A study of blood clots using photoacoustic imaging during sonothrombolysis

Abstract

Formation of blood clots or thrombus in healthy blood vessels can lead to serious or even life-threatening complications. Sonothrombolysis is a promising tool for lysing the blood clots non-invasively using focused acoustic waves. Ultrasound (US) imaging is commonly used to detect the blood clots presents in veins. In this work, we explore the use of a combined ultrasound and photoacoustic (PA) imaging clinical system during sonothrombolysis. PA imaging is a hybrid and emerging imaging modality which has garnered the attention of the biomedical imaging community in recent years. While US imaging has been used to visualize the blood clot, PA imaging enables the study of composition of the blood clot due to its optical absorption. Blood clots may be red, white or mixed due to the higher count of red blood cells (RBCs), white blood cells (WBCs) or it being a combination of RBCs and WBCs, respectively. Each clot type has a different photoacoustic signal. In our work, blood clots rich in RBCs are taken in transparent polyurethane tubes for sonothrombolysis. Meanwhile, the ultrasound and photoacoustic signal-to-noise ratios (SNR) are measured at fixed time intervals to evaluate the size and optical properties of the clot. Two cases were taken: blood clot + DI water and blood clot + blood and their US and PA SNR values were compared after 30 mins of sonothrombolysis treatment. The PA signal of the blood clot obtained after performing sonothrombolysis can be used to determine its final composition which may, in turn, help in the administration of clot-dissolving drugs.