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Arterial hyperintensity on fast fluid-attenuated inversion recovery images: a subtle finding for hyperacute stroke
M Maeda1, T Yamamoto, S Daimon
1Department of Medicine, Mie University School of Medicine, Maizuru Kyosai Hospital, Japan.
Background And Purpose:
Diffusion-weighted MR imaging is generally acknowledged to be more sensitive in detecting acute stroke than is conventional MR imaging. Our purpose in the present study was to evaluate the utility of fast fluid-attenuated inversion recovery (FLAIR) MR imaging compared with that of diffusion-weighted MR imaging for the diagnosis of hyperacute stroke.
Methods:
We reviewed patient records and cerebral MR images from all patients in a 13-month period from whom diffusion-weighted and fast-FLAIR imaging were obtained within 6 hours after symptom onset (n = 11). Special attention was paid to the presence or absence of arterial hyperintensity on FLAIR images and abnormally high-signal regions on diffusion-weighted images in the affected vascular territories.
Results:
Arterial hyperintensity was found in eight of 11 patients, all of whom had embolic or thrombotic infarctions with middle cerebral arterial (MCA) distribution. Arterial hyperintensity was negative in the remaining three patients; the vascular territories were the posterior circulation region in two of these patients and the MCA region in one, and the types of infarction in these same patients were lacunar in two and embolic in one. Regions with high-signal diffusion abnormalities relevant to the patients' symptoms were found in 10 of 11 patients. One patient showed no diffusion abnormalities but the presence of arterial hyperintensity in the affected MCA territory on the initial MR examination, and manifested embolic infarction along with arterial hyperintensity on the initial FLAIR image.
Conclusion:
Although diffusion-weighted MR imaging is highly sensitive to stroke, diffusion-weighted MR imaging alone may not rule out a possible infarction. Arterial hyperintensity on FLAIR images can precede diffusion abnormalities and may provide a clue to the early detection of impending infarction.
Insights
Fast fluid-attenuated inversion recovery (FLAIR) MR imaging shows arterial hyperintensity that may precede diffusion abnormalities, aiding early hyperacute stroke detection. Diffusion-weighted imaging alone may not rule out infarction.
Area of Science:
- Radiology
- Neurology
- Medical Imaging
Background:
- Diffusion-weighted MR imaging (DWI) is recognized for its high sensitivity in detecting acute stroke.
- Conventional MR imaging is less sensitive than DWI for acute stroke detection.
Purpose of the Study:
- To evaluate the diagnostic utility of fast fluid-attenuated inversion recovery (FLAIR) MR imaging compared to DWI for hyperacute stroke.
- To assess the significance of arterial hyperintensity on FLAIR in early stroke diagnosis.
Main Methods:
- Retrospective review of patient records and cerebral MR images (DWI and fast-FLAIR) within 6 hours of symptom onset.
- Analysis focused on arterial hyperintensity on FLAIR and diffusion abnormalities on DWI in affected vascular territories.
Main Results:
- Arterial hyperintensity was observed in 8 of 11 patients, primarily with embolic/thrombotic middle cerebral artery (MCA) infarctions.
- Diffusion abnormalities were present in 10 of 11 patients.
- One patient with no diffusion abnormalities showed arterial hyperintensity on FLAIR, indicating early infarction.
Conclusions:
- Arterial hyperintensity on fast-FLAIR MR imaging can precede diffusion abnormalities in hyperacute stroke.
- FLAIR imaging may offer an earlier diagnostic clue for impending infarction than DWI alone.
- DWI is sensitive but may not definitively rule out infarction in all hyperacute cases.