Method for determining the reliability of fMRI parameters
First Claim
1. A method for producing a functional magnetic resonance image (fMRI) of a subject'"'"'s brain using a magnetic resonance imaging (MRI) system, the steps comprising:
- a) operating the MRI system to perform a series of pulse sequences that acquire a series of NMR k-space data arrays over a period of time, during which the subject'"'"'s brain is caused to function in a preselected temporal pattern;
b) producing a time course MRI image data set of time domain voxel vectors from the series of k-space arrays, in which each time domain voxel vector is a set of data which indicates the NMR signal during said period of time from a region of the brain;
c) calculating an fMRI parameter from data in each time domain voxel vector;
d) calculating a confidence level indicator for each voxel vector using a technique in which the fMRI parameter is recalculated a plurality of times with different truncated subsets of data in the voxel vector;
e) producing the fMRI image using the calculated fMRI parameters and their corresponding confidence level indicators.
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Abstract
An EPI pulse sequence is performed by an MRI system which acquires images of the brain over a time interval during which the subject performs a function or is stimulated in a pattern. An fMRI parameter is calculated for each voxel which indicates those regions of the brain that are active during the study. The same acquired NMR data is employed in a jackknife method for recalculating the fMRI parameter many times and from the distribution of the recalculated values a confidence level indicator is produced. Low confidence level indicators are used to exclude regions which are otherwise indicated as active.
47 Citations
5 Claims
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1. A method for producing a functional magnetic resonance image (fMRI) of a subject'"'"'s brain using a magnetic resonance imaging (MRI) system, the steps comprising:
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a) operating the MRI system to perform a series of pulse sequences that acquire a series of NMR k-space data arrays over a period of time, during which the subject'"'"'s brain is caused to function in a preselected temporal pattern;
b) producing a time course MRI image data set of time domain voxel vectors from the series of k-space arrays, in which each time domain voxel vector is a set of data which indicates the NMR signal during said period of time from a region of the brain;
c) calculating an fMRI parameter from data in each time domain voxel vector;
d) calculating a confidence level indicator for each voxel vector using a technique in which the fMRI parameter is recalculated a plurality of times with different truncated subsets of data in the voxel vector;
e) producing the fMRI image using the calculated fMRI parameters and their corresponding confidence level indicators. - View Dependent Claims (2, 3, 4, 5)
i) comparing each truncated subset of data in the voxel vector with a corresponding truncated reference voxel vector;
to produce a recalculated correlation number; and
ii) calculating the confidence level indicator from statistical information derived from the recalculated correlation numbers.
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4. The method as recited in claim 3 in which the confidence level indicator is a confidence interval.
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5. The method as recited in claim 1 in which step e) is performed by
i) determining which regions of the brain are active by comparing the fMRI parameter for each region with a threshold value; -
ii) determining which calculated fMRI parameters are reliable by comparing their corresponding confidence level indicator with a confidence threshold; and
iii) indicating a region of the brain as active in the fMRI image if it is determined to be active and its calculated fMRI parameter is determined to be reliable.
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Specification