Post processing in medical segmentation with attemtion unet

I am doing a lesion segmentation for multiple sclerosis (MS), and at the moment I am using a attention unet for my thesis. The best validation dice score I have recieved is 0.771 and train 0.84. I am thinking of doing some post processing for removing some FP and FN in order to enhance the predictions. Any advice? currently I am using opening and closing, and I am not sure if this is the right approach.