Engineering considerations for a MR-PET scanner

An MR-PET scanner has the potential of acquiring anatomical, functional and gross metabolic tissue status through MRI/MRS and metabolic activity through PET. The ultimate goal of a hybrid scanner is to yield temporal and spatial coregistration of MR and PET data. One advantage of conducting a PET experiment in a magnetic field is that intrinsic inplane spatial resolution improves. This is important for small diameter PET rings whose spatial resolution may exceed the intrinsic spatial resolution of a PET image due to positron range blurring. Thus, especially for the case of high energy positron emitters (e.g., ¹¹C, ¹⁵O, ⁶⁸Ga, ⁸²Rb), the possibility of acquiring high resolution inplane images (< 2 mm/pixel) from animals should be possible. Positron range in a magnetic field is anisotropic. A positron with a momentum component transverse to the magnetic field limits the positron's range whereas a positron whose momentum is co-linear with the field is unaffected. As a first step toward realizing the development of such a multimodality device we have chosen to focus on evaluating the interaction of MR system components on PET system components and vice versa.