Detecting Pre-Occlusive Thrombosis via MMUS of SPIO-labeled Platelets: Blood clots, or "thrombi," are a leading cause of heart attacks and strokes, so detecting clots quickly and reliably is highly important. Currently, there are several detection techniques for thrombi, but they all have drawbacks. For example, Doppler ultrasound can only image anomalies in blood flow around clots – not the clots themselves, compression ultrasound cannot provide quantitative data, while x-rays and CT scans are expensive and give the patient high doses of radiation. The magnetomotive ultrasound (MMUS) system we are developing would use only a contrast agent, and a cost-effective, non-invasive, non-irradiating ultrasound exam to image blood clots, even in the early stages while they are still small.

Blood platelets which can be loaded with super-paramagnetic iron oxide particles (SPIOs) are a promising new contrast agent for detecting thrombosis via magnetomotive imaging. Specifically, thrombi form in response to arterial damage, when large quantities of platelets congregate at the damage site and form a stiff plug to prevent further bleeding. We plan to infuse blood platelets with SPIOs, producing a large quantity of “SPIO-labeled” platelets. These platelets will be inserted into the blood stream, where they will mix with the regular un-labeled platelets. Now, when a clot forms, a fraction of its platelets will be magnetically labelled. Since platelets congregate at high concentrations in thrombi, clots will contain high levels of magnetic particles, as shown in Figure 1, while other parts of the body will not.