Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-06-11
2001-01-09
Casler, Brian L. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C324S309000, C382S128000
Reexamination Certificate
active
06171241
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention provides a method for sampling motion of portions of a patient such as portions of the heart which have different movement characteristics and, more specifically, the method is directed toward using magnetic resonance imaging with variable separation tagging.
2. Description of the Prior Art
The advantageous use of magnetic resonance imaging wherein a patient or object is placed within a magnetic field with alternating generation of RF pulses and gradient pulses serving to excite nuclei within the area of interest and cause responsive emission of magnetic energy which is picked up by a receiver and may be processed by computer means followed by recording, display or production of hard copy of the results has long been known. See, generally, Atalar-McVeigh U.S. Pat. No. 5,512,825 and Conturo-Robinson U.S. Pat. No. 5,281,914, both of which are assigned to the owner of the present invention, the disclosures of which is expressly incorporated herein by reference.
It has been known to employ two sets of tagging planes oriented orthogonal to the image plane in imaging two dimensional heart wall motion with magnetic resonance imaging through spatial modulation of magnetization (SPAMM) approaches. See U.S. Pat. Nos. 5,111,820 and 5,217,016.
U.S. Pat. No. 5,275,163 discloses the use of magnetic resonance imaging and monitoring motion of a part of an object. Pulse and gradient sequences are applied in pairs with spatially differing tagging patterns with subtraction being employed to form a tagged image.
U.S. Pat. No. 5,352,979 discloses observing a phase angle response of volume elements in a slice or volume and imaging occurring before and during perturbations caused by external stimuli.
U.S. Pat. No. 5,379,766 discloses quantitative motion evaluation of a portion of an object by employing a high contrast tagging grid for detection of tagging patterns.
U.S. Pat. Nos. 5,315,248 and 5,545,993 disclose tracking of motion.
In spite of the foregoing contributions to the art, there remains a need for a method of providing high resolution images of myocardial motion wherein portions of the myocardium being imaged may have different movement characteristics.
SUMMARY OF THE INVENTION
The above-described need has been met by the present invention by providing a means for employing specific RF signals which establish a plurality of tag surfaces which pass through the myocardium and have variable spacing with respect to certain other tag surfaces.
In one embodiment, the imaging of regions of the myocardium wherein the tags will increase their separation over systole, will have tag planes which are placed relatively close together at end-diastole. In regions where the tags decrease their separation over systole, the tags are placed farther apart so they remain detectable at end-systole. For example, the first approach may be taken in connection with radial thickening and the second approach in connection with circumferential shortening.
Both of these types of measurements may be obtained simultaneously with the method of the present invention.
It is an object of the present invention to provide a magnetic resonance imaging method which through the use of variable separation tagging permits obtaining higher resolution sampling of the motion of a material or object.
It is another object of the present invention to provide such high resolution sampling of motion in connection with imaging myocardial motion.
It is a further object of the present invention to provide such a method wherein the customized spacing between tags will be based upon whether the tags increase or decrease their separation over systole during movements.
It is a further object of the present invention to provide such a method which can provide high resolution estimates of radial thickening and circumferential shortening of the myocardium simultaneously.
It is yet another object of the invention to provide such images through variable separation tagging which maintains detectability at end systole.
These and other objects of the invention will be more fully understood from the following description of the invention on reference to the illustrations appended hereto.
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Bolster, Jr. Bradley D.
McVeigh Elliot R.
Casler Brian L.
Eckert Seamans Cherin & Mellott , LLC
Silverman Arnold B.
The Johns Hopkins University School of Medicine
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