Effect of Fat Composition on Allylic Proton Transverse Relaxation and J‐Coupling Evolution at 9.4 T

• Published in: European journal of lipid science and technology 2025-01, Vol.127 (1), p.n/a
• Main Authors: Bly, Nathaniel, Carscadden, Adam, Dehod, Alexander, Tessier, Anthony G., Field, Catherine J., Yahya, Atiyah
• Format: Article
• Language: English
• Subjects: 9.4 T magnetic resonance spectroscopy; Adipose tissue; allylic protons; Composition effects; Correlation; Coupling; Diet; Edible oils; Linoleic acid; Linolenic acid; Nutrient deficiency; oleic acid; Protons; Spectroscopy; Spectrum analysis
• ISSN: 1438-7697; 1438-9312
• DOI: 10.1002/ejlt.202400081

Transverse (T2) relaxation and J‐coupling evolution of oleic, linoleic, and linolenic acid allylic protons are investigated at 9.4 T as an indirect means of assessing fat composition. We hypothesize that the relative proximity of one allylic proton group to the methyl end of the fatty acid impacts the measures. A Point RESolved Spectroscopy (PRESS) sequence was used for apparent (includes J‐coupling effects) T2 estimation. Spectra were acquired from oleic, linoleic, and linolenic acid, from edible oils, and from intraperitoneal adipose tissue of two groups of mice (n = 4 per group) randomized to a high or low ω‐3 diet. Apparent T2 values of 62, 106, and 220 ms were obtained for oleic, linoleic, and linolenic acid allylic protons, respectively. For oils containing negligible linolenic acid, apparent T2 values correlated with linoleic acid contribution to total unsaturation (R2 = 1). For oils containing linolenic acid, a correlation with linolenic acid contribution to total unsaturation was found (R2 = 0.91). In animal experiments, the mean allylic apparent T2 in the group fed the high ω‐3 diet was 72.3 ms compared to 66.1 ms measured from the low ω‐3 diet group. Signal yield with an echo time (TE) of 130 ms results in an inverse correlation with relative linolenic acid content (R2 = 0.99) for the oils. The presented work demonstrates that fatty acid allylic proton (≈2 ppm) transverse relaxation and J‐coupling evolution is affected by fat composition. Experiments were conducted on oil phantoms and on two groups of mice fed different diets at 9.4 T.