How do I schedule a project with the Duke Center for In Vivo Microscopy?

Go to the collaboration link for more information. You need to a CLICK HERE to download a project proposal form. Once you return a filled-out form through e-mail to Sally Zimney, our staff will review your request and we will contact you.

What is "MR microscopy"?

Founded on the same principles of magnetic resonance imaging (MRI), magnetic resonance microscopy (MRM) is different to some extent. MR images of small animals can be obtained on clinical MRI systems, but with limited resolution. Though both methods use picture elements (pixels), each based on signal from a volume of tissue (voxel), the difference is in the scale of voxels.

Three-dimensional datasets of perfusion fixed mice have been acquired at 50-micron isotropic resolution, nearly 80,000X higher resolution than a routine clinical body scan. Voxels less than 0.03 mm³ in volume are generally labeled “microscopic” to indicate spatial resolution finer than that discernible with the naked eye—thus the term magnetic resonance microscopy. For comparison, a human hair is roughly 50 microns in diameter and 100 microns equals 0.0039369999999999995 of an inch or 0.1 millimeter.

Voxels need to be 4000-times smaller in a microscopic image, so the signal will be 4000-times weaker. Clinical systems are generally not sufficiently sensitive. Dedicated systems for MRM have been built and are now commercially available, with gradients at least 5–100-times higher than clinical systems. Sensitivity is enhanced by working at higher magnetic fields through specially constructed probes and using specialized pulse sequences.

(References: Journal of Magnetic Resonance Imaging 16: 423-429, 2002, http://www.mrpath.com/, and ACS Brau, dissertation, Duke University, 2003.)

The "in vivo" part of the Center's name is Latin for within the living. Our live animal imaging studies involve elaborate custom-built devices to synchronize breathing and heart rate to obtain the best images possible.

Why is MR microscopy an important tool for medical research?

MRM is an ideal tool for research because MRM—

• Is non-destructive (tissues do not require physical sectioning and do not become dehydrated)
• Produces three-dimensional (3D) data (whole pathologies can be seen from all angles)
• Clearly delineates soft tissues in biological systems with proton stains and other unique contrast mechanisms

With the high resolution of MRM, scientists can see detail in very small specimens to study models of disease, toxicology, and effects of drug therapies using a limited number of living animals. The non-destructive nature and high resolution of 3D MRM enables studies on specimens as fragile as a developing mouse embryo without the distortion or destruction of traditional sectioning. Pathologists can use MR microscopy to examine tissue samples without conventional sectioning, and researchers can follow the same animals for longitudinal studies of disease models, toxicology, cancer, and effects of drug therapies.

How is in vivo small animal imaging different from clinical imaging?

The differences in size and physiology of humans vs. small animals pose dramatic obstacles for imaging, as listed in this table. Since small animals cannot be asked to "lie still" or "hold your breath," CIVM physiologists have overcome these obstacles with custom innovations that stabilize animals and limit the effects of breathing and cardiac motion. Engineers have developed new encoding strategies to extend spatial resolution.			Human	Rat	Mouse
		weight (grams)	70,000	250	25
		breaths /minute	12	85	120
		heartbeats / minute	60	300	600