Siemens Avanto 1.5T Mobile MRI System //
The Avanto is the most advanced system of this strength in the Siemens product line. It features an ultra-short, 150 cm-long whole-body superconductive 1.5T magnet, with 5th generation active-shielding technology with counter coils, External Interference Shielding and excellent homogeneity (based on 24 plan plot, 50 cm DSV type, 0.8 ppm). The system comes equipped with a 12-element Matrix head coil capable of ultra-fast parallel acquisition in 4- (CP mode), 8- (dual mode) or 12- (triple mode) channel settings. This MR system is integrated into a trailer equipped with functional imaging capabilities.
The base Avanto system was upgraded to include the SQ-engine Gradient System with AudioComfort. The SQ-engine gradients have maximum amplitude of 45 mT/minute for the longitudinal direction and 40 mT/minute for horizontal and vertical directions; the gradient slew rate is 200 T/m/second with a minimal rise time of 200 microsecond (from 0 - 40 mT/m amplitude). AudioComfort is an acoustic noise buffer that leads to a 30 dB attenuation of gradient noise (compared to conventional systems that lead to a 97% reduction in sound pressure) - a great benefit to functional imaging studies. The system is capable of BOLD EPI, diffusion-tensor imaging (DTI), perfusion and diffusion imaging, and spectroscopy.
The mobile scanner is equipped with a 128-channel BioSemi ActiveTwo electrophysiology system for recording high-density EEG during the performance of cognitive tasks (http://www.biosemi.com). Electrode caps for four different head sizes are maintained with the system. Software from Neurobehavioral Systems (http://www.neurobs.com) is available for precise presentation of visual and auditory stimuli and online monitoring of behavioral performance. The event-related potential software system ERPSS (courtesy of Steve Hillyard, UCSD, San Diego, CA) and EEGLab (courtesy of the Swartz Center for Computational Neuroscience, UCSD, San Diego, CA) are available for analysis of the EEG data.
In addition to the stimulus delivery and data acquisition equipment described below, the mobile data-acquisition system includes a group of centrally managed remotely operated PGP-encrypted tablet PCs for psychological assessment, digital video, and document imaging in forensic populations. Also installed, are the Biopac MP150 Data Acquisition System (BIOPAC Systems Inc., http://www.biopac.com) and the GSR EDA Galvanic Skin Response Amplifier (GSR100C; BIOPAC Systems Inc, http://www.biopac.com) in order to provide reliable and consistent real-time monitoring of skin conductance responses.
