Combination of surface and 'vertical' loop elements improves receive performance of a human head transceiver array at...

Area of Science:

• Medical Imaging
• Biophysics
• Electrical Engineering

Background:

• Ultra-high-field (UHF, ≥7T) MRI offers superior resolution but faces technical hurdles, particularly low radiofrequency (RF) transmit (Tx) coil efficiency due to increased power deposition.
• Tight-fit transceiver (TxRx) arrays improve Tx efficiency but are limited in receive (Rx) element numbers by available Tx channels, hindering optimal Rx performance.

Purpose of the Study:

• To develop a method for increasing the number of Rx elements in a human head TxRx surface loop array without compromising Tx performance.
• To optimize both Rx and Tx performance simultaneously in UHF human head MRI arrays.

Main Methods:

• Designed and constructed a prototype 16-channel tight-fit array with eight TxRx surface loops and eight additional Rx-only vertical loops.
• Evaluated the array's performance experimentally and numerically using human head voxel models and in vivo scans.

Main Results:

• The addition of vertical loops showed no measurable effect on the array's Tx efficiency.
• Maximum local specific absorption rate (SAR) increased by ≤3.4%.
• The 16-element array achieved a 30% improvement in central signal-to-noise ratio (SNR) in vivo compared to an 8-element array, with enhanced parallel Rx performance.

Conclusions:

• The novel array design successfully increases Rx elements without compromising Tx efficiency.
• This method enables simultaneous optimization of both Rx and Tx performance for human head arrays in UHF MRI.
• The developed array offers improved SNR and parallel imaging capabilities for advanced MRI applications.