Noninvasive optical imaging of thrombus formation in mechanical circulatory support devices

Abstract

We developed a hyperspectral imaging (HSI) method to image a rotary blood pump rotating at high speed, and we investigated the optical properties of blood associated with the blood clotting. In vitro antithrombogenic testing was conducted. Fresh porcine blood was circulated by a hydrodynamically levitated centrifugal blood pump while light pulsed at the same frequency as the rotational speed illuminated the bottom surface of the pump. Back scattering was captured with an HSI camera, and the spectral image in the wavelength range from 608 to 752 nm was constructed. Back scattering in the area of suspected thrombus formation decreased. The shape of the spectral image was consistent with that of the thrombus formed in the pump. Moreover, the hemoglobin concentration of the thrombus was quantified, and its value was significantly lower than the total hemoglobin concentration. Therefore, it is speculated that the decrease in back scattering is caused by a decrease in the number of red blood cells (RBCs) trapped in the thrombus area due to the surrounding blood flow. It was concluded that this optical technique is able to detect blood clotting using the behavior of RBCs as the optical marker for its detection.