Radiofrequency Coils for 7 Tesla MRI

Area of Science:

• Medical Imaging
• Biophysics
• Electrical Engineering

Background:

• Radiofrequency (RF) coils are critical components of magnetic resonance (MR) systems, enabling signal reception and transmission.
• Ultrahigh magnetic fields (UHF) offer higher signal-to-noise ratios but face limitations in commercially available RF coil technology.
• Integrated transmit body RF coils, common at lower field strengths, are notably absent at UHF due to technical and physical constraints.

Purpose of the Study:

• To provide a comprehensive overview of current state-of-the-art RF coils for 7 Tesla (7T) MRI applications.
• To introduce fundamental RF characteristics, terminology, and parameters relevant to MR imaging.
• To discuss the challenges and considerations for RF safety assessments, particularly for custom-designed coils and interactions with implanted medical devices.

Main Methods:

• Review of existing literature on RF coil development and applications in ultrahigh field MRI.
• Systematic compilation of RF coil designs currently in use for 7T MRI, covering anatomical regions from head to toe.
• Analysis of technical and physical constraints hindering the development of integrated transmit body RF coils at UHF.

Main Results:

• Detailed exposition of advanced RF coil technologies currently employed in 7T MRI across various body parts.
• Identification of specific RF characteristics and parameters crucial for optimizing UHF MRI performance.
• Discussion on the complexities of ensuring RF safety with novel, custom-built RF coils and their interaction with medical implants.

Conclusions:

• Significant progress has been made in RF coil development for 7T MRI, enabling exploration of UHF benefits.
• The absence of integrated transmit body RF coils at UHF remains a key technical challenge.
• Thorough RF safety assessments are paramount for custom coils and for understanding interactions with implanted devices in UHF MRI environments.