Thermal measurements of a muscle-mimicking phantom during ultra-high field magnetic resonance imaging
Nenhuma Miniatura disponível
Citações na Scopus
0
Tipo de produção
article
Data de publicação
2023
Título da Revista
ISSN da Revista
Título do Volume
Editora
WALTER DE GRUYTER GMBH
Autores
GARCIA, M. M.
OLIVEIRA, T. R.
BRUNS, C.
BERNARDING, J.
SVEJDA, J. T.
ERNI, D.
ZYLKA, W.
Citação
CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING, v.9, n.1, p.319-322, 2023
Resumo
At 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.
Palavras-chave
7T MRI, MR thermometry, MRI safety, proton resonance frequency (PRF), temperature mapping
Referências
- Winter L., Oezerdem C., Hoffmann W., van de Lindt T., Periquito J., Ji Y., Et al., Thermal magnetic resonance: physics considerations and electromagnetic field simulations up to 23.5 Tesla (1GHz), Radiat Oncol, 10, (2015)
- Hernandez D., Kim K.S., Michel E., Lee S.Y., Correction of 0 drift effects in magnetic resonance thermometry using magnetic field monitoring technique, Concepts Magn Reson, 46 B, pp. 81-89, (2016)
- Yuan Y., Wyatt C., Maccarini P., Stauffer P., Craciunescu O., Macfall J., Et al., A heterogeneous human tissue mimicking phantom for RF heating and MRI thermal monitoring verification, Phys Med Biol, 57, 7, pp. 2021-2037, (2012)
- Hasgall P.A., Di Gennaro F., Baumgartner C., Neufeld E., Lloyd B., Gosselin M.C., Et al., IT’IS Database for thermal and electromagnetic parameters of biological tissues, 4, (2022)
- Arduino A., Zanovello U., Hand J., Zilberti L., Bruhl R., Chiampi M., Et al., Heating of hip joint implants in MRI: The combined effect of RF and switched-gradient fields, Magn Reson Med, 85, 6, pp. 3447-3462, (2021)
- Herraez M.A., Burton D.R., Lalor M.J., Gdeisat M.A., Fast two-dimensional phase-unwrapping algorithm based on sorting by reliability following a noncontinuous path, Appl Opt, 41, 35, pp. 7437-7444, (2002)