title: Decreased metabotropic glutamate receptor type 1 availability in a patient with spinocerebellar ataxia type 6: A (11)C-ITMM PET study.
abstract: OBJECTIVE
  Imaging of metabotropic glutamate receptor type 1 (mGluR1), localized exclusively in the cerebellar Purkinje cells and related to cerebellar function, has recently become possible using positron emission tomography (PET). We report the initial mGluR1 imaging in a 74-year-old woman with spinocerebellar ataxia type 6 (SCA6).
  
  
  METHODS
  The patient and 9 age-matched healthy controls underwent PET scanning with a mGluR1 radiotracer, N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl] -4-(11)C-methoxy-N-methylbenzamide. Volumes-of-interest were placed on the anterior and posterior lobes, vermis, and flocculus. Binding potential (BPND) was calculated to estimate mGluR1 availability using the simplified reference tissue model. A partial volume correction was applied to the BPND values. Additionally, the volume of the whole cerebellum was measured using MRI.
  
  
  RESULTS
  The corrected BPND values of the cerebellar subregions and the volume of the whole cerebellum in the patient were 51.0% to 68.3% and 72.6%, respectively, of the controls. Thus, the magnitude of reduced BPND values was relatively larger than the magnitude of cerebellar atrophy in the patient.
  
  
  CONCLUSIONS
  These findings suggest that the measurement of mGluR1 availability is more sensitive than morphological measurements by MRI to detect reduced cerebellar function. Thus, imaging of mGluR1, probably reflecting the number and distribution of Purkinje cells, can be a specific and sensitive marker for estimation of cerebellar function.
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan; Department of Neurology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan. Electronic address: ishibashi@pet.tmig.or.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishibashi
authors.affiliation: Department of Neurology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Miura
authors.affiliation: Department of Neurology and Neurological Science, and Predictive and Preventive Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
authors.forename: Kinya
authors.initials: K
authors.lastname: Ishikawa
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ishii
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan.
authors.forename: Kiichi
authors.initials: K
authors.lastname: Ishiwata
mesh_terms: D000368:Aged; D001549:Benzamides / Q000493:pharmacokinetics; D001921:Brain / Q000000981:diagnostic imaging*; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D049268:Positron-Emission Tomography; D011485:Protein Binding / Q000187:drug effects; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D020754:Spinocerebellar Ataxias / Q000000981:diagnostic imaging*; D013844:Thiazoles / Q000493:pharmacokinetics
chemical_list: D001549:Benzamides; D002250:Carbon Radioisotopes; C573292:N-(4-(6-(isopropylamino)pyrimidin-4-yl)-1,3-thiazol-2-yl)-4-methoxy-N-methylbenzamide; D018094:Receptors, Metabotropic Glutamate; D013844:Thiazoles; C104077:metabotropic glutamate receptor type 1
keywords: (11)C-ITMM; Cerebellar function; Metabotropic glutamate receptor type 1; Neuroimaging; PET; Spinocerebellar ataxia type 6