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Fast magnetic resonance diffusion-weighted imaging of acute human stroke
1Harvard-Longwood Neurology Training Program, Harvard Medical School, Beth Israel Hospital, Boston, MA 02215.
Abstract:
Rapid MRI of the molecular diffusion of water demonstrated cerebral infarcts in 32 patients. We studied these patients at various times following the onset of ischemic symptoms and found that diffusion-weighted imaging revealed the infarcts sooner than conventional T2-weighted spin-echo imaging did; four hyperacute infarcts were shown only by diffusion-weighted imaging. Acute infarcts had lower apparent diffusion coefficients (ADCs) than noninfarcted regions did. This relative difference in ADC reached a nadir in the first 24 hours and rose progressively thereafter. Chronic infarcts showed a relative increase in diffusion and were readily distinguishable from acute infarcts. The technique takes less than 2 minutes to apply using a standard 1.5-tesla scanner in the clinical setting. Diffusion-weighted imaging has the potential to play a role in improving the early anatomic diagnosis of stroke and therefore in the development and implementation of early stroke interventions.
Insights
Diffusion-weighted imaging (DWI) rapidly detects cerebral infarcts earlier than T2-weighted imaging. This MRI technique aids in early stroke diagnosis and intervention by showing acute infarcts with lower apparent diffusion coefficients (ADCs).
Area of Science:
- Neuroradiology
- Medical Imaging
- Neurology
Background:
- Cerebral infarcts, or strokes, result from interrupted blood supply to the brain.
- Early and accurate diagnosis of ischemic stroke is crucial for timely intervention.
- Conventional MRI sequences may not detect hyperacute infarcts effectively.
Purpose of the Study:
- To evaluate the efficacy of rapid diffusion-weighted imaging (DWI) in detecting cerebral infarcts.
- To compare the sensitivity of DWI with conventional T2-weighted spin-echo imaging in early stroke detection.
- To characterize apparent diffusion coefficient (ADC) changes in acute and chronic infarcts.
Main Methods:
- Diffusion-weighted imaging (DWI) and conventional T2-weighted spin-echo MRI were performed on 32 patients with suspected cerebral infarcts.
- Patients were studied at various times post-symptom onset.
- Apparent diffusion coefficients (ADCs) were measured and compared between infarcted and non-infarcted brain regions.
Main Results:
- DWI detected cerebral infarcts, including four hyperacute cases missed by T2-weighted imaging.
- Acute infarcts exhibited lower ADCs than normal brain tissue, with the lowest relative ADC difference observed within 24 hours.
- Chronic infarcts showed increased diffusion, distinguishing them from acute lesions.
- The DWI technique requires less than 2 minutes on a standard 1.5-tesla scanner.
Conclusions:
- Rapid DWI is a sensitive technique for early detection of cerebral infarcts.
- DWI provides valuable information on infarct age through ADC quantification.
- This technique has significant potential for improving early stroke diagnosis and guiding interventions.