Rozprawy doktorskie na temat „Nuclear medicine”

Nuclear medicine images are degraded by blurring caused by the gamma camera system response function and the inherent Poisson noise of radioactivity. Well known digital filters proposed for the restoration of these images have been investigated in this thesis. Particularly, Metz filter and a two-step filter have been extensively studied by the FROC methodology. The effectiveness and practical limitations of the FROC methodology in the assessment of nuclear medicine images have also been investigated. It was observed from the results that the closeness of test patterns to the real clinical cases was a crucial factor for a successful assessment. Therefore, a method to simulate clinical bone scans with focal abnormalities at a given depth has been developed in this thesis. A binormal model is used for the analysis of the FROC and AFROC results. A method has been developed in this thesis to determine the parameters that completely specify the binormal model. Using this method it has been shown in this work that the two-step filter may be useful in detecting focal abnormalities from complicated structures such as bone scans at strict criteria. It also has been observed in this work, that the Metz filter is useful for the detection of focal abnormalities in flat noise fields, but not in complicated structures such as bone scans.

Patient motion either internal (organ motion) or external (body movement) can produce artefacts that can adversely affect nuclear medicine imaging. Motion artefacts can impair diagnostic information and potentially affect the image findings and prognosis for patients. The goal of this work was to investigate the effect of motion on nuclear medicine imaging and to improve image quality, lesion detectability, and tumour volume delineation by applying motion correction techniques. To investigate the effects of motion under controlled simulated conditions, a three dimensional phantom drive system was designed and constructed suitable for use with planar, SPECT, PET and CT scanners. The system was used with a range of nuclear medicine phantoms for testing proof of principle with planar, SPECT and PET imaging prior to undertake further work involving patients. Planar phantom and patient 99mTc_DMSA studies demonstrated improvements in image quality by the application of motion correction techniques. A comparison between the motion correction software using dynamic frame and list mode data showed that "MOCO" software with the use of the list mode data produced the best quantification results with phantom data, whereas determining the best approach was more difficult with patient data. The potential of using list mode data as an improved method of combining data into frames for subsequent analysis was demonstrated. Motion correction techniques would appear to offer great potential in lung imaging. Respiratory gated SPECT phantom studies have been carried out to simulate the visualisation of small defects in the lung. The CNRs and alternative free response receiver operating characteristic (AFROC) analysis have demonstrated that summing the gated data after the application of motion correction software significantly improved image quality, observer confidence and small defect detectability (less than 20 mm, p=O.0002). The results of these studies have shown the promising role of "MCFLIRT" software as a motion correction tool with gated SPECT data. Tumour volume delineation was investigated on PET images both with and without motion. The accuracy and consistency of the gradient-based software method for segmentation in PET images, which is commercially available from Mimvista Ltd was investigated. The results of comparing the measured volumes to the true volumes indicated significant differences (p=O.0005). It was found that the Signal:Background ratio and registering the PET to the CT data have significant effects on volume measurements, whereas, the effect of using different grey scale and plane of orientation were not found to have significant effects on the volume measurement. Motion correction techniques also showed to be potentially beneficial in PET imaging. Improvement in volume measurement as a result of summing the motion corrected gated data was demonstrated. The results of these studies have also shown the promising role of "MCFLIRT" as a motion correction tool with gated PET data.

The application of image processing techniques to radionuclide images acquired on a gamma camera - computer system has been investigated. Hepatic perfusion imaging studies with 99TcID-tin colloid were performed in patients with primary colorectal carcimma. The hepatic perfusion index perform~ poorly in the detection of those patients with occult or overt hepatic metastastes, as did mean transit times of liver colloid flow derived from deconvolution analysis. A discriminant function was developed which separated those patients with occult metastases from those without liver disease. A fully automatic algorithm to derive a left ventricular edge from each frame of an ECG gated cardiac blood pool study was developed and validated in patient studies. Left ventricular ejection fractions calculated from count rates within the edge were reproducible and correlated well with ejection fractions derived from the same images by a manual technique, and with ejection fractions derived from left ventricular cineangiography. Studies were performed in patients to evaluate the effectiveness of tomographic imaging of the myocardial perfusion imaging agent 99TcID-tBIN for detection of ischaemic heart disease. TOmographic reconstructions in the planes of the axes of the left ventricle gave better results than transaxial reconstructions or planar imaging. Choice of the optimum reconstruction filter for use in tomography using 99Tdffi-tBIN was examined by means of patient am phantom studies. These showed that more accurate diagnoses and better reconstructions were obtained with smoothing filters than by the use of sharp reconstruction filters. This work shows that optimum image processing techniques must be established to attain the best possible results with new radiopharmaceuticals for nuclear medicine investigations.

Semiconductor-based gamma-ray-imaging detectors are under development for use in high-resolution nuclear medicine imaging applications. These detectors, based on cadmium zinc telluride, hold great promise for delivering improved spatial resolution and detection efficiency over current methods. This dissertation presents work done on three fronts, all directed toward enhancing the practicality of these imaging devices. Electronic readout systems were built to produce gamma-ray images from the raw signals generated by the imagers. Mathematical models were developed to describe the detection process in detail. Finally, a method was developed for recovering the energy spectrum of the original source by using maximum-likelihood estimation techniques. Two electronics systems were built to read out signals from the imaging detectors. The first system takes signals from a 48 x 48-pixel array at 500 k samples per second. Pulse-height histograms are formed for each pixel in the detector, all in real time. A second system was built to read out four 64 x 64 arrays at 4 million pixels per second. This system is based on digital signal processors and flexible software, making it easily adaptable to new imaging tasks. A mathematical model of the detection process was developed as a tool for evaluating possible detector designs. One part of the model describes how the mobile charge carriers, which are released when a gamma ray is absorbed in a photoelectric interaction, induce signals in a readout circuit. Induced signals follow a "near-field effect," wherein only carriers moving close to a pixel electrode produce significant signal. Detector pixels having lateral dimensions that are small compared to the detector thickness will develop a signal primarily due to a single carrier type. This effect is confirmed experimentally in time-resolved measurements and with pulse-height spectra. The second part of the model is a simulation of scattering processes that take place when a gamma ray is absorbed within the detector volume. A separate simulation predicts the spreading of charge carriers due to diffusion and electrostatic forces. The models are used in a technique to improve the energy resolution of the detectors by estimation of the source spectrum using the Expectation-Maximization algorithm.

Dose as a result of radiation exposure is the notion generally used to disclose the imparted energy in a volume of tissue to a potential biological effect. The basic unit defined by the international system of units (SI system) is the radiation absorbed dose, which is expressed as the mean imparted energy in a mass element of the tissue known as "gray" (Gy) or J/kg. The procedure for ascertaining the absorbed dose is complicated since it involves the radiation transport of numerous types of charged particles and coupled photon interactions. The most precise method is to perform a full 3D Monte Carlo simulation of the radiation transport. There are various Monte Carlo toolkits that have tool compartments for dose calculations and measurements. The dose studies in this thesis were performed using the GEANT4 Application for Emission Tomography (GATE) software (Janet al., 2011) GATE simulation toolkit has been used extensively in the medical imaging community, due to the fact that it uses the full capabilities of GEANT4. It also utilizes an easy to-learn GATE macro language, which is more accessible than learning the GEANT4/C++ programming language. This work combines GATE with digital phantoms generated using the NCAT (NURBS-based cardiac-torso phantom) toolkit (Segars et al., 2004) to allow efficient and effective estimation of 3D radiation dose maps. The GATE simulation tool has developed into a beneficial tool for Monte Carlo simulations involving both radiotherapy and imaging experiments. This work will present an overview of absorbed dose of common radionuclides used in nuclear medicine and serve as a guide to a user who is setting up a GATE simulation for a PET and SPECT study.

Siemens Corporate Technology New Technology Fields Healthcare & Technology Concepts (CT NTF HTC) have proposed a novel electrostatic accelerator for nuclear medicine which aims at gradients of up to 10 MV m^-1. With beam currents of 100 μA at ≈10 MeV it might replace cyclotrons whilst being simpler, more reliable and more cost effective. The accelerator concept consists of concentric hemispherical metallic shells spaced by insulators and placed in a vacuum system. The shells are interconnected by high voltage diodes so that they form a voltage multiplier with its highest voltage in its centre. Particle beams can be accelerated towards the centre through a set of holes in the shells. In tandem mode, with a stripper in the centre and a negative ion source as injector, beams of twice the centre voltage can be achieved. This thesis presents several commissioning milestones of a test system for the novel electrostatic accelerator, thus validating the concept for commercial applications. An inter shell insulator has been designed and successfully tested to fields of 12 MV m^-1. A diode protection concept has been devised and validated in realistic breakdown scenarios. An AC drive system including control software has been developed, delivering a sinusoidal input voltage of up to 140 kV peak to peak at 80 kHz. An automatic process to carefully commission the high voltage system in vacuum has been created, implemented in a control system and successfully operated. A 4-shell prototype with these components has been successfully tested with achieved gradients of up to 5.5 MV m^-1. A negative hydrogen ion source has been constructed, commissioned and characterised with a purposely developed wire grid. Beam currents beyond 200 μA have been achieved. Beam transport from the ion source through the 7-shell system has been demonstrated in simulations which are based on experimental data from the ion source characterisation. A stripper system has been designed and constructed.

