Diminishing variance process for real-time reduction of motion artifacts in MRI
First Claim
1. A method for reducing motion artifacts in magnetic resonance images comprising the steps ofa) acquiring magnetic resonance image signals for multiple image frames,b) acquiring relative position data for each image frame,c) developing a histogram of positional shifts in frames based on said relative position data, andd) reacquiring magnetic resonance signals for selected image frames to reduce positional variance in said histogram.
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Abstract
A method whereby motion can be detected in real time during the acquisition of MRI data. This enables the implementation of several algorithms to reduce or eliminate this motion from an image as it is being acquired. The method is an extension of the acceptance/rejection method algorithm called the diminishing variance algorithm (DVA). With this method, a complete set of preliminary data is acquired along with information about the relative motion position of each frame of data. After all the preliminary data is acquired, the position information is used to determine which lines are most corrupted by motion. Frames of data are then reacquired, starting with the most corrupted frame. The position information is continually updated in an iterative process, therefore each subsequent reacquisition is always done on the worst frame of data. The algorithm has been implemented on several different types of sequences, and preliminary in vivo studies indicate that motion artifacts are dramatically reduced.
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Citations
14 Claims
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1. A method for reducing motion artifacts in magnetic resonance images comprising the steps of
a) acquiring magnetic resonance image signals for multiple image frames, b) acquiring relative position data for each image frame, c) developing a histogram of positional shifts in frames based on said relative position data, and d) reacquiring magnetic resonance signals for selected image frames to reduce positional variance in said histogram.
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14. Apparatus for providing magnetic resonance imaging signals with reduced motion artifacts comprising
a) means for acquiring magnetic resonance image signals for multiple image frames, b) means for acquiring relative position data for each image frame, c) means for developing a histogram of positional shifts in frames based on said relative position data, d) means for reacquiring magnetic resonance signals for selected image frames to reduce positional variance in said histogram, and e) means for using said magnetic resonance signals including reacquired magnetic resonance signals to produce an image.
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