Review on Pharmacoscintigraphy

Pharmacoscintigraphy is a non-invasive technique for determining the fate of drugs after administration into humans. Collecting valuable information through the pharmacoscintigraphyabout absorption and release mechanisms of drugs from formulations, and thus proving to be an invaluable tool in developing newer and more effective formulations. Such studies can be used to determine the behavior of drugs, formulation as well as diagnostic agents that are administered. In this technique, radiolabelled formulations are administered to patients by their intended route of administration. Their transit through the body is monitored using sophisticated imaging cameras. Since the amount of radiotracer that is used is very low, this is a safe, efficient, and accurate method for studying the behavior of drugs in the human body. Preclinical studies of newer drugs have successfully been carried out using the pharmacoscintigraphic technique

Clinical Applications of Technetium-99m Quantitative Single-Photon Emission Computed Tomography/Computed Tomography / 대한핵의학회잡지

Single-photon emission computed tomography/computed tomography (SPECT/CT) is an already established nuclear imaging modality. Co-registration of functional information (SPECT) with anatomical images (CT) paved the way to the wider application of SPECT. Recent advancements in quantitative SPECT/CT have made it possible to incorporate quantitative parameters, such as standardized uptake value (SUV) or %injected dose (%ID), in gamma camera imaging. This is indeed a paradigm shift in gamma camera imaging from qualitative to quantitative evaluation. In fact, such quantitative approaches of nuclear imaging have only been accomplished for positron emission tomography (PET) technology. Attenuation correction, scatter correction, and resolution recovery are the three main features that enabled quantitative SPECT/CT. Further technical improvements are being achieved for partial-volume correction, motion correction, and dead-time correction. The reported clinical applications for quantitative SPECT/CT are mainly related to Tc-99m-labeled radiopharmaceuticals: Tc-99m diphosphonate for bone/joint diseases, Tc-99m pertechnetate for thyroid function, and Tc-99m diethylenetriaminepentaacetic acid for measurement of glomerular filtration rate. Dosimetry before trans-arterial radio-embolization is also a promising application for Tc-99m macro-aggregated albumin. In this review, clinical applications of Tc-99m quantitative SPECT/CT will be discussed.

The Current Status of SPECT or SPECT/CT in South Korea / 대한핵의학회잡지

The first step to nuclear medicine in Korea started with introduction of the gamma camera in 1969. Although planar images with the gamma camera give important functional information, they have the limitations that result from 2-dimensional images. Single-photon emission computed tomography (SPECT) due to its 3-dimensional image acquisition is superior to earlier planar gamma imaging in image resolution and diagnostic accuracy. As demand for a hybrid functional and anatomical imaging device has increased, integrated SPECT/CT systems have been used. In Korea, SPECT/CT was for the first time installed in 2003. SPECT/CT can eliminate many possible pitfalls on SPECT-alone images, making better attenuation correction and thereby improving image quality. Therefore, SPECT/CT is clinically preferred in many hospitals in various aspects.More recently, additional SPECT/CT images taken from the region with equivocal uptake on planar images have been helpful in making precise interpretation as part of their clinical workup in postoperative thyroid cancer patients. SPECT and SPECT/CT have various advantages, but its clinical application has gradually decreased in recent few years. While some researchers investigated the myocardial blood flow with cardiac PET using F-18 FDG or N-13 ammonia, myocardial perfusion SPECT is, at present, the radionuclide imaging study of choice for the risk stratification and guiding therapy in the coronary artery disease patients in Korea. New diagnostic radiopharmaceuticals for AD have received increasing attention; nevertheless, brain SPECT will remain the most reliable modality evaluating cerebral perfusion.

Correlations between Tumor to Background Ratio on Breast-Specific Gamma Imaging and Prognostic Factors in Breast Cancer

