The adaptation of a general purpose laboratory minicomputer for nuclear medicine imaging is described. Electronic interfaces have been designed and constructed to link nucleonic equipment to a PDP 12 computer. A computer television display system has been developed to facilitate interactive processing of scintigraphic data. The main features of the television system are that it is relatively inexpensive and reliable. A domestic quality receiver has been adapted for use as a colour monitor. Any instrument that records data will produce a distorted or degraded version of the input signal. Generally, imaging equipment will produce a blurred image of the object, and in the case of scintigraphic imaging the blurs may be comparable to the size of the physiological structures being investigated. The process of refocussing the recorded data is called, in mathematical terms, deconvolution. In this study Fourier transform techniques have been developed as methods of implementing deconvolution. It is shown that the restoration of images in the presence of noise is likely to be a mathematically unstable process. Four methods of accommodating the problems associated with noise are described. Each method has built in optimisation of one form or another so that mathematically stable algorithms are used to implement deconvolution. This means that all the parameters used by the computer programs are determined automatically so that the computer operator is not required to select any parameters manually. A brief description of two dimensional digital filtering is given to enable comparison between filtering and deconvolution of scintigrams. A two dimensional lowpass filter is developed which automatically defines the passband frequency response appropriate to a particular scintigram. Finally, all the signal processing methods are tested on both simulated and clinical data. Results show that deconvolution offers advantages over digital filtering particularly for scintigrams obtained from morphic structures. Some of the problems of deconvolving certain types of scintigram are discussed.

No description available.

Radioiron labelled prophyrins were tested for tumor uptake using tissue culture and animal models. The following porphyrins were tested: hematohemin; protohemin; photo-protohemin; 2-formyl-4-vinyl, 2-vinyl-4 formyl, and 2,4-diformyl deuterohemin derivatives; meso-tetra (4 carbo-xyphenyl) hemin (TCP); tetra-Na-meso-tetra (4-sulfonato-phenyl) hemin (TPPS); and meso-tetra-(4-N-methylpyridyl) hemin tetraiodide (TMPI). ⁵²Fe was produced at TRIUMF by high energy proton spallation of a nickel target. The ⁵²Fe was separated from the other spallation products by solvent extraction with methyl isobutyl acetone and ion exchange chromatography when required. Tissue culture studies using P815 mouse tumor cells showed good uptake with protohemin, TCP, or TMPI. Mouse distribution and excretion studies indicated that the target organ for TMPI was the liver (and spleen) and its biological half-life was 270 days. Animal scans using rats with breast carcenomas with ⁵²Fe labelled protohemin, TCP and TMPI showed no tumor uptake at all. The radiation dose to a human was also calculated. / Pharmaceutical Sciences, Faculty of / Graduate

The distinction between cavernous haemangiomas of the liver (which are the second most common hepatic mass lesions) from malignant lesions, is often difficult. An incorrect diagnosis of cavernous haemangioma, in a patient with malignancy, may adversely influence the outcome of subsequent treatment in these patients, due to delay in therapy. Although previous studies have suggested that ⁹⁹ᵐTc erythrocyte blood pool scintigraphy is both highly sensitive and specific for haemangiomas, a basic flaw in all previous studies has been the small number of control patients studied. Bayesian analysis clearly shows that specificity for a test is dependant on the pre-test probability of the lesion being present. Thus all the studies done to date, may reflect an inappropriately high specificity for ⁹⁹ᵐTc scintigraphy, in diagnosing cavernous haemangiomas, because they have mainly studied patients with haemangiomas and relatively few patients with other lesions. This study was thus undertaken to clarify the true accuracy of this technique, in distinguishing haemangiomas from other hepatic mass lesions, by studying a large number of patients with haemangiomas and other hepatic mass lesions.

A research report submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Medicine in Nuclear Medicine. / Forty (40) female patients with breast masses underwent Technetium 99m Sestamibi scintigraphy in order to evaluate its usefulness in differentiating benign from malignant breast disease and to compare scintigraphy to mammography. Informed consent was obtained from each patient. Scintigraphy consisted of anterior chest and lateral and oblique breast planar images, obtained 5 minutes after intravenous injection of 20 rnecuries (740 MBq) Technetium 99m Sestamibi. Eleven (11) of the 40 patients also had Technetium 99m Methylene Diphosponate breast scintigraphy for comparison. Four nuclear medicine physicians of who three also graded the MDP images performed grading of the Sestamibi scintigraphic images. The grading method, although focussing on the absence (0) or presence (>0) of uptake of isotope, was also designed for comparison of the Sestamibi and MDP images. Statistical analysis showed good correlation between observer grading. Breast scintigraphy was compared to mammography in 27 ofthe 40 patients. Of the 26 malignant breast masses confirmed on histology, 19 were positively identified on Sestamibi scanning giving a sensitivity of 73%, 2 results were inconclusive (grading (0·1) and 5 had a grading 0, of the 8 patients with confirmed lymph node metastases, only 2 were positive on the Sestamibi scans, with 1 inconclusive result. Of the 19 benign breast masses, 9 were visible on Sestamibi scans with additional 3 inconclusive results (grading of 0-1). Statistical analysis showed no significant difference in the Sestamibi and MDP grading. In comparison to mammography, breast scintigraphy was less accurate in distinguishing benign from malignant breast masses. Mammography identified 85.7% of the malignant breast masses and 72.7% of the benign breast masses. Sestamibi scintigraphy identified 76.2% of the malignant breast masses and only 36.4% of the benign breast masses. / Andrew Chakane 2018

Thesis (doctoral)--Rijksuniversiteit te Utrecht.

