Ultralong TE In Vivo 1 H MR Spectroscopy of Omega-3 Fatty Acids in Subcutaneous Adipose Tissue at 7 T.

<bold>Background: </bold>Omega-3 (n-3) fatty acids (FA) play and important role in neural development and other metabolic diseases such as obesity and diabetes. The knowledge about the in vivo content and distribution of n-3 FA in human body tissues is not well established and the standard quantification of FA is invasive and costly.<bold>Purpose: </bold>To detect omega-3 (n-3 CH3 ) and non-omega-3 (CH3 ) methyl group resonance lines with echo times up to 1200 msec, in oils, for the assessment of n-3 FA content, and the n-3 FA fraction in adipose tissue in vivo.<bold>Study Type: </bold>Prospective technical development.<bold>Population: </bold>Three oils with different n-3 FA content and 24 healthy subjects.<bold>Field Strength/sequence: </bold>Single-voxel MR spectroscopy (SVS) with a point-resolved spectroscopy (PRESS) sequence with an echo time (TE) of 1000 msec at 7 T.<bold>Assessment: </bold>Knowledge about the J-coupling evolution of both CH3 resonances was used for the optimal detection of the n-3 CH3 resonance line at a TE of 1000 msec. The accuracy of the method in oils and in vivo was validated from a biopsy sample with gas chromatography analysis.<bold>Statistical Tests: </bold>SVS data were compared to gas chromatography with the Pearson correlation coefficient.<bold>Results: </bold>T2 relaxation times in oils were assessed as follows: CH2 , 65 ± 22 msec; CH3 , 325 ± 7 msec; and n-3 CH3 , 628 ± 34 msec. The n-3 FA fractions from oil phantom experiments (n = 3) were in agreement with chromatography analysis and the comparison of in vivo obtained data with the results of chromatography analysis (n = 5) yielded a significant correlation (P = 0.029).<bold>Data Conclusion: </bold>PRESS with ultralong-TE can detect and quantify the n-3 CH3 signal in vivo at 7 T.<bold>Level Of Evidence: </bold>1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:71-82. [ABSTRACT FROM AUTHOR]