Imaging of Acute Bilateral Paramedian Thalamic and Mesencephalic Infarcts
M. Gisele Matheusa and
Mauricio Castilloa
a From the Department of Radiology, University of North Carolina School of Medicine, Chapel Hill, NC
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FIG 1. Case 1. Axial FLAIR images (8500/110/2500/1 [TR/TE/TI/NEX]) show infarcts in the medial inferior thalami and extending into the medial and superior midbrain (territory of the artery of Percheron).
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FIG 2. Case 2. Axial T2-weighted images (5800/99/1 [TR/TE/NEX]) show areas of increased signal intensity in the paramedian thalamic and midbrain regions. Within the infarcts, there are hypointense areas suggesting the presence deoxyhemoglobin secondary to hemorrhages.
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FIG 3. Case 3.
A, Axial trace diffusion-weighted image (5700/138 [TR/TE], b = 1000 s/mm2) obtained 24 hours after the onset of symptoms shows bilateral thalamic areas of high signal intensity (white arrows) compatible with that of acute paramedian thalamic infarcts.
B, Axial T2-weighted image (5800/99/1 [TR/TE/NEX]) shows rounded areas (arrowheads) of increased signal intensity in the medial thalami.
C, Axial T1-weighted (440/17/1 [TR/TE/NEX]) postcontrast image obtained 12 days after image in panel A shows contrast enhancement in the bilateral thalamic infarcts (black arrowheads).
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FIG 4. Variations of the paramedian thalamic-mesencephalic arterial supply according to Percheron.
A, In the most common variation, there are many small perforating arteries arising from the P1 segments of the PCA.
B, The artery of Percheron is a single perforating blood vessel arising from one P1 segment.
C, The third type of variation is that of an arcade of perforating branches arising from an artery bridging the P1 segments of both PCAs.
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AJNR - American Journal of Neuroradiology