I’m using 3DSlicer to do a repeatability study where I make ADC measurements over two scans which are acquired with the usual “coffee-break” approach, the patient is scanned twice in the same hour. I was reading some literature and I see that in some repeatability studies Authors did an affine registration before doing the actual segmentation.
Isn’t this kind of approach giving ultimately a biased measure of test-retest (specifically a lower value of the coefficient of repeatability)? I thought that the objective of test-retest was to try to obtain a repeatability index that was relative to each measurement.
What are your thoughts about it?