Dual Modality Small Animal Imaging

The ideal biological imaging system would provide non-invasive, high-resolution, high-sensitivity, three-dimensional (3D) images of living systems. Positron Emission Tomography (PET) offers high sensitivity to a range of biological processes through the use of targeted radiolabeled probes. Unfortunately, precise signal localization can be extremely difficult due to low spatial resolution and the lack of anatomical information. Magnetic Resonance Imaging (MRI) can provide high spatial resolution and excellent soft tissue contrast, but suffers from poor signal strength leading to low sensitivity. Thus, these single modalities do not satisfy all requirements of imaging studies. The overall goal of the proposed effort is to combine the best features of PET and MR modalities for small animal studies into a single imaging instrument that will record data in both imaging modalities near simultaneously. The most immediate benefit of the melded system will be to provide high-resolution anatomical context for microPET studies. The Phase I project was aimed at demonstrating the feasibility of the proposed imaging system. Specifically, we designed and build PET detector modules that can be operated inside a small animal MR scanner. Effect of both PET and MR detectors on each other were analyzed and based on the results, the feasibility of Phase I was adequately demonstrated. The Phase II project will be aimed at design, construction and evaluation of a high performance PET insert for conducting simultaneous PET-MR imaging of small animals. Optimization of the photodetection technology; construction of high performance PET modules and eventually, a single ring scanner; and detailed characterization of performance will be carried out in Phase II. Commercial applications and other benefits: Over and above the use in nuclear medicine, the proposed technology will be useful in nuclear and particle physics, space research, homeland security, environmental monitoring and synchrotron studies.