12-channel receive array with a volume transmit coil for hand/wrist imaging at 7 T

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Radiology

Background:

• High-field MRI at 7 Tesla (T) offers enhanced signal-to-noise ratio for improved image resolution.
• Conventional transceive coils at 7 T can face challenges with wavelength effects and field inhomogeneities.
• Optimized coil designs are crucial for maximizing the benefits of ultra-high field MRI for small anatomical regions.

Purpose of the Study:

• To develop and evaluate a specialized coil configuration for high-resolution imaging of the hand and wrist at 7 T.
• To assess the performance of a 12-channel high-density receive array in conjunction with a birdcage transmit coil.
• To demonstrate the feasibility of achieving ultra-high resolution anatomical detail in the hand and wrist.

Main Methods:

• Development of a quadrature bandpass birdcage transmit coil and a 12-channel high-density receive array.
• Characterization of the coil system using workbench measurements and in vivo magnetic resonance imaging (MRI).
• Electromagnetic simulations to evaluate transmit field uniformity and specific absorption rate (SAR).

Main Results:

• The developed transmit coil is compatible with the receive array without requiring retuning.
• Ultra-high resolution images (0.19 × 0.19 × 0.5 mm³) of the wrist were acquired, revealing fine anatomical structures.
• Electromagnetic simulations indicated a near-uniform transmit profile across the hand, attributed to its small volume and low conductivity.

Conclusions:

• Optimized high-density receive arrays are a viable alternative to transceive arrays for 7 T hand and wrist imaging.
• This approach enables the acquisition of extremely fine resolution images, surpassing limitations associated with wavelength decrease at high fields.
• The developed coil configuration facilitates detailed visualization of small anatomical regions, advancing diagnostic capabilities.