Genetic manipulation focused in the murine animal model is generating a revolution in cardiovascular research. Thus, a serious need is emerging for micro imaging techniques capable of quantifying cardiovascular function in these very small animals. Conventional medical imaging equipment is very difficult to adapt for this application. Proportional Technologies, Inc has developed a mutiwire proportional gamma camera (MWGC) and short lived generator produced agent 178-Ta which provides high quality ventricular function assessment in humans. We propose to adapt this technology to obtain high quality nuclear angiography studies in this animal model. This technology provides the intrinsic advantages of essentially unlimited magnification through use of pinhole imaging geometry, high framing rate and accurate count based quantification of ventricular function. The increased rate capability and resolution of the MWGC and short half life of 178- Ta are also significant advantages. Monte-Carlo simulations of pinhole geometries have been carried out and image resolution and count statistics obtained in murine first pass radionuclide angiography (FPRA) were compared with human studies taking into account the 10 fold smaller ventricular dimension, four fold higher heart rate, and 10 fold lesser tissue traversal. Similar relative image resolution, temporal resolution and image statistics were achieved with much cleaner scatter-free images. Therefore, high quality FPRA imaging of the murine heart is feasible. In this project a dedicated murine imaging system will be developed and tested in the actual animal model.
Essentially, a revolution is occurring in the field of cardiovascular research and molecular medicine based upon transgenic animal models of cardiac disease using the murine model. Therefore, a practical low-cost murine cardiovascular imaging system based on the multiwire proportional detector will likely develop a significant market. The intrinsic capability of the nuclear imaging technique to provide essentially unlimited magnification and very high imaging rates makes it very competitive for such work.
