Evaluation of an open-face 8-channel transmit 64-channel receive 7T head coil for neuroimaging

Ultra-high field (UHF) 7 tesla (7T) MRI offers unique diagnostic opportunities for clinical neuroimaging. However, broader clinical implementation remains limited because the reduced radiofrequency (RF) wavelength at 7T causes RF transmit field ( ${\text{B}}_1^{+}$ ) inhomogeneity, resulting in spatial variation in image signal and tissue contrast. These effects are particularly pronounced in the skull base, temporal lobes, and posterior fossa, regions frequently implicated in neurological disease. RF parallel transmission (pTx) techniques can improve ${\text{B}}_1^{+}$ homogeneity through optimization of multiple transmit fields, while parallel imaging with multiple receive elements enables accelerated acquisitions. To fully exploit these advantages at UHF, RF coils combining high-performance transmit and high-density receive arrays are required.

An open-face eight-channel transmit 64-channel receive (8Tx64Rx) 7T head coil was developed with electrical and mechanical ergonomic features designed to improve usability and imaging homogeneity. The coil was evaluated in an in vivo validation study assessing ease of use, participant comfort, diagnostic value, and image quality using questionnaires and structured scoring sheets. Imaging performance of the 8Tx64Rx coil was compared with that of a commercially available regulatory approved 7T head coil featuring single transmit (sTx) and a 32-channel receive array. Diagnostic image quality acquired using circularly polarized (CP) mode and pTx mode was additionally assessed and compared.

The 8Tx64Rx coil demonstrated image quality that was equivalent or superior to the commercial 7T head coil across evaluated measures. In particular, improved signal homogeneity was achieved within the posterior fossa and temporal lobes. The coil also supported practical clinical use through favorable ergonomic performance and user comfort during scanning. Diagnostic image quality was enhanced when using pTx approaches compared with conventional transmit configurations.

The developed 8Tx64Rx 7T head coil demonstrates the potential to advance clinical neuroimaging at UHF by improving ${\text{B}}_1^{+}$ homogeneity in anatomically challenging brain regions while maintaining usability and diagnostic performance. These findings support the integration of combined high-density receive arrays and pTx technology to overcome key limitations of 7T MRI and facilitate broader clinical adoption.