Browse Prior Art Database

NMR Point Method for Imaging Motion

IP.com Disclosure Number: IPCOM000036056D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 19K

Publishing Venue

IBM

Related People

Feig, E: AUTHOR

Abstract

Earlier nuclear magnetic resonance (NMR) techniques have provided means for producing images of static objects. This disclosure describes an algorithm for imaging motion using standard NMR apparatus and a microprocessor to perform computations. Medical applications include, for example, observation of the motion of specific bits of tissue within the heart.

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NMR Point Method for Imaging Motion

Earlier nuclear magnetic resonance (NMR) techniques have provided means for producing images of static objects. This disclosure describes an algorithm for imaging motion using standard NMR apparatus and a microprocessor to perform computations. Medical applications include, for example, observation of the motion of specific bits of tissue within the heart.

It is assumed that the system to be imaged can be approximated by one composed of small subsystems (points) each of which is moving rigidly along a well-defined path. Using the method of fast-selective excitation, the desired point is selectively excited. The volume surrounding this point is then subjected to a spatially varying magnetic field H+G, where H is a large uniform field and G is a linear magnetic gradient along some vector v(G). Simultaneously, the free induction decay (FID) is collected. (For computational purposes FID is denoted as f(t).) The computational part of the new algorithm processes this data and obtains the projection of the path along the vector v(G). By obtaining three such FIDs, corresponding to linear gradients along three mutually perpendicular vectors, the path of the point is obtained.

In the algorithm, it is assumed that H = hkT and G = (ax + by cz) kT; and that the excited point traverses the path p(t) = (px(t), py(t), pz(t)). Then, assuming that the density of the particle remains constant with time, t

iqht iq
(1) f(t) = rK(t) e e o p(u) . Gdu...