An ultra high resolution ECG-gated myocardial imaging system for small animals

Abstract

Standard radionuclide imaging systems are of limited use due to their inability to resolve structures in small animals that represent an increasingly important model for the study of cardiovascular disease. We are developing an imaging system incorporating a scintillation camera with a pinhole collimator to acquire cardiac gated images of the mouse heart. A simulation study showed that the effective diameter of the pinhole was unaffected by the scatter component of photon penetration through the pinhole insert. We have performed a myocardial perfusion study with 0.4 FWHM resolution on a normal 25 gram mouse ECG-gated at over 400 beats per minute. We have demonstrated that it is possible to obtain cardiac-gated, myocardial perfusion images of mice at submillimeter spatial resolution.

Dynamic molecular imaging of cardiac innervation using a dual headpinhole SPECT system

“…Small-animal imaging studies associated with molecular imaging are rapidly growing (Massoud 2003, Weissleder 2001. Nuclear imaging of small animals involves the use of microPET (Cherry 2001), microSPECT (a dedicated small animal system) (McDonald 2000, Furenlid 2004, Beekman 2004, Meikle 2005, Goertzen 2005, Beekman 2005, Kim 2006, Zeniya 2006, Hesterman 2007, Vastenhouw 2007, and pinhole SPECT technologies (Strand 1993, Li 1995a, Weber, 1995, Ishizu 1995, Yukihiro 1996, Smith 1997a, Smith 1998, Ogawa 1998, Tenney 1999, Wu 1999, Wu 2000, Hirai 2000, Hirai 2001, Acton 2002a, Acton 2002b, Wu 2003, Schrammm 2003, Metzler 2004, Zimmerman 2004, Vanhove 2005, Metzler 2005a, Zhou 2005, Ostendorf 2006, Forrer 2006. For reviews of small animal imaging of single photon tracers see (Budinger 2002, Weber 1999, Peremans 2005.…”

“…The use of pinhole SPECT/CT technology allows for the more direct translation of development in small animal models to clinical application where SPECT/CT technology is most applicable. Other pinhole SPECT systems have been used to image the heart (Yukihiro 1996, Wu 1999, Wu 2000, Hirai 2000, Hirai 2001, Wu 2003, Vanhove 2005, Zhou 2005) (commercial patient SPECT systems) and dedicated small animal microSPECT systems (Coaanstantinesco 2005, Beekman 2005, Liu 2002).…”

“…SPECT imaging of small animals can be performed on commercial clinical imaging systems with specially designed pinhole collimators. A resolution on the order of 1 mm can be obtained in mice (Ogawa 1998) with 99m Tc agents and with cardiac gating for heart rates as high as 400 beats per minute (Wu 1999, Wu 2000. Combining a low-energy isotope with gold alloy pinholes allows for a resolution of a few hundred m in mice .…”

A new design for a SPECT small-animal imager

“…Small-animal1 imaging has emerged as an important area of nuclear-medicine research [1]. Animals such as mice serve as models for studies ranging from neural function to the course and treatment of coronary disease and cancer [2,3]. Autoradiography, where the animal is injected with a tracer, sacrificed, sectioned, and imaged using radiographic film, is still a widely employed method for "imaging" animal models.…”

“…One animal, followed throughout the course of the experiment, provides data for a number of time points, and inter-animal differences are easier to monitor as they are registered through the entire experiment rather than at a single data point. Typically a SPECT system for in-vivo animal imaging has consisted of a clinical Anger camera with a single-or multiple-pinhole collimator [2,4]. While these systems have produced good high-resolution images, they tend to be cumbersome and difficult to modify, and they require access to the expensive clinical camera.…”