Registered 4D CorDiff volume to the last timepoint (echo time) of GreCor volume. Last timepoint was chosen due to the highest contrast between the kidney and surrounding tissues.

Target kidney ROI first need to be constructed on the target (GreCor) either manually or automatically (manual in this example).  No ROI required on source (moving image).  However, registration relied on the fact that the volumes were acquired as part of the same exam so DICOM tags can be used for the initial alignment which is then finetuned by registration procedure.

Rigid registration was used in this example.  However, the volumes have very non-isotropic voxels

(1.5,1.5,7.5) mm, so the assumption of rigidity is very questionable and elastic deformation  may be used instead.

 

 

Optionally, the Target volume was made isotropic (1.5)mm^3.  This way the amount of information lost during the final reslicing is minimized.