Department of Radiology, Massachusetts General Hospital NMR Center and Harvard Medical School, Building 149, 13th Street, Charlestown, Massachusetts 02129, USA
The number of physiologic and metabolic phenomena amenable to
analysis using magnetic resonance (MR) techniques is increasing
every year. MR techniques can now evalutate tissue parameters
relevant to TCA cyclemetabolism, anerobic glycolysis, ATP levels,
blood-brain barrier permeability, macrophage infiltration, cytotoxic
edema, spreading depression, cerebral blood flow and volume,
and neurotransmitter function. The paramagnetic nature of certain
oxidation states of iron leads to the ability to map out brain
function using deoxyhemoglobin as an endogenous contrast agent,
and also allows for mapping of local tissue iron concentrations.
In addition to these metabolic parameters, the number of ways
to generate anatomic contrast using MR is also expanding; and
in addition to conventional anatomic scans, mapping of axonal
fiber tracts can also be performed using the anisotropy of water
diffusion. A strategy for integration of these multifarious
parameters in a comprehensive neurofunctional exam in neurodegenerative
illness is outlined in this paper. The goals of the integrated
exam, as applied to a given neurodegenerative illness, can be
subdivided into three categories: etiology, natural history,
and therapeutic end points. The consequences of oxidative stress
and/or mitochondrial dysfunction are explored in the context
of the various parameters that can be measured using the integrated
MR exam.
