title: Proton spectroscopic metabolite signal relaxation times in preterm infants: a prerequisite for quantitative spectroscopy in infant brain.
abstract: OBJECTIVE
  To determine relaxation times of metabolite signals in proton magnetic resonance (MR) spectra of immature brain, which allow a correction of relaxation that is necessary for a quantitative evaluation of spectra acquired with long TE. Proton MR spectra acquired with long TE allow a better definition of metabolites as N-acetyl aspartate (NAA) and lactate especially in children.
  
  
  METHODS
  Relaxation times were determined in the basal ganglia of 84 prematurely born infants at a postconceptional age of 37.8 +/- 2.2 (mean +/- SD) weeks. Metabolite resonances were investigated using the double-spin-echo volume selection method (PRESS) at 1.5 T. T1 was determined from intensity ratios of signals obtained with TRs of 1884 and 6000 msec, measured at 3 TEs (25 msec, 136 msec, 272 msec). T2 was determined from signal intensity ratios obtained with TEs of 136 msec and 272 msec, measured at 2 TR. Taking only long TEs reduced baseline distortions by macromolecules and lipids. For myo-inositol (MI), an apparent T2 for short TE was determined from the ratio of signals obtained with TE = 25 msec and 136 msec. Intensities were determined by fitting a Lorentzian to the resonance, and by integration.
  
  
  RESULTS
  Relaxation times were as follows: trimethylamine-containing compounds (Cho): T1 = 1217 msec/T2 = 273 msec; total creatine (Cr) at 3.9 ppm: 1010 msec/111 msec; Cr at 3.0 ppm: 1388 msec/224 msec; NAA: 1171 msec/499 msec; Lac: 1820 msec/1022 msec; MI: 1336 msec/173 msec; apparent T2 at short TE: 68 msec.
  
  
  CONCLUSIONS
  T1 and T2 in the basal ganglia of premature infants do not differ much from previously published data from basal ganglia of older children and adults. T2 of Cho was lower than previous values. T2 of Cr at 3.9 ppm and Lac have been measured under different conditions before, and present values differ from these data.
authors.affiliation: Department of Diagnostic Radiology, University of Cologne, Köln, Germany. kugel@uni-muenster.de
authors.forename: Harald
authors.initials: H
authors.lastname: Kugel
authors.forename: Bernhard
authors.initials: B
authors.lastname: Roth
authors.forename: Frank
authors.initials: F
authors.lastname: Pillekamp
authors.forename: Karsten
authors.initials: K
authors.lastname: Krüger
authors.forename: Oliver
authors.initials: O
authors.lastname: Schulte
authors.forename: Alexander
authors.initials: A
authors.lastname: von Gontard
authors.forename: Gabriele
authors.initials: G
authors.lastname: Benz-Bohm
mesh_terms: D000328:Adult; D001479:Basal Ganglia / Q000378:metabolism*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D019102:Infant, Very Low Birth Weight / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011522:Protons; D013997:Time Factors
chemical_list: D011522:Protons