Prostate cancer is the second leading cause of death in the United States in 2009. Radical prostatectomy (complete
removal of the prostate) is the most common treatment for prostate cancer, however, differentiating prostate tissue from
adjacent bladder, nerves, and muscle is difficult. Improved visualization could improve oncologic outcomes and
decrease damage to adjacent nerves and muscle important for preservation of potency and continence. A novel Stokes
polarimetry imaging (SPI) system was developed and evaluated using a dog prostate specimen in order to examine the
feasibility of the system to differentiate prostate from bladder. The degree of linear polarization (DOLP) image maps
from linearly polarized light illumination at different visible wavelengths (475, 510, and 650 nm) were constructed. The
SPI system used the polarization property of the prostate tissue. The DOLP images allowed advanced differentiation by
distinguishing glandular tissue of prostate from the muscular-stromal tissue in the bladder. The DOLP image at 650 nm
effectively differentiated prostate and bladder by strong DOLP in bladder. SPI system has the potential to improve
surgical outcomes in open or robotic-assisted laparoscopic removal of the prostate. Further in vivo testing is warranted.
Endometriosis is one of the most common causes of chronic pelvic pain and infertility and is characterized by the
presence of endometrial glands and stroma outside of the uterine cavity. A novel laparoscopic polarization imaging
system was designed to detect endometriosis by imaging endometrial lesions. Linearly polarized light with varying
incident polarization angles illuminated endometrial lesions. Degree of linear polarization image maps of endometrial
lesions were constructed by using remitted polarized light. The image maps were compared with regular laparoscopy
image. The degree of linear polarization map contributed to the detection of endometriosis by revealing structures inside
the lesion. The utilization of rotating incident polarization angle (IPA) for the linearly polarized light provides extended
understanding of endometrial lesions. The developed polarization system with varying IPA and the collected image
maps could provide improved characterization of endometrial lesions via higher visibility of the structure of the lesions
and thereby improve diagnosis of endometriosis.
We demonstrate the detection of iron oxide nanoparticles taken up by macrophages in atherosclerotic plaque with differential phase optical coherence tomography (DP-OCT). Magneto mechanical detection of nanoparticles is demonstrated in hyperlipidemic Watanabe and balloon-injured fat-fed New Zealand white rabbits injected with monocrystalline iron oxide nanoparticles (MIONs) of <40 nm diam. MIONs taken up by macrophages was excited by an oscillating magnetic flux density and resulting nanometer tissue surface displacement was detected by DP-OCT. Frequency response of tissue surface displacement in response to an externally applied magnetic flux density was twice the stimulus frequency as expected from the equations of motion for the nanoparticle cluster.
A Stokes polarimetry imaging (SPI) system utilizes an algorithm developed to construct
degree of polarization (DoP) image maps from linearly polarized light illumination.
Partial-thickness tears of turkey tendons were imaged by the SPI system in order to
examine the feasibility of the system to detect partial-thickness rotator cuff tear or
general tendon pathology. The rotating incident polarization angle (IPA) for the linearly
polarized light provides a way to analyze different tissue types which may be sensitive to
IPA variations. Degree of linear polarization (DoLP) images revealed collagen fiber
structure, related to partial-thickness tears, better than standard intensity images. DoLP
images also revealed structural changes in tears that are related to the tendon load. DoLP
images with red-wavelength-filtered incident light may show tears and related
organization of collagen fiber structure at a greater depth from the tendon surface. Degree
of circular polarization (DoCP) images exhibited well the horizontal fiber orientation that
is not parallel to the vertically aligned collagen fibers of the tendon. The SPI system's
DOLP images reveal alterations in tendons and ligaments, which have a tissue matrix
consisting largely of collagen, better than intensity images. All polarized images showed
modulated intensity as the IPA was varied. The optimal detection of the partial-thickness
tendon tears at a certain IPA was observed. The SPI system with varying IPA and
spectral information can improve the detection of partial-thickness rotator cuff tears by
higher visibility of fiber orientations and thereby improve diagnosis and treatment of
tendon related injuries.
Differential phase optical coherence tomography (DPOCT) is introduced to measure optical path length changes in response to pulsed laser irradiation (585 nm). An analytical equation that includes thermoelastic surface displacement and thermorefractive index change is derived to predict optical path length change in response to pulsed laser irradiation for both "confined surface" and "free surface" model systems. The derived equation is tested by comparing predicted values with data recorded from experiments using two model systems. Thermorefractive index change and the thermal expansion coefficient are deduced from differential phase change (d) and temperature increase (T0) measurements. The measured n(T0)(T0)+dn/dT[=1.74·10–4±1.7·10–6 (1/K)] in the free surface experiment matches with the National Institute of Standards and Technology (NIST) data value [=1.77·10–4 (1/K)]. Exclusion of lateral thermal expansion in the analytical model for the confined surface experiment causes difference between the measured dn/dT[=–2.3·10–4±7.3·10–6(1/K)] and the NIST value [=–9.45·10–5 (1/K)]. In spite of the difference in the confined surface experiment, results of our studies indicate DPOCT can detect dynamic optical path length change in response to pulsed laser irradiation with high sensitivity, and applications to tissue diagnostics may be possible.
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