title: Quantitative proton MR spectroscopic imaging of the mesial temporal lobe.
abstract: OBJECTIVE
  To evaluate variations in regional metabolite concentrations in the anterior mesial temporal lobe (ATL), and compare metabolite concentrations between the allocortex and neocortex using quantitative proton MR spectroscopic imaging (MRSI).
  
  
  METHODS
  Metabolite concentrations and ratios were measured in 20 healthy young subjects with the use of a multislice spin-echo (SE) sequence (TR/TE=2300/280 msec). Quantitation of MRSI data was performed by means of the phantom replacement methodology.
  
  
  RESULTS
  The highest choline (Cho) concentration (4.1 +/- 1.1 mM) was found in the ATL (P=0.0015 compared to the middle mesial temporal lobe (MTL), and P=0.0008 compared to the posterior mesial temporal lobe (PTL)). The ATL also had a higher Cho/creatine (Cr) ratio and a lower N-acetyl aspartate (NAA)/Cho ratio compared to other examined regions (P <0.0001 and P < or = 0.052, respectively). In the allocortical regions, the average Cho concentration (3.5 +/- 0.8 mM) was 68% higher, and the NAA concentration (9.5 +/- 1.8 mM) was 13% lower than in the neocortex (P <10(-6) and P <0.008, respectively). Cho/Cr was 64% higher, NAA/Cr 14% lower, and NAA/Cho 47% lower in the allocortex than in the neocortex (P <10(-6), P=0.013, and P <10(-6), respectively).
  
  
  CONCLUSIONS
  The mesial temporal lobe shows high levels of Cho, which presumably reflect a difference in cellular composition between the allocortex and neocortex. Regional metabolite variations must be considered when pathological conditions involving the mesial temporal lobe are evaluated.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: Atilla
authors.initials: A
authors.lastname: Arslanoglu
authors.forename: David
authors.initials: D
authors.lastname: Bonekamp
authors.forename: Peter B
authors.initials: PB
authors.lastname: Barker
authors.forename: Alena
authors.initials: A
authors.lastname: Horská
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D013702:Temporal Lobe / Q000033:anatomy & histology* / Q000378:metabolism*
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline