Trio mri system

A 3-T Siemens Trio MRI system was used to collect echoplanar imaging data (repetition time = 2.0 s, echo time = 30 ms, flip angle = 81°; 36 axial slices: matrix = 64 × 64, 3.7-mm³ resolution, collected in two separate scans including 184 and 178 volumes), a high-resolution T1-weighted MPRAGE anatomical volume (192 sagittal slices, matrix = 224 × 256, field of view = 224 × 256 mm², slice thickness = 1 mm, no gap, TE=2.56ms, TI=1100ms, TR=2100ms) and a fieldmap for geometric distortion correction. The only difference in acquisition parameters across the two data collection sites was that the MPRAGE had TE=2.38 ms at the Medical University of South Carolina site. Otherwise, scanning parameters were identical as was the version of the hardware (TrioTim) and software (Syngo MRB17). Stimuli were presented using a high-resolution rear-projection system (Avotec, Stuart, FL), and responses were recorded using a fiber-optic response pad (MRA Inc., Washington, PA). A computer running E-Prime (Version 1.1 SP3, Psychology Software Tools, Pittsburgh, PA) controlled stimulus presentation, which was synchronized with the collection of brain volumes via trigger pulses from the magnet.

During a 1.5-hour MRI session, MRI data were acquired using a 3T Siemens Trio MRI system equipped with a standard quadrature head coil, using T2*-sensitive gradient-recalled single shot echo planar pulse sequence. Anatomical images were collected with spin echo imaging in the axial plane parallel to the AC-PC line with TR = 300 msec, TE = 2.5 msec, bandwidth = 300 Hz/pixel, flip angle = 60 degrees, field of view = 220 × 220 mm, matrix = 256 × 256, 32 slices with slice thickness = 4mm with no gap. A slice thickness of 4 mm was utilized to consider the optimum level of signal-to-noise ratio; this is common in other fMRI studies, but could cause suboptimal tissue specificity. Functional MRI images were obtained using a single-shot gradient echo planar imaging (EPI) sequence. Thirty-two axial slices parallel to the AC-PC line covering the whole brain were acquired with TR = 2,000 msec, TE = 25 msec, bandwidth = 2004 Hz/pixel, flip angle = 85 degrees, field of view = 220×220 mm, matrix = 64×64, 32 slices with slice thickness = 4mm and no gap. Finally, a high-resolution 3D Magnetization Prepared Rapid Gradient Echo (MPRAGE) sequence was used to obtain sagittal images for multi-subject registration (TR = 2530 ms; echo time (TE) = 3.34 ms; bandwidth = 180 Hz/pixel; flip angle (FA) = 7°; slice thickness = 1mm; field of view = 256×256 mm; matrix = 256 × 256).

Task-based scans were collected from 26 Methamphetamine and 27 Control subjects. One Methamphetamine subject was excluded due to excessive head motion (> 2 mm translational displacement, > 1.5 degrees rotation), leaving a final sample of 25. Eighteen Control and 15 Methamphetamine subjects underwent resting-state fMRI in the same session while viewing a black screen for 5 min. Imaging was performed on a 3-T Siemens Trio MRI system, with 302 functional task-based and 152 resting-state T2*-weighted, echoplanar images (EPI) acquired (slice thickness = 4 mm; 34 slices; TR = 2 s; TE = 30 ms; flip angle = 90°; matrix = 64 x 64; fov = 200 mm). High-resolution, T2-weighted, matched-bandwidth (MBW) and magnetization-prepared rapid-acquisition gradient echo (MPRAGE) scans were also acquired. The orientation for these scans was oblique axial to maximize brain coverage and to optimize signal from ventromedial PFC.