Magnetic Resonance Imaging of Rat’s Brain and Spine Using Curved Four-channel Phased Array Coil

Magnetic resonance imaging (MRI) techniques such as anatomical and diffusion tensor imaging (DTI) have been widely applied to investigate the central nervous system (CNS). However, commercial MRI coils could not provide sufficient signal-to-noise ratio (SNR) at the neck due to cervical lordosis (inward curvature), therefore hampering the applications from brain to the spine. The aim of this work was to design and implement a 4-channel curved array coil that provides uniform sensitivity along the CNS, improving studies of the head and spinal column. The 4-channel curved array coil was fabricated on a flexible printed circuit board that could be bent to fit the rat’s contour along the neck while a homemade low input impedance preamplifier eliminates the crosstalk between overlapping coils elements. We evaluated the performance of the coil through anatomical imaging of phantom and rat cervical spine, and finally perform rat cerebrospinal DTI and tractography to show the benefits of a curved array coil. Compared to conventional array coils, the curved array coil offered 1.3- and 1.45-fold SNR gain in phantom and anatomical images of the rat cervical spine respectively. In addition, the contrast-to-noise ratio (CNR) between gray and white matter in spine was alleviated. By combining Wideband MRI technique, the 3D anatomical and high-resolution diffusion weighted images were obtained with a 11-fold acceleration. In reproducibility of DTI, the experimental reproducibility deviation angle acquired by curved array coil was 77% of that by plane array coil. Moreover, the DTI tractography of rat nervous system using the curved array coil was more complete. The 4-channel curved array platform was successfully implemented for rat cerebrospinal MRI. We evaluated its performance by phantom as well as in vivo anatomical imaging and further demonstrated the feasibility of rat cerebrospinal DTI. With improved SNR and CNR, the curved array coil platform could improve or even create new possibilities for biomedical applications in cerebral nervous system.