PMC8597371_01
(A) Coronal section with bilateral para-median thalamic hyperintensities with extension to the midbrain; (B and D) TOF MRA revealed a bilateral fetal-type posterior circle of Willis, with arrows pointing where the two P1 segments of PCAs should have been; (C and E) ADC axial images illustrates bilateral para-median thalamic and midbrain diffusion restriction; (F) DWI axial image showing focal areas of restricted diffusion in bilateral paramedian thalami; (G) MRA shows a full fetal variant of the PCA (yellow arrows), left hypoplastic vertebral artery (blue arrows) and anatomic variant of right ACA (red arrows). ACA: Anterior cerebral artery; ADC: Apparent diffusion coefficient; DWI: Diffusion-weighted imaging; MRA: Magnetic resonance angiography; PCA: Posterior cerebral artery; TOF; Time-of-flight
RJME-62-1-289-fig1.jpg
PMC8597371_01_RJME-62-1-289-fig1.jpg
F1
MRI done three days later showed features of a subacute infarction in paramedian thalami and rostral midbrain bilaterally (right>left) (Figure 1). TOF MRA was performed. The examination revealed a bilateral fetal-type posterior circle of Willis, demonstrated by the lack of visualization of the P1 segment of the PCA, with the P2 segment continuing with the PCoA, which shows an increased caliber (Figure 1).