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README.txt %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% ABOUT %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The Oakland Reconstruction Toolbox is designed to offer multiple methods of reconstruction of images from radially sampled NMR data collected on Bruker AVII or AVIIIHD systems in MATLAB. It could easily be adapted for other scanner data. Reconstruction methods include Standard Gridding, Gridding with Oversampling, Gridding with Oversampling and Deapodization, Filtered Back Projection, and Filtered Back Projection with Spatial Filtering. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% INSTRUCTIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Before using the toolbox, make sure to add the toolbox (the folder OaklandReconstructionToolbox) and its subfolders to the MATLAB path. The current folder should be 'OaklandReconstructionToolbox' when the code is run. You will also need to change the directory names appropriately. When inserting scan data into the 'Expts' file, be sure to insert it into the folder associated with the correct system. Also, the folder containing the scan data should simply be labeled with the correct scan number. It should contain a method file that includes Kx and Ky coordinates. The function oaklandReconstruct.m is intended to provide access to all reconstruction techniques. When running this file, it will ask for which system the scan was generated on and a scan number. If you would like to use your own trajectory coordinates, you can call oaklandReconstructForceK.m and pass trajectory coordinates as arguments. If the scan folder is organized correctly and the file 'method' is undisturbed, the Kx and Ky coordinates will be read successfully. If an error is thrown, the method file was likely disturbed by a user. Try to add a space to every line where Kx and Ky are identified in the method document. Next, it will ask which reconstruction algorithm is desired. It will then call the algorithm and output the data into the folder 'Images.' The techniques are basically characterized as a gridding approach or a filtered back projection approach. Gridding approaches include Standard Gridding, Gridding with Oversampling, and Gridding with Oversampling and Deapodization. Filtered back projection approaches include Standard Filtered Back Projection and Filtered Back Projection with Spatial Filtering. Through experimentation, we have determined Gridding with Oversampling and Deapodization to be the most accurate method. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% VARIABLES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% stdGridding,m, griddingOS.m, and griddingDeapodize.m important variables complexMatrix - matrix that contains 3 tuples of coordinates and values for every sample fineVals - values interpolated on to the ultrafine grid imageMat - the image resulting from the reconstruction thus far imaginaryData - the imaginary components of the FID Kx, newKx - K space x coordinates from a radial sample Ky, newKy - K space y coordinates from a radial sample neighbors - the neighborhood around a standrad Cartesian grid point used to asssign its values radVec - vector of approximate radii at which samples are taken realData - the real components of the FID stdVals - values interpolated on to the standard grid thetaVec - angular values at which radial samples are taken transformedData - complex data resulting from 2DFFT x - meshgrid of approximate x locations at which samples were taken xScale - how much x coordinates are scaled by to achieve 256x256 K-space y - meshgrid of approximate x locations at which samples were taken yScale - how much y coordinates are scaled by to achieve 256x256 K-space %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% stdFBP.m and fbpSpatialFilt.m important variables data - nonuniform complex K space data fil - the spatial filter that corrects for the parabolic structure in reconstructed images imageMat - the image resulting from the reconstruction thus far imaginaryData - the imaginary components of the FID interpData - K space data interpolated to evenly spaced points along diameter p - the polynomial coeffecients fit for the single tube scan projections - matrix of projection data radVec - vector of approximate radii at which samples are taken realData - the real components of the FID thetaVec - angular values at which radial samples are taken transformedData - complex data resulting from FFT %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% OTHER GENERAL REMARKS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The functions testFBP.m and testOS.m have been included to allow for experimentation in reconstruction techniques. The variables are the same as those from stdFBP.m and stdGridding.m, respectively. There was a discrepancy between the original code and the naming conventions used in the corresponding documents. Thus, variable names were changed. If, for some reason, a reconstruction fails, go to the ReconstructionMethods folder, then the OriginalMethods folder. You can replace the nonworking code with this, in hopes that the issue was related to some change in variables used. This software is for research purposes only. It was developed in the Xia Lab at Oakland University with assistance from Farid Badar, Simon Miller, and Dr. Yang Xia. For any questions about how to operate the toolbox, email [email protected].
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MRI reconstruction from radial k-space samples
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