The generation of segments for the different segmentation schemes is driven by additional configurations such as illustrated below for the Epi/Endo segmentation.
▪6 Number of segments (N): The 360° of a full rotation will be divided into (N) equal angles. 6 is the recommended setting.
▪Full box: If enabled, sectors with an angle (360°/N) will be used, otherwise (360°/N-20°) creating gaps of 20°.
▪LV: Radius in pixels of the circular LV ROI representing contrast in the cavity.
▪Transmural: This setting allows subdividing the sectors in the radial direction in an attempt to quantify the transmural perfusion gradient. The example illustrated below was obtained with 6 segments and 3 transmural sectors.
▪Linearity corr: If this box is enabled, the program will perform a correction as described below.
The selection for the segments number is illustrated below. It includes the division into 4, 6, 12, 24, 60 and 120 angular segments of decreasing size.
The AHA 16 and AHA 17 selections are specific: they will apply 6 sectors in the basal and mid-cavity slices, and 4 sectors in the apical slices. AHA 17 includes as a 17th segment the apical cap. These definitions can only be applied with at least 4 slices.