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Cerebral infarction: time course of signal intensity changes on diffusion-weighted MR images
J H Burdette1, P E Ricci, N Petitti
1Department of Radiology, Wake Forest University School of Medicine, Bowman Gray Campus, Winston-Salem, NC 27157-1088, USA.
Objective:
The objective of this study was to determine the time course of signal intensity changes on diffusion-weighted MR images after cerebral infarction.
Materials And Methods:
Echoplanar diffusion-weighted MR images were obtained at 1.5 T in 212 patients referred for suspected cerebral infarction over a 6-month period. Of those patients, 85 met strict criteria for inclusion in this study: final clinical diagnosis of stroke, reliable timing of clinical ictus by history, and neurologic symptoms persisting longer than 48 hr after onset. Using adjacent or contralateral normal brain for comparison, diffusion-weighted images were visually analyzed retrospectively to evaluate for abnormalities in signal intensity. Because three patients were scanned on two occasions and five patients had two anatomically separable infarctions, 93 reliably dated brain lesions were analyzed.
Results:
Diffusion-weighted images showed abnormal findings in 13 (100%) of 13 lesions less than 1 day old, 46 (96%) of 48 lesions 1-4 days old, 16 (94%) of 17 lesions 5-9 days old, three (60%) of five lesions 10-14 days old, and zero (0%) of 10 lesions more than 14 days old.
Conclusion:
Abnormal signal intensity was present on all diffusion-weighted MR studies obtained in patients within 24 hr of acute cerebral infarction and in up to 94% of patients scanned during the first 2 weeks after ictus. The percentage of abnormal diffusion studies declined with time, and no signal intensity abnormality was seen in stroke patients scanned more than 2 weeks after symptom onset.
Insights
Diffusion-weighted MRI detects acute cerebral infarction within 24 hours and shows high accuracy up to two weeks post-stroke. Abnormalities decrease over time, with no signal changes seen after 14 days.
Area of Science:
- Radiology
- Neurology
- Medical Imaging
Background:
- Cerebral infarction, or stroke, is a leading cause of disability.
- Diffusion-weighted magnetic resonance imaging (DW-MRI) is a key technique for early stroke detection.
- Understanding the temporal evolution of DW-MRI signal changes is crucial for accurate diagnosis.
Purpose of the Study:
- To investigate the time course of signal intensity alterations on DW-MRI following cerebral infarction.
- To establish the diagnostic window for DW-MRI in acute stroke detection.
Main Methods:
- Retrospective analysis of 93 brain lesions in 85 patients with confirmed stroke and reliable symptom onset timing.
- Echoplanar DW-MRI performed at 1.5 T.
- Visual assessment of signal abnormalities compared to normal brain tissue.
Main Results:
- 100% of lesions <1 day old showed abnormalities.
- 96% of lesions 1-4 days old and 94% of lesions 5-9 days old were abnormal.
- Abnormalities decreased to 60% for lesions 10-14 days old and 0% for lesions >14 days old.
Conclusions:
- DW-MRI is highly sensitive for detecting acute cerebral infarction, especially within the first 24 hours.
- Abnormal signal intensity on DW-MRI is present in up to 94% of strokes within the first two weeks.
- The diagnostic utility of DW-MRI for cerebral infarction diminishes significantly after two weeks post-ictus.