Dong Zhou1, JingWei Zhang2, Pascal Spincemaille1, and Yi Wang1,2
1Radiology Department, Weill Cornell Medical College, New York, NY, United States, 2Biomedical Engineering, Cornell University, Ithaca, NY, United States
The
error in digitizing the dipole convolution1 may become
substantial when there is abrupt susceptibility change within a voxel. To
evaluate this error, we assessed the accuracy
of quantitative susceptibility mapping in a gadolinium balloon
phantom with a range of large susceptibility values (0.4 – 3.2 ppm) and imaging
resolutions (0.7 – 1.8 mm) at both 1.5T and 3T. Systematic underestimation of the
susceptibility values was observed with decreasing imaging resolution. Numerical
simulations were performed to match the experimental findings. These show that the
underestimation originates directly from the changes in the voxel sensitivity function and that the amount of underestimation is
affected not only by imaging resolution, but also magnitude contrast, the use of k-space filters in the image reconstruction, and
details of the susceptibility inclusions such as the susceptibility value and geometry.
