Work

Power Scaling Methods for RF Excitation Fields in MRI Systems

Year: 2025

Type: article

Abstract: In this paper, we analyze the homogeneity of the transmitted radiofrequency (RF) field by applying different power scaling methods ranging from low-field (12.8 MHz, 0.3 T) to high-field (298 MHz, 7.0 T) magnetic resonance imaging (MRI) systems. Homogeneity strongly depends on RF power scaling, especially in higher-field MRI. While no notable homogeneity problem is usually observed in lower-field MRI, strong center brightening occurs at a higher field, owing to shortened wavelength. In particular, the dependence of homogeneity on RF power scaling appears during the initial MRI system calibration. In this study, we evaluate the 10-g averaged specific absorption rate (SAR) to evaluate RF safety. This rate may suffer from severe phase interferences, especially in the case of higher-field MRI, due to the increased strength of the static magnetic field and the complex distribution of electrical properties in structures, such as the human head. In particular, the 10-g averaged SAR level is up to six times higher in higher-field MRI with entire-area RF power scaling than with center scaling. Overall, this study establishes the importance of accounting for MRI scan homogeneity and RF safety during MRI examinations.

Source: Journal of electromagnetic engineering and science

DOI: 10.26866/jees.2025.2.r.289

Authors: Seon-Eui Hong, Giuseppe Carluccio, Christopher M. Collins, Hyung-Do Choi, Sukhoon Oh

Language: English

Topic: Advanced MRI Techniques and Applications

Subfield: Radiology, Nuclear Medicine and Imaging

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $115

Funders: Ministry of Science, ICT and Future Planning, Institute for Information and Communications Technology Promotion