CTSC:MGHresources:Integrated MR-PET imaging system

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The bay 8 laboratory contains the first human MR-PET system installed in the US. It is an insert PET camera (Siemens Healthcare) employing APD photodiode detectors and is capable of simultaneous recording of the MR and PET image in the brain.

This is a 3T Siemens TIM Trio 60 cm (RF coil ID) 32 channel MRI. It is installed in the Charlestown facility in Building 75, across the street from the other bays. Building 75 also contains an RF laboratory, wet-lab and office space for the Martinos Center. The bay 8 3T is set up for EPI, second order shimming, CINE, MR angiography, diffusion, perfusion, and spectroscopy capabilities for both neuro and body applications. This system uses the same gradients as the 1.5 T Avanto (45 mT/m strength, 200T/m/s slew rate). The system is equipped with the standard “TIM” 32 RF channel receivers accommodating up to 32 element array coils. Bay 8 also contains an assortment of audio, visual, and sensory stimuli equipment for fMRI studies including rear projection, audio stimulation, a subject response device and eye-tracking setup.

The PET system consists of the following major components:

• PET gantry with 32 detector cassettes, gantry handling device with cable handling function, cooling system, acquisition electronics module, processing reconstruction station and power supply cabinet. The gantry physical ID and OD are 36 cm and 60 cm, respectively. The axial FOV is 19.25 cm and the transaxial FOV is ~30 cm. Each of the 32 PET detector modules consists of six 12×12 LSO crystal arrays read out by a 3×3 array of APDs (Hamamatsu 8664-55, Japan). The individual crystal size is 2.5×2.5×20 mm3. The APD signals are processed and shaped by an on-board charge-sensitive preamplifiers and pole-zero circuit. The signals from the PET modules are taken from the gantry via 10-meter long cables to the acquisition electronics module. The gantry handling device performs multiple functions: supports the PET detector gantry, supports signal cables and cooling tubes connected to the gantry, incorporates a sliding rail platform to allow transaxial positioning of the gantry, incorporates an articulated cable race that allows axial positioning of the gantry. An internal control system regulates the gantry internal temperature. The air/water based cooling system includes a compressor and a chiller.

• The acquisition electronics module includes an embedded command and control computer to control the various hardware components such as the detector array, data collection circuits, etc. The embedded computer also acts as a server on a dedicated Ethernet network.

• Also connected to this network is the processing and reconstruction station (PC, Intel Xeon X5355 @2.66 GHz quad processor; OS: Windows Server 2003; Memory: 16 GB) that serves as the primary user interface to the BrainPET subsystem. Running on this workstation is the acquisition workplace software application that supports acquisition, reconstruction, data management, and workflow definition.