Room: Exhibit Hall | Forum 6
Purpose: In-vivo MRS detection of the 2HG is an important emerging technique in neuro-oncology. The purpose of this study is to develop a 2HG MRS phantom and evaluate its applicability with clinical MRS protocols.
Methods: A 50mM 2HG salt was added and dissolved in the GE spectroscopy solution in a 40mL container. This 2HG container was soaked into another larger container filled with GE MRS Solution. MRS data were acquired using a single voxel PRESS sequence (TR 2s, TE 97msec, 128 averages) with a 20 channel phase array head coil on Siemens 3T Prisma scanner. A 2x2x2cm (8mL) was placed entirely inside the 2HG compartment, guided by 3D FLAIR images. Also, two water reference scans were performed for metabolite quantification. The phantom underwent scan monthly, weekly and daily. MRS data were analyzed using in-house Matlab scripts and LCModel software. The LCModel basis set included calculated spectra of 20 metabolites including 2HG.
Results: The 2HG concentrations measured from the monthly, weekly and daily scans were 6.73 Â± 0.09 mM, 6.65 Â± 0.16 mM and 6.69 Â± 0.13 mM, respectively, which corresponded to 95% confidence intervals (CI) of 0.18, 0.32 and 0.26 mM and coefficients of variance of 1.34%, 2.41% and 1.94%, respectively. The accuracy of the measurements ranged from 1.3% to 3.4%. These stability results of the 2HG measurement were consistent with those of other metabolites. Signal intensity, B0 shimming and frequency drifting were very stable during each study and over the few months. FWHM of voxel B0 shimming ranged 3.9-6.8Hz. There was no correlation between the measured 2HG concentration and the FWHM value.
Conclusion: We have built a phantom for periodic testing of the clinical 2HG MRS protocol. We demonstrated that with this phantom the 2HG could be differentiated from other metabolites and accurately quantified with high repeatability.
MRS, Quality Assurance, Quantitative Imaging