<p>Patients suffering from different forms of neurodegenerative diseases, such as: Creutzfeldt Jacob Disease (CJD), Alzheimer disease (AD), mild cognitive impairment (MCI), frontotemporal dementia and Parkinson’s disease (PD) were examined with Positron Emission Tomography (PET) and the combination of different radiotracers: ¹⁵O-water, N-[¹¹C-methyl]-L-deuterodeprenyl (DED), [¹⁸F] 2-fluorodeoxyglucose: (FDG), N-methyl-[¹¹C]2-(4-methylaminophenyl)-6-hydroxybenzothiazole (PIB) and L-[¹¹C]-3,4-dihydroxiphenyl-alanine (DOPA). The radiotracers and the combinations of different radiotracers were selected with the intention to detect, in the brain, patterns of neuronal dysfunction, astrocytosis, axon degeneration or protein aggregation (amyloid), in the brain which are pathognomonic for specific diseases and may contribute to improve clinical differential diagnoses. Examinations in healthy volunteers were performed to allow comparisons with patients. In addition, animal studies were conducted to complement the information. In some cases, the PET findings could be compared with the results of autopsies.</p><p>In contrast to the micropathology, in which only a limited part of a tissue (obtained post-mortem or by biopsy) is inspected, one PET acquisition provides an image of the whole system (e.g.: the brain and the cerebellum). This form of imaging pathology is “<i>in vivo</i>”, where the examination is innocuous for the patient. </p><p>This thesis is an attempt to stimulate the development of new tracers, new tracer combinations and methods that directly or indirectly describe the anatomo-physiopathological changes produced in the brain in neurodegenerative diseases. A better description of different diseases can be obtained, confirming or questioning the clinical diagnoses and widening our understanding of the mechanisms underlying neurodegeneration. Different pathologies can produce similar symptoms and thus causing confusion regarding clinical diagnosis. The used PET combinations improved the accuracy of the diagnoses. The incipient knowledge emerging from a new neuroimaging pathology in combination with other disciplines may open the way to new classifications of dementias and neurodegenerative diseases based on an “<i>in vivo</i>” pathology. </p>

Diagnosis of diabetes mellitus, presence of hyperglycemia, and/or insulin resistance confer cardiovascular risk, particularly for diastolic dysfunction. Diabetes is associated with elevated myocardial norepinephrine (NE) content, enhanced sympathetic nervous system (SNS) activity, altered resting heart rate, and depressed heart rate variability. Positron emission tomography (PET) using the NE analogue [11C]meta-hydroxyephedrine ([11C]HED) provides an index of myocardial sympathetic neuronal integrity at the NE reuptake transporter (NET). The hypothesis of this project is that (i) hyperglycemia imparts heightened sympathetic tone and NE release, leading to abnormal sympathetic neuronal function in the hearts of diabetic rats, and (ii) these abnormalities may be reversed or prevented by treatments to normalize glycemia. Sprague Dawley rats were rendered insulin resistant by high fat feeding and diabetic by a single dose of streptozotocin (STZ). Diabetic rats were treated for 8 weeks with insulin, metformin or rosiglitazone, starting from either 1 week (prevention) or 8 weeks (reversal) after STZ administration. Sympathetic neuronal integrity was evaluated longitudinally by [11C]HED PET. Echocardiography measures of systolic and diastolic function were completed at serial timepoints. Plasma NE levels were evaluated serially and expression of NET and β-adrenoceptors were tested at the terminal endpoints. Diabetic rats exhibited a 52-57% reduction of [11C]HED standardized uptake value (SUV) at 8 weeks after STZ, with a parallel 2.5-fold elevation of plasma NE and a 17-20% reduction in cardiac NET expression. These findings were confirmed by ex vivo biodistribution studies. Transmitral pulse wave Doppler echocardiography established an extension of mitral valve deceleration time and elevated early to atrial velocity ratio, suggesting diastolic dysfunction. Subsequent treatment with insulin but not metformin restored glycemia, reduced plasma NE by 50%, normalized NET expression, and recovered [11C]HED SUV towards non-diabetic age-matched control. Diastolic dysfunction in these rats persisted. By contrast, early treatment with insulin, metformin, or rosiglitazone delayed the progression of diastolic dysfunction, but had no effect on elevated NE and reduced [11C]HED SUV in diabetic rats, potentially owing to a latent decrease in blood glucose. In conclusion, diabetes is associated with heightened circulating and tissue NE levels which can be effectively reversed by lowering glycemia with insulin. Noninvasive interrogation of sympathetic neuronal integrity using [11C]HED PET may have added value in the stratification of cardiovascular risk among diabetic patients and in determining the myocardial effects of glycemic therapy.

