title: A short echo 1H spectroscopy and volumetric MRI study of the corpus striatum in patients with obsessive-compulsive disorder and comparison subjects.
abstract: OBJECTIVE
  It is likely that the corpus striatum is involved in obsessive-compulsive disorder (OCD). Prior studies have inconsistently found alterations in caudate volumes in patients with OCD. This study was undertaken in the hope that N-acetylaspartate and volumetric measures together would elucidate the presence and nature of corpus striatum volumetric abnormalities in OCD.
  
  
  METHODS
  Thirteen patients meeting the DSM-IV criteria for OCD, who had been medication free for a minimum of 6 weeks, and 13 psychiatrically normal matched comparison subjects participated in the study. Short echo 1H magnetic resonance spectroscopy (1H-MRS) was used to measure levels of N-acetylaspartate and several other cerebral metabolites from a 4.5-cm3 volume in the left corpus striatum of all 26 subjects. Metabolite levels were estimated by fitting the time domain spectroscopy data with a noninteractive computer program. Volumes of the left and right head of the caudate nucleus in each subject were determined by semiautomatic segmentation of the volumetric images.
  
  
  RESULTS
  N-Acetylaspartate levels from the left corpus striatum were significantly lower in the patients with OCD than in the comparison subjects. There were no differences in either left or right caudate volume between the two groups.
  
  
  CONCLUSIONS
  Despite the lack of differences in caudate volumes between the OCD patients and the comparison subjects, the lower level of N-acetylaspartate in the left corpus striatum of the patients suggests reduced neuronal density in this region. Inconsistent volumetric findings among prior studies may reflect a poorer sensitivity of magnetic resonance imaging morphometry for detecting neuronal loss compared with 1H-MRS measurement of N-acetylaspartate.
authors.affiliation: Department of Nuclear Medicine and Magnetic Resonance, St. Joseph's Health Centre, Ont., Canada.
authors.forename: R
authors.initials: R
authors.lastname: Bartha
authors.forename: M B
authors.initials: MB
authors.lastname: Stein
authors.forename: P C
authors.initials: PC
authors.lastname: Williamson
authors.forename: D J
authors.initials: DJ
authors.lastname: Drost
authors.forename: R W
authors.initials: RW
authors.lastname: Neufeld
authors.forename: T J
authors.initials: TJ
authors.lastname: Carr
authors.forename: G
authors.initials: G
authors.lastname: Canaran
authors.forename: M
authors.initials: M
authors.lastname: Densmore
authors.forename: G
authors.initials: G
authors.lastname: Anderson
authors.forename: A R
authors.initials: AR
authors.lastname: Siddiqui
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002452:Cell Count; D003342:Corpus Striatum / Q000033:anatomy & histology* / Q000378:metabolism / Q000473:pathology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D006859:Hydrogen; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009474:Neurons / Q000166:cytology; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology
chemical_list: D001224:Aspartic Acid; D006859:Hydrogen; C000179:N-acetylaspartate