High-efficiency, high-resolution SPECT techniques for cardiac imaging

Current standard clinical SPECT techniques provide a resolution of at best 1 cm and sensitivity in the order of 10. Performance is largely determined by the collimator. Basic geometry couples resolution and sensitivity; the problem of high-resolution imaging is a formidable one because, to image at constant Signal-to-Noise, resolution improvements must be supported by simultaneous sensitivity improvements that scale with the fourth power of resolution. However, current standard systems are designed to also accommodate whole body studies and, thus, routinely provide large-area detectors. Single-organ imaging does not need the same field of view, which, then, can be better utilized with collimation schemes that magnify or cast more copies (i.e. acquire several views) simultaneously on the detector. As demonstrated by the recent experience of small animal imaging, these collimation techniques can be readily coupled to existing detectors to offer better performance than standard parallel-hole collimation. Similar approaches have been explored for a number of years for cardiac imaging. The same ideas also apply to other single-organ studies (e.g. brain and breast) as well as to pediatric imaging.