The purpose of this study was to investigate the correlations between tumor-to-background ratio (TBR) obtained from breast-specific gamma imaging (BSGI) and the prognostic factors of breast cancer. Sixty-seven patients with invasive ductal carcinoma who underwent preoperative BSGI were enrolled. The BSGI images were visually scored from 1 to 5 according to a breast imaging reporting and data system (BIRADS). The TBR results obtained from positive BSGI images were compared according to the following prognostic factors: tumor size; axillary lymph node metastasis; nuclear grade (NG); histologic grade (HG); subtype; Ki-67; and the expression profile of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Among 67 images, 60 were classified as a positive finding (sensitivity 89.6%). A higher TBR value was significantly correlated with tumor size ≥ 2 cm (P = 0.001), axillary lymph node metastasis (P = 0.007), high HG (P = 0.029), negative PR status (P = 0.036), and Ki-67 ≥ 14% (P = 0.007). The TBR showed a significant difference between the luminal A and non-luminal A subtypes (P = 0.007). On multivariate analysis, TBR had a high correlation with tumor size ≥ 2 cm, axillary lymph node metastasis, and negative PR status (P = 0.003, 0.048, and 0.030, respectively). A high TBR on BSGI was significantly correlated with poor prognostic factors of breast cancer. Luminal A subtype, a breast cancer subtype with more favorable prognosis, was associated with a low TBR on BSGI.

O SUS na medicina nuclear do Brasil: avaliação e comparação dos dados fornecidos pelo Datasus e CNEN / SUS in nuclear medicine in Brazil: analysis and comparison of data provided by Datasus and CNEN

Objetivo: Investigar o acesso a procedimentos ambulatoriais de medicina nuclear por intermédio do Sistema Único de Saúde (SUS) do Brasil e analisar a correspondência dos dados fornecidos por este sistema com os da Comissão Nacional de Energia Nuclear (CNEN). Materiais e Métodos: Foram obtidos e avaliados os dados disponíveis no Datasus quanto a quantidade de câmaras de cintilação, procedimentos ambulatoriais de 2008 a 2012, esfera administrativa responsável por estes procedimentos, tipo de prestador de serviços e terceirização de serviços. Também foi feita comparação com os dados de estabelecimentos autorizados pela CNEN. Resultados: O estudo mostrou que ainda falta amadurecimento do sistema quanto à sua completa alimentação, especialmente no campo de equipamentos disponíveis. Foi possível elencar os procedimentos mais realizados e verificar o crescimento da especialidade no período estudado. Estabelecimentos privados são responsáveis pela maior parte dos procedimentos cobertos pelo SUS. Entretanto, muitos estabelecimentos de saúde não são autorizados pela CNEN. Conclusão: O Datasus oferece dados importantes para uma análise como a feita neste estudo, embora alguns pontos ainda demandem atenção. O trabalho mostrou, quantitativamente, a realidade brasileira quanto ao acesso a procedimentos de medicina nuclear oferecidos pelo/para o SUS. .

Objective: To investigate the outpatient access to nuclear medicine procedures by means of the Brazilian Unified Health System (SUS), analyzing the correspondence between data provided by this system and those from Comissão Nacional de Energia Nuclear (CNEN) (National Commission of Nuclear Energy). Materials and Methods: Data provided by Datasus regarding number of scintillation chambers, outpatient procedures performed from 2008 to 2012, administrative responsibility for such procedures, type of service providers and outsourced services were retrieved and evaluated. Also, such data were compared with those from institutions certified by CNEN. Results: The present study demonstrated that the system still lacks maturity in terms of correct data input, particularly regarding equipment available. It was possible to list the most common procedures and check the growth of the specialty along the study period. Private centers are responsible for most of the procedures covered and reimbursed by SUS. However, many healthcare facilities are not certified by CNEN. Conclusion: Datasus provides relevant data for analysis as done in the present study, although some issues still require attention. The present study has quantitatively depicted the Brazilian reality regarding access to nuclear medicine procedures offered by/for SUS. .

Evaluation of the scattered radiation components produced in a gamma camera using Monte Carlo method

INTRODUCTION: This paper presents a simulation for evaluation of the scattered radiation components produced in a gamma camera PARK using Monte Carlo code SIMIND. It simulates a whole body study with MDP (Methylene Diphosphonate) radiopharmaceutical based on Zubal anthropomorphic phantom, with some spinal lesions. METHODS: The simulation was done by comparing 3 configurations for the detected photons. The corresponding energy spectra were obtained using Low Energy High Resolution collimator. The parameters related with the interactions and the fraction of events in the energy window, the simulated events of the spectrum and scatter events were calculated. RESULTS: The simulation confirmed that the images without influence of scattering events have a higher number of valid recorded events and it improved the statistical quality of them. A comparison among different collimators was made. The parameters and detector energy spectrum were calculated for each simulation configuration with these collimators using 99mTc. CONCLUSION: The simulation corroborated that LEHS collimator has higher sensitivity and HEHR collimator has lower sensitivity when they are used with low energy photons.

