Apparent T(2) relaxation times of lipid and macromolecules: a study of high-grade tumor spectra.
OBJECTIVE
To determine T(2) relaxation times of lipid and macromolecules (Lip/MMs) observed by (1)H magnetic resonance spectroscopy ((1)H MRS) of metastases (MET) and glioblastomas (GBM), so that they may be better characterized.


METHODS
(1)H spectra were acquired at multiple echo times from brain lesions using point-resolved spectroscopy sequence (PRESS) at TE = 30 msec either with metabolite-nulling (six GBM and 11 MET), or without metabolite-nulling (four MET and one mucocele). All lesions were previously untreated and had subsequent histopathological classification.


RESULTS
The T(2) of the 1.3-ppm Lip/MM peak was concentration-dependent, but at high concentrations it was significantly different (P = 0.015) between GBM (42 +/- 6 msec) and MET (63 +/- 18 msec). The broad 2.05-ppm and 0.09-ppm Lip/MM peaks had similar T(2)s in MET and GBM. The T(2) of the narrow 2.05-ppm Lip/MM peak sometimes observed had a T(2) of 100 +/- 17 msec in MET and 75 msec in the mucocele.


CONCLUSIONS
We observed significantly higher T(2) of the 1.3-ppm Lip/MM peak in MET compared with GBM at high 1.3-ppm proton concentrations, in agreement with a higher 1.3/0.9-ppm peak ratio found in MET. The relatively long T(2) of the 2.05-ppm Lip/MM peak sometimes observed in MET may cause it to be confused with N-acetyl aspartate (NAA).
Opstad
Kirstie S
KS
Division of Basic Medical Sciences, St George's, University of London, London, UK. kopstad@sgul.ac.uk
Griffiths
John R
JR
Bell
B Anthony
BA
Howe
Franklyn A
FA
D001932:Brain Neoplasms / Q000378:metabolism*; D005217:Fat Emulsions, Intravenous; D005260:Female; D005909:Glioblastoma / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism; D046911:Macromolecular Substances / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D018709:Statistics, Nonparametric
D005217:Fat Emulsions, Intravenous; D046911:Macromolecular Substances