Advantage aw 4

Reconstructed data were transferred to an external workstation (Advantage AW 4.4, GE Healthcare) for analysis. On reformatted horizontal long-axis slices, the left ventricle (LV) and right ventricle (RV) were subdivided into a total of six segments (LV basal and midventricular lateral wall, LV basal and midventricular septum, LV septal and lateral apical segments, and RV basal and midventricular lateral wall). Cardiac segments in our study were defined based on the recommendations of the American Heart Association Writing Group on Myocardial Segmentation and Registration for Cardiac Imaging.[15 (link)] A semiquantitative analysis of regional ¹⁸F-DOPA uptake was performed by placing a circular volume of interest (VOI) of 2.3cm³, automatically generated by the computer, into these four segments. The size of the VOI was standardized for all images by using a semi-automatic volume analysis tool (GE Healthcare, Milwaukee, USA). A semiquantitative uptake analysis using the upper limit of the standardized uptake value (SUV_max) and the averaged standardized uptake value (SUV_mean) was used to quantify ¹⁸F-DOPA uptake in these regions. SUV_max and SUV_mean were normalized to blood pool ¹⁸F-DOPA activity measured in the aortic arch of each patient (= SUV_max-N and SUV_mean-N).

Images were transferred to a dedicated workstation (Advantage AW 4.4, GE Healthcare) with a dedicated CACS software (SmartScore 4.0, GE Healthcare). All pixels with an attenuation equal or above the lowest threshold (e.g., ≥ 130 HU for 120-kV scans) having an area ≥ 1 mm² are automatically color marked, and lesions are manually selected by creating a region of interest around all lesions found in a coronary artery. The software then calculates the CAC score, as previously described.^{20 (link)} In brief, a score for each region of interest is calculated by multiplying the density score (i.e., the thresholds) and the area of calcifications. A total CAC score is then determined by adding up the scores for each CT slice. Importantly, the software computes an overall CAC score and vessel-wise CAC scores. Of note, the thresholds for CACS are only applied to pixels with a density equal or larger than the lowest threshold and an area of ≥ 1 mm². This eliminates single pixels with a density above the thresholds due to noise. All datasets were analyzed by two experienced readers in random order, and measurements from both readers were averaged.^{8 (link)} CAC risk categories were defined according to the following CAC score boundaries: 0, 1-100, 101-400, > 400.