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. 2024 Jan 12;13(2):e030512. doi: 10.1161/JAHA.123.030512

Figure 1. Workflow of 99mTc‐PYP SPECT/CT with volumetric H/L ratio.

Figure 1

Segmentation of the lungs took place on CT images using an automated algorithm based on an HU threshold value of −400. The volumes of interest in the LV myocardium were generated by auto contouring 40% to 50% of maximum heart count. The volumetric H/L ratio was calculated as mean count of the heart divided by that of the lungs. 99mTc‐PYP indicates technetium‐99m‐pyrophosphate; CT, computed tomography; H/L, heart to lung; HU, Hounsfield unit; LV, left ventricular; SPECT, single‐photon emission computed tomography; and VOIs, volume of involvement.