Horizon lx mr scanner

MRI scans followed standard procedures at the YNPRC and NCCC as described elsewhere (Hopkins et al., 2019 (link)) and were designed to minimize stress. In brief, the chimpanzees were first sedated (using ketamine (10 mg/kg) or telazol (3–5 mg/kg)) before being anesthetized with propofol (40–60 mg/(kg/h)). Then, the animals were transported to the MR imaging facility. After completion of the MRI acquisition, the animals were returned to their home facility and temporarily monitored in single housing, to ensure a safe recovery from the anesthesia, before returning to their social group.
T1-weighted images of 144 chimpanzees (6 from YNPRC, 138 from NCCC) were acquired with two 1.5T G.E. echo-speed Horizon LX MR scanner (GE Medical Systems), one at YNPRC and one at NCCC. Data was collected in transverse plane using a gradient echo protocol (repetition time, TR = 19.0 ms; echo time, TE = 8.5 ms; number of signals averaged = 8; scan matrix: of 256 × 256) with a reconstructed image resolution of 0.7 × 0.7 × 1.2 mm. The remaining 77 chimpanzees (all from YNPRC) were scanned on a 3.0-T Siemens Trio platform (Siemens Medical Solutions USA, Inc.). T1-weighted images were acquired using a 3D gradient echo sequence (pulse repetition, TR = 2300 ms; echo time, TE = 4.4 ms; number of signals averaged = 3; scan matrix of 320 × 320) yielding an 0.6 × 0.6 × 0.6 mm image resolution).