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. Author manuscript; available in PMC: 2020 Jul 1.
Published in final edited form as: J Magn Reson Imaging. 2018 Dec 17;50(1):106–113. doi: 10.1002/jmri.26552

FIGURE 1:

FIGURE 1:

Overview of QSM postprocessing steps to visualize and quantify cartilage canals of the femoral head. (a) Original 3D GRE magnitude image (single slice, cropped to a field-of-view of 23.4 × 23.4 mm2 for display). (b) Cartilage mask generated after segmentation of the 3D GRE magnitude image using ITK-SNAP. This mask was used to measure cartilage volume. (c) Original 3D GRE phase image. (d) Laplacian unwrapped phase of the segmented cartilage. (e) Field map after SHARP filtering. (f) QSM map generated after magnetic susceptibility calculation using an L2-regularized algorithm. (g) Cartilage canal vessel mask generated after applying a threshold value of 0.025 ppm to the QSM map. This mask was used to measure vessel volume and vessel density. (h) Vessel density map generated by calculating the local density of vessels in a sphere with a 2.1 mm diameter.