The stiffness of biological tissues could be assessed by measuring the propagation of mechanically induced waves on its
surfaces that could help identifying various tissue pathologies. Here we present results for the volumetric assessment of
mechanical waves propagating on both surfaces of the crystalline lens measured with the Phase-Sensitive Swept Source
Optical Coherence Tomography (PhS-SSOCT) technique. The results indicate that the system could detect vibrations of
as small as 0.03 μm in amplitude induced on the surface of crystalline lens, and hence, PhS-SSOCT could potentially be
used to assess stiffness of a crystalline lens.
A new approach to distinguish normal fat, well-differentiated (WD), and dedifferentiated liposarcoma (LS) tumors is demonstrated, based on the use of optical coherence tomography (OCT). OCT images show the same structures seen with conventional histological methods. Our visual grading analysis is supported by numerical analysis of observed structures for normal fat and WDLS samples. Further development could apply the real-time and high resolution advantages of OCT for use in liposarcoma diagnosis and clinical procedures.
Experimental assessment of stiffness of crystalline lens of the eye can help in understanding several ocular diseases. Studies have shown that stiffness of the eye lens increases with age that might contribute to loss of accommodation. The stiffness of the lens could be assessed by measuring mechanically induced surface waves
propagating on its surface. Here we present preliminary results on phase sensitive spectral domain optical coherence tomography (PhS-SDOCT) measurements of the vibrations induced on surface of an eye lens. The system shows an axial resolution of 8 μm, phase sensitivity of 0.01 radians, imaging depth of up to 3.4 mm in air and a scanning speed of 29 kHz for a single A-line. The results indicate that the system could detect vibrations as small as 0.45 μm induced on the surface of crystalline lens, and hence, PhS-SDOCT could be potentially used to assess stiffness of a crystalline lens.
KEYWORDS: Blood, Capillaries, Biomedical optics, Optical coherence tomography, Tissues, Diagnostics, Laser therapeutics, In vitro testing, In vivo imaging, Surgery
We have developed a phase stabilized swept source optical coherence tomography (PhS-SSOCT), that shows an
axial resolution of 10 μm, phase sensitivity of 0.04 radians, imaging depth of up to 6 mm in air and a scanning speed of
20 kHz for a single A-line. In this paper, the PhS-SSOCT is applied to quantify gas microbubbles in blood in vitro. The
results indicate that the system is able to detect bubbles of diameters greater than 10 μm using the structural image and
the microbubbles of diameter less than 10 μm could be detected using the temporal phase response. Images of the
bubbles of diameters 600 μm, 405 μm and 6 μm along with their phase responses are presented. Results indicate that the
PhS-SSOCT could be potentially used for rapid assessment of blood microbubbles in vivo that cause diseases associated
with decompression sickness, venous and arterial gas emboli and barotraumas. Eventually, PhS-SSOCT can be utilized
as an early diagnostic tool for clinical purposes.
A new method for monitoring ultra-small changes in blood hematocrit (~0.2%) based on measurement of refractive
index changes in vitro using Phase Sensitive Spectral Domain Optical Coherence Tomography modality (PhS-SDOCT)
is introduced. The developed system has an axial resolution of ~8 μm, phase sensitivity of ±0.01 radians, imaging depth
of 3.4 ± 0.01 mm in air, and image acquisition speed of 29 kHz. The experimental accuracy for monitoring refractive
index changes as a function of hematocrit level in blood is found to be ±1.5x10-4 (±0.2%). Obtained results indicate that
the PhS-SDOCT can be used to monitor ultra-small changes in the hematocrit and in vitro and, potentially, in tissue
blood vessels in vivo.
The refractive index is a basic optical property of a medium which is of great importance in physics, chemistry
and most of biomedical applications. In our current study we monitor the change in refractive index for aqueous
solutions of glucose, CaCl2, MgCl2, NaCl, KCl and urea using a phase sensitive spectral domain optical coherence
tomography (ph-SOCT) system. For instance, glucose induced changes in the phase are found to be 0.079 rad/mM
in 200μm thick cuvette for clear media and that is in good agreement with literature and our previous obtained data
using phase sensitive low coherence optical reflectometry(PS-OLCR). The importance of this study is to
demonstrate the capability of ph-SOCT to monitor ultra small changes in refractive index in clear media and the
accuracy for glucose sensing is estimated to be ±2.6×10-6.
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