Longitudinal registration brain MRI

What is the best way to compare segments from MRIs with different geometry (individual scans of the same subject)? Do I have to register all the MRIs in order to compare the segments to each other? What is the easiest way to do this? I have not had luck with affine or landmark registration, there is no change “sticking” to the output volume when I change module…

Context: I have a set of MRI-images with corresponding manual and machine-learning-derived tumor segments, shoving longitudinal tumor developments. I want to register all the MRIs to the first MRI, so the geometry of the segments can be compared in respekt of visualization of growth, as well as dice-coefficient between manual and machine-derived, longitudinally.