title: MR spectroscopy features of brain in patients with mild and severe obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  We investigated whether there are differences in metabolite ratios of different brain regions between mild and severe obstructive sleep apnea (OSA) patients.
  
  
  METHODS
  A total of 17 mild OSA and 14 severe OSA patients were enrolled. N-acetyl aspartate (NAA)/creatine (Cr), choline (Cho)/Cr and NAA/Cho ratios were calculated by using multivoxel magnetic resonance spectroscopy (MRS) (TR: 1500, TE: 135 ms) from hippocampus, putamen, insular cortex, thalamus and temporal white matter. The relationship between the two groups was evaluated with Mann-Whitney U test.
  
  
  RESULTS
  NAA/Cr ratios obtained from hippocampus was found to be significantly increased in severe OSA patients compared to mild OSA patients (P=.004). Cho/Cr ratios obtained from hippocampus and putamen in severe OSA patients were significantly increased when compared to mild OSA patients (P=.003 and P=.004, respectively). In addition, NAA/Cho ratios of putamen were significantly decreased in severe OSA patients when compared to mild OSA (P=.032).
  
  
  CONCLUSIONS
  MRS identified hypoxia-related metabolite and microstructural changes in hippocampus and putamen. The metabolite changes of increase in NAA/Cr and Cho/Cr ratios and decrease in NAA/Cho ratio were more pronounced with increasing severity of OSA syndrome.
authors.affiliation: Department of Radiology, Bezmialem Vakif University School of Medicine, İstanbul, Turkey. Electronic address: alpay_alkan@hotmail.com.
authors.forename: Alpay
authors.initials: A
authors.lastname: Alkan
authors.forename: Resul
authors.initials: R
authors.lastname: Sharifov
authors.forename: Muhammed Emin
authors.initials: ME
authors.lastname: Akkoyunlu
authors.forename: Rukiye
authors.initials: R
authors.lastname: Kiliçarslan
authors.forename: Huseyin
authors.initials: H
authors.lastname: Toprak
authors.forename: Ayse
authors.initials: A
authors.lastname: Aralasmak
authors.forename: Levent
authors.initials: L
authors.lastname: Kart
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000378:metabolism*; D013788:Thalamus / Q000378:metabolism
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline
keywords: Brain; MR spectroscopy; Obstructive sleep apnea