The Evaluation of Scattering Effects for Various Source Locations within a Phantom in Gamma Camera / 의학물리

(131)I is a radiological isotope being used widely for treatment of cancer as emitting gamma-ray and it is also applied to estimate the function of thyroid for its accumulation in thyroid. However, (131)I is more difficult to quantitate comapred to (99m)Tc, because (131)I has multiple energy gamma-ray emissions compared to (99m)Tc which is a mono energetic gamma-ray source. Especially, scattered ray and septal penetration resulted by high energy gamma ray have a bad influence upon nuclear medicine image. The purpose of this study was to estimate scatter components depending on the different source locations within a phantom using Monte Carlo simulation (GATE). The simulation results were validated by comparing with the results of real experiments. Dual-head gamma camera (ECAM, Chicago, Illinois Siemens) with high energy, general-purpose, and parallel hole collimators (hole radius: 0.17 cm, septal thickness: 0.2 cm, length: 5.08 cm) was used in this experiment. The NaI crystal is 44.5x59.1 cm in height and width and 0.95 cm in thickness. The diameter and height of PMMA phantom were 16 cm and 15 cm, respectively. The images were acquired at 5 different locations of (131)I point source within the phantom and the images of (99m)Tc were also acquired for comparison purpose with low energy source. The simulation results indicated that the scattering was influenced by the location of source within a phantom. The scattering effects showed the same tendency in both simulation and actual experiment, and the results showed that the simulation was very adequate for further studies. The results supported that the simulation techniques may be used to generalize the scattering effects as a function of a point source location within a phantom.

Survey of Current Status of Quality Control of Gamma Cameras in Republic of Korea / 핵의학분자영상

PURPOSE: It is widely recognized that good quality control (QC) program is essential for adequate imaging diagnosis using gamma camera. The purpose of this study is to survey the current status of QC of gamma cameras in Republic of Korea for implementing appropriate nationwide quality control guidelines and programs. METHODS: A collection of data is done for personnel, equipment and appropriateness of each nuclear medicine imaging laboratory's quality control practice. This survey is done by collection of formatted questionnaire by mails, emails or interviews. We also reviewed the current recommendations concerning quality assurance by international societies. RESULTS: This survey revealed that practice of quality control is irregular and not satisfactory. The irregularity of the QC practice seems due partly to the lack of trained personnel, equipment, budget, time and hand-on guidelines. CONCLUSION: The implementation of QC program may cause additional burden to the hospitals, patients and nuclear medicine laboratories. However, the benefit of a good QC program is obvious that the hospitals can provide good quality nuclear medicine imaging studies to the patients. It is important to use least cumbersome QC protocol, to educate the nuclear medicine and hospital administrative personnel concerning QC, and to establish national QC guidelines to help each individual nuclear medicine laboratory.

Coded Aperture Gamma Camera for Thyroid Imaging: Monte Carlo Simulation / 의학물리

A coded aperture camera has been developed to improve the signal-to-noise ratio (SNR) while keeping the spatial resolution of a pinhole gamma camera. The purpose of this study was to optimize a coded aperture camera and to evaluate its possibility for thyroid imaging by Monte Carlo simulation. A clinical gamma camera, a pinhole collimator with 1.0 mm hole diameter, and a 79x79 modified uniformly redundant array (MURA) mask were designed using GATE (Geant4 Application for Tomographic Emission). The penetration ratio, spatial resolution, integral uniformity and signal-to-noise ratio (SNR) were simulated and evaluated as a function of the mask thickness. The spatial resolution of the coded aperture camera was consistent with the various mask thickness, SNR showed a maximum value at 1.2 mm mask thickness and integral uniformity was improved by increasing mask thickness. Compare to the pinhole gamma camera, the coded aperture camera showed improved SNR by a factor of 30 while keeping almost the same spatial resolution. In this simulation study, the results indicated that high spatial resolution and ultra-high SNR of the thyroid imaging are feasible using a coded aperture camera.

