Evaluation of 7 Tesla pTx Body Coils Regarding Transmit and Receive Performance

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Device Engineering
• Radiology

Background:

• Standardized transmit-receive (pTx) body coils for 7 Tesla (7T) MRI are unavailable.
• Custom coil development leads to diverse designs with varying transmit element types, layouts, and channel counts.
• This diversity necessitates performance comparisons of existing coil arrays.

Purpose of the Study:

• To investigate and compare the transmit and receive performance of eight different 7T body MRI coils.
• To evaluate coils including one remote and seven local radiofrequency (RF) arrays.
• To identify optimal coil configurations for 7T body MRI applications.

Main Methods:

• Phantom measurements were performed on a 7T scanner using a consistent phantom and imaging protocol.
• Transmit performance was assessed by B1+ efficiency and coverage.
• Receive performance was evaluated using signal-to-noise ratio (SNR), coverage, noise correlation, and g-factors.

Main Results:

• B1+ efficiency varied from 2.02 to 4.33 μT/√kW, with local arrays outperforming the remote array.
• Central SNR ranged from 278 to 1072, peaking with an 8Tx32Rx configuration.
• Coverage and acceleration performance improved with higher receive channel counts, with specific arrays excelling in different directions.

Conclusions:

• No single 7T body MRI coil design offers universally superior performance across all metrics.
• Coil designs present trade-offs between B1+ efficiency, coverage, SNR, and acceleration.
• The 8Tx32Rx local array (C5) demonstrates a promising balance of high SNR, coverage, and acceleration, making it a potential compromise for 7T body MRI.