Cerebral Blood Flow and Chemical Shifting in Normal Pressure Hydrocephalus: Evaluation of Therapeutic Indication and Efficacy by Chemical Imaging and Blood Flow Mapping
Date Issued
2003-12-31
Date
2003-12-31
Author(s)
Tu, Yong-Kwang
DOI
912314B002341
Abstract
Normal pressure hydrocephalus (NPH) resulted from cerebrovascular accidents,
head injury or other causes is a common disease among aged patients. This disease is
characterized by the presence of symptoms of diffused brain dysfunction without
those of intracranial hypertension. Deterioration of mental function, manifested
initially as impairment of memory, insidiously progresses to confusion and severe
deterioration of intellectual function, associate with disturbance of gait and bladder
control. Because of the similar clinical manifestation and imaging finding on CT or
MR, it is very difficult to differentiate this disease from brain atrophy or Alzheimer’s
disease. Shunting procedure to drain cerebrospinal fluid (CSF) in NPH patients may
effectively reverse these clinical problems, however, if the differential diagnosis is
not properly made this surgery sometimes become unnecessary or even harmful.
Various tests have been investigated for the differentiation of these conditions,
yet none was proven to be ideal. Demonstration of CSF circulation dynamics by
cisternography with isotope intrathecal injection or employing CT and MR technique
was tried but the results were equivocal. One recent study of regional blood flow
measurement showed that both conditions caused the reduction of flow over the
periventricular areas of the brain but the results of cerebrovascular reactivity are
different between NPH and brain atrophy. Thus, we hypothesize that in a reversible
clinical condition such as NPH, although rCBF is depleted due to the pressure effect
from dilated ventricles, neuronal metabolic activity should remain normal or
suboptimal. On the contrary, both rCBF and neuronal metabolic activity should be
very low in the irreversible condition of brain atrophy.
In vivo proton magnetic resonance spectroscopy allows noninvasive evaluation
of brain metabolism on patients with neurological disease. During the past 3 years,
we conducted two studies to evaluate the biochemical changes of the brain
parenchyma with proton magnetic resonance spectroscopy (H-MRS) and the
changes of regional cerebral blood flow (rCBF) in patients with moderate head
injury and intracerebral hemorrhage. We demonstrate a good correlation among
H-MRS, rCBF and patients clinical outcome in these two diseases. Recently, we are
able to apply imaging software to reconstruct proton single voxel spectroscopy into
chemical shifting imaging (CSI). With this technique, rCBF mapping can be
superimposed with CSI and MR imaging for analysis.
Subjects
Normal Pressure Hydrocephalus
Regional Cerebral Blood
Flow
Flow
Chemical Shifting Imaging
Magnetic Resonance
Spectroscopy
Spectroscopy
Ventriculo-peritoneal Shunting
Publisher
臺北市：國立臺灣大學醫學院外科
Type
report
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