IMAGING TECHNOLOGIES

Director: Dr. Stanley Fricke

One of the major obstacles in translating interventions in animal models of CNS injury to future human applications is the inability to follow changes in the CNS over time after injury and in response to interventions. These resources are expensive in terms of both equipment and expertise. This NCARRN provides core access to state-of-the-art imaging, including access to expertise in designing, executing and analyzing imaging experiments and will also provide technical assistance in gathering pilot data.

Animal Imaging: Magnetic Resonance Imaging
Functional magnetic imaging (fMRI) provides a novel means for following anatomical reorganization longitudinally in vivo after injury and to define the contribution of specific remodeling to the recovery of function observed. Investigators will have the opportunity to use somatosensory fMRI on rat brain as a means for characterizing plasticity after spinal cord injury and for assessing treatment outcomes. Images are acquired on site using a 7.0 Tesla small animal magnetic resonance imaging system (Bruker Bio-Spin, Billerica, MA). Anatomic MRI sequence protocols in general terms consist of: (1) those which most favor the display of anatomic resolution across the brain and spinal cord (T1-type TURBO-RARE protocol after the administration of MnCl2), and (2) those which most favor the display of iron-oxide content hypointensity (T2-like Gradient Echo-Fast Imaging Sequence after the administration of MnCl2)

Animal Imaging: MRI visualization of iron-oxide microsphere labeled neural stem cells in vivo
Our recent work (see Figure) demonstrates that MRI can be used in vitro and in vivo to identify individual iron oxide labeled neural stem cells. Phase and fluorescence microscopy performed after high resolution MRI confirms the iron-microsphere label within an individual cell. MRI can be used in vivo after spinal cord injury and transplantation to track aggregates of such cells near and at a distance from sites of injury in both hemisection and contusion injury models. Specific capabilities on site include: high field MRI and spectroscopy for small animal studies using a 7.0 Tesla Bruker Bio-Spin system (Billerica, MA). This system is housed in the Department of Neuroscience at Georgetown University and is fully available to investigators under the NCARRN.

The Small Animal Imaging NMR Laboratory (SAIL) has extensive laboratory space in the basement of the Research Building at Georgetown University with a main magnet room, an operators? area, a well-equipped electronics workshop, an animal surgery, a large office area and storage areas. The main magnet room houses a 7.0 Tesla horizontal bore magnet (300 MHz 1H) interfaced with a Bruker spectrometer/imager running Paravision 2.1. The animal surgery unit is equipped with rodent ventilators, inhalation anesthesia apparatus (halothane and isoflurane), infusion pumps, thermostatically controlled heating pads, recovery humidicribs, stereotaxic devices, a blood-gas machine, MacLab physiological monitoring of blood pressure and temperature, as well as various surgical instruments. A separate ventilator and anesthesia apparatus, including non-magnetic heating blankets, are dedicated for use in the magnet room. Physiological monitoring is performed using Luxtron fluroptic probes and respiration monitors. Dr. Stanley Fricke is the director of SAIL. Dr. Fricke is a nuclear physicist specializing in imaging. The SAIL performs MRI on animals that weigh less than 500 gm. Participating faculty will use the animal MRI for studies in CNS trauma, degeneration and disease that involve brain chemistry and morphology. The research projects as part of the NCARRN will conduct studies with the advice and participation of Dr. Fricke.

A research-dedicated 3.0 Tesla Siemens (Erlangen, Germany) Trio whole-body MRI system with EPI (echo planar imaging) capability is located in the Center for Functional and Molecular Imaging (CFMI), Georgetown University Medical Center, and is available to NCARRN participants. The gradient system has 40mT/m maximum strength with a slew-rate of 200T/m/sec. The RF-system includes 8 parallel receiver channels each with a 1MHz bandwidth. The Trio is also equipped with the iPAT technology (similar to SENSE from Philips) that can be used to reduce susceptibility artifacts around the base of the brain without increasing SAR (specific absorption ratio). The facilities also includes 2 robot manipulators (one planar - for elbow and shoulder studies and one wrist manipulator) that will be used for studies of motor recovery following stroke (both to quantitatively measure recovery and also for robot-assisted therapy). The idea is to carefully characterize the nature of the motor recovery (assessed with the robots) in relation to neural change (measured with fMRI).

See Center for Functional and Molecular Imaging website a GU