Section 1 of this thesis contains an introduction to method development in organic synthesis, multicomponent reactions, sulfonyl azides, tracer development in 11C chemistry and the biological target. Section 2 describes the use of sulfonyl azides in carbonylative chemistry. Paper I covers development of a diazotransfer protocol. In total, 30 arylsulfonyl azides were synthesised from primary sulfonamides (20–90% yield). 15N mechanistic studies were carried out and in Paper II, the products were converted into sulfonamides, sulfonylureas and sulfonyl carbamates (19–90% yield). For ureas and carbamates, a two-chamber protocol was employed to release CO from Mo(CO)6. 15N mechanistic studies showed that the sulfonamides were formed by direct displacement of azide. Section 3 covers imaging and biological studies of the angiotensin II receptor subtype 2 (AT2R). In Paper III, 12 11C-sulfonyl carbamates were prepared in isolated radiochemical yields of 3–51% via Rh(I)-mediated carbonylation. The first non-peptide AT2R agonist, C21, was labelled (isolated RCY 24±10%, SA 34–51 GBq/µmol). C21 was tested in a prostate cancer assay, followed by biodistribution and small-animal PET studies. In Paper IV, a 11C-labelled AT2R ligand prepared via Pd(0)-mediated aminocarbonylation was used for autoradiography, biodistribution and small-animal PET studies.   Section 4 describes the development of a multicomponent method for the synthesis of 3,4-dihydroquinazolinones (Paper V). 31 3,4-dihydroquinazolinones were synthesized via a cyclic iminium ion.

The aim of this work was studying of the coordination properties of TACN macrocyclic derivatives with aminophosphinate pendant arms. Two ligands were prepared, one with two pendant arms NODPam and one with three pendant arms NOTPam. Because of degradation of ligand NODPam during its synthesis, only the ligand NOTPam was studied further. Acid-base properties of ligand and termodynamic stability of aluminium and gallium complexes were studied. Formation and disociation studies were performed with the complexes. Coordination of fluoride ions to aluminium complex was studied using ion selective fluoride electrode. Finally coordination of complex AlFx with ligand NOTPam was studied using 19F and 27Al NMR spectroscopy. Selected experiments were made also with ligand NOTA. Key words: macrocyclic complexes, positron emission tomography, phosphinic acids

La Tomographie par Émission de Positon (TEP) combinée à l'imagerie scanner est intéressante pour la planification de traitement en radiothérapie. Elle réduit la variabilité inter et intra-observateur dans la définition du volume cible et permet de visualiser les hétérogénéités biologiques. Plusieurs algorithmes de segmentation ont été proposés mais aucun ne fait consensus. Pour valider ces algorithmes, les simulations de Monte-Carlo offrent la possibilité de maîtriser la vérité terrain et l'ensemble des paramètres d'acquisition.Nous avons proposé plusieurs méthodologies d'amélioration du réalisme des simulations. Des jeux de données présentant une variabilité anatomique, une hétérogénéité tumorale réaliste et intégrant les mouvements respiratoires ont ainsi été générés.Ces données ont été utilisées dans une première étude sur la segmentation du volume cible. Plusieurs algorithmes ont été comparés dans le cadre de la planification de traitement. L'utilisation de données simulées a permis de relier la précision de la segmentation à la qualité de la couverture de la vérité terrain. Nous avons aussi étudié l'impact de la respiration sur la précision de la segmentation.L'utilisation d'un algorithme de segmentation avancé permettant de définir un sous-volume plus actif pour la prescription d'une dose hétérogène a été proposée. Plusieurs scénarios de prescription ont été comparés en terme de probabilité de contrôle tumorale (TCP) calculée sur la TEP. La variabilité de la TCP liée aux paramètres d'acquisitions a été quantifiée. L'impact du contraste et de la taille du sous-volume fut étudié. Pour finir l'apport d'un ajout de compartiments à de telles prescriptions a été analysé. / There has been an increasing interest for the use Positron Emission Tomography (PET) combined with Computed Tomography for radiotherapy treatment planning. It improves target volume delineation by reducing inter and intra-observer variability and allows visualizing biological heterogeneities. Plethoras of segmentation algorithm have been proposed but there is a lack of consensus regarding which one to use. Monte Carlo simulations are interesting to validate these algorithms since they allow creating datasets with known ground-truth and for which all acquisition parameters are controlled.We proposed several methodologies for improving the realism of simulations. Several datasets incorporating patient specific variability in terms of anatomy and activity distributions, realistic tumor shape and activity modeling and integrating the respiratory motions were created.These data were used in a first study concerning target volume definition. Several algorithms were compared for radiotherapy treatment planning. The accuracy of segmentation was related to the quality of ground-truth volume coverage. We also studied the impact of respiratory motion on segmentation accuracy.We investigated the use of an advanced segmentation method able to define high uptake sub-volumes, for heterogeneous dose prescriptions. Several scenarios of prescriptions were compares in terms of Tumor Control Probability (TCP) computed on PET images. Variability of this TCP due to acquisition parameters was quantified. The impact of contrast and size of sub-volume was studied. Finally we studied the usefulness of the addition of compartments to such heterogeneous prescriptions.

