title: Structural and Functional Magnetic Resonance Imaging of the Cerebellum: Considerations for Assessing Cerebellar Ataxias.
abstract: Magnetic resonance imaging (MRI) of the brain is of high interest for diagnosing and understanding degenerative ataxias. Here, we present state-of-the-art MRI methods to characterize structural alterations of the cerebellum and introduce initial experiments to show abnormalities in the cerebellar nuclei. Clinically, T1-weighted MR images are used to assess atrophy of the cerebellar cortex, the brainstem, and the spinal cord, whereas T2-weighted and PD-weighted images are typically employed to depict potential white matter lesions that may be associated with certain types of ataxias. More recently, attention has also focused on the characterization of the cerebellar nuclei, which are discernible on spatially highly resolved iron-sensitive MR images due to their relatively high iron content, including T2 (*)-weighted images, susceptibility-weighted images (SWI), effective transverse relaxation rate (R2 (*)) maps, and quantitative susceptibility maps (QSM). Among these iron-sensitive techniques, QSM reveals the best contrast between cerebellar nuclei and their surroundings. In particular, the gyrification of the dentate nuclei is prominently depicted, even at the clinically widely available field strength of 3 T. The linear relationship between magnetic susceptibility and local iron content allows for determination of iron deposition in cerebellar nuclei non-invasively. The increased signal-to-noise ratio of ultrahigh-field MRI (B0 ≥ 7 T) and advances in spatial normalization methods enable functional MRI (fMRI) at the level of the cerebellar cortex and cerebellar nuclei. Data from initial fMRI studies are presented in three common forms of hereditary ataxias (Friedreich's ataxia, spinocerebellar ataxia type 3, and spinocerebellar ataxia type 6). Characteristic changes in the fMRI signal are discussed in the light of histopathological data and current knowledge of the underlying physiology of the fMRI signal in the cerebellum.
authors.affiliation: Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany. andreas.deistung@med.uni-jena.de.
authors.forename: Andreas
authors.identifier: http://orcid.org/0000-0002-2427-1302
authors.initials: A
authors.lastname: Deistung
authors.affiliation: Department of Neurology, University of Duisburg-Essen, Essen, Germany.|Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.
authors.forename: Maria R
authors.initials: MR
authors.lastname: Stefanescu
authors.affiliation: Department of Neurology, University of Duisburg-Essen, Essen, Germany.|Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Ernst
authors.affiliation: Institute of Diagnostic and Interventional Radiology and Neuroradiology, University of Duisburg-Essen, Essen, Germany.|Department of Neuroradiology, University of Giessen-Marburg, Giessen, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Schlamann
authors.affiliation: Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany.|Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ladd
authors.affiliation: Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany.|Michael Stifel Center for Data-driven and Simulation Science Jena, Friedrich Schiller University Jena, Jena, Germany.
authors.forename: Jürgen R
authors.initials: JR
authors.lastname: Reichenbach
authors.affiliation: Department of Neurology, University of Duisburg-Essen, Essen, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Timmann
mesh_terms: D002524:Cerebellar Ataxia / Q000473:pathology*; D002531:Cerebellum / Q000098:blood supply* / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D010100:Oxygen / Q000097:blood
chemical_list: D010100:Oxygen
keywords: Ataxia; Cerebellar cortex; Cerebellar nuclei; Functional MRI; Quantitative susceptibility mapping; Structural MRI