years was 109.5 (16.8) ml . min(-1) . (1.73 m2)(-1). This compared with a predicted figure of 107.0 (17.0) ml . min(-1) . (1.73 m2)(-1) when the paediatric reference range published by Piepsz et al. was adjusted to be consistent with the BNMS GFR guidelines. When the GFR results in the present study were calculated according to the single-sample and two-sample methods used by Piepsz et al., there was close agreement with the results obtained in the latter study [116.7 (24.2) vs. 114.7 (25.8) ml . min(-1) . (1.73 m2)(-1)]. Children with abnormal 99mTc-DMSA scans had significantly lower GFR than those with normal scans (P=0.003). CONCLUSION: There is a consistent difference between the GFR results in children with normal 99mTc-DMSA scans obtained in the present study and the unadjusted results of Piepsz et al. that can be explained by the different methods of calculating GFR in the two studies. Given the larger number of children in the latter study, it is proposed that centres evaluating GFR according to the BNMS method should adopt the Piepsz et al. reference range adjusted for consistency with the BNMS guidelines. This gives a mean GFR (SD) in children of 2 years and over of 107 (17) ml . min(-1) . (1.73 m2)(-1).

Interpretation of captopril renography using artificial neural networks.

The purpose of this study was to develop a method based on artificial neural networks for interpretation of captopril renography tests for the detection of renovascular hypertension caused by renal artery stenosis and to assess the value of different measurements from the test. A total of 250 99mTc-MAG3 captopril renography tests were used in the study. The material was collected from two different patient groups. One group consisted of 101 patients who also had undergone a renal angiography. The angiographies, which were used as gold standard, showed a significant renal artery stenosis in 53 of the 101 cases. The second group consisted of 149 patients, who's captopril renography tests all were interpreted as not compatible with significant renal artery stenosis by an experienced nuclear medicine physician. Artificial neural networks were trained for the diagnosis of renal artery stenosis using eight measures from each renogram. The neural network was then evaluated in separate test groups using an eightfold cross validation procedure. The performance of the neural networks, measured as the area under the receiver operating characteristic curve, was 0.93. The sensitivity was 91% at a specificity of 90%. The lowest performance was found for the network trained without use of a parenchymal transit measure, indicating the importance of this feature. Artificial neural networks can be trained to interpret captopril renography tests for detection of renovascular hypertension caused by renal artery stenosis. The result almost equals that of human experts shown in previous studies.

Dificultades en la interpretación del renograma diurético en niños / Difficulties in the interpretation of diuretic renal scintigraphy in childrens

El renograma diurético continúa siendo el estudio funcional de carácter no invasivo de elección en la evaluación de pacientes con hidronefrosis y probable obstrucción pielo-ureteral. Para una adecuada interpretación de éste es esencial dar una meticulosa atención a factores como la preparación previa del paciente, la selección del radiofármaco, la dosis y administración del diurético, la interpretación de las imágenes y el conocimiento de los potenciales errores de la técnica. Para la mayoría de los pacientes el protocolo F+20 es suficiente, sin embargo el protocolo F-15 puede ayudar a clarificar los casos equívocos del protocolo F+20. Las técnicas invasivas como el test de Whitaker son reservadas para aquellos pacientes con hidronefrosis severa o con insuficiencia renal en donde el diagnóstico clínico aún persiste equívoco después de haber efectuado el renograma. Las recientes publicaciones de guías de protocolos estandarizados y consensos internacionales han contribuido a unificar criterios y así mejorar la agudeza diagnóstica y la reproducibilidad de la técnica.

A dynamic renal phantom for nuclear medicine studies.

Dynamic radionuclide renal study (renography) provides functional and structural information of the kidney and urinary tract noninvasively. Our purpose in this study is to describe the construction and test results of a dynamic renal phantom with different clinical features of radionuclide renography. The phantom consisted of five pieces of different shaped Plexiglas boxes: Two kidneys, one liver, two square shaped boxes (one heart and one bladder). The bladder was internally divided into two compartments in order to collect each kidney output separately. The dynamic circulation of the phantom was maintained under a hydrostatic pressure approximately equal to 13.3 kPa (average human blood pressure). The standard dose distribution among different organs and different renographic parameters were calculated from series of normal patients study (91 with 99mTc-DTPA, 68 with 99mTc-EC). All the studies were performed with same camera (Siemens Orbiter Digitrac 7500) equipped with LEAP (low energy all purpose) collimator using ADAC Pegasys II analytic package program under the same clinical procedure. Different regions of interest (ROIs) were drawn for concerning organs and counts per second (CPS) were collected for each ROI. The series of renogram curves were generated by phantom-studies with different flow rates for left kidney (LK) and right kidney (RK). The renal index (RI) for an individual study was calculated as the product of two indexes: "Relative Renal Function" (RRF) (water-volume of LK/RK) and "Relative Renal Time" (RRT) (Tmax of LK/RK). The most significant correlation was found in total CPS for LK and RK between the EC group and phantom studies (p < 0.001). The calculated RI values were used to simulate the patients' study with different clinical features. The dynamics were found reproducible. The phantom is suitable for using in calibration and quality control protocols of the renogram procedure used in Nuclear Medicine.