Laser speckle decorrelation time-based platelet function testing in microfluidic system

Abstract

Platelet aggregation and adhesion are critically involved in both normal hemostasis and thrombosis during vascular injury. Before any surgery, it is important to identify the number of platelets and their functionality to reduce the risk of bleeding; therefore, platelet function testing is a requirement. We introduce a novel evaluation method of assessing platelet function with laser speckle contrast imaging. The speckle decorrelation time (SDT) of the blood flowing through a microfluidic channel chip provides a quantitative measure of platelet aggregation. We compared SDTs of whole blood and platelet-poor blood, i.e., whole blood stripped of its buffy coat region, and found a marked reduction in decorrelation time for platelet-poor blood. The measured SDT of platelet-poor blood was 1.04 ± 0.21 ms, while that of whole blood was 2.64 ± 0.83 ms. To further characterize the sensitivity of our speckle decorrelation time-based platelet function testing (SDT-PFT), we added various agonists involved in platelet aggregation, including adenosine diphosphate (ADP), epinephrine (EPI), and arachidonic acid (AA). In this study, the results show that whole blood with ADP resulted in the largest SDT, followed by whole blood with AA, whole blood with EPI, whole blood without agonist, and platelet-poor blood with or without agonist. These findings show that SDT-PFT has the potential for rapid screening of bleeding disorders and monitoring of anti-platelet therapies with only a small volume of blood.

Decorrelation Time Mapping as an Analysis Tool for Nanobubble-Based Contrast Enhanced Ultrasound Imaging

“…DT was defined as the time shift required for the correlation coefficient to reach 0.5, similar to Jeon at al. 39,47 NLC mode US videos of each model were captured and stored as real-valued matrices ( m × n × t ) ( m - image depth, n - image width, t - number of frames collected at frame rate, fs ; matrix depiction in Fig. 4-A.)…”

Quantitative blood flow estimationin vivoby optical speckle image velocimetry

“…A speckle pattern remains unchanged over time if the laser light interacts with a static medium. However, if the sample is not static (e.g., blood flowing in a living tissue), the laser speckle pattern would be dynamic, as shown in our previous studies [33][34][35][36].…”

Real-time imaging of nanobubble ultrasound contrast agent flow, extravasation, and diffusion through an extracellular matrix using a microfluidic model

“…Decorrelation time was defined as the time shift required for the autocorrelation coefficient to reach 0.5. 41,42 Analysis was conducted for continuous imaging experiments with both S-NBs and L-NBs. For each reported data point, approximately 10 adjacent pixels from the same depth were taken as the ROI.…”

“…Decorrelation time is defined as the time-shift for the correlation coefficient to reach 0.5. 41,42 Non-zero decorrelation time indicates that there is a pattern between imaging frames. We used this analysis to differentiate flowing bubbles from bubbles that are slowly diffusing through the matrix.…”