Proposta de metodologia para tratamento individualizado com iodo-131 em pacientes portadores de hipertireoidismo da doença de Graves / Proposal of a methodology for individualized iodine-131 therapy for Graves' disease in patients with hyperthyroidism

OBJETIVO: Diferentes métodos são usados para determinar atividade do radioiodo para tratamento de hipertireoidismo (doença de Graves). Alguns não consideram a dose absorvida pela tireóide ou os parâmetros necessários para este cálculo. A relação entre dose absorvida e atividade administrada depende da meia-vida efetiva, da captação do iodo e da massa da tireóide de cada paciente. O objetivo deste trabalho é propor uma metodologia para tratamento individualizado com 131I em pacientes portadores de hipertireoidismo da doença de Graves. MATERIAIS E MÉTODOS: Usou-se um simulador de tireóide-pescoço desenvolvido no Instituto de Radioproteção e Dosimetria contendo solução de 131I, para calibração da gama-câmara e sonda cintilométrica do Serviço de Medicina Nuclear do Hospital Universitário Clementino Fraga Filho da Universidade Federal do Rio de Janeiro. RESULTADOS: O campo de visão colimador-detector apresentou valores compatíveis com o tamanho da glândula para as distâncias de 25 cm (sonda de captação) e 45,8 cm (gama-câmara). Os fatores de calibração (cpm/kBq) foram 39,3 ± 0,78 e 4,3 ± 0,17, respectivamente. O intervalo entre 14 e 30 horas da curva de retenção permite o cálculo de atividade entre dois pontos, para determinação da meia-vida efetiva do iodo na tireóide. CONCLUSÃO: A utilização de equipamentos usualmente disponíveis em serviços de medicina nuclear é viável, tornando esta metodologia simples, eficaz e de baixo custo.

OBJECTIVE: Several methods are utilized for determining the radioiodine activity in the treatment of Graves' disease (hyperthyroidism). Some of this methods do not take into consideration the thyroid absorbed dose or the necessary parameters for this estimation. The association between absorbed dose and administered activity depends on effective half-life, iodine uptake and thyroid mass of each patient. The present study was aimed at developing a methodology for individualized 131I therapy for Graves' disease in patients with hyperthyroidism of the Graves' disease. MATERIALS AND METHODS: A neck-thyroid phantom developed at Instituto de Radioproteção e Dosimetria, containing a standard solution of 131I, was utilized for calibrating the scintillation gamma camera and uptake probe installed in the Department of Nuclear Medicine of the Hospital Universitário Clementino Fraga Filho da Universidade Federal do Rio de Janeiro. RESULTS: The view angle of the collimator/detector assembly presented values compatible with the thyroid gland size for distances of 25 cm (uptake probe) and 45.8 cm (scintillation gamma camera). Calibration factors were 39.3 ± 0.78 and 4.3 ± 0.17 cpm/kBq, respectively. The 14-30-hour interval in the retention curve allows the estimation of activity between two points for determining the effective iodine half-life in the thyroid. CONCLUSION: The utilization of equipment usually available in nuclear medicine clinics is feasible, so this is a simple, effective and low cost methodology.

Voxel-based investigations of regional cerebral blood flow abnormalities in Alzheimer's disease using a single-detector SPECT system

PURPOSE: To evaluate the feasibility of using the Statistical Parametric Mapping (SPM) program for an automated, voxel-by-voxel assessment of regional cerebral blood flow (rCBF) deficits in Alzheimer's disease (AD) subjects relative to age-matched controls studied with a conventional, single-detector SPECT system. METHODS: We used a databank of 99mTc-HMPAO images of 19 patients with a diagnosis of probable AD and 15 elderly healthy volunteers; data were acquired using an Orbiter-Siemens single-detector SPECT system. Using SPM, images were transformed spatially, smoothed (12mm), and the data were compared on a voxel-by-voxel basis with t-tests. RESULTS: There were significant rCBF reductions in AD patients relative to controls involving regions predicted a priori to be affected in AD, namely the left temporal and parietal neocortices, and the right posterior cingulate gyrus (p<0.05, corrected for multiple comparisons). DISCUSSION: The location of rCBF reductions in AD subjects in our study is consistent with the deficits detected in previous functional imaging studies of AD using higher-resolution devices. This suggests the potential usefulness of using SPM for the analysis of data acquired with single-detector SPECT systems, despite the limited sensitivity and spatial resolution of such equipment.

