Functional Image Contrast

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Functional image contrast reflects aspects of tissue function rather than structure. A variety of techniques currently exist for imaging at various levels of tissue function, including changes in tissue blood flow, metabolism, or receptor binding. It is totally noninvasive, does not require exposure to ionizing radiation, and is widely available at medical centers. fMRI has become the standard modality for visualizing regional brain activation in response to sensorimotor or cognitive tasks and is now widely used in cognitive and systems neuroscience.
FMRI is simply MRI scanning in which significant tissue contrast can be attributed to blood flow and/or metabolism.Nearly all studies of taskspecific activation using functional neuroimaging
rely …show more content…

Epilepsy:
Perfusion MRI can also be used to identify active seizure foci in patients with epilepsy partialis continua, The use of BOLD fMRI for detecting ictal alterations in hemodynamics has also been demonstrated.
Dementia:
Studies of regional brain function in dementia may contribute to differential diagnosis and early diagnosis and may provide a means of assessing response to therapeutic intervention. Specific patterns of activation may also suggest strategies for cognitive rehabilitation.
Neuropsychiatric
Disorders: fMRI has been used to further understanding of this phenomenon. Activation of the left temporal region seems to be diminished in all schizophrenics who experience hallucinations, whereas right temporal activation seems to be increased in response to verbal stimuli (Woodruff and others 1997). Dierks and others (1999) demonstrated activation of Heschl’s gyrus during auditory hallucinations, further supporting involvement of primary sensorimotor regions in hallucinosis.
1 Detre, John A, and Thomas F Floyd. "Functional MRI and its applications to the clinical …show more content…

18F6Fluorodopa
(18Fdopa) is one of the most commonly used ligands for studying the dopaminergic system in movement disorders. Epilepsy:
Complex partial seizures in a significant proportion of patients remain uncontrolled despite optimal medical therapy. Surgical removal of epileptogenic foci in partial seizures such as intractable temporal lobe epilepsy results in significant improvement in control of the seizures and the quality of life.PET may reduce the need for invasive EEG as part of the preoperative localisation of surgical targets in the future.
Some centres have proposed using PET as a routine preoperative evaluation tool for patients undergoing epilepsy surgery. However, PET does not provide additional information if the MRI has identified the obvious cause of the epilepsy, such as hippocampal sclerosis.51 Therefore, PET is likely to be most useful in situations where
MRI is equivocal or normal.
Brain
tumours:FDG PET can provide important prognostic information as increased glucose metabolism of gliomas correlates with higher histological grades (III and IV)

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