In this dissertation, we discuss the development of new phase transfer agents, which are capable of rapid fluorination of silicon. These are 18-C-6 derivatives containing a hydroxyl group in the side arm (podand), also known as C-pivot lariats. The syntheses of these lariats including several that have not been previously reported and their efficient purification are described. The synthesis route leads to a robust and generalized approach to obtain these lariats on the gram scale. These agents were initially designed for applications in positron emission tomography (PET). In this medical imaging modality, tracer agents containing silicon have found promising utility as fluoride receptors for more rapid radiolabeling. Phase transfer agents are generally required for 18F-labeling due to the low solubility in organic reaction media and reactivity of cyclotron-generated [18F]potassium fluoride. We envisioned that 18-C-6 derivatives may serve as both phase transfer agents as well as nucleophilic catalysts (CENCs). In this conception, CENCs were rapidly pre-complexed with KF followed by silicon fluorination, which takes advantage of a previously established silicon dianion mechanism. In collaboration with researchers at the NIH, we studied the effect of various linkers connecting the metal chelating unit to the nucleophilic hydroxyl group on the radiofluorination of silicon under mild condition. A hydrolysis resistant aryl silicon fragment has also been developed that contains various functional groups for convenient attachment to the potential PET radiotracer agents. In a second project, we demonstrate the unique reactivity of γ-silyl allenyl esters. Taking advantage of the silyl group as a fluoride acceptor, these allenoates readily underwent addition to a variety of carbon electrophiles, including aryl fluorides, to afford all-carbon quaternary centers bearing an ethynyl group. Surprisingly, in the presence of aldehydes, exclusive bis-substitution occurs at the γ-position to afford the dicarbinol. Details relating to reaction optimization and substrate scope for both the reactions are presented. Dicarbinol allenes were subsequently converted to highly substituted δ-lactones, a novel 6-hydro-2-pyrone as single diastereomers. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

This thesis combines phenomenological and neuroscientific research to elucidate the effects of psychedelic agents on the human brain, mind and psychological well-being. Psychoactive plants have been used for thousands of years for ceremonial and ritual purposes. Psychedelics are psychoactive substances that affect cognitive processes and alter perception, thoughts, and mood. Illegalization of psychedelics in the 1960s rendered them impossible to study empirically but in the last couple of decades, relaxed legal restrictions regarding research purposes, renewed interest in the effects of psychedelic drugs and new brain imaging techniques have started to reveal the possibilities of these mind-altering substances. Psychedelics mainly affect the serotonin receptor 5-HT2A which in turn affect the functioning of largescale cortical areas by changing cerebral blood flow, alpha oscillations, and functional connectivity. These cortical changes not only induce immediate alterations in perception and cognition but have been shown to have positive effects in therapeutic interventions for depression, anxiety, and addiction, and also positively affect well-being in general. Although the pharmacology and neurobiology of psychedelics are still poorly understood, the potential benefits justify empirical research on psychedelics in humans.

