7 Tesla 22‐channel wrap‐around coil array for cervical spinal cord and brainstem imaging

Purpose Increased signal‐to‐noise ratio and blood oxygenation level‐dependent sensitivity at 7 Tesla (T) have the potential to enable high‐resolution imaging of the human cervical spinal cord and brainstem. We propose a new two‐panel radiofrequency coil design for these regions to fully exploit the advantages of ultra‐high field. Methods A two‐panel array, containing four transmit/receive and 18 receive‐only elements fully encircling the head and neck, was constructed following simulations demonstrating theB 1 +and specific absorption rate (SAR) benefits of two‐panel over one‐panel arrays. This array was compared with a previously reported posterior‐only array and tested for safety using a phantom. Its anatomical, functional, and diffusion MRI performance was demonstrated in vivo. Results The two‐panel array produced more uniformB 1 +across the brainstem and cervical spinal cord without compromising SAR, and achieved 70% greater receive sensitivity than the posterior‐only array. The two‐panel design enabled acceleration of R = 2 × 2 in two dimensions or R = 3 in a single dimension. High quality in vivo anatomical, functional, and diffusion images of the human cervical spinal cord and brainstem were acquired. Conclusion We have designed and constructed a wrap‐around coil array with excellent performance for cervical spinal cord and brainstem MRI at 7T, which enables simultaneous human cervical spinal cord and brainstem functional MRI. Magn Reson Med 78:1623–1634, 2017. © 2016 International Society for Magnetic Resonance in Medicine.