title: Proton MR spectroscopy of central neurocytoma using short and long echo time: new proofs for the existence of glycine and glutamate.
abstract: OBJECTIVE
  Central neurocytomas (CNCs) are rare benign tumors typically located in the lateral ventricle of the central nervous system. The authors report five patients with CNCs and review 16 previously published studies that included 52 patients with CNCs to explore the magnetic resonance spectroscopic features of CNCs.
  
  
  METHODS
  Five patients with CNCs were retrospectively reviewed. They were examined using point-resolved spectroscopic series with short and/or long echo times. The integrals of choline, creatine, and the 3.55-ppm peak were determined using Magnetic Resonance User Interface software, and the metabolite ratios relative to creatine were obtained. In two cases, T2 relaxation times of choline and the metabolite resonance at 3.55 ppm were calculated using data points acquired with different echo times and an exponential decay model.
  
  
  RESULTS
  Consistent with previously published studies, all five patients showed highly increased choline and reduced N-acetylaspartate and creatine. Four patients in the present study and 35 in published data demonstrated prominent peaks at 3.55 ppm, which were assigned to glycine because of its relaxation pattern and long T2 relaxation time. In addition, increased in vivo glutamate and glutamine was also confirmed in three patients examined with short echo times. Alanine and lactate peaks were observed in three and two patients, respectively.
  
  
  CONCLUSIONS
  The present study shows that the 3.55-ppm peak characteristic of CNC should be assigned to glycine according to its T2 relaxation time. Besides increased glycine and choline, the presence of glutamate or glutamine, which appears on series with short echo times, may further confirm the diagnosis of CNC.
authors.affiliation: Huaxi MR Research Center, Department of Radiology, West China Hospital of Sichuan University, No 37 Guo Xue Xiang, Chengdu, 610041, China.
authors.forename: Mengqi
authors.initials: M
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yue
authors.forename: Tomonori
authors.initials: T
authors.lastname: Isobe
authors.forename: Akira
authors.initials: A
authors.lastname: Matsumura
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Yang
authors.forename: Hong
authors.initials: H
authors.lastname: Quan
authors.forename: Haoyang
authors.initials: H
authors.lastname: Xing
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Gong
mesh_terms: D000293:Adolescent; D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002551:Cerebral Ventricle Neoplasms / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D018306:Neurocytoma / Q000378:metabolism*; D055815:Young Adult
chemical_list: D001224:Aspartic Acid; D018698:Glutamic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline; D005998:Glycine