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Objectives: Previously in rodent and swine models, we have shown that external low intensity focused ultrasound (liFUS) can be used to modulate pain responses. To ensure no adverse heating events occur with liFUS modulation in a non-invasive manner, we perform initial work in swine to show that magnetic resonance thermometry imaging (MRTI) is capable of measuring <2.0 °C changes at the L5 DRG. Further, we show that our device can be constructed in an MR-compatible fashion to minimize artifact., Methods: Three MRTI techniques (referenceless, corrected proton resonance frequency shift (PRFS), and PRFS) were applied to assess accuracy of detecting thermal changes at the L5 DRG in unheated euthanized swine. A region of interest (ROI) that includes the L5 DRG was delineated, within which MRTI temperature changes were spatially averaged (ground truth 0 °C). In separate experiments with phantoms, B0 field-inhomogeneity, RF transmit (B1+) and fast gradient echo (fSPGR) magnitude images were acquired to downselect liFUS device materials that produce the least MRI artifacts., Results: Referenceless, corrected PRFS, and PRFS MRTI resulted in temperature measurements of 0.8 ± 1.1 °C, 1.1 ± 1.3 °C and 5.2 ± 5 °C, respectively. Both materials caused B0 perturbation but minimal B1+ and MRTI artifacts. The presence of imaging artifacts did not preclude thermal imaging of the region., Significance: We provide preliminary data suggesting that referenceless MRTI can adequately detect small thermal changes at the DRG that may occur with neuromodulation, which is one of the first steps in creating a table of safe parameters for liFUS therapy in humans., Competing Interests: Declaration of Competing Interest This study was sponsored by the National Institute of Health Grant 2R01CA166379. Dr. Pilitsis receives grant support from Medtronic, Boston Scientific, Abbott, NIH 2R01CA166379, NIH R01EB030324, NIH Blueprint 3U54EB015408, and NIH U44NS115111. She is the medical advisor for Aim Medical Robotics and has stock equity. Dr. Clif Burdette and Mr. Williams are employees of Acoustic Medsystems. Dr. Desmond Yeo and Dr. Matthew Tarasek are employees of GE Global Research. The authors have no competing interests to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)