(Sunday, 7/12/2020) [Eastern Time (GMT-4)]
Room: AAPM ePoster Library
Purpose: in the body is found primarily as triglycerides. However, increased levels of diglycerides have been reported in certain diseases. The objective of the presented work is to determine a method of measuring changes in relative concentrations of diglycerides and triglycerides at 3 T using commonly employed in vivo magnetic resonance spectroscopy (MRS) techniques, such as Point RESolved Spectroscopy (PRESS) and STimulated Echo Acquisition Mode (STEAM).
Methods: glycerol proton resonances of triglycerides and 1,2-/1,3-diglycerides (1,2-/1,3-DG), which appear in MRS spectra at 3.7 – 5.3 parts per million (ppm), strongly overlap at 3 T, making it difficult to determine their relative concentrations. The scalar coupling evolution of the glycerol protons of dicaprylin (100% diglyceride) and tricaprylin (100% triglyceride) to PRESS and STEAM echo time (TE) was investigated experimentally to determine a suitable TE that enables quantification of the relevant amounts of diglyceride and triglyceride in a sample containing both. TE was varied from 40 ms – 300 ms for PRESS and from 20 ms – 300 ms for STEAM in steps of 10 ms.
Results: with a TE of 20 ms, results in a 1,3-DG resonance that overlaps directly with triglyceride signal centered at 4.14 ppm. The amount of triglyceride signal contaminating it can be determined from the 4.29 ppm triglyceride resonance. The presence of 1,2-DG can be detected by a peak at 3.72 ppm from which the 4.29 ppm triglyceride signal can be adjusted to account for 1,2-DG signal contamination. Therefore, the amounts of 1,2-DG and 1,3-DG relative to the amount of triglycerides can be determined from three peaks, namely, those that resonate at approximately 3.72, 4.24 and 4.29 ppm.
Conclusion: was determined that STEAM with a TE of 20 ms is suitable for determining relative concentrations of diglycerides and triglycerides at 3 T.
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