A Tomografia por Emissão de Pósitrons (PET - Positron Emission Tomography) é uma modalidade de imagens para o diagnóstico em Medicina Nuclear. São utilizados radiofármacos emissores de pósitrons que possibilitam obter imagens que representam o processo bioquímico dessas substâncias no órgão ou tecido de interesse in vivo. São detectados, em coincidência, os fótons provenientes da aniquilação pósitron/elétron, que ocorre dentro do corpo do paciente. Esta informação é posteriormente utilizada para a reconstrução do objeto em estudo. Atualmente, existem dois tipos de equipamentos capazes de realizar estudos tomográficos por emissão de pósitrons: o dedicado e a câmara PET/SPCET. Este trabalho abordou este último tipo, que permite também a realização de exames habituais de Medicina Nuclear, que usam emissores de fótons. Existem dificuldades inerentes ao método de aquisição destas imagens que afetam a quantificação de índices ou atividade. Elas estão relacionadas ao fato de a emissão de radiação obedecer a uma distribuição de Poisson, às interações físicas da radiação com o corpo do paciente e com o detector, ao ruído devido à natureza estatística destas interações e de todo o processo de detecção, assim como à metodologia de aquisição dos exames (preparo e posicionamento do paciente, taxa de contagens etc.). Correções são propostas na literatura que não são totalmente implementadas pelos fabricantes: de espalhamento, de atenuação, de eventos aleatórios, do tempo morto, de decaimento, da resolução espacial e de outras características do equipamento. O objetivo deste trabalho foi o de realizar um estudo dos métodos aplicados por dois fabricantes, assim como algumas influências das características técnicas das câmaras PET/SPECT na obtenção do índice de SUV (Standardized Uptake Value). Para isso, dados de simuladores físicos, dispostos em várias montagens, foram obtidos com uma câmara no modo 3D e outra no modo 20. Constatou-se também que a forma das fontes usadas para calibração influencia no resultado final e impõe novos desafios para a quantificação em uma situação clínica. Por fim, no momento da quantificação, a região de interesse deve ser escolhida de acordo com aquela usada para a determinação dos coeficientes de correção e calibração. Verificou-se que é viável realizar quantificações com câmaras PET/SPECT, inclusive o índice SUV. Para tanto, além das correções citadas anteriormente, é imprescindível ter o equipamento bem ajustado, assim como a obtenção de coeficientes para normalização da sensibilidade e correção do efeito de volume parcial. / Positron Emission Tomography (PET) is a Nuclear Medicine imaging modality for diagnostic purposes. Pharmaceuticals labeled with positron emitters are used and images which represent the in vivo biochemical process within tissues can be obtained. The positron/electron annihilation photons are detected in coincidence and this information is used for object reconstruction. Presently, there are two types of systems available for this imaging modality: the dedicated systems and those based on gamma camera technology. In this work, we utilized PET/SPECT systems, which also allows for the traditional Nuclear Medicine studies based on single photon emitters. There are inherent difficulties which affect quantification of activity and other indices. They are related to the Poisson nature of radioactivity, to radiation interactions with patient body and detector, noise due to statistical nature of these interactions and to all the detection processes, as well as the patient acquisition protocols. Corrections are described in the literature and not all of them are implemented by the manufacturers: scatter, attenuation, randoms, decay, dead time, spatial resolution, and others related to the properties of each equipment. The goal of this work was to assess these methods adopted by two manufacturers, as well as the influence of some technical characteristics of PET/SPECT systems on the estimation of SUV. Data from a set of phantoms were collected in 3D mode by one camera and 20, by the other. We concluded that quantification is viable in PET/SPECT systems, including the estimation of SUVs. This is only possible if, apart from the above mentioned corrections, the camera is well tuned and coefficients for sensitivity normalization and partial volume corrections are applied. We also verified that the shapes of the sources used for obtaining these factors play a role on the final results and should be dealt with carefully in clinical quantification. Finally, the choice of the region of interest is critical and it should be the same used to calculate the correction factors.

