Characterizing Muscle and Subcutaneous Adipose Tissue Imaging Phantoms for NMR Application

Abstract

Medical imaging techniques are being increasingly used to derive quantitative information, requiring a new type of imaging phantom for validation. Here, we describe the T2 relaxation properties of an emulsified two-phase imaging phantom for validating a nuclear magnetic resonance (NMR) sensor for measuring fluid volume in vivo. The phantoms simulate muscle and subcutaneous adipose tissues (SCAT) and assure the repeatability and accuracy of the technique. We determined that the 40% phantoms model muscle tissue and 70% model SCAT. The microstructure of the 40% phantoms was changed by controlling temperature and stir rate. Lower temperature and stir rate produced phantoms with a significantly larger average droplet size than higher temperature and stir rate. Microstructure changes did not alter the T2 relaxation behavior (p = 0.05) but altered relative diffusion time. We changed the fabrication protocol by comparing reagent-grade peanut oil to cooking-grade peanut oil and creating the water and lipid phases separately versus together. There was no significant difference (p = 0.05) in T2 relaxation of the 40% and 70%. The phantoms are stable, robust, and reproducible.