Variations in the threshold’s values for border zone and dense scar produce significant changes in the scar parameters obtained by ADAS-3D.

Background ADAS-3D software elaborates Cardiac Magnetic Resonance (CMR) images to obtain a quantitative evaluation of dense scar and border zone (BZ), including BZ channels, which can be useful for ventricular tachycardia ablation and for risk-stratification. However, most prior reports with ADAS-3D used flexible thresholds (60%±5% and 40%±5% of maximum pixel signal intensity -PSI) to define dense scar and BZ. It is unknown which is the impact of such variations of the thresholds values on the measurements obtained with ADAS-3D. Objective To quantify the degree of change in ADAS-3D measurements when different thresholds for dense scar and BZ are employed. Methods Single-center retrospective observational cohort study including 87 consecutive patients with previous myocardial infarction who underwent CMR. ADAS-3D software semi-automatically processed CMR sequences. We compared the scar measurements obtained using the 9 possible combinations of thresholds (55%/60%/65% and 35%/40%/45% of maximum PSI). Results The overall comparison between thresholds showed highly significant differences (p<0.001) in all scar parameters. Not a single patient maintained the same number of BZ channels with all the thresholds settings. A percentage difference of up to 200% in BZ channels numbers and channels mass was observed in all 36 comparisons. An absolute difference of up to 10 channels was also recorded. Of note, the highest median channel mass (obtained with the thresholds 35-65) was 59-fold higher as compared to the lowest one (obtained with the 45-55 cut-offs). Conclusions Variations in threshold values result in statistically significant and high-magnitude changes in the quantification of scar parameters by ADAS-3D.