An Evaluation of the Benefits of Simultaneous Acquisition on PET/MR Coregistration in Head/Neck Imaging

Figure 2

Example of poorly ranked coregistration results. From left to right: coronal MR image, fused PET/MR, and PET image from (a) PETMRo, (b) PETMRreg_ELX^RR, (c) PETMRreg_ELX^DR, (d) PETMRreg_MRD^RR, and (e) PETMRreg_MRD^DR. RR with Elastix (b) and Mirada (d) shows an overall misalignment of the brain contour between PET and MR. This misalignment is only partially recovered by DR with Mirada (e) and better recovered by DR with Elastix (c). However, the lymph node tumor is completely absent in the PET component of PETMRreg_MRD^RR and its localization is not perfectly corresponding in PETMRreg_ELX^DR (c) as in PETMRo (a). The Dice scores for this case are PETMRo = 0.79, PETMRreg_ELX^RR = 0.26, PETMRreg_ELX^DR = 0.52, PETMRreg_MRD^RR = 0.19, and PETMRreg_MRD^DR = 0.25.

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