Cardiac and respiratory gating for a small animal SPECT-CT system

We present the design and construction of a murine cardiac imaging system integrated into a dedicated small animal microSPECT-CT scanner. The system, including a fast x-ray shutter and slow contrast infusion system, is designed with compact and relatively inexpensive components and permits the use of traditional inexpensive iodine-based CT contrast. SPECT cardiac gating is performed by list mode acquisition in which a voltage that increases linearly during each cardiac cycle is digitized and stored with each detected gamma event. Cardiac CT/SPECT scans using the gating/infusion system demonstrate high wall-blood pool contrast and clear visualization of left and right ventricles and the ascending and descending aorta in the CT images and more clearly defined visualization of the myocardium in the SPECT images compared to their ungated counterparts.