Magnetic resonance (MR) imaging systems

The MR imaging systems at the Center for In Vivo Microscopy are unique, using specially designed high-field magnets and gradients interfaced to state-of-the-art clinical imaging consoles.

2T medium bore MR microscope	7T medium bore MR microscope	9.4T MR microscope
in vivo rat/mouse imaging and hyperpolarized gas studies	in vivo rat/mouse cardiovascular and neurologic imaging	small specimens, such as mouse or rat brains
Oxford 30-cm horizontal bore magnet GE EXCITE console 2 sets of 18 Gauss/cm shielded gradients–15 cm clear bore provide very rapid switching at 180 mT/m over 150 mm field of view (FOV) and 400 mT/m over 120 mm FOV Scan-synchronous ventilator system 1 MHz receiver	Magnex 21-cm horizontal bore magnet GE EXCITE console provides simultaneous excitation in 2 channels and reception in 8 channels at frequencies from 60–300 MHz Uses include structural and functional phenotyping in the mouse, and MR histology 2 sets of shielded gradients provide very rapid switching at 400 mT/m over 120 mm FOV and 770 mT/m over 90 mm FOV	Oxford 8.9 cm vertical bore magnet GE EXCITE console 2 sets of 95 Gauss/cm shielded gradients–5.4 cm clear bore Resolution down to 10 microns

Micro-CT / microX-ray This equipment can be configured for conventional x-ray or micro-CT. The micro-CT system is used for cardiopulmonary imaging in the mouse and Digital Subtraction Angiography (DSA). Phillips x-ray system Custom-made rotating platform High-resolution CCD detector Custom computerized control system Custom-made synchronous ventilator	System configured for DSA	Micro-CT system and console area
Custom-built ventilators Transport cart Used during in-vivo imaging for controlled delivery of anesthetic, breathing, and hyperpolarized gas LabVIEW-controlled breathing cycles for such things as breathing pattern, inspiration/expiration/held breath, breathing rate, tidal volume, switching between gases We can transport an anesthetized animal with a portable small animal ventilator that can take animals from one imaging modality to another Views of transport cart and ventilator

Ultrasound Visualsonics Vevo 770 Ultrasound system operates at 40 MHz with spatial resolution down to 30 microns

Biological support for specimen and live animal imaging Specimens: Perfusion-fixation and staining involves micro-surgically inserting perfusion catheters into arteries/veins and pumping to flush and perfuse-fix the vascular system. The whole body specimen is then paced in a tube for imaging. In vivo imaging: The animal is kept still with anesthesia, and we monitor animals closely with custom LabVIEW programs for real-time monitoring and control of heart rate, body temperature, blood gas, and carotid pressure. Mechanical ventilation is available for each of our imaging systems.

Polarizer for hyperpolarized gases

• The stable, inert gas isotopes ³He and ¹²⁹Xe, when hyperpolarized, emit an MRI signal nearly 1 million times stronger than what is attained in thermal equilibrium. This enhancement more than overcomes the low density of gases, allowing us to image the gases with exquisite resolution.
• Hyperpolarized ³Helium is the most advanced of the hyperpolarized gases. Current efforts are directed towards ultra-high-resolution imaging of ventilation in asthmatic mice. An imaging session uses 10–100 ml of ³He for mice and 100-1000 ml for rats.
• We also produce hyperpolarized ¹²⁹Xenon, which is now a major part of our experiments on the 2T magnet. ¹²⁹Xe can be imaged beyond the air spaces, including brain, liver, kidneys, and the vascular system.
• Our hyperpolarized gas imaging effort is supported by precision delivery of the gases, specialized MRI pulse sequences and reconstruction algorithms, precision measurement of polarization, and other quality assurance tools, such as phantoms.

Polarization system for production of ³He and ¹²⁹Xe and polarization measurement system.

Optical microscope and histological slide scanner

Conventional microscopic examination of tissues is an important component of many of our studies. Bright field microscopy is used to confirm tumor vascular density as determined non-invasively by DSA or MR, and is used to confirm the severity of pulmonary injury in our MR and CT studies of fibrosis and emphysema.

• Nikon Eclipse microscope fully equipped for bright field, phase contrast, and photo-microscopy

• Histological slide scanner is able to image a complete section. This large field of view allows direct comparison, for example, to our MRM of the mouse whole brain.

Nikon microscope with digital camera

Histological slide scanner