The imaging process can be thought of as the acquisition of data and the processing and display of data. The image quality of the acquired data is assessed using objective methods. The spatial transfer characteristic was measured using the MTF, and the noise properties assessed using Wiener spectra for gamma camera and film-screen systems. An overall measure of image quality, noise equivalent quanta, can then be calculated. The image quality of the displayed data is assessed using subjective methods. Contrast detail test objects have been used for film-screen systems and forced choice experiments for nuclear medicine data. The Wiener spectrum noise measurement has been investigated as a measure of uniformity. Simulated and gamma camera flood images were produced. Observer tests were carried out to give a contrast at which the non-uniform flood images could be distinguished from the uniform flood images. Wiener spectra were produced and single number indices derived. Statistical tests were performed to determine the contrast at which the uniform and non-uniform Wiener spectra can be distinguished. Results showed that Wiener spectra measurements can be used as a measure of uniformity under certain conditions. The application of resolution and noise measurements to the evaluation of film-screen systems and radiographic techniques has been considered. The results follow the trends presented in the literature. Provided that the scanning equipment is available tests on film-screen systems are practical to perform and are an important addition to other evaluation tests. Results show the ideal observer approach of measuring the resolution, noise and hence noise equivalent quanta, is a practical method of assessing image quality in a hospital environment.

Topographic classification is a nonlinear technique used to enhance nuclear medicine images for tumor detection. Second-order directional derivatives are computed at each pixel location after performing a least-squares fit of the underlying surface using a bivariate cubic polynomial. The eigenvalues and their corresponding eigenvectors computed from the Hessian matrix determine which topographic feature is assigned to the image pixel. Parameter selection for the mask size, curvature threshold, and angle thresholds are chosen to yield the "best" classified image. The classifier is applied to clinical images of cancer patients provided by the Department of Nuclear Medicine at the University of Arizona. Background noise associated with the photon-starved data is suppressed using a Difference-of-Gaussians (DOG) filter prior to pixel classification. Results indicate the feasibility of using this technique to isolate possible tumor sites which will assist the clinician during patient examination.

Amb la revolució de la tecnologia digital d’obtenció d’imatges radiològiques i l’increment de la potència computacional, el camp de la quantificació d’imatges mèdiques ha sorgit. El fet de poder programar un ordinador per a que detecti patrons d’interès en imatges radiològiques i pugui derivar-ne d’aquests indicadors numèrics amb valor clínic fa que, sens dubte, aquest àmbit de coneixement tingui un gran potencial en entorns mèdics i de recerca. En aquesta tesi es presenten un conjunt de contribucions científiques en aquest context. En particular, es descriu el disseny i la implementació d’una sèrie d’estratègies computacionals de quantificació d’imatges de medicina nuclear i neuroradiologia. A continuació es detalla com aquestes tècniques han demostrat ser d’utilitat per a l’estudi de malalties molt rellevants en l’actualitat com són el càncer de mama, el limfoma no-Hodgkin, la pielonefritis, la malaltia d’Alzheimer, la malaltia de Parkinson i l’abús de cànnabis.
Con la revolución de la tecnología digital de obtención de imágenes radiológicas y el aumento de la potencia computacional, el campo de la cuantificación de imágenes médicas ha emergido. El hecho de poder programar un ordenador para que detecte patrones de interés en imágenes radiológicas y pueda derivar de ellos una serie de indicadores numéricos con valor clínico hace que, sin duda, este ámbito de conocimiento tenga un gran potencial en el entorno médico y de investigación. En esta tesis se presentan un conjunto de contribuciones científicas en este contexto. En particular, se describe el diseño y la implementación de una serie de estrategias computacionales de cuantificación de imágenes de medicina nuclear y neuroradiología. A continuación se detalla cómo estas técnicas han demostrado ser de utilidad en el estudio de patologias muy relevantes en la actualidad como son el cáncer de mama, el linfoma no-Hodgkin, la pielonefritis, la enfermedad de Alzheimer, la enfermedad de Parkinson i el abuso de cánnabis.
With the revolution of digital medical imaging and the increasing computational power, the field of quantitative medical image analysis emerged. By programming a computer to detect patterns of interest in medical images and derive clinically meaningful numerical indicators from them, this field shows promising potential for healthcare and medical research systems. In this thesis, the design and implementation of computer-based quantification techniques in nuclear medicine and neuroradiological images led to several contributions in this field. These image-derived indicators contributed to complement the visual diagnosis and to further understand the pathophysiology of important health issues such as breast cancer, non-Hodgkin lymphoma, pyelonephritis, Alzheimer’s disease, Parkinson’s disease and cannabis abuse.

The main purpose of LARAMED project (LAboratoty of Radioisotopes for MEDicine), founded at LNL-INFN, is the R&D on cyclotron production of conventional, such as Tc-99m (TECHN-OSP projects), and emerging, such as Cu-67 (COME project), metallic medical radioisotopes. The aim of my PhD has been the development, optimization and automation of post-irradiation target processing systems, enabling to recover in high yield highly pure radioisotopes (RI), one of the most critical steps in the RI cyclotron production. The possibility of a reactor-produced molybdenum-99 shortage, used as parent nuclide of in 99Mo/99m Tc generators, is still a potential scenario. The direct cyclotron-production of Tc-99m through the (p,2n) reaction on a Mo-100 target seemed to be a reliable solution. In the framework of TECHN-OSP project, a technology for enabling the in-hospital cyclotron self-production of Tc-99m, in order to afford the availability of the most used radiometal in diagnostic applications in case of shortages, has been developed. The Tc-99m cyclotron-production optimization included the design of a solid target, the development of an automatic module for target processing and enriched target material recovery study. In this thesis, the description of Tc-99m production experiments, performed in collaboration with the Sant’Orsola Hospital in Bologna, and the development of the automatic module for target processing, are well detailed. During my PhD I had the opportunity to collaborate with the Canadian research group at TRIUMF (Vancouver, CA), also working on Tc-99m cyclotron-production, by contributing at the optimization and automation of molybdenum target dissolution and purification procedure of cyclotron-produced Tc-99m. In this thesis a comparison between the two developed, Italian and Canadian, target processing setup is also reported. Alongside that, I have collaborated to COME project whose purpose is the evaluation of the cyclotron production efficiency of Cu-67, a particularly interesting RI for its application in “theranostics”. The large scale cyclotron-production of this RI is still a poorly studied key point. In order to define the Cu-67 best cyclotron-production route, we focused our attention on unknown cross-section measurement of nuclear reactions on a Zn-70 target (35-70MeV energy range). Essential for this project was the development and optimization of a high yield separation and purification procedure of Cu-67 from the Zn-70 bulk and the co-produced Ga-67 contaminant that, having the same γ-lines of Cu-67 (both decay to Zn-67 with similar half-lives), poses a serious issue for the determination of the activity of Cu-67. The description of the experiments, performed in collaboration with ARRONAX, is reported in this thesis. Finally, the clinical needs of larger amount of the PET radiometal generator-produced Ga-68 prompted TRIUMF Life Sciences division to investigate Ga-68 cyclotron-production from liquid target since it is based on the existing medical-cyclotron network and technology. This technique will improve the availability of Ga-68 in hospitals housing an appropriate cyclotron by making them independent self-producers. Since the major problem affecting liquid targets is the contamination with radioactive/stable metals (e.g. iron) coming from the dissolution of some material from vacuum isolation or target body components during the irradiation, a separation and purification procedure together with a semi-automatic system, particularly focused on the purification of Ga-68 from Zn and Fe, have been developed. The main purpose is to obtain a final product suitable for medical use and to enable radiolabeling and in-vivo imaging studies with cyclotron produced 68Ga-DOTATOC.
Il progetto LARAMED (LAboratoty of Radioisotopes for MEDicine), fondato presso i LNL-INFN, ha come scopo l’R&D per la produzione da ciclotrone di radioisotopi metallici convenzionali, come il Tc-99m (progetto TECHN-OSP, ed emergenti, come il Cu-67 (progetto COME), per uso medicale. L'obiettivo del mio dottorato di ricerca è stato lo sviluppo, ottimizzazione e automazione di sistemi di processamento dei target irraggiati al fine di estrarre, in alta resa e purezza, il radioisotopo (RI) di interesse, uno dei passaggi più critici nella produzione da ciclotrone dei RI per la medicina. La possibilità di un’ulteriore crisi di produzione da reattori nucleari di Mo-99, nuclide genitore nei generatori Mo-99/Tc-99m, è ancora uno scenario possibile. La produzione diretta di Tc-99m da ciclotrone per mezzo della reazione nucleare Mo-100(p,2n) sembra essere una soluzione alternativa affidabile. Nell’ambito del progetto TECHN-OSP è stata sviluppata una tecnologia in grado di rendere le radiofarmacie delle Medicine Nucleari, che ospitano un ciclotrone appropriato, indipendenti nella produzione di Tc-99m al fine di sopperire ad ogni eventuale carenza nell’approvvigionamento dei generatori. L’ottimizzazione della produzione ha previsto la progettazione di un target, lo sviluppo di un modulo automatico per il processamento del target e lo studio del recupero del materiale arricchito costituente il target stesso. In questa tesi sono descritti i test di produzione di Tc-99m, eseguiti in collaborazione con l'ospedale Sant'Orsola di Bologna, ed in particolare lo sviluppo di un modulo automatico di processamento del target. Nel corso del dottorato, ho avuto l'opportunità di collaborare con il gruppo di ricerca canadese al TRIUMF (Vancouver, CA), anch’esso coinvolto nell’ottimizzazione della produzione di Tc-99m da ciclotrone, contribuendo all'ottimizzazione e automazione delle procedure di dissoluzione e purificazione di Tc-99m da target di Mo-100. In questa tesi viene anche riportato un confronto tra i due sistemi di processamento target da me sviluppati, in Italia e in Canada. Parallelamente ho collaborato al progetto COME il cui obiettivo risiede nella valutazione dell'efficienza di produzione di Cu-67 da ciclotrone, RI particolarmente interessante per le sue applicazioni in “teranostica”. La produzione da ciclotrone su larga scala di questo RI è ancora un punto chiave scarsamente studiato. Al fine di definire la migliore via di produzione di Cu-67, abbiamo focalizzato l’attenzione su misure di sezioni d’urto inedite (target Zn-70, protoni incidenti di energie 35-70MeV). Essenziale per questo progetto è stato lo sviluppo di un processo altamente efficiente di separazione di Cu-67 dal target e dal Ga-67, coprodotto che, avendo le stesse linee γ del Cu-67, crea problemi nella determinazione dell'attività di Cu-67. La descrizione degli esperimenti, eseguita in collaborazione con ARRONAX, è riportata in questa tesi. Infine, le esigenze cliniche di una maggiore quantità di Ga-68, RI PET attualmente prodotto da generatore Ge-68/Ga-68, hanno spinto il gruppo di ricerca del TRIUMF a studiare la produzione di Ga-68 da ciclotrone a partire da un target liquido di Zn-68, al fine di migliorare la disponibilità di Ga-68 negli ospedali che ospitano un ciclotrone appropriato rendendoli produttori indipendenti. Poiché il problema principale che colpisce la produzione da target liquido è la contaminazione da metalli (es. Fe) provenienti dalla degradazione di alcuni componenti del corpo del target, è stata sviluppata una procedura di separazione e purificazione del Ga-68 da Zn e Fe. Lo scopo principale è quello di ottenere un prodotto finale adatto all’uso medico e di consentire la radio-marcatura di (Ga-68)-DOTATOC e studi di imaging in vivo con Ga-68 prodotto da ciclotrone.

