Joint reconstruction of activity and attenuation using MR-based priors: Application to clinical TOF PET/MR

Attenuation correction is critical to accurate PET quantitation. However, it is challenging to extract accurate attenuation from MR data because of distinct physics of MR and PET. The goal of this study is to achieve robust and accurate attenuation correction in PET/MR. We combine an MR-segmentation based approach and a joint estimation approach synergistically by using an MR-segmentation based attenuation map as an MR-based prior for joint estimation. We evaluate the joint estimation algorithm with MR-based priors using time-of-flight (TOF) PET/MR clinical data. It is demonstrated that the joint estimation method using MR-based priors can recover the attenuation of metal implants, internal air cavities and bones in a robust way.