Systems and methods for rescaling image intensities with diffusion MRI to synthesize complex diffusive geometries
View Patent ↗A method for scaling MR signal intensity after noise has been removed is disclosed. Because the signal in a DTI series varies with the apparent diffusivity in the direction of an applied gradient, one can multiply image data collected under actual clinical conditions with a spatially-dependent scaling function to synthesize different spatial diffusion distributions, after removal of noise. Recombination of the data with the removed noise preserves the bias in the system.
1. A method for synthesizing data obtained from a DTI protocol in an MRI system, comprising:
scanning with the MRI system a plurality of DTI directions of a test object having a plurality of anisotropic structures at least twice, wherein the test object comprises:
a plurality of water-filled capillaries arranged into an array; and
a housing, wherein the housing is substantially filled with a liquid, the array is housed within the housing, and the array has a generally polygonal-like shape and includes a plurality of arrays stacked in a plurality of rows in the housing and thereby forming a macro-array;
producing at least two sets of resultant images and associated data for each DTI direction;
determining an amount of noise in each of the resultant images;
removing the noise from the resultant images to yield a noiseless image;
scaling the data obtained from the scanning;
adding the removed noise to the data; and
calculating a new tensor.
2. The method of claim 1 , wherein the step of removing the noise further includes subtracting the two sets of images and observing values that are greater than zero.
3. The method of claim 1 , wherein the step of removing noise from the images includes computing a histogram of values in a pixel for the duplicates copied and determining the distribution of noise around a mean.
4. The method claim 1 , wherein the step of scanning a plurality of DTI directions includes scanning a first DTI direction of the test object, orienting a second DTI direction of the test object at 60 degrees from the first direction, and scanning the second DTI direction of the test object.
5. The method claim 1 , wherein the step of scanning a plurality of DTI directions includes scanning a first DTI direction of the test object, orienting a second DTI direction of the test object at 90 degrees from the first direction, and scanning the second DTI direction of the test object.
6. A non-transitory computer-readable medium storing instructions that, when executed on a programmed processor, carry out a method for synthesizing data obtained from a DTI protocol in an MRI system, comprising:
instructions for scanning a plurality of DTI directions of a test object having a plurality of anisotropic structures at least twice, wherein the test object comprises:
a plurality of water-filled capillaries arranged into an array; and
a housing, wherein the housing is substantially filled with a liquid, the array is housed within the housing, and the array has a generally polygonal-like shape and includes a plurality of arrays stacked in a plurality of rows in the housing and thereby forming a macro-array;
instructions for producing at least two sets of resultant images and associated data for each DTI direction;
instructions for determining an amount of noise in each of the resultant images;
instructions for removing the noise from the resultant images to yield a noiseless image;
instructions for scaling the data obtained from the scanning;
instructions for adding the removed noise to the data; and
instructions for calculating a new tensor.
7. The computer-readable medium of claim 6 , wherein the instructions for removing the noise include instructions for subtracting the two sets of images and observing values that are greater than zero.
8. The computer-readable medium of claim 6 , wherein the instructions for removing the noise include instructions for computing a histogram of values in a pixel for the duplicates copied and determining the distribution of noise around a mean.
9. The computer-readable medium of claim 6 , wherein the instructions for scanning a plurality of DTI directions include instructions for scanning a first DTI direction of the test object and scanning a second DTI direction of the test object, wherein the second direction is rotated by 60 degrees from the first direction.
10. The computer-readable medium of claim 6 , wherein the instructions for scanning a plurality of DTI directions include instructions for scanning a first DTI direction of the test object and scanning a second DTI direction of the test object, wherein the second direction is rotated by 90 degrees from the first direction.
11. A system for synthesizing data obtained from a DTI protocol in an MRI system, comprising:
means for scanning a plurality of DTI directions of a test object having a plurality of anisotropic structures at least twice, wherein the test object comprises:
a plurality of water-filled capillaries arranged into an array; and
a housing, wherein the housing is substantially filled with a liquid, the array is housed within the housing, and the array has a generally polygonal-like shape and includes a plurality of arrays stacked in a plurality of rows in the housing and thereby forming a macro-array;
means for producing at least two sets of resultant images and associated data for each DTI direction;
means for determining an amount of noise in each of the resultant images;
means for removing the noise from the resultant images to yield a noiseless image;
means for scaling the data obtained from the scanning;
means for adding the removed noise to the data; and
means for calculating a new tensor.
12. The system of claim 11 , wherein the means for removing the noise includes means for subtracting the two sets of images and observing values that are greater than zero.
13. The system of claim 11 , wherein the means for removing the noise includes means for computing a histogram of values in a pixel for the duplicates copied and determining the distribution of noise around a mean.
14. The system of claim 11 , wherein the means for scanning a plurality of DTI directions includes means for scanning a first DTI direction of the test object and a second DTI direction of the test object, wherein the second direction is rotated by 60 degrees from the first direction.
15. The system of claim 11 , wherein the means for scanning a plurality of DTI directions includes means for scanning a first DTI direction of the test object and a second DTI direction of the test object, wherein the second direction is rotated by 90 degrees from the first direction.