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Subcortical hypoperfusion associated with asymptomatic white matter lesions on magnetic resonance imaging
J Hatazawa1, E Shimosegawa, T Satoh
1Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Japan. hatazawa@akita-noken.go.jp
Background And Purpose:
We examined whether hemodynamic and metabolic abnormalities in the cerebral white matter, basal ganglia, and thalamus are associated with asymptomatic white matter lesions (WML) depicted on MR images.
Methods:
A positron emission tomographic study with H2(15)O, C15O, and 15O2 was performed in eight normal control subjects without any WML (mean +/- 1 SD age, 68.5 +/- 10.2 years) and in 15 asymptomatic subjects with WML (71.3 +/- 8.5 years) to measure regional cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and oxygen metabolic rate.
Results:
In the cerebral white matter in the asymptomatic subjects with WML, significantly lower CBF (20.3 +/- 3.9 mL/100 mL per minute; P < .05) and significantly higher OEF (0.43 +/- 0.08; P < .05) were found compared with those for control subjects (23.5 +/- 2.6 mL/100 mL per minute and 0.37 +/- 0.06, respectively). The severity of WML was not related to the magnitude of hypoperfusion. In the basal ganglia, significantly lower CBF (44.9 +/- 6.9 mL/100 mL per minute; P < .01) and significantly higher OEF (0.54 +/- 0.08; P < .01) were found in the WML group than in control subjects (70.1 +/- 12.0 mL/100 mL/min and 0.39 +/- 0.03, respectively). In the thalamus, there was no significant difference in CBF and OEF between the control and WML groups.
Conclusions:
Hypoperfusion of the cerebral white matter and basal ganglia in asymptomatic WML subjects may be induced by the arteriosclerosis of long penetrating medullary arteries and lenticulostriate arteries but may not be directly related to the production of WML. The role of hypoperfusion in the production of WML and acceleration of its development remains to be elucidated.
Insights
Asymptomatic white matter lesions (WML) are linked to reduced cerebral blood flow and increased oxygen extraction in the white matter and basal ganglia. However, this hypoperfusion may not directly cause WML development.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Asymptomatic white matter lesions (WML) are common findings on MRI scans.
- The underlying hemodynamic and metabolic causes of WML are not fully understood.
Purpose of the Study:
- To investigate hemodynamic and metabolic abnormalities in the brain associated with asymptomatic white matter lesions (WML).
- To determine if these abnormalities are present in the cerebral white matter, basal ganglia, and thalamus.
Main Methods:
- Positron emission tomography (PET) with H2(15)O, C15O, and 15O2 was used.
- Regional cerebral blood flow (CBF), cerebral blood volume, oxygen extraction fraction (OEF), and oxygen metabolic rate were measured.
- A study group of 15 asymptomatic subjects with WML was compared to 8 healthy control subjects.
Main Results:
- Subjects with WML showed significantly lower CBF and higher OEF in the cerebral white matter and basal ganglia compared to controls.
- No significant differences in CBF and OEF were observed in the thalamus between groups.
- The severity of WML did not correlate with the degree of hypoperfusion.
Conclusions:
- Hypoperfusion in the cerebral white matter and basal ganglia may stem from arteriosclerosis of specific arteries.
- Hypoperfusion might not be directly responsible for the initial development of WML.
- Further research is needed to clarify the role of hypoperfusion in WML development and progression.