Neuroimaging clinics of North America
-
Neuroimaging Clin. N. Am. · Nov 2003
ReviewNeuroimaging and mechanisms of drug abuse: interface of molecular imaging and molecular genetics.
Whereas ligand studies can inform the end-products of dysregulation of genetic expression, reporter gene imaging can provide the means to understand the genetic origin of these end-products. As with radioligand studies, in vivo direct measurement of gene expression will allow genetic processes to be monitored over time in the same subject, use of a subject as his/her own control in intervention studies (i.e., measurement before and after an intervention), and monitoring the spatial distribution of molecular events in the whole brain. Furthermore, reporter gene imaging, by advancing knowledge of the biologic mechanisms of disease states, has important clinical implications, particularly in the development and monitoring of treatments. We expect PET to play a prominent role in the elucidation of substance abuse mechanisms and contribute significantly to the development of innovative treatment strategies.
-
Neuroimaging Clin. N. Am. · Nov 2003
ReviewThe role of positron emission tomography imaging in movement disorders.
PET imaging provides the means to study neurochemical, hemodynamic, or metabolic processes that underlie movement disorders in vivo. Because the extent of presynaptic nigrostriatal dopaminergic denervation can be quantified in PD even at an early or preclinical stage of the disease, PET imaging may allow the selection of at-risk subjects for neuroprotective intervention trials. These techniques may also provide markers to follow progression of disease or evaluate the effects of neurorestorative interventions in patients who have more advanced disease. ⋯ Studies have shown striatal dopamine receptor loss in selected subtypes of dystonic patients. In conclusion, it is expected that PET will help us to better understand the pathophysiology of movement disorders, increase the diagnostic accuracy, allow preclinical diagnosis, monitor disease progression, and evaluate the efficacy of therapeutic agents. Pharmacologic radioligand displacement studies and the development of new nondopaminergic ligands may further aid in the unraveling of cerebral mechanisms that underlie movement disorders.
-
Neuroimaging Clin. N. Am. · Nov 2003
ReviewPositron emission tomography and single photon emission CT molecular imaging in schizophrenia.
We reviewed findings from PET and SPECT studies that have contributed to our understanding of the pathophysiology and treatment of schizophrenia. The most robust set of findings pertains to imaging of presynaptic dopaminergic function in the striatum. The results of these studies have been consistent in showing that schizophrenia, at least during episodes of illness exacerbation, is associated with increased activity of DA neurons; this increased presynaptic activity is associated with positive symptoms and good therapeutic response. ⋯ The results that have been produced by this field to date suggest that PET will significantly contribute to unraveling the biologic bases of psychiatric disorders and may contribute to their clinical management. Moreover, it is foreseeable that PET will become increasingly involved in the development of new psychiatric medications. Expanding the availability of PET and the current radiopharmaceutical portfolio will be critical for these predictions to become reality.
-
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.
-
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.