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Neuroimage Analysis Center: Collaborations |
Neurologic imaging |
MRI provides images that are reflective of regional differences in proton concentrations and the physico-chemical environment of protons (e.g. water protons show different MR behavior from protons in larger molecules (lipids, proteins, etc.); protons in hydration water show different MR behavior than protons in unbound water). In particular, gray matter can be distinguished from white matter and CSF (cerebro-spinal fluid) by those proton characteristics.
Since pathological changes in tissue composition can alter proton distribution, tumoral infiltration, edema, and bleeding can be distinguished from the surrounding healthy tissues. Three main applications (schizophrenia, multiple sclerosis, Alzheimer' s Disease and neurosurgical guidance) are the paradigms for three basic approaches to the extraction of information: quantitative manual, quantitative automated, and qualitative. These approaches are driven by the capability of MRI to characterize tissues.
Several
MRI-based studies of age-related volumetric changes in the gray and white
matter of healthy human volunteers have shown that atrophy is associated
with normal aging and can be recognized as a relative increase in intracranial
fluid compartments on MR images. Recent studies have supported this finding.
MRI studies focusing on mildly impaired AD patients have uniformly
reported significant and striking differences between MRI measures of the
medial temporal lobe in AD patients and controls. Thus, with the help
of MRI, volume measurement has been reported as an excellent means of differentiating AD patients
from controls.
Guttmann, Benson, Warfield et al... 2000
More information on the NAC's Alzheimer's Disease research
Conventional
spin echo (CSE) MRI, has been the gold standard for imaging of MS since
its sensitivity to white matter abnormalities was first identified in the
early 1980s. Active lesions were detected by intravenously-administered paramagnetic
contrast agents in regions with a compromised blood-brain-barrier. The different
histological components of a lesion modulated MRI signal intensity to different
extents.
Several studies, including a preliminary analysis of a longitudinal MR study
of the natural course of MS with automated methods indicated that changes
in MR-based lesion load measurements are significantly correlated to changes
in clinical outcome measures, such as the expanded disability status scale (EDSS)
and the number or frequency of attacks.