Pseudo-CT generation in brain MR-PET attenuation correction: comparison of several multi-atlas methods

TL;DRAbstract

Simultaneous MR-PET imaging opens new perspectives for understanding many aspects of brain function. However, accurate brain attenuation correction (AC) is required for absolute PET quantification. Radiodensity maps for AC are not readily available in PET-MR. Various strategies have been proposed to generate substitute attenuation maps. Recently, it has been shown that multiatlas techniques for AC outperform methods based on MR imaging sequences, such as Ultrashort-Echo-Time. We recently investigated several multiatlas methods to build a patient-specific pseudoCT, all based on multiatlas registration and label propagation, and introduced a novel maximum probability method (MaxProb). Here, a new database of 40 MR/CT image pairs (atlases) was used. Pairwise nonrigid registration of each atlas MR image to the target MR image yielded a geometric transformation that we used for propagating the atlas CT into the target’s space. The synthetic CT was generated by voxelwise atlas selection and

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