MRS of Pilocytic Astrocytoma: The Peak at 2ppm May Not Be NAA

    loading  Checking for direct PDF access through Ovid



To determine whether the chemical shift of residual N-acetylaspartate (NAA) signal in pilocytic astrocytomas (PA) is consistent with the position of the NAA peak in controls.


MR spectra from 27 pediatric World Health Organization (WHO) grade I pilocytic astrocytoma patients, fifteen patients with WHO grade II and high-grade (III–IV) astrocytomas, and 36 controls were analyzed. All spectra were acquired with a short echo time (35 ms), single voxel point-resolved spectroscopy sequence on clinical 3 tesla scanners. Fully automated LCModel software was used for processing, which included the fitting of peak positions for NAA and creatine (Cr).


The chemical shift difference between the NAA and Cr peaks was significantly smaller (by 0.016 ± 0.005 parts per million, P < 1e–10) in PAs than in controls and was also smaller than what was observed in infiltrative astrocytomas.


The chemical shift position of the residual NAA peak in PAs is not consistent with NAA. The signal likely originates from an N-acetyl group of one or more other chemicals such as N-acetylated sugars.

Related Topics

    loading  Loading Related Articles