Middle cerebellar peduncles: Magnetic resonance imaging and pathophysiologic correlate

Figure 1 Anatomy of the middle cerebellar peduncles. A: Diagram shows the pontine crossing fibers (PCF) (red and pink long arrows) originating from the contralateral pontine nuclei and conforming the middle cerebellar peduncles (MCP) (only afferent fibers constitute MCP); B and C: Diffusion tensor imaging (DTI) tractography after seed ROIs placed in the bilateral MCP. Note the representation of the PCF (red on B). Here, we can envision the origin of well described signs on conventional T2 sequences such as the “hot cross bun sign” or “trident sign” where there is involvement of the PCF or central pons and sparing of the corticospinal tracts (CST) and tegmentum. Sagittal DTI (C) including the main efferent pathway (purple ascending fibers, arrow) through the pontine tegmentum and superior cerebellar peduncles which constitutes part of the dentate-rubro-thalamic tract. (DTI was acquired on a GE-3T Magnet, b = 0 and 1000 s/mm² with 25 directions; Brain Lab Software was used to fuse T2-WI with DTI acquisition; and tractography was performed using a tensor deflection algorithm). ROIs: Regions of interest.