Method for analyzing and correcting measurement variability in pet images

Abstract

A computer-implemented method for correcting measurement variability across a scanner field of view within an image scan, such as in PET imaging. The method operates on a slice-by-slice application and identifies and negates scan inconsistencies across the scanner field of view by normalizing values across the image scan as a function of reference signals measured across the field of view.

What is claimed is: 
     
         1 . A method for correcting image measurement variability across a scanner field of view within an image scan of an imaging device, the method comprising:
 providing the image scan, wherein the image scan comprises image slices of a tissue; and   identifying and negating scan inconsistencies in the image scan across the scanner field of view by a data processor mathematically adjusting values across the image slices relative to a reference signal.   
     
     
         2 . The method according to  claim 1 , further comprising:
 normalizing values across the image scan as a function of reference signals across the image scan and measured across the field of view.   
     
     
         3 . The method according to  claim 2 , further comprising adjusting measured signals in the image scan by multiplying each of the measured signals by an adjustment value provided by the reference signal. 
     
     
         4 . The method according to  claim 1 , further comprising:
 measuring an imaging agent in a region of interest within each of the image slices;   measuring the imaging agent in a reference region within the each of the image slices; and   normalizing a measured imaging agent in the region of interest within the each of the image slices as a function of measured imaging agent differences across reference regions of the image slices.   
     
     
         5 . The method according to  claim 4 , further comprising normalizing each of the image slices to a consistent ratio of the measured imaging agent between the region of interest and the reference region. 
     
     
         6 . The method according to  claim 1 , further comprising:
 identifying a region of interest within the image scan and extending across a plurality of the image slices;   measuring an imaging agent in the region of interest within each of the plurality of image slices;   identifying the reference signal for each of the image slices;   determining a ratio of the measured imaging agent between the region of interest and the reference signal for the each of the plurality of slices;   normalizing the reference signals across the slices; and   adjusting a measured imaging agent in the one of the slices according to a corresponding normalization change to the reference signal for the one of the plurality of slices.   
     
     
         7 . The method according to  claim 1 , wherein providing the image scan comprises adjusting and coordinating the image slices to form the image scan. 
     
     
         8 . The method according to  claim 1 , wherein the reference signal is obtained from reference regions of a patient tissue within the image scan. 
     
     
         9 . The method according to  claim 8 , further comprising calibrating by comparing two scans of the patient tissue and measuring and comparing imaging agent signals in each of a predetermined reference region of imaging agent uptake and one or more predetermined interest regions having a higher imaging agent uptake than the reference region across corresponding slices of the two scans. 
     
     
         10 . The method according to  claim 1 , wherein the reference signal is obtained from a separate phantom scan of a uniform radiation or measured signal source across the field of view. 
     
     
         11 . The method according to  claim 10 , further comprising:
 determining a mean value for the field of view from the phantom scan; and   adjusting measured signals during the image scan by multiplying each of the measured signals by an adjustment value of a scanning slice of the scan including the measured signal, wherein the adjustment value that is equal to an excursion of the measured signal from the phantom signal determined for the same scanning slice divided by the mean value for the field of view.   
     
     
         12 . The method according to  claim 1 , further comprising:
 measuring an imaging agent in a region of interest within each of the image slices;   measuring an imaging agent in a reference region within each of the image slices or an adjacent slice; and   mathematically adjusting the region of interest in the plurality of slices as a function of measured imaging agent differences across reference regions of the plurality of slices.   
     
     
         13 . The method according to  claim 12 , further comprising:
 determining a ratio of the measured imaging agent between the region of interest and the reference region for each of the plurality of slices; and   mathematically adjusting determined ratios across the plurality of slices to obtain normalization across the image slices.   
     
     
         14 . The method according to  claim 12 , further comprising comparing trajectories or percent changes between at least one of: regions of interest and reference regions, as they traverse at least two of the plurality of slices. 
     
     
         15 . The method according to  claim 12 , further comprising normalizing by the mathematical adjustment each of the plurality of slices to a ratio of the measured imaging agent between the region of interest and the reference region. 
     
     
         16 . The method according to  claim 12 , wherein the reference region comprises a tissue volume that is resistant to accumulation of the imaging agent. 
     
     
         17 . The method according to  claim 12 , wherein the reference region comprises white matter brain tissue. 
     
     
         18 . The method according to  claim 12 , wherein the reference region is a predetermined non-specific binding region for the imaging agent. 
     
     
         19 . A non-transitory recordable medium including encoded instructions on a recordable medium for automatically executing steps according to  claim 12 .