OBJETIVO: Avaliar a viabilidade de emprego do programa Statistical Parametric Mapping (SPM) para investigar de forma automatizada, voxel-a-voxel, a presença de déficits de fluxo sanguíneo cerebral regional (FSCr) em pacientes com doença de Alzheimer (DA) comparados a sujeitos-controle pareados para idade, usando imagens de SPECT adquiridas com um equipamento convencional de detector único. MÉTODOS: Foi utilizado um banco de imagens adquiridas após injeção de 99mTc-HMPAO em 19 pacientes com diagnóstico provável de DA e 15 voluntários idosos saudáveis, usando um equipamento de SPECT Orbiter-Siemens de detector único. Empregando o programa SPM, as imagens foram transformadas espacialmente, suavizadas (12mm FWHM), e comparadas estatisticamente voxel-a-voxel entre os dois grupos, usando o teste de T. RESULTADOS: Foram identificadas reduções significativas de FSCr nos pacientes com DA comparados aos controles em regiões previstas a priori como afetadas por esta forma de demência, quais sejam os neocórtices temporal e parietal em hemisfério esquerdo e o cíngulo posterior direito (p<0,05, corrigido para comparações múltiplas). DISCUSSÃO: A localização dos focos de redução de FSCr em pacientes com DA no nosso estudo é, de forma geral, consistente com os achados de déficits cerebrais detectados em estudos anteriores de neuroimagem funcional na DA realizados com equipamentos de resolução espacial mais alta. Isto sugere o potencial de utilidade do programa SPM para a análise de dados de SPECT adquiridos com equipamentos de detector único, apesar da sensibilidade e resolução espacial limitadas de tais aparelhos.

Folate Receptor Targeted Imaging Using Poly (ethylene glycol)-folate: In Vitro and In Vivo Studies

The aim of this study was to ascertain the folate receptor (FR) targetability by an in vitro study and to acquire FR-targeted images in vivo models by using synthetic folate conjugates. PEG-folate was synthesized and labeled with (99m)Tc and fluorescein isothiocynate (FITC). Cell uptake studies were carried out in KB cells (FR-positive) and A549 cells (FR-negative) using FITC- and the (99m)Tc-labeled conjugates. The radiolabeled conjugate was intravenously injected to KB tumor xenografted mice. After it was injected, gamma images were recorded at 30 min, 1, 2, 3 and 4 hr. Cell uptake studies showed a difference between the KB cells and the A549 cells by flow cytometry analysis and gamma counting. On in vivo images, the tumor-tonormal muscle ratio was greater than 4. It ascertained that the PEG-folate conjugate specifically binds to the FR expressed on tumor cells in vitro. Moreover, it was possible to acquire the FR-targeted gamma images using PEG-folate conjugates in tumor models.

Development of Program for Renal Function Study with Quantification Analysis of Nuclear Medicine Image / 대한핵의학회잡지

PURPOSE: In this study, we developed a new software tool for the analysis of renal scintigraphy which can be modified more easily by a user who needs to study new clinical applications, and the appropriateness of the results from our program was studied. MATERIALS AND METHODS: The analysis tool was programmed with IDL5.2 and designed for use on a personal computer running Windows. For testing the developed tool and studying the appropriateness of the calculated glomerular filtration rate (GFR), 99mTc-DTPA was administered to 10 adults in normal condition. In order to study the appropriateness of the calculated mean transit time (MTT), 99mTc-DTPA and 99mTc-MAG3 were administered to 11 adults in normal condition and 22 kidneys were analyzed. All the images were acquired with ORBITOR, the Siemens gamma camera. RESULTS: With the developed tool, we could show dynamic renal images and time activity curve (TAC) in each ROI and calculate clinical parameters of renal function. The results calculated by the developed tool were not different statistically from the results obtained by the Siemens application program (Tmax: p=0.68, Relative Renal Function: p=1.0, GFR: p=0.25) and the developed program proved reasonable. The MTT calculation tool proved to be reasonable by the evaluation of the influence of hydration status on MTT. CONCLUSION: We have obtained reasonable clinical parameters for the evaluation of renal function with the software tool developed in this study. The developed tool could prove more practical than conventional, commercial programs.

