Perhaps they are gathering additional information in the P2 part of the 2/3 trial and correlating it to those Pet scans. If this could be done it would save money and time in a larger P3 or P4.
It's all speculation, but other than the delay in late 2017 (which I believe was due to FDA issues not AVXL issues) Missling hasn't dropped a stitch so far when it comes to being prepared for, so I expect a pleasant surprise when we finally know exactly how Cognision works into the process.