Quantification of brain creatine concentration using PRESS sequence and LCModel: comparison with HPLC method

To investigate the accuracy for quantification of brain total creatine (Cr) concentration using in vivo long echo time (TE) PRESS sequence with an external standard and LCModel. Ten swine and an external standard containing a detectable compounds of known concentration were studied by using 1.5 T GE Signa scanner and the standard head coil; the single-voxel proton magnetic resonance spectroscopy (
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H-MRS) data was acquired from the 20-mm cubic VOI which was placed in the swine brain and external standard respectively by using the PRESS sequence with TE=135 msec, TR=1500 msec, and 128 scan averages. The quantification of Cr was accomplished by the linear combination of model spectra (LCModel). After MRS examination, each animal was sacrificed, and in vitro Cr concentration was analyzed by high performance liquid chromatography (HPLC). In the MRS group, the mean concentration of Cr was 9.37plusmn0.137mmol/kg; in the HPLC group, the mean concentration of Cr was 8.905plusmn0.126 mmol/kg. There were no statistically significant differences between two methods (P=0.491), which indicated that long TE PRESS sequence with an external standard can accurately detect the brain Cr concentration. The application of LCModel introduces more convenience for the MRS quantification