Investigation of the Signal Characteristics of a Small Gamma Camera System Using NaI(Tl)-Position Sensitive Photomultiplier Tube / 대한핵의학회잡지

PURPOSE: We characterized the signals obtained from the components of a small gamma camera using NaI(Tl)-position sensitive photomultiplier tube (PSPMT) and optimized the parameters employed in the modules of the system. MATERIALS AND METHODS: The small gamma camera system consists of a NaI(Tl) crystal (60x60x6 mm3) coupled with a Hamamatsu R3941 PSPMT, a resister chain circuit, preamplifiers, nuclear instrument modules (NIMs), an analog to digital converter and a personal computer for control and display. The PSPMT was read out using a resistive charge division circuit which multiplexes the 34 cross wire anode channels into 4 signals (X+, X-, Y+, Y-). Those signals were individually amplified by four preamplifiers and then, shaped and amplified by amplifiers. The signals were discriminated and digitized via triggering signal and used to localize the position of an event by applying the Anger logic. The gamma camera control and image display was performed by a program implemented using a graphic software. RESULTS: The characteristics of signal and the parameters employed in each module of the system were presented. The intrinsic sensitivity of the system was approximately 8x103 counts/sec/microcurie. The intrinsic energy resolution of the system was 18% FWHM at 140 keV. The spatial resolution obtained using a line-slit mask and 99mTc point source were, respectively, 2.2 and 2.3 mm FWHM in X and Y directions. Breast phantom containing 2~7 mm diameter spheres was successfully imaged with a parallel hole collimator. The image displayed accurate size and activity distribution over the imaging field of view. CONCLUSION: We proposed a simple method for development of a small gamma camera and presented the characteristics of the signals from the system and the optimized parameters used in the modules of the small gamma camera.

Development of a Small Gamma Camera Using NaI ( T1 ) - Position Sensitive Photomultiplier Tube for Breast Imaging / 대한핵의학회잡지

PURPOSE: The conventional gamma camera is not ideal for scintimammography because of its large detector size ( 500 mm in width) causing high cost and low image quality. We are developing a small gamma camera dedicated for breast imaging. MATERIALS AND METHODS: The small gamma camera system consists of a NaI (Tl) crystal (60 mm X60 mm X6 mm) coupled with a Hamamatsu R3941 Position Sensitive Photomultiplier Tube (PSPMT), a resister chain circuit, preamplifiers, nuclear instrument modules, an analog to digital converter and a personal computer for control and display. The PSPMT was read out using a standard resistive charge division which multiplexes the 34 cross wire anode channels into 4 signals (X, X, Y, Y ). Those signals were individually amplified by four preamplifers and then, shaped and amplified by amplifiers. The signals were discriminated and digitized via triggering signal and used to localize the position of an event by applying the Anger logic. RESULTS: The intrinsic sensitivity of the system was approximately 8,000 counts/.'ec/pCi. High quality flood and hole mask images were obtained. Breast phantom containing 2-7 mm diameter spheres was successfully imaged with a parallel hole collimator. The image displayed accurate size and activity distribution over the imaging field of view. CONCLUSION: We have succesfully developed a small gamma camera using NaI(T1)-PSPMT and nuclear instrument modules. The small gamma camera developed in this study might imprnve the diagnostic accuracy of scintimammography by optimally imaging the breast.

Real-time energy correction in digital gamma camera / 医疗卫生装备

This paper introduces the generating principle of energy correction table for digital gamma camera and elaborates a method for real-time energy correction. According to the position information of the collected events, correction cells are determined. With the correction value in four adjacent correction cells, coefficient of energy correction is worked out through bilinear interpolation. Finally, real-time energy correction for the collected events is achieved through software programming.

Application of Renal Gamma Camera in the Evaluation of Renal Disease / 대한비뇨기과학회지

Excretory urography is the procedure most commonly used to evaluate the upper urinary tract in urologic patients. The excretory urogram provides an excellent evaluation of anatomic changes in the kidney, but is a poor indicator of renal function. Renal gamma camera using radionuclide is a simple and non-invasive method for evaluation of renal function in renal disease. The excretory urogram and renal gamma camera were discussed comparing to 43 cases of severe abnormal anatomic changes in excretory urogram and 4 cases of contraindication of excretory urogram. The results obtained were as follows. 1. Non-visualization in excretory urogram were 19 cases and 6 cases were maintained renal function. Renal gamma camera was superior to excretory urogram in evaluating renal function. 2. 20 cases were hydronephrotic kidney and 14 (70%) cases were maintained good function in renal gamma camera. 3. Renal gamma camera provided better information about total and differential renal function than excretory urogram and creatinine clearance in bilateral renal disease. 4. Renal gamma camera was a safe and non-invasive method in the evaluation of the upper urinary tract, when excretory urogram was contraindicated.