Diffusion-Weighted MR Imaging in the Acute Phase of Transient Ischemic Attacks
Alex Roviraa,
Antoni Rovira-Golsa,
Salvador Pedrazaa,
Elisenda Grivéa,
Carlos Molinab and
José Alvarez-Sabínb
a Department of Radiology, Hospital Universitari Vall d’Hebron, Barcelona, Spain
b Department of Neurology, Hospital Universitari Vall d’Hebron, Barcelona, Spain
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FIG 1. Diffusion-weighted images obtained in a 75-year-old man with transient left paresis.
A, Axial diffusion-weighted image depicts hyperintense signal indicative of acute infarction in the precentral gyrus of the right frontal lobe.
B and C, Additional subsidiary lesions in the same arterial territory (middle cerebral artery) are shown at different levels (parietal and temporal cortex).
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FIG 2. Axial MR images obtained in a 40-year-old man with transient right hemiparesis 5 days after onset of symptoms.
A–C, T2-weighted (A), fast-FLAIR (B), and diffusion-weighted (C) imaging all reveal a small, acute ischemic lesion in the thalamocapsular region equally well. Note absence of prior ischemic lesions in A and B that helped identify the TIA-related infarct.
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FIG 3. Plot of the relationship between TIA symptom duration and presence of TIA-related lesions on diffusion-weighted images.
A significant statistical correlation existed between symptom duration and presence of TIA-related lesions (P = .025); the significance was lost when only patients with symptoms lasting less than 6 hours were included in the analysis (P = .513).
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FIG 4. Axial MR images obtained 4 hours after onset of symptoms in a 65-year-old woman with sudden-onset left-sided pure motor hemiparesis lasting 6 hours.
A and B, Fast-FLAIR (A) does not show the clinically appropriate small lesion in the right insular cortex, which is well visualized on a diffusion-weighted (B) image.
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FIG 5. Axial MR images obtained in a 75-year-old man with transient left hemiparesis.
A, Fast-FLAIR T2-weighted MR image shows multiple focal lesions in the subcortical white matter. It is not possible to discern whether any of the lesions are acute.
B, Diffusion-weighted MR section obtained at the same level as A depicts a single focus of high signal intensity in the left centrum semiovale suggestive of acute infarction.
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FIG 6. Axial MR images obtained 3 days after symptom onset in a 75-year-old man with left hemiparesis that rapidly resolved within 4 hours of onset.
A and B, Small cortical ischemic lesions in the right middle frontal gyrus are better visualized on a diffusion-weighted image than on a T2-weighted image.
C, A subsequent infart was overlooked on this follow-up T2-weighted MR image obtained 4 months after A and B.
D, A follow-up fast-FLAIR MR image obtained at the same time as C helps identify a small lesion at the same location as the prior ischemic lesions, indicating a chronic infarct.
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FIG 7. Axial MR images obtained in a 65-year-old man with aphasia that rapidly resolved within 3 hours of onset.
A, A diffusion-weighted image obtained 2 days after symptom onset clearly depicts a small, acute cortical ischemic lesion in the opercula of the left frontal lobe.
B, A follow-up fast-FLAIR MR image obtained 3 months later shows a small cortical lesion with high signal intensity at the same location as the lesion in A, indicating a chronic infarct. This subsequent infarct might have been overlooked had the reader not been aware of the location of the lesion on the initial diffusion-weighted image.
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FIG 8. Plot of the relationship between TIA cause and the presence of multiple TIA-related lesions on diffusion-weighted images. Although the small number of patients in some groups impeded correlation analysis, patients with large-vessel disease and significant stenosis showed more multiple lesions.
Note.—SV indicates small-vessel disease; LV w SS, large-vessel disease with significant stenosis; LV wo SS, large-vessel disease without significant stenosis; CE, cardioembolism; and Unk/MTO, unknown or more than one mechanism.
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AJNR - American Journal of Neuroradiology