Brain tissue oxygen saturation (StO₂) from near-infrared spectroscopy (NIRS) helps determine the optimal mean arterial pressure (MAPopt) for cerebral autoregulation (CA), but consistency across platforms remains unclear. This study compared MAPopt agreement between ICM+ and Moberg Analytics systems in 92 pediatric cardiac arrest patients, using single- and multi-window approaches with and without artifact reduction (AR). Single-window MAPopt availability was similar (48% vs. 48%, p=0.16), with a mean absolute difference of 1.0mmHg and 94% of differences within ±5mmHg. Multi-window analysis improved availability (ICM+: 76%, Moberg: 79%, p<0.001) but slightly reduced agreement (mean absolute difference: 2.5mmHg, 87% within ±5mmHg). AR further increased availability without affecting agreement. While MAPopt values were comparable, differences between platforms underscore the need for standardization to ensure reliable clinical use.