NMR MICRO-IMAGING FACILITY

The NMR Micro-Imaging Facility was established in 1997 to provide investigators with high-field magnetic resonance micro-imaging (micro-MRI) capabilities in a basic science setting. Micro-MRI is a technology similar to clinical MRI, but optimized for the study of small structures (100 mm in size or less). It has many of the same advantages as clinical MRI, including the ability to make images of living specimens in a non-destructive, non-invasive manner, a variety of intrinsic contrast parameters which are easily manipulated (T₁, T₂, T1_r, and diffusion), and the ability to increase image contrast by the delivery of external contrast agents. The smaller radio-frequency coils and higher magnetic field strengths used in micro-MRI (5-6 times stronger than those used in clinical MRI) greatly increase the spatial resolution in micro-MRI relative to clinical MRI, and the imaging of organs and tumors in small animals (principally mice) is feasible. A large number of possible experiments are available within the realm of micro-MRI depending on the choice of experimental parameters and the interests of the investigators. These include the monitoring of tumor size, location, and progression, tumor vascularization, oxygen tension, and the development of targeted contrast agents.

The equipment in this facility includes a 7 Tesla wide-bore magnet (89 mm bore size), a commercial shielded gradient set (Bruker Micro 2.5) capable of producing gradient fields up to 50 gauss/cm with our gradient power amplifiers, a probe for mounting the sample and the radio-frequency coils necessary for exciting and detecting nuclear magnetic resonance signals. Dr. Hensley has constructed radio-frequency coils of the Alderman-Grant design and has tested them for in vivo imaging of mice and ex vivo imaging of mouse embryos and excised tumors. A Bruker AM-300 console controls the imaging sequence and the amplification and digitization of the magnetic resonance signals. Both the software for generating the pulse sequences and the methodology for reconstructing the images from the raw data and subsequent image analysis are in place.

Illustrations or unpublished data in these reports should not be used without permission of the author.

Fox Chase Cancer Center

Scientific Report 1998