Traditional Posters: Miscellaneous

Yan Zhang¹, Shizhe Li¹, Jun Shen<sup>1

1</sup>National Institute of Mental Health, Bethesda, MD, United States

The process of lineshape deconvolution is an inverse problem. A new referencing deconvolution method is proposed, which uses Tiknohov regularization to restrain the noise amplification. To determine the optimal regularization, the noise to signal ratio in frequency domain was defined as a function of the regularization parameter. It was found that this function yielded a well-defined L-curve with the transition point that marks the optimal regularization parameter. The method was validated on 1H spectral data which were acquired on human brain with single voxel at 3T. The spectral quality was markedly improved after the data were processed with the proposed method.

903. Electronic Reference for Absolute Quantification of Brain Metabolites by 1H-MRS on Clinical Whole Body Imager.

Hubert Desal¹, Nashiely Pineda Alonso², Serge Akoka<sup>2

1</sup>Neuroradiology, CHU de Nantes, Nantes, PdL, France; ²Chemistry, Université de Nantes, CEISAM, UMR 6230, Nantes, PdL, France

The ERETIC method is a promising avenue of research for absolute concentration quantification by MRS. However, in its initial form, this technique cannot be implemented on most clinical MR scanners. We propose a new strategy, which consists in transmitting the ERETIC signal before the localized spectroscopy acquisition. This approach was evaluated on phantoms and on volunteers. The results were compared to those obtained using the water signal as reference. A very good correlation between the values obtained using the two methods was observed. Moreover, the ERETIC method overcomes many of the drawbacks of the other absolute quantification methods.

904. Sampling Strategy Effects on in Vivo 2D J-Resolved Spectroscopy Quantification

Tangi Roussel¹, Sophie Cavassila¹, Hélène Ratiney<sup>1

1</sup>CREATIS, CNRS UMR 5220, Inserm U630, INSA-Lyon, Université de Lyon 1, Université de Lyon, Villeurbanne, France

Till now, in vivo two-dimensional spectroscopy related studies did not investigate sampling strategies of the indirect dimension as a way of improving the quantification of metabolite concentrations. This paper presents a study carried out on simulated J-PRESS data containing macromolecular contamination. 2D J-Resolved spectroscopy quantification accuracy was evaluated for several sampling strategies and compared to 1D MRS quantification accuracy. In vivo 2D quantification following these strategies is shown. By handling macromolecular contribution by truncation strategy, a 2D MRS experiment leads to a more accurate quantification compared to 1D MRS time equivalent experiment, as demonstrated by a reduction of bias and standard deviation.

905. In Vitro and in Vivo Validation of Absolute Quantitation of Brain Proton MR Spectra (¹H-MRS) with Respect to Heterogeneous Tissue Compositions

Alexander Gussew¹, Marko Erdtel^1,2, Reinhard Rzanny¹, Juergen R. Reichenbach<sup>1

1</sup>Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany; ²University of Applied Sciences Jena, Jena, Germany

This work describes in vitro and in vivo validation of absolute quantitation of ¹H-MRS brain data with respect to heterogeneous tissue distributions within the MRS-volume. NAA concentrations were estimated from metabolite and water spectra obtained from MRS-voxels containing different metabolite and water concentrations and were compared with nominally adjusted values. The maximal error was 4% compared to 41%, if the tissue heterogeneity was neglected. Inter-individual distributions of NAA-, Cr- and tCho-concentrations obtained in insular cortex of volunteers had twice less scatter when taking into account the heterogeneous tissue composition in the voxel.

906. Spectral Fitting of High Resolution Rat Brain Extract NMR Data by LCModel with a Simulated Basis Set