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Background
The artery of Percheron is an uncommon anatomic variant which produces nonfocal neurologic deficits with occlusion. Early recognition and diagnosis of this condition is important to prevent unnecessary testing and delay of treatment. Additionally, there are many mimics of this condition that may be difficult to exclude on initial imaging. Therefore, it is crucial for radiologists and radiologists in training to recognize this diagnosis and recommend appropriate follow-up imaging as needed.

Educational Goals / Teaching Points
We will start by outlining the anatomic variations of the thalamus. Next, we will present cases of the variations of infarctions of the artery of Percheron. Then, we will present cases that may mimic artery of Percheron infarctions and discuss how to differentiate them.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The French neurologist Percheron described three variations of the paramedian thalamic-mesencephalic arterial supply with the eponymous anatomic variant originating from one of the P1 segments of a single PCA which supplies the bilateral medial thalami. The superior mesencephalic arteries, which supply the rostral midbrain, may arise from either the P1 segment of the PCA or from a common origin with the paramedian arteries. Therefore, when present, the artery of Percheron (AOP) supplies the paramedian thalami and variably supplies the rostral midbrain. As a result, ischemic AOP strokes result in characteristic imaging findings. Four specific patterns of ischemic AOP infarction have been described (in a case series published in AJNR by Lazzaro et al. Notably, all four subtypes involve the paramedian thalami. In decreasing order of prevalence, the patterns are bilateral paramedian thalami with midbrain, bilateral paramedian thalami without midbrain, bilateral paramedian thalami with anterior thalamus and midbrain, and bilateral paramedian thalami with anterior thalamus without midbrain. Excluding mimics of AOP infarcts is vital for appropriate patient care. Differential considerations include other vascular thrombo-occlusive disease, toxic/metabolic etiologies, neurodegenerative disease, and infection. Knowledge of these pathologies will help guide further patient management.

Conclusion
It is fundamental for a radiologist and radiologist in training to be able to identify a possible artery of Percheron occlusion. Our educational exhibit will detail the artery of Percheron infarctions and common mimics so that we can guide clinicians to proper workup and treatment.