Image processing and analysis at the core lab
SRS
If the participating centers adopted resolution recovery acquisition protocols (GE Evolution for Cardiac, Philips Astonish, Siemens IQ SPECT or D-SPECT), they uploaded both raw data (for quality control) and reconstructed data for processing. Data submitted to the core lab were de-identified, and the core lab readers were unaware of treatment allocation. Quality control of the raw data was performed for all studies. Collected counts, presence of artefacts, patient motion, presence of interfering visceral activity, its intensity and distance from myocardial wall, detectable attenuation artifacts were all taken into consideration in determining ischemic burden. The core lab processed the DICOM data in a standard format for qualitative analysis. The SPECT images were reconstructed using an Iterative Reconstruction Algorithm, and the INVIA Corridor 4DM v2017 software was adopted for semi-quantitative analysis, providing perfusion defect scores (SSS, SRS, SDS), and perfusion defects extent globally and for specific vascular territories using a 17-segment model.