The lung has been satisfactorily modelled as a fractal, and change in lung structure due to disease is assumed to change the fractal dimensionality of the lung. It is hypothesized that those changes in fractal dimension affect perceptually relevant elements (perceived texture) of the lung, and therefore the fractal dimension may prove to be a predictor of diagnosis. If the fractal dimensionality reflects structure in ways more accurately reflecting changes in lung structure than can be achieved by nuclear medicine physicians, then it may also prove useful as a diagnostic tool. Fractal dimension is linearly related to the slope of the power spectrum (SPS) as plotted on log-log paper, and the SPS was used as the metric reflecting the fractal dimension. Seventy-two cases were selected that were either normal, had congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), or pulmonary embolism (PE). Five of the cases had both CHF and COPD. The lung scans from these cases were digitized, with appropriate corrections for linearization, edge artifacts, target nonuniformities and film gamma. Fast Fourier Transforms provided the power spectrum from which the SPS was calculated. Four nuclear medicine physicians read the original lung scans and rated their certainty about the presence of two texture elements, the extensiveness of disease involvement, and presence of the three diseases used (CHF, COPD, and PE). The results found the SPS to be significantly related to both texture ratings and diagnostic certainty, but inferior as a predictor of disease to either texture rating or diagnostic certainty. This study reveals the SPS to be a promising but incomplete candidate for machine-algorithm generated diagnosis.

Nuclear Quadrupole Resonance (NQR) is a radio-frequency (RF) spectroscopic technique, that allows the detection of solid-state compounds containing quadrupolar nuclei; a property of the majority of pharmaceutical products. This thesis investigates the application of NQR in medicines authentication, where accurate \ fingerprints" of the examined materials must be obtained, in response to the global threat of low quality and counterfeit medicines. In practice, a complete NQR system contains a database with profiles of commercial medicines, built using characteristic features of the NQR signals. However, several issues including the weak NQR signals, prolonged measurement times and the evident variability among medicines can influence the accuracy of the profiles and limit the current use of NQR in the field. The expected signal amplitude is often affected by the uncertainty regarding the compound's temperature, which may cause the signalto- noise ratio (SNR) to be substantially reduced; this phenomenon is commonly known as o -resonance effects. An extended echo-train signal data model is introduced, which exploits the dependence of the signal amplitude on the o -resonance excitation frequency and temperature. Herein, the Cramer-Rao lower bound, able to efficiently determine conditions for optimised detection, is derived. The stability and degradation of medicines is influenced by several factors. Being able to determine the variability between medicines produced by the same manufacturer is crucial in medicines authentication. Herein, the investigation of batch-to-batch variability of analgesic paracetamol of the same producer is presented, with the findings pointing out the need for long term monitoring of a product's \ fingerprint". Last, a study is presented that focuses on versatile methodologies which can reduce the measurement times by identifying limits in the accuracy of the estimation parameters. The results indicate that these proposed solutions can help optimising the utility of the applied signal processing method.

Background: Single photon emission computed tomography (SPECT) with dopamine transporter (DAT) and dopamine D2 receptor (D2R) ligands can visualise the integrity of the nigrostriatal dopamine system. Parkinson’s disease (PD) and the atypical parkinsonian diseases (APD), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), have similar symptoms and dopamine depletion, but differ in pharmacological response and prognosis. Clinical differentiation between PD and APD is often difficult in the early stages. The aims of the thesis were to evaluate the differential diagnostic and prognostic value of SPECT in early PD, MSA and PSP, to map the pattern of progression with dopamine SPECT, and map the pattern of dopamine SPECT in non-affected elderly volunteers with a prospective approach. Also, we evaluated the methodological aspects of dopamine SPECT with respect to image evaluation tools, reconstruction parameters and gamma cameras. Methods: 172 patients, included in an on-going clinical prospective study on idiopathic parkinsonism, participated in the SPECT study. Also, 31 age-matched healthy controls (HC) were followed within this study. SPECT was done with 123I-FP-Cit (DAT SPECT) and 123I-IBZM (D2R SPECT). Regions of interest (ROI) were used as a standard method for semi-quantitative image analysis. Results: SPECT uptake ratios from different gamma cameras could be equalised through correction equations derived from images of a brain-like phantom, provided that attenuation correction was applied. The ROI method had high reproducibility. SPECT uptake  in HC, measured with the ROI method and a volume based (VOI) method rendered similar trends, but gender and age differences in SPECT uptake were more marked with the VOI method, and less pronounced in DAT SPECT compared to D2R SPECT with both methods. The DAT SPECT uptake was significantly reduced in very early disease stage of PD and APD compared to HC. DATSPECT uptake was more reduced in PD with postural and gait disturbance (PIGD) compared to tremor-dominant PD. Decline in DAT SPECT uptake during the first year was more pronounced in PD and PSP compared to HC. D2R SPECT uptake overlapped between untreated PD and APD. After initiated treatment, the D2R SPECT uptake was significantly higher in MSA patients compared to PD, PSP and HC. Decline in D2R SPECT uptake during the first year was not significantly different between patients or compared to HC. Conclusions: 123I-FP-Cit SPECT is a valuable and sensitive method to detect early stage idiopathic parkinsonism. A different level of uptake between PIGD-PD compared to TD-PD indicates a prognostic potential. It is not possible to differ between PD, MSA and PSP in early stage with 123I-FP-Cit SPECT and no differential diagnostic value was found using 123I-IBZM SPECT in the early, untreated stage of PD, MSA and PSP. A different pattern of uptake of this ligand in MSA compared to PD and PSP during the first years of L-dopa treatment may, however, indicate a diagnostic value during the follow-up period.

Nuclear medicine imaging using a gamma camera is a sensitive tool for mapping various physiological and biological processes in vivo. In some respects, the instrumentation for gamma-ray imaging is highly developed. Nevertheless, current technology in nuclear medicine has some significant limitations in the area of spatial resolution. Scintillator-based imaging systems most likely have reached their limits of spatial resolution. Achieving higher spatial resolution will require the use of semiconductor detectors. The first part and major focus of this dissertation is the development of a prototype imaging system based on modular CdZnTe semiconductor arrays. Each modular array is approximately 1.5 mm thick, and is patterned on one surface into a 64 x 64 array of pixels with 380-micron pitch. We present details of the design, the electronics, and system performance. The second part of this dissertation presents results on a coincidence-type surgical probe. The sensitivity of a surgical probe for tumor detection is often limited by spatial variations in radiotracer uptake in normal tissue. We are developing a probe for use with 111In that uses coincidences between the 171 keV and 245 keV gamma rays for background suppression. The performance of a coincidence probe was compared to that of single-gamma probe for the task of detecting radiolabeled tumor models in a water phantom containing an inhomogeneous background. A single-element NaI(Tl) probe was placed in random locations throughout the tank; the tumor was attached to the probe in half of the trials. Count data were recorded in three channels: 171 keV, 245 keV, and 416 keV. A linear discriminant was calculated from the data. The detectability index, d', was derived from the data and used to compare the optimal linear discriminant against the single-gamma energy peaks for counting times up to 30s. For a realistic 15s exposure time, d' for the linear discriminant attains a near-perfect value of 3. In contrast, the single-photon channel d' is always near zero, so this channel is worthless for background discrimination. Coincidence detection using linear discriminants shows promise for in vivo tumor localization with 111In-labelled radiopharmaceuticals.

