Optical coherence tomography to investigate optical properties of blood during coagulation

Abstract

Abstract. This study investigates the optical properties of human blood during the coagulation process under statics using optical coherence tomography (OCT). OCT signal slope (OCTSS) and 1/e light penetration depth (d 1/e ) were obtained from the profiles of reflectance versus depth. Results showed that both OCTSS and d 1/e were able to sensitively differentiate various stages of blood properties during coagulating. After 1 h clotting, OCTSS decreased by 47.0%, 15.0%, 13.7%, and 8.5% and d 1/e increased by 34.7%, 29.4%, 24.3%, and 22.9% for the blood samples at HCT of 25%, 35%, 45%, and 55%, respectively. The slope of d 1/e versus time (S r , ×10 − 4 mm/s), associated with clot formation rate decreased from 6.0 ± 0.3, 3.7 ± 0.5 to 2.3 ± 0.4 with the increasing of HCT from 35%, 45%, to 55%. The clotting time (t c ) from the d 1/e evolution curves was estimated to be 1969 ± 92 s, 375 ± 12 s, 455 ± 11 s, and 865 ± 47 s for the blood of 25%, 35%, 45%, and 55%. This study demonstrates that the parameters (t c and S r ) from the variations in d 1/e had better sensitivity and smaller standard deviation. Furthermore, blood hematocrit affecting backscattering properties of blood during coagulation was capable of being discerned by OCT parameters. It is concluded that OCT is a potential technique to quantify and follow the liquid-gel transition of blood during clotting. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Measurements of fundamental properties of homogeneous tissue phantoms

“…However, some studies show techniques which use OCT for the determination of the microscopic properties. 21,[48][49][50] In-depth scanning allows for investigation of internal inhomogeneities, which are mainly caused by trapped air bubbles and clustering of nanoparticles. No significant inhomogeneities were detected in the produced phantoms.…”

Monitoring the blood coagulation process under various flow conditions with optical coherence tomography

“…The blood samples of various HCT levels were prepared by resuspending the concentrated RBCs into the native plasma separated from the whole blood. 19 All measurements were performed within 12 h after the blood was collected to ensure the porcine blood was kept fresh. Experiment 1 was performed in the model with calcium chloride as a trigger factor.…”

“…2. 19,20 A time curve was set up by plotting the d 1∕e values obtained from the entire observation. From the d 1∕e versus time signals, the clotting time (t c ) and coagulation rate (S r ) were determined by averaging the results of triplicates for each sample.…”

“…[10][11][12][13][14][15][16][17][18] Recently, we reported that OCT technique was able to characterize the whole blood coagulation process and the effects of anticoagulants on blood coagulation in the static state. 19,20 The 1∕e light penetration depth (d 1∕e ) [the point where the signal attenuated to 37% (1∕e) of the point with the greatest reflectance] versus time of blood coagulation process was able to differentiate various stages of blood properties during coagulation in the static state. The study developed two parameters: (1) clotting time (t c ), defined as the period of time where the 1∕e light penetration depth curve started to be stabilized, and (2) rate of fibrin formation (S r ), defined as the slope of d 1∕e within the period of time where d 1∕e increased dramatically following the induction of blood coagulation from the variations in d 1∕e versus time.…”

“…The study developed two parameters: (1) clotting time (t c ), defined as the period of time where the 1∕e light penetration depth curve started to be stabilized, and (2) rate of fibrin formation (S r ), defined as the slope of d 1∕e within the period of time where d 1∕e increased dramatically following the induction of blood coagulation from the variations in d 1∕e versus time. 19 The aim of this study was to evaluate whether the OCT technique and the parameters can characterize and monitor the flowing blood coagulation process that mimics physiological states. The d 1∕e versus time was measured, and t c and S r were obtained from the circulated porcine blood in a flow conduit throughout the entire process of blood clotting at flow rates of 5 to 25 mm∕s with tubing diameters of 0.9 to 2 mm.…”