Figure 1: (a) and (b) show two representative examples of CT scans performed at 20 weeks. Clear mineralization of the wall portion is visible. Through further image processing, the region of the implanted valve can be selected. Determination of calcium volume is then performed, with calcium defined as every sample >100 and <400 HU. (c) shows the correlation between this CT-based calcium volume determination (in mm³) and the calcium content (μg/g dry weight) as measured with the spectrophotometer.