Relaxation-corrected ecg-triggering and navigator-gating technique
AssigneeUniversity of Massachusetts
InventorsShaokuan Zheng, Mitchell Albert
Life of this patent
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Abstract
A system and method for recording magnetic resonance images with reduced relaxation-related artifacts. The system and method improve the conventional methods for acquiring magnetic resonance images of in vivo tissue by augmenting the procedures for eliminating artifacts caused by motion with procedures for eliminating artifacts caused by spin of the magnetic resonance-active nuclei in the specimen of interest. One procedure to eliminate such spin inhomogeneities is to require a delay defined by the time N*T1, where N is a numerical value greater than or equal to 5 and T1 is the characteristic time constant for decay of spins back to the equilibrium longitudinal state. Another procedure uses a value of N less than 5.
Claims20
In a magnetic resonance imaging system having a computer-based control apparatus that controls the timing of the taking of magnetic resonance images based on a muscular state of a body part of a living subject, the improvement comprising:
- a set of instructions recorded on a machine-readable medium, the set of instructions when operating configured to control the operation of the system in response to two conditions to provide two mutually exclusive outcomes, so as to:
- permit the taking of a magnetic resonance image (a “shot”) when both a muscular condition is within an acceptable range and when, for all shots after a first shot, an elapsed time since the last shot was taken is at least N*T1, where T1 is a time constant representative of a decay rate for a specimen of interest in a magnetic resonance process and N represents a numerical value greater than one, and N*T1 is of sufficient duration to allow a plurality of nuclear spins in said specimen of interest to decay back to a statistically defined spin state after the last shot;
- and
- leave said spin state of said plurality of nuclear spins undisturbed when at least one of said muscular conditions is not within said acceptable range and, for all shots after a first shot, said condition that said time elapsed since said last shot is at least N*T1 is not satisfied;
- and
- said set of instructions configured to provide as output at least one of an image displayed to a user, a stored image, and transmission of the image to a remote location for storing or viewing.
In a magnetic resonance imaging method operating on a computer-based control apparatus that controls the timing of the taking of magnetic resonance images based on a muscular state of a body part of a living subject, the improvement comprising the steps of:
- determining whether or not a muscular condition of a body part of a living subject is within an acceptable range;
- determining whether or not, for all shots after a first shot, a time elapsed since the last shot was taken is at least N*T1, where T1 is a time constant representative of a decay rate for a specimen of interest in a magnetic resonance process and N represents a numerical value greater than one, and N*T1 is of sufficient duration to allow a plurality of nuclear spins in said specimen of interest to decay back to a statistically defined spin state after the last shot;
- if both determining steps result in a positive outcome, permitting the taking of a magnetic resonance image (a “ normal shot”);
- if either determining step results in a negative outcome, inhibiting the taking of a “normal shot”, leaving said spin state of said nuclear spins undisturbed, and repeating the two determining steps until both outcomes are positive;
- and
- after said step of permitting the taking of a magnetic resonance image is performed, providing as output at least one of an image displayed to a user, a stored image, and transmission of the image to a remote location for storing or viewing.
Dependencies are inferred from the claim text.