El uso de los ordenadores en Medicina Nuclear ha permitido la cuantificación de exploraciones, sobre todo las dinámicas. Debido a la gran cantidad de información presente en estos estudios es preciso efectuar una compresión de estos datos, de forma que hagan más fácil su interpretación. Una de las formas de reducción consiste en la obtención de imágenes paramétricas. El objetivo de este trabajo se centra en analizar la utilidad de estas imágenes paramétricas para la cuantificación de estudios dinámicos en tres aplicaciones. La primera aplicación es en los estudios de perfusión miocárdica que se utilizan para evaluar la irrigación del miocardio cuando se sospecha la existencia de enfermedad coronaria. En estos estudios se registran imágenes de esfuerzo y de redistribución, e interesa cuantificar la diferencia entre ambas. Nuestro objetivo fue cuantificar las diferencias entre las imágenes de esfuerzo y reposo por medio de una imagen paramétrica de “washout”, para lo cual es necesario eliminar la actividad extracardíaca y superponer ambas imágenes. Para comprobar la eficacia de diferentes métodos utilizables, se diseñó un modelo simulado por computador que incluía miocardio, fondo y posibles artefactos, a los que se les añadió un ruido. Se simularon imágenes de esfuerzo y reposo con cambios controlados en su distribución. Para efectuar la estimación del fondo se probaron diversos métodos de interpolación. Las pruebas realizadas demuestran que el método de Watson modificado es el que tiene el mejor comportamiento. Para alinear las imágenes de esfuerzo y redistribución de forma automática, probamos diversos algoritmos basados en la correlación. La correlación bidimensional restringida a la zona de mayor captación del miocardio, utilizando pixels alternos, se muestra como un método capaz de alinear las imágenes de esfuerzo y redistribución con suficiente precisión. Una vez efectuado el alineamiento de las imágenes se calculé la imagen paramétrica de “washout”. La cuantificación por medio de los valores medios en los diversos sectores estudiados, da resultados acordes con los teóricos. El método se aplicó sobre casos reales, obteniendo resultados concordantes con la patología. De esta parte se concluye que el método formado por la sustracción de fondo, la alineación de las imágenes y la construcción de la imagen paramétrica de “washout” es factible para la cuantificación de estudios planares de perfusión miocárdica. La segunda aplicación es sobre la ventriculografía isotópica en equilibrio, que es una exploración que permite estudiar el contenido de las cavidades ventriculares a lo largo del ciclo cardiaco, permitiendo estudiar el funcionalismo ventricular. Ha sido muy difundida la utilización de imágenes paramétricas de amplitud y fase del primer armónico del desarrollo de Fourier, que proporcionan información sobre la contractilidad y el sincronismo cardiaco. En este trabajo proponemos la utilización de dos armónicos para obtener nuevas imágenes paramétricas que reflejen las distintas fases del ciclo cardiaco. Estas corresponden a los parámetros: amplitud, tiempo de telesistole, fracción de eyección, máximas velocidades de vaciado y llenado y tiempos en los que se producen, además de una cuantificación utilizando el valor medio y desviación estándar de los valores de los parámetros en cada ventrículo. Los objetivos planteados fueron implementar el método compararlo con el estándar de un armónico. Se ha aplicado el método a un grupo formado por 13 voluntarios sanos, 10 hombres y 3 mujeres, lo que nos ha permitido estimar el rango de normalidad de los distintos parámetros en cada ventrículo. Los valores medios y desviaciones estándar de estos parámetros son distintos en los dos ventrículos. También se ha encontrando que los valores de tiempo de telesistole obtenidos con uno y dos arménicos son significativamente distintos siendo más altos y más dispersos, los obtenidos con un armónico. Las imágenes paramétricas calculadas mediante dos armónicos son más uniformes, existiendo diferencias significativas con los valores obtenidos mediante un armónico. El método también fue aplicado en varios sujetos con patología. En conjunto, puede concluirse que el método propuesto utilizando dos armónicos obtiene unos parámetros capaces de discriminar diversas patologías, siendo de utilidad para el estudio del funcionalismo cardíaco. La última aplicación es en los estudios de motilidad ciliar los cuales sirven para estudiar el comportamiento de los cilios de las mucosas que recubren las vías respiratorias. Su misión es transportar las partículas que se hayan depositado sobre ellos, hacia el exterior, a través de la boca. La velocidad con que estos cilios transportan estas partículas es importante ya que se ha observado que los enfermos con afección de las vías respiratorias presentan una disminución de esta capacidad protectora. Se ha desarrollado un método que permite cuantificar la velocidad de transporte en cualquier parte de la trayectoria. El método puede aplicarse los dos epitelios ciliadas que se encuentran en el organismo humano, corno son la mucosa nasal y la bronquial. Un conjunto de 14 sujetos normales voluntarios fue estudiado por esta técnica. El promedio de la velocidad media, en este grupo fue de S.3±1.4 mm/min. También se estudió un grupo de 16 laringectomizados, obteniendo un valor de 3.6±1.2 mm/min. La diferencia significativa hallada (p<0,005) demuestra que, en las personas laringectomizadas, se produce una alteración en la función de transporte probablemente l por atrofia de la mucosa nasal. El método implementado permite cuantificar con precisión la velocidad de transporte incluso en las diferentes partes del trayecto, pudiendo detectar zonas con motilidad ciliar anómalas por lo que puede ser de utilidad en el diagnóstico.
The aim of this work is to analyze the usefulness of the parametric images in the quantification of dynamic studies. To this purpose, they have been applied in three different situations. First, in myocardial perfusion this thesis studies to quantify the difference between the stress and redistribution images. In this case, a parametric image of washout was used. Methods of background substraction to eliminate non-cardiac activity and of superimposition of both stress and redistribution images were studied and their efficacy checked by means of a computer-simulated model. The results of the quantification method were in agreement with the theoretical ones. It was also applied to real images and the results were in agreement with the patient's pathology. The second application is on equilibrium radionuclide angiocardiography, in which the utilization of two harmonics is proposed in order to calculate parametric images of amplitude, time to end-systole, ejection fraction, peak ejection and peak tilling rates, and time-to-peak ejection and time-to-peak filling rates. The quantification of these images was made by using the mean and standard deviation of the values of these functional parameters for each ventricle. The method has been applied to the studies of 13 healthy volunteers, which has allowed us to determine the range of normal values for each parameter. It was also applied to subjects with cardiac pathology. The last application is studies of ciliary motility. A method has been developed which allows to quantity the velocity of transportation in any part of the trajectory of a drop of radiopharmaceutical placed on the nasal cilia. This technique was applied to 14 normal subjects and to 16 laringectomized patients. It was found that the velocity was lesser in the pathological group (3.6±1.2 mm/min) than in normals (5.3±1.4 mm/min), being the difference statistically significant (p<0,005). This demonstrates that in laringectomized patients an alteration of the transportation function occurs, probably for atrophy of nasal mucosa.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The phantoms used in Brazil are mostly imported and have relatively high financial cost. Although these phantoms can be considered as essentials for use in quality control, probably high quotas and import bureaucracy are obstacles to their acquisition by the nuclear medicine departments. The main objective of this work was the development of national phantoms for use in quality control of scintillation cameras used in nuclear medicine and for training professional personnel. Initially, we sought to know the interest of medical physicists and radiation protection supervisors in the acquisition of phantoms. After that, it was initiated the construction of three distinct types of physical phantoms, the SENCOR, to evaluate the sensitivity and the center of rotation; the SIMUFÍGADO, which is a liver phantom; and the ANTROFÍGADO, which is an anthropomorphic liver phantom in three versions. Besides these, we set up a computational phantom liver based on a physical phantom using Visual Monte Carlo. The conclusion obtained from inquiring professionals is that there is motivation for sharing and acquiring of national phantoms. The results obtained from characterization of materials used in the development of the phantoms should that such materials are suitable for the construction of such objects, observing only a change in color of acrylics irradiated with doses above 10 kGy. Through analysis of images of non anthropomorphic phantoms it is possible to study several parameters, such as sensitivity of the scintillation cameras, center of rotation, matrix size of pixels, the energy window, counting density and organs geometry. The images obtained from ANTROFÍGADO in SPECT and PET/CT systems can be useful to simulate the geometry of the healthy liver and cirrhotic liver, serving this object to the study of simulations of diagnostic analysis of location and evaluation of morphology and anomalies in the liver. Even though industrial processes for production of phantoms proposed here represent a significant increase in the final cost of these objects, it can be said that it is possible to reproduce many copies of these objects using the same methodology employed in the manufacture of the prototypes here studied.
Os objetos simuladores utilizados no Brasil são, em sua maioria, importados e de custo financeiro relativamente elevado. Embora esses objetos possam ser considerados essenciais para o uso em controle de qualidade, os custos financeiros elevados e a burocracia da importação, provavelmente, são empecilhos para a aquisição deles por parte dos serviços de medicina nuclear. O objetivo central deste trabalho foi o desenvolvimento de objetos simuladores nacionais para uso em controle de qualidade de câmaras de cintilação utilizadas em medicina nuclear e em treinamento de profissionais da área. Inicialmente, buscou-se conhecer o interesse de físicos médicos e supervisores de radioproteção em adquirir objetos simuladores e deu-se início à construção de três tipos distintos de objetos simuladores físicos: o SENCOR, para avaliação de sensibilidade e centro de rotação; o SIMUFÍGADO, que é um simulador de fígado; e ANTROFÍGADO, que é um objeto simulador antropomórfico de fígado em três versões. Além desses, elaborou-se um objeto simulador computacional de fígado baseado num simulador físico usando o Visual Monte Carlo. Pôde-se concluir, a partir da consulta aos profissionais que há motivação para o compartilhamento e aquisição de objetos simuladores nacionais. Nos resultados da caracterização dos materiais empregados para preparação dos objetos simuladores, observou-se que tais materiais são adequados para a construção dos objetos, observando-se apenas uma alteração na coloração dos acrílicos irradiados com doses acima de 10 kGy. Por meio de análises das imagens dos objetos simuladores físicos não antropomórficos é possível o estudo de parâmetros como sensibilidade das câmaras de cintilação, centro de rotação, tamanho de matriz de pixels, janela energética, densidade de contagem e geometria de órgãos. Por meio das imagens adquiridas dos ANTROFÍGADO em sistemas de SPECT e PET/CT pode-se simular a geometria do fígado sadio e com cirrose hepática, servindo tais imagens para análises diagnósticas simuladas de localização e avaliação da morfologia e das anomalias do fígado. Mesmo que processos industriais para produção dos objetos simuladores aqui propostos representem um acréscimo significativo nos custo final desses objetos, é correto afirmar que é possível reproduzir muitos exemplares desses objetos simuladores seguindo a mesma metodologia empregada na confecção desses protótipos.

