The Medical College of Wisconsin, Inc.

Metriflow, Inc.

Richard E Halbach

Paul R Moran

Thomas A Knox

Frederick J Antonich

Joseph H Battocletti

Anthony Sances, Jr

An NMR blood flowmeter applies a continuous transverse excitation signal and a constant, homogeneous polarizing magnetic field to blood flowing through an active region. The polarizing magnetic field is contoured at opposite boundaries of this active region, and by switching these contours and collecting the resulting NMR signals, data is obtained from which the various components of blood flow may be calculated.

Blood flow imaging using a CW NMR technique

Blood flow in human limbs is measured non-invasively by a nuclear magnetic resonance blood flowmeter which includes a pair of polarizing magnets whose fields are stabilized by electromagnets in each pole piece that are energized in accordance with the magnetic flux of the magnets as sensed by a Hall effect sensor. Blood molecules are either self-tagged by the polarizing field or are separately tagged by a tag coil whose field is orthogonal to the polarizing field. Once tagged, the variation in the magnetic moment of the molecule due to the tagging is detected by the variation in voltage in the receiver coil which is located orthogonally to the transmitter coil so as to reduce crosscoupling therebetween. Two sets of scanner coils, one located parallel to and the other orthogonal to the polarizing field directions, respectively, are energized to create a pair of intersecting null planes which act to cancel nuclear magnetic resonance response detected by the receiver everywhere but along the line where the two null planes intersect. By varying the current in the scanner coils, the resulting line of intersection of the null planes can be moved in two dimensions so as to scan the limb thereby allowing blood flow measurement at various locations within the limb.

Nuclear magnetic resonance blood flowmeter

Growing community of inventors

Brookfield, WI, United States of America

Richard E Halbach