Contrast optimization of Macaca mulatta basal ganglia in magnetic resonance images at 4.7 Tesla

To determine whether high field MRI could distinguish among the different r egions of the basal ganglia, the brains of two Macaca mulatta monkeys were explored in vivo using a 4.7 T MR imager. Gradient-echo (GE) and spin-echo images were acquired with proton-density, T-1 and T-2(*) weightings. Five G E images with increased susceptibility effects were generated using a GESFI D sequence, from which T-2* maps were also reconstructed. The first echo of the GESFID sequence (TE = 12.6 ms) produced the best contrast-to-noise rat io (CIN) between the pallidium and the putamen, the pallidium and the thala mus, the substantia nigra and the surrounding white matter, and the substan tia nigra and the subthalamic nucleus. An increased T-2*-weighting (TE = 37 .2 ms) was necessary to maximize C/N between the putamen and the surroundin g white matter, and between the subthalamic nucleus and the surrounding whi te matter. A dual GE sequence with a short TE ( approximate to 10 ms) and a longer one (approximate to 30 ms) thus effectively localizes basal ganglia subregions at 4.7 T. (C) 2001 Elsevier Science B.V. All rights reserved.