The World Health Organization published in 2004 a bulletin addressing the gap between research, technology, and its implementation in the health systems of different countries (Haines, Kuruvilla, & Borchert, 2004). Among the barriers described for the implementation of new knowledge in the medical practice is the lack of connection between research results and policy makers. This happens in different subfields within the medical field. The focus of this project is to analyze the differences in implementation of radionuclide therapy technology between the EU and the US. The hypothesis is that this technology has been implemented in the EU earlier and more often than in the US, and that this variation can be connected to the differences in the policies relevant to nuclear medicine. Nuclear medicine is a unique field because of the way radioactive material is used to create diagnostic images and treat illnesses (mostly cancer). Although radiation is used every day in radiotherapy and radiology, the main difference between these two fields and nuclear medicine is the type of radiation used. Radiotherapy and radiology use closed sources of radiation, or particle accelerators that produce radiation, while nuclear medicine uses open sources of radiation that are injected into the patient’s body. This is an important difference because the accelerators used in radiotherapy and radiology can be turned on and off unlike the open sources of radiation used for nuclear medicine. If not handled properly, open sources of radiation may cause radiation contamination. Additionally, the radioactive material must be supplied on a daily basis. With nuclear medicine is possible to create diagnostic images of the body, and to record bodily functions all the way down to the molecular level. It is also possible to treat certain illnesses, such as some types of cancer, in a targeted manner. This is possible because the radioactive material is “connected” with a chemical compound (or drug) that carries the radioactive atoms to a desired location in the body; this is called targeted therapy. It is also possible to inject the radioactive material directly into the organ or region of interest. The targeted therapy and injected techniques are two processes that are part of radionuclide therapy technology. In order to check the status of the implementation of radionuclide therapy I used the practice guidelines published on the websites of the European Association of Nuclear Medicine (EANM) and the Society of Nuclear Medicine (SNM) in the US. Assuming that the practice guidelines are evidence of well-established and implemented techniques in the regions, these documents were evaluated according to their content and publication date. The content analysis was focused on the type of practices described: diagnostic, general, or therapy, as well as the type of radioactive material (or radioactive isotopes) used in such practices. The practice guidelines evaluation was done in Nvivo, a text analysis software. In addition to the analysis of practice guidelines, a bibliometric analysis of four databases (Pubmed, Medline, Biosis, and ISI Web of Science) was conducted in four databases. The keywords used for the search were (“radionuclide therapy” AND case AND report) OR (radioinmunotherapy AND case AND report). Case reports are publications that expose the day-to-day practice of physicians, and allow medical personnel to take a detail look into a specific case. The records from these sources were analyzed in Vantage Point, a bibliometric analysis software. From the policy landscape, three main types of policies were studied in relation to the practice of nuclear medicine: first, the education standards for the different professionals involved; second, the policies related to the approval of radiopharmaceuticals in the different drug administration entities; and finally, the policies concerning the production of radionuclide therapies in the two regions. The main finding of this project is that Europe and US have different policy approaches that affect, directly or indirectly, the nuclear medicine field. The main differences are in the standards of education for nuclear medicine specialist that is divided between radiologist and nuclear medicine specialists in the US; the production of radioactive material, which is commercially supplied by a very few reactors in the world, none of them in the US; and the drug administration institutions, which have very different approaches approving new drugs. Aditionally, Europe has implemented more radionuclide therapy technologies than US. From the practice guidelines analysis, it was evident that the US started publishing guidelines for nuclear medicine several years before Europe. The US published its first guideline in 1994, while the EU’s first guideline was published in 2000. However, as of July 2013, the European association had published more guidelines with 54 unique ones versus 49 from the US. EU also leads in the number of guidelines in regards to therapy, with 13 versus 2 from the US. Additionally, there is more variety in the radioisotopes used in therapy than the ones in diagnostics, and all the radioisotopes are mentioned in the European guidelines, while the US doesn’t have guidelines that mention Lu-177, Re-186, and Y-90 isotopes. From the bilbiometric analysis it was evident that Europe had published case reports for more time and more frequently than the US regarding radionuclide therapy. The first case report record from Europe was published in 1988, almost a decade before the first case report in the US. Additionally, the US has only 10 publications that match the keywords while the EU has 37. In conclusion, the EU has more practice guidelines on radionuclide therapies regarding more types of illnesses and more radioisotopes, and Europeans have published more case reports on these therapies, which indicates that the EU has implemented radionuclide therapy technology more fully than has the US. The differences in the policies and standards in education for Nuclear Medicine may influence this difference, because EU has a more standardized education and a more unified professional field than US. While the EU has a proposed syllabus for nuclear medicine practitioners, medical physicists, and radiopharmacists, in the US the education is neither standardized nor unified. Two different boards can certify physicians specializing in nuclear medicine: the American Board of Radiology and The American Board of Nuclear Medicine. The first one does a Nuclear Radiology certification for which the physicians are not required or allowed to conduct radionuclide therapies, while the American Board of Nuclear Medicine requires more nuclear medicine training and involves diagnostics and therapy. These differences are important in the implementation of radionuclide therapy techniques, because not all the nuclear medicine physicians in the US are trained on this aspect or allowed to practice it. For that reason a fraction of the professionals may not be interested or informed about these techniques, leaving the field of nuclear medicine in the US behind its EU counterpart. The policies that involve the production of radioisotopes and the market for this good deeply affects the status of the field in both regions. Since most of the radionuclide materials for therapies are produced in nuclear reactors, this is a very complex topic. Nuclear reactors are recognized for their capability to produce nuclear energy and not frequently associated with medicine. The precautionary approach that some regions apply to this topic may affect the availability of the radioisotopes in local markets. The EU has more nuclear reactors capable of the production of materials for radionuclide therapies, while the production of radioisotopes in the US is less and it focused on research. Therefore, the EU has a more stable and reliable supply of radioisotopes, which allows them to use the technology in everyday practice. Finally, the drug administration entities seem to differ in the clarity of their procedures for the approval of radiopharmaceuticals. The EU tools for approval are clear and easy to find, which may encourage European researchers to work on new radiopharmaceuticals and to carry their findings to the application level. The European Medicines Agency has a Radiopharmaceutical Drafting Group that supports the creation and approval of radiopharmaceuticals. In addition, one of the practice guidelines from the European Association of Nuclear Medicine (EANM) is about the approval of new drugs. This is not replicated in the US; although the Food and Drug Administration (FDA) has a special group that works with radiation therapies and devices, there are no references to a group that relates to radiopharmaceuticals, or the information is not as easy to find. It also looks like the Society of Nuclear Medicine (SNM) is focusing more on research and approval of Positron Emission Tomography (PET) radiopharmaceuticals than on therapy based ones. This is understandable since the radioactive material for PET images is produced in cyclotrons available at many clinics and hospitals around the world. In conclusion, nuclear medicine is a very diverse field that is capable of important contributions to medicine. However, the radioactive nature of the material needed for the development of new radionuclide therapies presents a barrier to the development of new drugs. The availability of the drug and the personnel trained in these matters are the most important factors for the successful use of this technology. Although the US and the EU have been collaborating more and more in the creation of standardized procedures for nuclear medicine, it is evident that the EU has more experience in the day to day application of the technology, and the technology is also more accessible in the EU by the physicians interested in it. A trained and informed group of professionals can raise awareness in the public and influence the policy making by monitoring agencies to create clearer paths for drug approvals, and pushing for laws that approve the research and production of alternatives for radioisotopes production such as Low Enriched Uranium reactors.

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2007.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 74).
Serving customers in a nuclear medicine supply chain requires frequent and responsive replenishments. Nuclear medicine is a special category of perishable goods that is subject to rapid, but predictable radioactive decay. This study examines the viability of differentiating service through segmenting customers in Tyco Healthcare's (THC's) nuclear medicine supply chain. More specifically, the network of pharmacies that THC serves is divided into two groups-THC-affiliate pharmacies and independent pharmacies-and their demand characteristics are examined. This study rejects the hypothesis that THC should differentiate service by pharmacy affiliation after comparing the demand characteristics of the THC and independent pharmacies. Alternatively, the study tests the hypothesis that product segmentation is a viable option by comparing the demand characteristics of THC's products. This study does not reject the alternative hypothesis and presents proposed policy for coordinated replenishment. To facilitate the comparative analyses, THC's nuclear medicine supply chain is first described. Finally, recommendations on how to improve supply chain performance follow the hypothesis testing.
by Young-bai Michael Yea and Hui Zou.
M.Eng.in Logistics

