Quantitative photoacoustic characterization of blood clot in blood: A mechanobiological assessment through spectral information

Abstract

Formation of blood clots, called thrombus, can happen due to hyper-coagulation of blood. Thrombi, while moving through blood vessels can impede blood flow, an important criterion for many critical diseases like deep vein thrombosis and heart attacks. Understanding mechanical properties of clot formation is vital for assessment of severity of thrombosis and proper treatment. However, biomechanics of thrombus is less known to clinicians and not very well investigated. Photoacoustic (PA) spectral response, a non-invasive technique, is proposed to investigate the mechanism of formation of blood clots through elasticity and also differentiate clots from blood. Distinct shift (increase in frequency) of the PA response dominant frequency during clot formation is reported. In addition, quantitative differentiation of blood clots from blood has been achieved through parameters like dominant frequency and spectral energy of PA spectral response. Nearly twofold increases in dominant frequency in blood clots compared to blood were found in the PA spectral response. Significant changes in energy also help in quantitatively differentiating clots from blood, in the blood. Our results reveal that increase in density during clot formation is reflected in the PA spectral response, a significant step towards understanding the mechanobiology of thrombus formation. Hence, the proposed tool, in addition to detecting thrombus formation, could reveal mechanical properties of the sample through quantitative photoacoustic spectral parameters.

Photoacoustic power azimuth spectrum for microvascular evaluation

“…However, the imaging resolution in PACT is limited by the center frequency and bandwidth of the transducer [ 29 ]. Research has revealed that the frequency components of PA signals are related to the sizes and contents of the absorbers [ 30 , 31 ]. PA frequency analysis has been widely applied in examining fatty livers [ 32 ], bones [ 33 ], and blood cells [ 34 ].…”

Photoacoustic Spectral Sensing Technique for Diagnosis of Biological Tissue Coagulation: In-Vitro Study

“…Previously, PA techniques have been also investigated to study thermal coagulation of tissues based on changes in PA signal amplitudes due to changes in optical properties of tissues during coagulation [32]. However, such PA amplitude-based differentiation is often not reliable because the PA signal strength depends nonlinearly on an input laser energy and a distance between tissue sample and acoustic sensor [15]. In this regard, our proposed PA spectral sensing technique is more robust and predictable as it utilizes the frequency of PA response that is relatively less sensitive to experimental parameters, compared to the case of PA pressure amplitudes.…”

“…Moreover, the proposed technique relies on changes in the elastic property of tissue that serves as a potential fingerprint in coagulated tissue study. Our approach has been previously adopted to diagnose different pathological conditions involving minute changes in elastic properties [15,33]. This exhibits the versatility and sensitivity of our PA spectral sensing technique.…”

“…As a noninvasive and nonionizing diagnosis technique, this utilizes nano-second laser pulses to generate bipolar acoustic waves thermo-elastically from light-absorbing tissues, which are referred to as PA response [13]. Intrinsic properties of the target tissue, such as optical absorption and tissue elasticity, can be characterized by PA responses in terms of peak pressure amplitude, pulse width, and relaxation time [14][15][16]. Since thermal coagulation of tissues induces significant deformation in tissue elasticity, intact and coagulated tissues can be differentiated sensitively by using their PA responses.…”

Formação de imagem fotoacústica induzida por laser e raios X

“…BEARD, 2009) reflete, a concentração em termos do coeficiente de absorção óptica e as características de microestruturas dos tecidos também podem refletir em mudanças do espectro de frequências acústicas contidas nos sinais FA gerados no tecido de interesse. Por exemplo, durante o tempo de coagulação, a absorção óptica varia à medida que o sangue se transforma em coágulo, podendo ser utilizada para estagio de coágulos (KARPIOUK et al, 2008;BISWAS et al, 2017).…”