FIG. 3.

Calibration of contrast-free vessel caliber with automated intensity-based caliber measures. (A) Workflow for utilizing a synthetic volume of tubes to determine the correlation between S_MAX, the maximum Gaussian kernel scale that maximizes the vesselness value in the Hessian-based vessel enhancement filter, and caliber measures from intensity projections of the volume. Forward projected centerline tree image in inset Sec. 4 has been thickened for clarity. (B) Example of the profiles across the line selection shown in insets Secs. 2 and 4 in (A). Vessel diameter in the intensity projected image (blue line), D_PROJ, was measured using an automatic full width at half-maximum approach. S_MAX is the maximum value in the line selection across the tube in the S_MAX forward projection image (red line). (C) Plot of S_MAX plotted against D_PROJ measured across multiple sections along each of the tubes in the image.