Advances in Multimodality Molecular Imaging Instrumentation

Molecular imaging is a rapidly emerging field, providing noninvasive visual quantitative representations of fundamental biological processes in intact living subjects. The novelty of multimodality molecular imaging lies in the fact that it seeks to shed new light on both structure and function by creating images that directly or indirectly reflect specific cellular and molecular events (e.g. gene expression) that can reveal pathways and mechanisms responsible for disease within the context of physiologically authentic and intact environments within living subjects. Since the commercial introduction of PET/CT in 2001 and SPECT/CT in 2004, adoption of the technology has been rapid, particularly for oncology. Advances in CT and PET instrumentation have been incorporated into the very latest PET/CT designs, and SPECT/CT has also benefited from the advances in CT technology. The latest addition to multimodality clinical imaging is a combined MR/PET device. The availability of fast scintillators with high stopping power has revived interest in PET time-of-flight in order to increase signal to noise ratio in PET imaging. There has been significant progress during the past few years in image reconstruction methods through the introduction of statistically-based algorithms and resolution recovery into the clinical setting. The idea of using energy resolve CT for attenuation correction of PET data is an active research arena in multimodality imaging. Within the past couple years, the most widely-addressed issue related to CT-based attenuation correction has been respiratory motion and the artifacts created by the mismatch between CT and PET. An application for which PET/CT is also having an impact is that of radiotherapy treatment planning. Molecular imaging is increasingly being used to monitor response to therapy, both for chemotherapy and for radiation therapy, and for combinations of each. This review talk will follow the development of multimodality molecular imaging instrumentation for clinical use from conception to present-day technology and assess the status and future potential for such devices.