"A whole body (80 cm) 8 Tesla magnetic resonance imaging system has been assembled and utilized to acquire MRI images from the human brain at both 4.7 and 8.0 Tesla. In this work, the performance of the magnet system will be reviewed. High resolution images which display excellent S/N and image quality were obtained at 4.7 Tesla. For instance, in the 1k x 1k matrix 4.7 T images, the medullary veins are clearly visible. In addition, the 4.7 Tesla images do not display the center brightness that have characterized images obtained at 4 Tesla. Preliminary 8 Tesla images reveal a complete absence of penetration depth problem. In addition, the images are devoid of the fat signal. Little or no dielectric effects could be observed at 8 Tesla. The images are surprizingly homogeneous and free of artifacts. In addition, while susceptibility did not inhibit the acquisition of high quality images, signs of susceptibility are clearly present on gradient recalled echo images with long echo times (14 and 18 msec). Importantly, the signal to noise of the 8 Tesla images, while initially disappointing, is hereby reported to be excellent. Axial, sagital and coronal gradient recalled echo images obtained at 8 Tesla reveal excellent anatomical detail, with good depiction of the microvasculature of the brain along with satisfactory white and gray matter contrast. It is also noteworthy that very little RF power is required to excite the spins at 8 Tesla. It appears that power requirements in magnetic resonance do not continue to increase with the square of the frequency in a Jean-Rayleigh manner as predicted, but rather, power actually decreases relative to what is required at 4 Tesla. In this sense, the power density spectrum is more Planck-like."
P.-M. L. Robitaille, Proc. Phys. Phenon. High Magnetic Fields-III.