Evaluation of optimal echo time for 1H-spectroscopic imaging of brain tumors at 3 Tesla.
OBJECTIVE
To compare the spectral quality of short echo time (TE) MR spectroscopic imaging (MRSI, TE = 30 msec) with long-TE MRSI (TE = 144 msec) at 3 Tesla in normal brain and tumor tissue.


METHODS
Spectroscopic imaging (chemical-shift imaging (CSI)) data of 32 patients with histopathological confirmed brain lesions were acquired at 3 Tesla (3T) using TEs of 30 msec and 144 msec. Tumor-relevant metabolites (trimethylamine (TMA), creatine compounds (tCr), and N-acetylated compounds (tNAA)) were analyzed with LCModel software, which applies prior knowledge by performing a frequency domain fit using a linear combination of model spectra.


RESULTS
Short-TE spectra provided up to twice the signal-to-noise ratio (SNR) compared to TE = 144 msec. The estimated fitting error was improved up to 30% for TMA and tCr, but was slightly reduced (10%) for tNAA. Quantification in terms of absolute concentrations was consistent at both TEs.


CONCLUSIONS
Since other metabolites observable at TE < 30 msec may be of diagnostic relevance, short-TE MRSI should be the preferred method at 3T for the evaluation of focal lesions in brain tissue; however, TE = 144 msec can serve as an option for MRS in regions with potential baseline problems.
Hattingen
Elke
E
Institute of Neuroradiology, Johann Wolfgang Goethe University of Frankfurt/Main, Frankfurt, Germany. elke.hattingen@kgu.de
Pilatus
Ulrich
U
Franz
Kea
K
Zanella
Friedhelm E
FE
Lanfermann
Heinrich
H
D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D003401:Creatine / Q000378:metabolism; D017352:Echo-Planar Imaging / Q000379:methods; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008744:Methylamines / Q000494:pharmacology; D008875:Middle Aged; D013997:Time Factors
D008744:Methylamines; C023336:trimethylamine; D003401:Creatine