Neuroimaging clinics of North America
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Neuroimaging Clin. N. Am. · Nov 2003
ReviewPositron emission tomography imaging of the aging brain.
PET imaging provides a vital means to study the human brain in vivo in aging and early disease states. PET studies using selective markers for brain metabolism and neurotransmitter function have uncovered a wealth of information on healthy and pathologic brain aging, and its relationship to behavior and mood states. Recognition of inherent potential confounds in the use of PET in aging studies is essential to the proper interpretation of these data.
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Factors that place constraints on radio-chemists who are seeking to design and develop radiopharmaceuticals for PET imaging studies include the short half-lives of 11C and 18F, minimum radiochemical yield and specific activity requirements, and high radiation fields that are associated with multi-Curie quantities of PET radionuclides. Nevertheless, during the past 20 years, considerable progress has been made in the development and application of a variety of PET radiotracers for a range of imaging studies in human subjects. We have highlighted a few areas of radiochemistry that focused on PET radiotracers that are described in this issue. Although the number of PET radiotracers synthesized is in the hundreds [6], much work remains to develop specific and useful PET radiotracers for a host of new and exciting noninvasive imaging applications.
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Neuroimaging Clin. N. Am. · Nov 2003
Review Historical ArticleMolecular imaging of the brain: a historical perspective.
The rapid expansion of modern molecular imaging methods since the time of their initial conception in the 1970s has given rise to numerous discoveries of molecular mechanisms that underlie brain function in health and disease. Uses in clinical diagnosis and therapy monitoring are still evolving. Future clinical trials, in which molecular imaging is imbedded and correlated with clinical outcomes, will be critical to advancing new uses for patient management. Receptor occupancy studies are already well integrated into many drug development studies and clinical trials; such studies will provide a basis for new studies that will further advance clinical uses of brain molecular imaging.
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Neuroimaging Clin. N. Am. · Nov 2003
ReviewImaging the epileptic brain with positron emission tomography.
Positron emission tomography (PET) has an established role in the noninvasive localization of epileptic foci during presurgical evaluation. [18F]fluorodeoxyglucose (FDG) PET is able to lateralize and regionalize potentially epileptogenic regions in patients who have normal MR imaging and is also useful in the evaluation of various childhood epilepsy syndromes, including cryptogenic infantile spasms and early Rasmussen's syndrome. Novel PET tracers that were developed to image neurotransmission related to gamma-aminobutyric acid (GABA) [with [11C]flumazenil] and serotonin-mediated [with alpha-[11C]methyl-L-tryptophan (AMT)] function provide increased specificity for epileptogenic cortex and are particularly useful when FDG PET shows large abnormalities of glucose metabolism. Detailed comparisons of PET abnormalities with intracranial electroencephalographic findings also improve our understanding of the pathophysiology of human epilepsy.
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Extensive PET imaging research on AD has been conducted since PET scanners became available in the early 1980s. PET imaging using FDG, now commercially available, can detect early metabolic changes in AD and differential metabolic features of various dementing disorders. ⋯ Limited prospective studies demonstrated the effects of PET imaging in dementia management, which precludes the approval of FDG PET for more widespread, reimbursable use. Further evidence for the efficacy of PET imaging through well-organized clinical studies, as well as continuing efforts in technologic development and basic research to characterize functional alterations in dementing disorders in living patients, are equally important to achieve the goal of better dementia care.