22 March 2016 Feasibility of reduced-dose 3D/4D-DSA using a weighted edge preserving filter
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A conventional 3D/4D digital subtraction angiogram (DSA) requires two rotational acquisitions (mask and fill) to compute the log-subtracted projections that are used to reconstruct a 3D/4D volume. Since all of the vascular information is contained in the fill acquisition, it is hypothesized that it is possible to reduce the x-ray dose of the mask acquisition substantially and still obtain subtracted projections adequate to reconstruct a 3D/4D volume with noise level comparable to a full dose acquisition. A full dose mask and fill acquisition were acquired from a clinical study to provide a known full dose reference reconstruction. Gaussian noise was added to the mask acquisition to simulate a mask acquisition acquired at 10% relative dose. Noise in the low-dose mask projections was reduced with a weighted edge preserving (WEP) filter designed to preserve bony edges while suppressing noise. 2D log-subtracted projections were computed from the filtered low-dose mask and full-dose fill projections, and then 3D/4D-DSA reconstruction algorithms were applied. Additional bilateral filtering was applied to the 3D volumes. The signal-to-noise ratio measured in the filtered 3D/4D-DSA volumes was compared to the full dose case. The average ratio of filtered low-dose SNR to full-dose SNR was 1.07 for the 3D-DSA and 1.05 for the 4D-DSA, indicating the method is a feasible approach to restoring SNR in DSA scans acquired with a low-dose mask. The method was also tested in a phantom study with full dose fill and 22% dose mask.
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Erick L. Oberstar, Michael A. Speidel, Brian J. Davis, Charles Strother, Charles Mistretta, "Feasibility of reduced-dose 3D/4D-DSA using a weighted edge preserving filter", Proc. SPIE 9783, Medical Imaging 2016: Physics of Medical Imaging, 978302 (22 March 2016); doi: 10.1117/12.2216087; https://doi.org/10.1117/12.2216087

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