Open-Access, Low-Magnetic-Field MRI System for Lung Research

An open-access magnetic resonance imaging (MRI) system is being developed for use in research on orientational/ gravitational effects on lung physiology and function. The open-access geometry enables study of human subjects in diverse orientations. This system operates at a magnetic flux density, considerably smaller than the flux densities of typical other MRI systems, that can be generated by resistive electromagnet coils (instead of the more-expensive superconducting coils of the other systems).

The human subject inhales air containing 3He or 129Xe atoms, the nuclear spins of which have been polarized by use of a laser beam to obtain a magnetic resonance that enables high-resolution gas space imaging at the low applied magnetic field. The system includes a bi-planar, constant-current, four-coil electromagnet assembly and associated electronic circuitry to apply a static magnetic field of 6.5 mT throughout the lung volume; planar coils and associated circuitry to apply a pulsed magnetic-field-gradient for each spatial dimension; a single, detachable radio-frequency coil and associated circuitry for inducing and detecting MRI signals; a table for supporting a horizontal subject; and electromagnetic shielding surrounding the electromagnet coils.

This work was done by Ross W. Mair, Matthew S. Rosen, Leo L. Tsai, and Ronald L. Walsworth of the Harvard-Smithsonian Center for Astrophysics; Mirko I. Hrovat of Mirtech, Inc.; Samuel Patz of Brigham and Women’s Hospital; and Iullian C. Ruset and F. William Hersman of the University of New Hampshire for Johnson Space Center.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Harvard-Smithsonian Center for Astrophysics
Cambridge, MA 02138

Refer to MSC-24182-1/3-1, volume and number of this NASA Tech Briefs issue, and the page number.

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