Introduction. Fused Positron Emission Tomography and Computed Tomography (PET/CT) is an emerging investigative tool in cardiovascular disease that provides an imaging-based quantification of pathophysiological processes of interest. The purpose of this thesis was to study the application of PET to identify fundamental pathophysiological processes driving 3 forms of cardiovascular disease: aortic stenosis, myocardial infarction, and atherosclerosis. Methods. Aortic Stenosis. Patients with a spectrum of calcific aortic valve disease (n=121) who underwent PET-CT imaging for the identification of valvular calcification (18Ffluoride) and inflammation (18F-fluorodeoxyglucose, 18F-FDG) underwent serial imaging and clinical follow-up over 2 years. Baseline imaging findings were compared with echocardiographic and CT markers of disease progression and clinical outcome. Myocardial Infarction. Patients underwent PET-CT imaging with 18F-fluciclatide (a novel αvβ3-selective radiotracer highlighting active angiogenesis, inflammation and fibrosis) after ST-segment elevation MI (n=21), alongside stable patients with chronic total occlusion (CTO) of a major coronary vessel (n=7), and healthy volunteers (n=9). Myocardial radiotracer uptake was compared with clinical and cardiac magnetic resonance imaging (CMR) markers of infarction and remodeling. Atherosclerosis. Patients with a spectrum of atherosclerotic disease categorized as stable or unstable (recent MI) underwent PET/CT imaging with 18F-fluciclatide (n=46). Thoracic aortic 18F-fluciclatide uptake was compared with aortic atherosclerotic burden quantified by CT plaque thickness, plaque volume and calcium scoring. Histological validation. Tissue from the aortic valve, myocardium and carotid arteries of study subjects was acquired and examined ex vivo using histology and autoradiography. Results. Aortic Stenosis. Baseline valvular 18F-fluoride uptake correlated strongly with the rate of progression in AVC (r=0.80, p < 0.001) and with haemodynamic progression (mean aortic valve gradient r=0.32, p=0.001). It emerged as independently associated with clinical outcome after age and sex-adjustment (HR 1.55 [1.33-1.81], p < 0.001). 18F-FDG demonstrated moderate correlations with disease progression as assessed by CT (r=0.43, p=0.001) and echocardiography (18F-FDG r=0.30, p=0.001), and was associated with clinical outcomes independent of age and sex (HR 1.35 [1.16-1.58], p < 0.001). Valvular 18F-fluoride uptake correlated with immunohistochemical markers of calcification activity. There was no correlation between 18F-FDG uptake and inflammation. Myocardial Infarction. 18F-Fluciclatide binding was demonstrated in ex vivo peri-infarct myocardium and uptake was increased in vivo at sites of acute infarction compared to remote myocardium (tissue-to-background ratio (TBRmean) 1.34±0.22 vs 0.85±0.17 respectively, p < 0.001) and myocardium of healthy volunteers (TBRmean 1.34±0.22 vs 0.70±0.03; p < 0.001). There was no 18F-fluciclatide uptake at sites of established prior infarction in patients with CTO, with myocardial activity similar to healthy volunteers (TBRmean 0.71±0.06 vs. 0.70±0.03,p=0.83). 18F-Fluciclatide uptake occurred at sites of regional wall hypokinesia (wall motion index ≥1 vs 0; TBRmean 0.93±0.31 vs 0.80±0.26 respectively, p < 0.001), was increased in segments displaying functional recovery (TBRmean 0.95±0.33 vs 0.81±0.27, p=0.002) and associated with increase in probability of regional recovery. Atherosclerosis. 18F-Fluciclatide vascular binding ex vivo co-localised with regions of increased αvβ3 integrin expression, and markers of inflammation and angiogenesis. 18F-Fluciclatide uptake in vivo correlated with measures of aortic atherosclerotic burden: plaque thickness (r=0.57, p=0.001), total plaque volume (r=0.56, p=0.001) and the CT aortic calcium score (r=0.37, p=0.01). Patients with recent MI had greater aortic 18F-fluciclatide uptake than those with stable disease (TBRmax 1.33 vs 1.21, p=0.01). Conclusions. In a range of cardiovascular diseases, PET-CT can provide insights into key pathophysiological processes, guide patient risk stratification and prognosis, and identify important biomarkers of disease activity that can be used for the development of future therapeutic interventions.

Computed tomography imaging has revolutionised modern medicine and we can now study the body in greater detail than ever before. Cardiac computed tomography has the potential to provide information not just on coronary anatomy, but also on myocardial function, perfusion and viability. This thesis addresses the optimisation and validation of computed tomography imaging of the heart using a wide volume 320-multidetector scanner. Computed tomography coronary angiography now has diagnostic accuracy comparable to invasive coronary angiography. However, radiation dose remains an important concern. It is therefore important to minimise computed tomography radiation dose while maintaining image quality. I was able to demonstrate that iterative reconstruction and patient tailored imaging techniques led to a 39% reduction in radiation dose in computed tomography coronary angiography, while maintaining subjective and objective assessments of image quality. In addition, I demonstrated that diagnostic images can be obtained in 99% of unselected patients presenting with suspected coronary artery disease when using single heart-beat 320- multidetector computed tomography coronary angiography. Computed tomography myocardial perfusion imaging can provide additional and complementary information as compared to computed tomography coronary angiography that can aid diagnosis and management. I established both quantitative and qualitative assessment of computed tomography myocardial perfusion imaging and validated it against both a clinical “gold-standard”, fractional flow reserve during invasive coronary angiography, and a physiological “gold-standard”, positron emission tomography with oxygen-15 labelled water. Finally, I was able to show that techniques to reduce radiation dose can also be applied to computed tomography myocardial perfusion imaging, leading to a 60% reduction in radiation dose, while maintaining image quality. In my thesis, I have established that comprehensive cardiac angiographic and perfusion imaging can be performed with wide volume computed tomography in a broad generalizable population of patients with relatively low radiation exposure. These techniques provide both structural and functional assessments from a single imaging modality that are valid and readily applicable to the clinic in the assessment and management of patients with suspected coronary artery disease.