Thesis (doctoral)--Katholieke Universiteit te Nijmegen.

Orientador: Gláucia Maria Bovi Ambrosano / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-17T23:08:34Z (GMT). No. of bitstreams: 1 Santos_LuisAntonioNogueirados_D.pdf: 2779322 bytes, checksum: 13f963d0d475b047589e806517aa9a48 (MD5) Previous issue date: 2011 / Resumo: A Displasia fibrosa (DF) é uma condição benigna caracterizada pela substituição do tecido ósseo por tecido fibroso desorganizado e osso imaturo. A lesão é resultante de uma mutação pós-zigótica do gene GNAS 1, que codifica a proteína Gs?, localizada no cromossomo 20q13.2, e possui expressão fenotípica variável. Sua classificação ainda é, porém, controversa e motivo de diversas pesquisas. O manejo da DF pode ser tornar um problema em função de tamanho, extensão da lesão e envolvimento anatômico. Exames imaginológicos comumente empregados para o diagnóstico e controle da DF são a radiografia convencional e a tomografia computadorizada. No presente estudo, realizamos uma analise clinica, radiográfica e cintilográfica da DF. A cintilografia óssea foi utilizada para avaliar a taxa de metabolismo ósseo da lesão e o padrão de distribuição do radiofármaco em portadores de DF monostótica. Assim, foram estudados 17 casos de DF, e sua taxa de metabolismo ósseo foi calculada de acordo com o proposto por Kaban et al, 1995. Dos casos estudados, 94.11% apresentaram imagem hipercaptante restrita à maxila ou mandíbula e todos possuíam elevado metabolismo ósseo. Não houve relação entre o fator de atividade óssea com a idade do paciente e localização anatômica. O aspecto radiográfico mais comum foi forma esclerótica, 47%, seguido do aspecto misto, 35.3%, e a forma lítica com 17.6%. Não foi possível estabelecer relação entre padrão de imagem cintilográfica e imagem radiográfica, entretanto o método foi útil para diferenciar lesões maduras e lesões ativas / Abstract: Fibrous dysplasia (FD) is benign bone disease characterized by maturation disorder of the bone forming mesenchyma where the lamellar bone marrow is replaced with abnormal fibrous-osseous tissue. This type of lesion results in a postzygotic mutation of GNAS 1, which encodes the Gs? protein and can be found on the 20q13.2 chromosome, and presents variable phenotypic expressions. The classification of this lesion is controversial and has been the aim of many studies. The management of FD can cause problems, depending on its size, extent of injury, and anatomic involvement. Plain film and computed tomography are commonly employed imaging studies for the diagnosis and control of FD. In the present study, bone scintigraphy was used to assess the rate of bone metabolism and the standard of radionuclide distribution in patients with monostotic FD. Radionuclide bone scans were performed in 17 cases of histopathologically proven FD. In addition, the rate of bone metabolism was calculated according to that proposed by Kaban et al. 1995. In 94.11% of the cases, images of increased uptake to the maxilla or mandible could be observed, all of which presented a high bone turnover. No significant relationship could be determined between bone activity and patient age or anatomic site. The studied lesions constituted casual radiological findings, including sclerotic lesions (47%), mixed aspects (35.3%), and lytic appearances (17.6%). The present study was unable to establish a relationship between the bone scan standard and radiological findings. Nevertheless, this method is still a helpful parameter for the diagnosis of both mature and active lesions / Doutorado / Radiologia Odontologica / Doutor em Radiologia Odontológica

The investigation of an abdominal mass in a child is a common problem in the radiology department of the Red Cross Children's Hospital. The majority of these masses involve the urinary tract. The commonest neoplasm is a Wilms' tumour of the kidney. Against a pathological and clinical background, the investigation of Wilms' tumour by diagnostic imaging is presented. The imaging modalities currently utilised are the intravenous urogram (IVU), ultrasound (US), computed tomography (CT) and magnetic resonance (MR). Using the material available in the last decade, the principles, techniques and imaging characteristics of these modalities are investigated and compared. These results are reflected against those reported in the medical literature. This literature is not yet extensive as the current technology has only been available for the last six to seven years. The IVU has in the past been the main imaging modality and we still use it extensively. Its strengths and weaknesses are discussed. In the last five years US has taken its place as the primary method of diagnostic imaging. We have found that with our increasing experience that this is justified. The use of US and IVU in a practiced hand is a powerful diagnostic combination. CT as a primary investigation is not readily available at our institution. We have used it for comparative purposes in about 20% of our recent cases. CT has not added greatly to our initial diagnostic impression. However, it has been most useful for follow up of metastasis and for assessing the normality of the lungs before ceasing chemotherapy. Our experience with MRI is limited and confined to unusual presentations in the last year. Other modalities such as arteriography and nuclear medicine have special indications which are to be discussed. The remaining tumours of the upper urinary tracts are all rare, but are reported and the literature researched. In the lower urinary tract the main pelvic lesion is a rhabdomyosarcoma. The comparative advantages of the IVU, US, CT and MRI are also noted. In the pelvis, US has also become the primary imaging modality, and is replacing contrast medium cystography. However, examples of the latter are included as it still has a place, particularly in the less sophisticated institutes. CT and MRI, when available, have imaging advantages in the pelvis and are becoming the methods of choice for follow up. The main objective of this document has been to investigate the available imaging techniques, but, against this overall theme, the clinical care of the child is most important. With this in mind the treatment protocols that are used at our hospital are noted in the appendices to the thesis.

No description available.