Dissertation (MTech (radiography))—Peninsula Technikon, Cape Town, 2003
Five of the seventeen countries with Nuclear Medicine facilities in Africa have training programmes for Nuclear Medicine Technologists (NMT's). Four of the countries are in Northern Africa (Algeria, Morocco, Tunisia, and Egypt) and only one in Southern Africa (South Africa). The training programmes vary from country to country and therefore there is no common basis to facilitate regional co-operation. Nuclear Medicine Technologists working in sub-Saharan countries do not have formal training in Nuclear Medicine and have mostly been recruited from related fields of Radiological Technology. A number of NMT's in these centres have enjoyed International Atomic Energy Agency (IAEA) fellowship training in other countries or have attended regional training courses. Knowledge and skills, learned in well established Nuclear Medicine departments with supportive infrastructure, are on the whole difficult to transfer to a local situation without such support. Because of the nature of the specialty the numbers required for training are small and it would therefore not be cost-effective for Higher Education Institutions in these countries to set up training programmes. There is also a lack of expertise in this field in Africa. Training was initially supported outside the countries with loss of personnel to the departments and in many instances loss of manpower as these trainees leave their countries and do not return. Under an IAEA/African Regional Co-operative Agreement (AFRA) project; "Establishing a Regional Capability in Nuclear Medicine", the following related to training of NMT's: 1. Harmonisation of training programmes for Nuclear Medicine Technologists in AFRA countries 2. Assess the feasibility of running a Distance Assisted Training (DAT) programme for Nuclear Medicine Technologists It was hoped that in this way, full use could be made of available expertise and facilities in the region, the cost of training could be reduced and the standard of patient health care improved.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Background: In neuroblastoma, the presence of distant metastases is associated with a poor prognosis. Aim: To assess the relationship between the findings on ¹²³I-MIBG scan and outcome in patients with neuroblastoma at the Red Cross War Memorial Children's Hospital (RCWMCH). Methods: A single observer reviewed the ¹²³I-MIBG scans and clinical data of patients who had a histologically confirmed diagnosis of neuroblastoma and a baseline ¹²³I-MIBG scan and at least one follow up scan after chemotherapy cycles 4 or 7 between January 2001 and May 2015. Follow up extended to June 2016. Disease burden was assessed using the Curie scoring (CS) method. Results: Thirty four stage 4 patients were included in the analysis. Twenty nine (85%) were older than 12 months, with a median age at diagnosis of 32.5 months (range 6 - 93 months). 62% of primary tumours were located in the adrenal gland and half were NMYC amplified. Twenty (59%) patients died, 90% of deaths occurring in patients older than 12 months. No deaths were recorded in the 13 months after recruitment ended. The baseline CS did not predict outcome (alive or dead) or duration of survival. Patients with CS >2 (n = 5) on the cycle 4 scan had a median survival of 19.5 months compared with 29 months for those with a score ≤ 2 (n = 17, p = 0.88). Patients with a CS > 2 on the cycle 7 scan (n = 7) had a median survival of 28 months compared with 35 months for those with CS ≤ 2 (n = 14, p = 0.93). There was no relationship between the magnitude of the decrease in CS between the baseline and post cycle 4 or 7 scans and outcome. Conclusion: In these 34 high risk patients, the baseline CS and CS at cycle 4 or cycle 7 were not significantly indicative of survival. This is similar to other studies that did not find the pre-treatment score or the post treatment MIBG scan to be a predictor of outcome.

Aim The reproducibility of differential renal function (DRF) estimates on 99mTc-mercaptoacetyltriglycine (99m Tc-MAG3) is good in the majority of children. There is however a small but important group with poor reproducibility which, if not recognized, could affect clinical decision making. Some factors, such as age and glomerular filtration rate (GFR), have been implicated as causes for poor reproducibility. The aim of this study is to formally investigate image characteristics associated with the reproducibility of DRF measurements. Patients and methods The image characteristics and reproducibility of the DRF estimates of the 127 patients in cohort 1 was used to identify the characteristics associated with reproducibility. The associations between these image characteristics and reproducibility were then tested in a second cohort of 227 patients. The DRF measurements were calculated using two internationally accepted methods for calculating DRF, the HERMES area under the curve (HAUC) method and the HERMES Rutland Patlak (HRP) method. The images were visually inspected to categorise the categorical variables and processed to obtain the values of the continuous variables. The variables investigated included two nonimaging variables, age (in months) and GFR which included measured or estimated GFR values. The association between each variable and the reproducibility of DRF measurement for both the HAUC and the HRP methods was tested with univariate linear regression. The results of the univariate linear regression were used to plan the multiple linear regression combinations. All possible combinations were tested with multiple linear regression. Results The goodness-to-fit for the multiple regression models were much higher for all the combinations analysed in cohort 1 than in cohort 2. In cohort 1 the R2 -values ranged from 0.3510 to 0.4906 for log MAXMINHAUC and 0.3284 to 0.4500 for log MAXMINHRP. In cohort 2, they ranged from 0.1675 to 0.2163 for log MAXMINHAUC, and 0.1706 to 0.2191 for log MAXMINHRP. The combinations with the highest R2 -value for multiple linear regression analyses were similar in cohort 1 and 2. The only individual variable which was significant in all the multiple linear regression combinations for cohort 1 and 2 for both log MAXMINHAUC and log MAXMINHRP was LEFT KIDNEY TO BACKGROUND RATIO. RIGHT KIDNEY TO BACKGROUND RATIO, RIGHT RENAL MARGINS WELL DEFINED, RIGHT RENAL MARGINS POORLY VISUALISED and TIME VISUALISATION RIGHT CALYCES were significant in most of the combinations analysed. A high kidney to background ratio, RIGHT RENAL MARGINS WELL DEFINED and higher AGE predicted a good reproducibility. A low kidney to background ratio and later TIME VISUALISATION RIGHT CALYCES predicted poor reproducibility. The variables LEFT RENAL AREA, LEFT BACKGROUND AREA, BOTH RENAL MARGINS SMOOTH and RIGHT RENAL MARGINS IRREGULAR were not-significant in any combinations analysed cohort 1 and 2 for both log MAXMINHAUC and log MAXMINHRP. The remaining variables inconsistently predicted reproducibility in log MAXMINHAUC and log MAXMINHRP for both cohort 1 and 2. Conclusion: The only variables which consistently predicted good and poor reproducibility for the measurement of DRF on 99mTc-MAG3 renograms performed according to the EANM guidelines for both log MAXMINHAUC and log MAXMINHRP were AGE, LEFT KIDNEY TO BACKGROUND RATIO, RIGHT KIDNEY TO BACKGROUND RATIO, RIGHT RENAL MARGINS WELL DEFINED and TIME VISUALISATION RIGHT CALYCES. Consideration should be given to incorporating the kidney to background ratio into the renal processing screen display as a valuable quality control step. The DRF values should be interpreted with caution if the kidney to background ratio is < 2.0.

Background: In neuroblastoma, the presence of distant metastases is associated with a poor prognosis. Aim: To assess the relationship between the findings on ¹²³I-MIBG scan and outcome in patients with neuroblastoma at the Red Cross War Memorial Children's Hospital (RCWMCH). Methods: A single observer reviewed the ¹²³I-MIBG scans and clinical data of patients who had a histologically confirmed diagnosis of neuroblastoma and a baseline ¹²³I-MIBG scan and at least one follow up scan after chemotherapy cycles 4 or 7 between January 2001 and May 2015. Follow up extended to June 2016. Disease burden was assessed using the Curie scoring (CS) method. Results: Thirty four stage 4 patients were included in the analysis. Twenty nine (85%) were older than 12 months, with a median age at diagnosis of 32.5 months (range 6 - 93 months). 62% of primary tumours were located in the adrenal gland and half were NMYC amplified. Twenty (59%) patients died, 90% of deaths occurring in patients older than 12 months. No deaths were recorded in the 13 months after recruitment ended. The baseline CS did not predict outcome (alive or dead) or duration of survival. Patients with CS >2 (n = 5) on the cycle 4 scan had a median survival of 19.5 months compared with 29 months for those with a score ≤ 2 (n = 17, p = 0.88). Patients with a CS > 2 on the cycle 7 scan (n = 7) had a median survival of 28 months compared with 35 months for those with CS ≤ 2 (n = 14, p = 0.93). There was no relationship between the magnitude of the decrease in CS between the baseline and post cycle 4 or 7 scans and outcome. Conclusion: In these 34 high risk patients, the baseline CS and CS at cycle 4 or cycle 7 were not significantly indicative of survival. This is similar to other studies that did not find the pre-treatment score or the post treatment MIBG scan to be a predictor of outcome.

Purpose: There are conflicting results from studies on whether the ventilation (V) scintigraphy can be safely omitted or replaced by a chest x-ray. These studies were based on planar ventilation perfusion (V/Q) scintigraphy. We evaluated the value of the V single photon emission computed tomography (SPECT) on the final conclusion drawn from a V/Q SPECT and the possible role of the chest x-ray as a surrogate for the V SPECT. Methods Raw data of V/Q SPECT images and chest x-ray acquired within 48 hours over 18 months period were retrieved, reprocessed and reviewed in batches. The V SPECT, Q SPECT and chest x-ray were reviewed separately and in combination. Data on the presence and character of defects and chest x-ray abnormalities were recorded. The V/Q SPECT images were interpreted using the criteria in the EANM guideline and the Q SPECT and chest x-ray images were interpreted using the PISAPED criteria. Agreement between the diagnosis on the V/Q SPECT review and the Q SPECT and chest x-ray review was analysed. Results 21.1% of the patients were classified as 'PE present’ on the V/Q SPECT review whereas 48.9% were classified as 'PE present’ on the Q SPECT and chest x-ray review. Only 5.4% of defects seen on V SPECT had matched chest x-ray lung field opacity. Conclusion Our study showed that the omission of a V SPECT led to a high rate of false positive diagnoses and that the ventilation scan cannot be replaced by a chest x-ray.

