By labelling both vertebral arteries, the territories supplied by one vertebral artery (PICA) can be distinguished from those supplied by both vertebral arteries (AICA and SCA) and from the contralateral vertebral artery (contralateral PICA) (Fig. In ASL, arterial blood water is magnetically labelled and then imaged, and with selective labeling, the arterial perfusion territories can be visualised. Recently, the cerebellar PICA-perfusion territories have been made visible in vivo in individual subjects by the use of super-selective (territorial) arterial spin labeling (ASL) MRI, which is a non-invasive technique to measure brain perfusion without the need to administer an exogenous contrast agent. SCA can dominate as well, and for instance, supply the inferior vermian territory in addition to the superior vermis. A PICA-AICA is characterised by a small AICA and large PICA cortical supply. ![]() As a result, even dominant AICA strokes do not produce lateral medullary infarcts (or Wallenberg syndromes). Nevertheless, even in extreme dominance of the AICA over the PICA (AICA-PICA variant), a small and possibly unrecognisable PICA limited to its medullary territory exists. It may be confined to the anterior surface, but the AICA may also supply lateral portions of the posterior and/or superior surface of the cerebellum (Fig. The territory perfused by the AICA varies in reciprocity with the PICA and SCA. Anastomoses between peripheral branches of the PICA, AICA, and SCA are consistently present among individuals. Subacute cerebellar infarcts may be missed on imaging due to a phenomenon called “fogging.”īranches of the PICA, AICA and superior cerebellar artery (SCA) run on the surface of the cerebellum, while more peripheral branches run in the cerebellar fissures and give rise to cortical arteries. Small infarcts typically affect the cortex and often present as incidental cavities. Anterior inferior cerebellar artery-infarcts can be mistaken for lateral PICA-infarcts. The PICA supplies at least the medial part of the posterior cerebellar surface. The posterior inferior cerebellar artery (PICA)-territories can be visualised with super-selective territorial ASL MRI. Key Messages: MRI is the modality of choice for diagnosing cerebellar infarction. 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. 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. ![]() 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. 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. Because of few or atypical clinical symptoms and a relatively low sensitivity of CT scans, many cerebellar infarctions may be detected only with MRI. Background: MRI is the imaging modality of choice for diagnosing brain infarction.
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