Figure 6.

Multimodal image registration can be performed to improve staging and radiotherapy planning of rectal cancer. Axial contrast enhanced computed tomography (CT) at the portal phase (A) and rigid registration of the axial T2w magnetic resonance (MR) image (B). Rigid registration reduces the misalignment between the anatomical structures in the two modalities. A, B: Volume selection (rectangular white thin line) for non-rigid registration is performed; C, D: Non-rigid registration compensates for the more complex deformations due to the different acquisition setting; E, F: Following non rigid registration, MR can be fused with the positron emission tomography (PET) image (F) and the result is super-imposable on the PET-CT image (E).