This study was conducted with the support of the Combined Breast Clinic at our institution which consists of the Departments of Surgery, Radiology and Radiation Oncology. The work was done in three parts. The literature showed somewhat lengthy imaging procedure for scintimammography which were not whole suitable to the setting of the Combined Breast Clinic. Initially a Pilot Study was conducted to determine the practicality of the imaging procedure. The results of this study were promising but the imaging procedure was time consuming. Certain modifications were subsequently done in the imaging method of the Formal Study to accommodate more number of patients into the study without jeopardizing the quality of the images. This study, however, had a shortcoming in that the way this study was structured one could not demonstrate lesion by lesion analysis of each breast lesion detected on clinical examination, mammography and scintimammography with their respective biopsy results. Our Formal Study and the literature suggested that scintimammography is of value in patients with indeterminate mammograms due to its high negative predictive value. Therefore, a separate Additional Study, with the same scintigraphic method, was conducted on patients with clinical breast lumps with indeterminate mammographic lesions. Special emphasis was placed on lesion by lesion comparison of each breast lesion detected by clinical examination or scintimammography or both with the biopsy results of that particular lesion.

Includes bibliographical references (leaves 72-90).
Sentinel lymph node (SLN) biopsy is being used increasingly for staging early breast carcinoma in place of complete axillary lymph node dissection. The optimal method to identify the SLN and has not been clearly elucidated in the literature. A number of techniques have been proposed for identifying SLN/s. The main debate centres on whether to use a blue dye or radiopharmaceutical method either singly or in combination.

Background: Majority of patients with unilateral hydronephrosis (HN) detected on ultrasound (US) do not require pyeloplasty. Indications for pyeloplasty are in patients with symptomatic obstruction (recurrent flank pain), complications such as urinary tract infection, a drop in differential renal function (DRF) of more than 10% and a progressive increase in the anterior posterior diameter (APD) in subsequent studies. Schlotmann et al, Piepsz et al and Harper et al have demonstrated the measurement of the cortical transit time (CTT) to predict the need for patient who may require pyeloplasty. Objectives: To assess if the CTT would have predicted a drop in DRF in patients with unilateral HN on the affected side. In addition to assess whether the CTT would differ on the first renogram between those patients who had a pyeloplasty and those who did not have a pyeloplasty at the Red Cross War Memorial Children’s Hospital (RCWMCH). Methods: Sixty eight (68) patients with at least two renograms with unilateral HN with a normal contralateral kidney were observed retrospectively between December 2000 and May 2015. The CTT was recorded for the upper, middle and lower third of each kidney and the mean used as the CTT of the kidney. Each renogram was processed three times to measure the DRF using the Rutland Patlak and Integral methods. The mean of the three DRF measurements was used for analysis. Results: The mean CTT of the left and right hydronephrotic kidneys were 6.0minutes and 6.7minutes respectively. A significant relationship was demonstrated in the CTT and DRF as well as CTT and APD in the first renogram of those patients who did not have a pyeloplasty (p < 0.05). There was no difference between the DRF of the first and second renograms in those patients who did not have a pyeloplasty. In the 20 patients who had a pyeloplasty, there was a drop of more than 10% in the DRF of 3 patients. No difference was seen in the DRF or in the CTT between the first and second renogram. The CTT was shorter in the second renogram in 9 of the 20 patients who had a pyeloplasty. No significant difference was found in the CTT or DRF when comparing the group who had surgery against the group who did not have surgery. Conclusion: The current study was unable to demonstrate in our series of patients that CTT can predict those patients who would require pyeloplasty. This may be owing to the retrospective nature of the study and the reliance on the clinical notes for the US data and surgical notes. In future, a prospective study evaluating the relationship between CTT and a drop in the DRF should be undertaken in this unit.

Includes bibliographical references
Objectives: To assess initial experience with the use of a new SPECT-CT in the evaluation of lesions. Methods: The folder number, radiopharmaceutical used and type of scan of patients examined with a new Siemens T6 SPECT-CT between 2 April and 31 December 2013 were retrieved. The number of 99m Tc -MDP bone scans was sufficient for a detailed analysis. The scans were re-processed and reported by the observer before he was given any clinical information. Whole body planar, whole body planar plus SPECT and whole body planar plus SPECT-CT images were assessed successively in three separate sessions at least two weeks apart. At each session, the certainties of detection, localisation, and categorisation of each lesion were recorded. Results: A total of 539 lesions were seen on the whole body, SPECT and CT images in 133 patients. The whole body images showed no lesions in three patients and 378 lesions in 130 patients, 117(31%) lesions in areas not covered by the SPECT. SPECT detected 122 additional lesions in 79 patients. Thirty-nine (12.2%) lesions were seen only on CT in 32 (24.1%) patients. F or the 261 lesions seen on the planar images in the SPECT FOV, lesion detection was definite in 233 (89.3%), localisation definite in 151(57.9%) and categorisation definite in 123 (47.1%) lesions. On the SPECT, definite lesion detection, localisation and categorisation were recorded respectively for 259 (99.2%), 228 (87.4%) and 176 (67.4%) of the 261 lesions. Lesion detection, localisation and categorisation certainties were definite for 100%, 99.1% and 94.7% of the SPECT-CT lesions respectively. Conclusion: Whole body planar scintigraphy is essential in lesion detection. SPECT markedly improves lesion detection and localisation and CT enhances lesion categorisation.

Thesis (MSc)--Stellenbosch University, 2005.
ENGLISH ABSTRACT: Introduction: Quality assurance in Nuclear Medicine is of utmost importance in order to ensure optimal scintigraphic results and correct patient management. A customised Quality Management System (QMS) should be documented and implemented by following the international guidelines set by the International Standardisation Organization (ISO). Materials & Methods: A Quality Control Manual (QCM), defining the departmental quality policy, mission, vision and objectives was customised following the framework of a tried and tested design. As ISO focuses on client satisfaction and staff harmony, the following departmental objectives were audited in working towards the accreditation of the Nuclear Medicine Department of Tygerberg Hospital: referring physician satisfaction, patient satisfaction as well as staff satisfaction and harmony. Information was collected by means of questionnaires completed by referring physicians and staff members. One-on-one interviews were executed on patients. An international ISO accredited Nuclear Medicine department was visited to establish the suggested path to follow en route to successful ISO accreditation and certification. Results: Referring physicians indicated overall satisfaction with service provision, but a need for electronic report and image transfers seemed too dominant. The patient satisfaction survey resulted into overall satisfaction with personal service providing, but the provision of written and understandable information, long waiting times and t equipment must receive attention. Staff questionnaires indicated a general lack of communication between different professional groups and the need for interpersonal loyalty and team building. Improvement measures were identified to ensure the continuous improvement of the QMS by focusing on these quality parameters. Conclusion: The department has QA procedures in place, but does not meet all criteria for external accreditation. In order to ensure departmental harmony and sustainability of client and staff satisfaction, the departmental objectives in measured and improved where needed. The successful implementation and continuous improvement of a customised QMS, following the guidelines outlined in the QCM will lead to successful accreditation.
AFRIKAANSE OPSOMMING: Inleiding: Die belangrikheid van kwaliteit versekering in Kerngeneeskunde vir die versekering van optimale flikkergrafiese resultate en korrekte pasient handtering kan nie onderskat word me. 'n Klantgerigte Kwaliteitsbeheersisteem (KBS) moet gedokumenteer en geimplimenteer word vir die Kerngeneeskunde Departement deur die riglyne te volg soos uiteengesit deur die Internationale Standardiserings Organisasie (ISO). Materiale & Metodes: 'n Kwaliteitskontrol handleiding (KB), wat die departementele kwaliteitsbeleid, die missie en visie asook die departementele doelwitte definieer is ontwerp en saamgestel vir die Kerngeneeskunde departement van Tygerberg Hospitaal. Hierdie ontwerp is gebaseer op die raamwerk van 'n aanvaarde kwalteitsbeheersisteem. ISO fokus op klante tevredenheid asook personeel harmonie en tevredenheid. Vir hierdie rede is daar 'n tevredenheidpeiling uitgevoer op die klante en personeel in die strewe na ISO akkreditasie en sertifikasie. Inligting was versamel deur vraelyste wat ingevul was deur die verwysende geneeshere, pasiente en personeel. Resultate: 'n Kwaliteitskontrole handleiding was saamgestel VIr gebruik in die Kerngeneeskunde department. Die interne audit resultate het aangedui dat die verwysende geneeshere tevrede is met die algehele dienslewering. Die behoefde aan elektronies versende verlae en beelde was dominerend. Die pasient tevredenheidspeiling het bevestig dat die pasiente tevrede is met persoonlike dienslewering, maar 'n tekort aan verstaanbare en geskrewe inligting was geidentifiseer. Die lang wagtye en stukkende apparaat is ook gebiede wat verbertering benodig. Algemene gebrek aan komminukasie tussen die verskillende beroepsgroepe, die behoefte aan interpersoonlike lojaliteit en span werk was die hoof bevindinge van die personeel tevredenheidspeiling. Verbeterings maatreels, gefokus op hierdie departementele doelwitte, was geidentifiseer ten eide te verseker dat die KBS voordurend verbeter en in stand gehou word. Samevatting: Alhoewel die departement wel KB prosedures in plek het, voldoen dit nie aan al die criteria vir eksterne akkreditasie nie. Ten einde departementele harmonie en kliente tevredenheid te verseker, met die oog op ISO sertifikasie, moet die departmenteIe doelwitte deurlopend gemeet en verbeter word.

