60-year-old with left visual field defects.
(a) Artery of Percheron infarct
(b) Bilateral PCA infarct
(c) Left ICA occlusion
(d) Right ICA occlusion
(e) Basilar tip aneurysm
Hemorrhage: No
Hydrocephalus: No
Herniation: No
Gray-white differentiation/wedge-shaped hypodensity/cortical involvement: Yes.
Region 1: Cortical hypodensity in the medial right occipital and right temporal regions, suspicious for acute infarct (coronal).
Region 2: Small wedge-shaped left lateral cerebellar infarct, age-indeterminate though likely chronic.
Deep gray nuclei: Subtle hypodensities are noted in the right more than left thalami.
Hyperdense vessels: None
1. Given the clinical history of visual field defects, scrutiny of the occipital lobe is essential. Although the occipital cortical hypodensity may best be noted on the coronal reconstruction, keen interpreters may note the cortical hypodensity also involves the right medial temporal in addition to the occipital regions on axial imaging.
2. Additional focused upon the deep gray nuclei reveals subtle thalamic hypodensities, right more than left.
Subsequent brain MRI demonstrates acute right medial temporal-occipital lobe and right thalamic infarcts (elevated DWI, low ADC signal) corresponding to the right posterior cerebral artery vascular territory. Additional small left thalamic acute/subacute infarct is present (elevated DWI, low/isointense ADC signal). Small chronic left cerebellar infarct.
Identification of this posterior cerebral artery infarct is best served with scrutiny of the medial temporal-occipital cortices on axial and coronal imaging, which can be easily overlooked. Once identification of a right posterior cerebral artery infarct is noted, the distal structures within this vascular territory should be interrogated, specifically the ipsilateral thalamus. In this case, the left thalamus also demonstrates an acute/subacute infarct. An artery of Percheron anatomic variant is possible given bilateral thalamic infarcts, though less favored as this infarct is usually symmetric and involves the paramedian thalamic portions. Also, other PCA distribution cortex is infarcted.
Recall that the thalami are supplied by posterior cerebral arteries. Otherwise the majority of the deep grey nuclei and capsular structures are supplied by anterior and middle cerebral arteries.
Recall that the posterior cerebral artery supplies the inferior temporal lobe, and the middle cerebral artery supplies the superior temporal lobe.
On axial imaging, note how this PCA infarct involves the temporal lobe parenchyma below the temporal horn of the lateral ventricle.
1. Practical considerations for detecting temporal-occipital region infarcts.
2. Reviewing MRI signal characteristics for infarcts of varying ages.
3. Anatomic review of the posterior cerebral artery vascular territory.
In this case the presence of bilateral thalamic infarcts indicates:
(a) Artery of Percheron infarct
(b) Bilateral PCA infarct
(c) Left ICA occlusion
(d) Right ICA occlusion
(e) Basilar tip aneurysm