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Time course of the apparent diffusion coefficient after cerebral infarction.
F Ahlhelm1, G Schneider, M Backens
1Department of Neuroradiology, University of Saarland, 66424 Homburg/Saar, Germany. frah1@gmx.de
European Radiology
|August 27, 2002
Summary
This study shows apparent diffusion coefficient (ADC) changes in cerebral infarction, revealing a distinct time course in the affected brain region and contralateral hemisphere. ADC measurements offer precise infarction onset determination.
Area of Science:
- Neuroimaging
- Radiology
- Cerebrovascular Diseases
Background:
- Cerebral infarction leads to complex changes in brain tissue diffusion characteristics.
- Understanding these diffusion changes is crucial for accurate diagnosis and prognosis.
- The influence of ischemia on the contralateral hemisphere is not fully elucidated.
Purpose of the Study:
- To quantitatively evaluate apparent diffusion coefficient (ADC) changes in the center of cerebral infarction.
- To investigate the impact of ischemia on the contralateral hemisphere's diffusion properties.
- To determine the accuracy of ADC calculation for pinpointing infarction onset.
Main Methods:
- Diffusion echo-planar imaging (EPI) was performed on 52 patients with cerebral infarction.
- ADC maps were generated using three diffusion gradient strengths (b=30, 300, 1100 s/mm²).
- Measurements were taken from 5 hours to over 12 months post-symptom onset.
Main Results:
- ADC in the infarction center was initially lower than contralateral regions, declining for ~28 hours to a minimum.
- ADC then increased, reaching 'pseudonormalization' around 5 days, with chronic infarctions showing higher ADC values.
- Contralateral hemispheres exhibited higher ADC than physiological conditions, declining in the first 2-3 days before increasing.
Conclusions:
- ADC calculation provides more precise determination of infarction onset compared to diffusion-weighted imaging alone.
- Diffusion in the center of infarction is isotropic, unaffected by gradient orientation.
- Changes in the contralateral hemisphere's ADC are significant and must be considered when calculating ADC ratios.