Multi-modality imaging of small animals

Over the last few years there has been a great demand for noninvasive, dedicated, small-animal imaging systems for biomedical research applications. In this dissertation we will discuss the development and performance of two gamma-ray systems and a dual modality CT/SPECT system. Initially we introduce FASTSPECT, a stationary, scintillator-based, single-photon emission computed tomography (SPECT) system that was originally built as a brain imager. We discuss its transformation into a small-animal imaging system and validate its performance by presenting high-resolution images of phantoms and animals. Furthermore, we discuss the development of an in vivo imaging protocol for rat myocardial models using FASTSPECT. The infarct size obtained from the images is quantified and compared with the myocardial infarct size measured from histology. Semiconductor detectors can exhibit good spatial and energy resolution, and therefore offer a promising alternative to scintillation technology. We discuss the performance of a semiconductor detector system, previously developed in our group, for planar and tomographic imaging of small animals. The same gamma-ray detector is used in a dual modality system for imaging mice. The system combines an anatomical imaging modality, x-ray CT, with a functional modality, SPECT. We present the development of the CT/SPECT system and illustrate its performance by presenting high-resolution images of phantoms and mice. Finally, we introduce a procedure for evaluating estimation methods without the use of a gold standard.