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Figure A
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NEUROIMAGING AND BIPOLAR ILLNESS
Until very recently, neuroimaging has played a relatively limited role
in the psychiatric evaluation of children. There are now new developments
in functional imaging which hold great promise for psychiatry. New strategies
for demonstrating abnormalities in bipolar patients using imaging are
being developed at Mayo Clinic.
One theory about the etiology of bipolar disorder is based on the observation
that lithium is an effective mood stabilizer for many patients. Defects
in signaling may result in clinical symptoms. A second theory states
that bipolar disorder is aggravated by abnormal connections between
various brain regions. Such abnormal connections may result in impaired
feedback loops, which are associated with manic and depressed states.
Two relatively new neuroradiological techniques may be especially suited
for the diagnosis of bipolar disease and other psychotic illnesses.
Magnetic resonance spectroscopic imaging (MRSI) allows for the direct
study of brain function. Diffusion tensor imaging (DTI) allows for mapping
of the connections within the living brain. As a result, white matter
connections between various brain regions can be studied. In collaboration
with Dr. John D. Port in the Department of Radiology, psychiatrists
at Mayo Clinic are studying these new applications. |
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Figure B
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The supplied images are an example from one study subject. The reference
image (A, upper left) shows a T1-weighted reference slice overlaid with
the location of the PRESS voxel and the phase encode grid. Quantitative
creatine, myo-inositol and N-acetyl-aspartate levels (A, upper right,
lower left, and lower right images, respectively) as determined by LCModel
are also shown. In these metabolite maps, values are linearly scaled
such that yellow voxels have the maximum concentration of a given metabolite,
with darker shades representing lesser concentrations. Green voxels
have standard deviations greater than 19% and are considered "unreliable"
by LCModel criteria.
Figure B shows the spectrum from the right thalamus, corresponding
to the red arrow in Figure A; note the quantitative values for each
metabolite.
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