Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPGARCIA, M. M.OLIVEIRA, T. R.CHAIM, K. T.OTADUY, M. C. G.BRUNS, C.BERNARDING, J.SVEJDA, J. T.ERNI, D.ZYLKA, W.2024-03-132024-03-132023CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING, v.9, n.1, p.319-322, 20232364-5504https://observatorio.fm.usp.br/handle/OPI/58694At ultra-high field MRI (Bo>7T) it is crucial to predict and control the patient safety. Commonly patient safety is controlled by the power deposited in the tissue (specific absorption rate - SAR). However, temperature distributions do not always correlate directly with SAR distributions, which makes temperature control also a crucial parameter to guarantee patient safety. In this work, temperature changes were accessed by MR thermometry, specifically by the proton resonance frequency shift technique (PRF). A phantom mimicking muscle tissue was used to evaluate the temperature rise caused by the radiofrequency (RF) absorption during 7T MRI, applied through a commercial birdcage head coil. A pulse-sequence protocol was implemented for both, the generation of temperature increase and the MR thermometry. To control the temperature, a digital thermometer was used, and oil tubes were utilized to dismiss the drift effects for PRF. Measurements of the phantom's dielectric characteristics, i.e. conductivity and permittivity, were in good agreement with the literature values for muscle. Spatio-temporal evaluations showed a temperature increase in time via RF exposure and the feasibility of measuring temperature maps using the PRF shift method. The accuracy of the PRF shift method increased when the drift effects were quantified and dismissed, indicating a PRF reading accuracy differing less than 0.5 °C from the thermometer. Results also validate our heating and temperature imaging protocol. This study is a valuable contribution to the evaluation of heating effects caused by RF absorption and demonstrates potential impact on future thermal investigations, which may use different heating sources, as well validate thermal simulations.engopenAccess7T MRIMR thermometryMRI safetyproton resonance frequency (PRF)temperature mappingmagnetic resonance imagingmusclenatural frequenciespetroleum reservoir evaluationthermometers7t mrimeasurements ofmr thermometrymri safetypatient safetyphantomsproton resonance frequencyresonance frequency shifttemperature mappingphantomsarticleCopyright WALTER DE GRUYTER GMBH10.1515/cdbme-2023-1080