High frequency linear array scanner for the imaging of small rodents

Mice are particularly popular as laboratory animals as they are relatively inexpensive to keep and are genetically very similar to humans. This together with the ease with which their genome can be manipulated has led to their increasing use as models of human disease processes. While the full range of imaging techniques can be utilised for imaging the mouse, the heart is particularly challenging as a result of rapid heart rate and required image resolution. Echocardiography is a powerful yet relatively inexpensive technique for cardiac imaging potentially able to address these issues. A real time high frequency linear array scanner coupled with a physiological signal capture package has been developed for the functional study of the mouse heart. This system overcomes the limitations of clinical cardiac ultrasound scanners previously employed for this purpose. A commercially available linear array scanner intended for muskuloskeletal imaging (Dynamic Imaging Ltd., Livingston, UK) has been modified to extend the frequency range up to 28 MHz and frame rate to 300 frames per second. The physiological signal capture system and a software analysis package enable the display of captured cine-loops and corresponding physiological signals. Over 100 mice have been scanned to date. Investigations underway include comparison of LV function in mice which had undergone coronary artery ligation under general anesthesia with sham operated animals acting as controls, the application and value of ultrasonic contrast agents and the dependence of functional assessment of the mouse heart on scanning frequency.