Thesis (MScMedSc (Medical Imaging and Clinical Oncology. Nuclear Medicine))--University of Stellenbosch, 2007.
Introduction: Whole body bone scintigraphy with Tc-99m MDP is able to provide a survey of the entire skeleton. The question arises if it is mandatory to perform a whole body bone scan in all patients, irrespective of the clinical indication. The aim of this study is to determine the implications of performing limited imaging in patients who had whole body bone scan for various clinical patholgy with Tc-99m MDP, in order to determine if limited imaging would be acceptable in selected pathologies. This may enable gamma camera time to be optimally utilized in units with limited facilities. Materials and Methods: Reports of 3015 patients with various clinical pathologies who had whole body bone scans with Tc-99m MDP in our department from January 2002 to December 2004 were retrospectively reviewed. The presence of pathologic radiotracer uptake was analyzed in order to establish the pattern of distribution. Clinically significant skeletal lesions were classified according to the anatomical regions where they were located viz; skull (including the neck), axial skeleton (including the pelvis and shoulders) and limbs. Results: Our results showed that in patients with lung cancer, soft tissue sarcoma, and myeloma, there was an error in more than 25% of patients when limited imaging was performed. In patients with cancer of the breast, prostate, kidney, gastrointestinal system, and reproductive system and lymphoma there is an error in less than 5% of patients when limited imaging is employed. For iv patients with more localized musculoskeletal disorders such as suspected stress fractures, complicated joint prosthesis and avascular necrosis of the femur head, regional imaging of the area of pathology showed a percentage error of less than 6%.

Orientador: Celso Dario Ramos
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-16T23:06:04Z (GMT). No. of bitstreams: 1 Lima_MarianadaCunhaLopesde_D.pdf: 5311684 bytes, checksum: 4e6a0ba6a1a013ca5e9a995b127a5a95 (MD5) Previous issue date: 2010
Resumo: A diferenciação entre obstrução mecânica e dilatação das vias urinárias sem obstrução é extremamente importante para se determinar o tratamento correto. O objetivo deste trabalho foi avaliar a utilidade do estudo renal dinâmico com diurético (ERDD) com L,L-etilenodicisteína marcada com tecnécio-99m (EC-99mTc) em pacientes com resultados indeterminados ou possíveis falso-positivos para obstrução no ERDD com ácido dietilenotriaminopentacético marcado com 99mTc (DTPA-99mTc). Noventa e dois pacientes foram estudados, sendo 63 do sexo masculino e 29 do sexo feminino, com idades variando de um mês a 74 anos (média 16,6 +/-21,25 anos), num total de 103 rins com padrão cintilográfico indeterminado (20/103) ou possível resultado falso positivo para obstrução atribuível à função glomerular reduzida ou dilatação acentuada das vias excretoras (83/103) no ERDD com DTPA-99mTc (<60% de excreção do radiofármaco em 20 minutos - tempo em que 50% do radiofármaco foi excretado pelos rins (T½) >15 minutos). Os pacientes foram então submetidos a ERDD com EC-99mTc, sendo realizadas imagens dinâmicas antes e após a administração venosa de furosemida e seguindo-se o mesmo protocolo de aquisição de imagens utilizado com DTPA-99mTc. O intervalo de tempo entre os ERDD com DTPA-99mTc e com EC-99mTc variou de 2 a 64 dias. As taxas de excreção aos 20 minutos após a injeção de furosemida foram calculadas para ambos radiofármacos e foram estatisticamente comparadas utilizando-se o teste t pareado. A porcentagem de excreção após a administração de furosemida foi de 25,3% +/- 18,2% para DTPA-99mTc e de 41,2 +/- 26,1% para EC-99mTc (p<0,0001). Utilizando-se EC-99mTc, obstrução foi excluída em 36 de 103 rins, com excreção >60%. Dez dos 83 rins (12,0%) que apresentavam padrão obstrutivo ao DTPA-99mTc revelaram-se indeterminados no ERDD com EC-99mTc. Houve concordância nos resultados do ERDD com EC-99mTc e com DTPA-99mTc em 54/83 rins com padrão obstrutivo (65,1%) e em 3/20 rins com padrão indeterminado (15,0%). O estudo com EC-99mTc é mais efetivo que o com DTPA-99mTc na exclusão de obstrução das vias urinárias, apresentando menos resultados falso-positivos e indeterminados. O radiofármaco EC-99mTc pode substituir o DTPA-99mTc na avaliação de pacientes com dilatação do trato urinário
Abstract: The differentiation between mechanic obstruction and dilation without obstruction is critical to determine the correct treatment approach. The aim of this study was to evaluate the utility of diuretic dynamic renal scintigraphy (DDRS) with 99mTc-EC in patients with indeterminate or possible false-positive results for urinary obstruction by 99mTc-DTPA DDRS. A total of ninety-two patients (63 male; mean age 16.6 ± 21.25 years) were studied, with a total of 103 kidneys presenting indeterminate (20/103) or possible false-positive results for obstruction attributable to reduced renal function or severe kidney dilation (83/103) by 99mTc-DTPA DDRS (<60% of radiopharmaceutical excreted in 20 minutes - half-time clearance (T½) >15 minutes). Patients were reimaged after intravenous injection of 99mTc-EC, with dynamic images before and after furosemide administration using the same acquisition parameters applied in the previous 99mTc-DTPA study. Time interval between 99mTc-DTPA and 99mTc-EC renograms was 2 to 64 days. The percentage of excreted material 20 minutes after furosemide was calculated using both radiopharmaceuticals, and were statistically compared using the paired samples t test. The excretion after furosemide injection was 25.3%±18.2% for 99mTc-DTPA and 41.2±26.1% for 99mTc-EC, with a statistically significant difference between both radiopharmaceuticals (p<0.0001). Using 99mTc-EC obstruction was excluded in 36 of 103 kidneys, which excreted > 60%. A total of 10 of 83 kidneys (12.0%) with an obstructive pattern by 99mTc-DTPA study turned out to be indeterminate by 99mTc-EC DDRS. There was an agreement between 99mTc-EC and 99mTc-DTPA studies in 54 of 83 kidneys with obstructive (65.1%) and in 3 of 20 (15.0%) with indeterminate patterns. 99mTc-EC is more effective than 99mTc-DTPA for excluding obstruction, presenting less false-positive and indeterminate results. 99mTc-EC can substitute 99mTc-DTPA to evaluate patients with urinary tract dilation
Doutorado
Fisiopatologia Cirúrgica
Doutor em Ciências

Na rotina clínica de felinos domésticos, algumas modalidades de diagnóstico por imagem, como a ultra-sonografia, radiografia simples e urografia excretora, já são amplamente utilizadas. A cintilografia é uma técnica não invasiva, capaz de oferecer informações funcionais de rins individualmente, porém é considerada uma modalidade menos usual. O objetivo deste estudo foi determinar o tempo de excreção renal de felinos domésticos através da cintilografia, em animais com parâmetros ultra-sonográficos e radiográficos dentro dos limites da normalidade. Foram utilizados 15 animais, 9 machos e 6 fêmeas, e estes foram divididos em grupos de animais não submetidos à anestesia e anestesiados. Foi estabelecido o tempo para o radiofármaco obter acúmulo máximo em cada um dos rins e o tempo para este acúmulo máximo ser reduzido pela metade. Não houve diferença estatística entre os valores dos animais não-anestesiados e anestesiados, nem entre machos e fêmeas, tampouco entre os rins esquerdo e direito.
In internal medicine of domestic cats, imaging modalities, such as ultrasonography, radiography and intravenous pylogram are widely used. Scintigraphy is a non-invasive technique, which provides functional information of each individual kidney; however, it is not widely available or utilized currently in veterinary medicine. The aim of this study was to determine the time of excretion of each kidney in normal domestic cats using nuclear scintigraphy. Fifteen cats (9 males and 6 females) determined to be within normal limits for radiographic and ultrasonographic renal parameters, were divided into two experimental groups (awake and anesthetized cats). Time to maximum radiopharmaceutical activity (T max) and time to decline to half maximum radiopharmaceutical activity (half-time) were determined in each kidney for each cat. No statistical difference was found between groups (awake vs. anesthetized) or sex (males vs. females), or between left and right kidneys.

A avaliação da técnica de cintilografia da perfusão pulmonar foi realizada em 10 cães machos, da raça Rottweiler, radiograficamente normais e soronegativos para dirofilariose, utilizando-se o macroagregado de albumina sérica humana marcado com tecnécio-99m ([99mTc](MAA)) como radiofármaco. Cada animal sedado foi submetido a três diferentes tratamentos, com administração de 50.000, 100.000 e 300.000 partículas de MAA. As imagens obtidas com as doses variadas do radiofármaco, foram comparadas de forma qualitativa e quantitativa, incluindo nesta última a avaliação do índice de perfusão pulmonar e homogeneidade das imagens. Não foram observadas diferenças significativas entre as imagens durante a avaliação visual e cálculo da quantificação relativa da perfusão pulmonar. Porém, o cálculo da uniformidade integral demonstrou diferença significativa na homogeneidade da imagem pulmonar entre as diferentes doses de MAA. Pode-se concluir que existe um aumento na homogeneidade da imagem diretamente relacionado ao número de partículas de magroagregado de albumina injetado, ainda que tal diferença não tenha sido percebida pela análise qualitativa.
The evaluation of pulmonary perfusion scintigraphy technique was accomplished in 10 Rottweiler male dogs, with normal thoracic radiographs and negative for Dirofilaria immitis, using macroaggregated human serum albumin tagged with technetium-99m ([99mTc](MAA)) as radiopharmaceutical. Each sedated animal was subimited to 3 different treatments, with administration of 50.000, 100.000 and 300.000 particles of MAA. The obtained images with diverse radiopharmaceutical doses were qualitative and quantitative compared, including in this the evaluation of radiopharmaceutical distribution and the homogeneity index. There were observed no significative differences between the images during the visual evaluation and calculation of the relative quantification of the lung perfusion. However, the integral uniformity calculation demonstrated significative difference at the homogeneity of the lung image between the different MAA doses. That leads to the conclusion that there is an increase at the images homogeneity directly related to the number of albumin macroaggregated particles injected, though difference has not been realized by the qualitative analysis.