Crossed cerebellar diaschisis: insights into oxygen challenge MRI.

Hyperoxia during T2*-weighted magnetic resonance imaging (oxygen challenge imaging (OCI)) causes T2*-weighted signal change that is dependent on cerebral blood volume (CBV) and oxygen extraction fraction (OEF). Crossed cerebellar diaschisis (CCD), where CBV is reduced but OEF is maintained, may be used to understand the relative contributions of OEF and CBV to OCI results. In subjects with large hemispheric strokes, OCI showed reduced signal change in the contralesional cerebellum (P=0.027, n=12). This was associated with reduced CBV in contralesional cerebellum (P=0.039, n=9). CCD may be a useful model to determine the relative contribution of CBV to signal change measured by OCI.