MRI of Cerebellar Infarction.

BACKGROUND

MRI is the imaging modality of choice for diagnosing brain infarction. Because of few or atypical clinical symptoms and a relatively low sensitivity of CT scans, many cerebellar infarctions may be detected only with MRI. With adequate recognition of cerebellar infarction on MRI and prompt initiation or optimisation of preventive therapeutic measures, more dramatic strokes may be avoided in selected cases.

SUMMARY

We first briefly review the clinical presentation of cerebellar infarctions, followed by a short refresher on cerebellar anatomy and pathophysiological mechanisms of cerebellar infarcts. Then, we review the arterial cerebellar perfusion territories recently made visible with territorial arterial spin labeling (ASL), followed by a discussion and illustration of the MRI appearance of cerebellar infarcts in different stages. Similar to large cerebellar infarcts, recent studies investigating volumetric MRI datasets have now shown that small cerebellar infarcts occur in typical spatial patterns, knowledge of which may help in the diagnosis of even the smallest of cerebellar infarcts on MRI. Key Messages: MRI is the modality of choice for diagnosing cerebellar infarction. The posterior inferior cerebellar artery (PICA)-territories can be visualised with super-selective territorial ASL MRI. The PICA supplies at least the medial part of the posterior cerebellar surface. Anterior inferior cerebellar artery-infarcts can be mistaken for lateral PICA-infarcts. Small infarcts typically affect the cortex and often present as incidental cavities. Subacute cerebellar infarcts may be missed on imaging due to a phenomenon called "fogging."