Monitoring radiotherapy with functional OCT: Microvascular responses and correlations with MRI

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Polarized light microscopy for quantitative assessment of colorectal cancer: Can we predict local recurrence?

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Preclinical quantitative in-vivo assessment of skin tissue vascularity in radiation-induced fibrosis with optical coherence tomography.

Radiation therapy (RT) is widely and effectively used for cancer treatment but can also cause deleterious side effects, such as a late-toxicity complication called radiation-induced fibrosis (RIF). Accurate diagnosis of RIF requires analysis of histological sections to assess extracellular matrix infiltration. This is invasive, prone to sampling limitations, and thus rarely used; instead, current practice relies on subjective clinical surrogates, including visual observation, palpation, and patient symptomatology questionnaires. This preclinical study demonstrates that functional optical coherence tomography (OCT) is a useful tool for objective noninvasive in-vivo assessment and quantification of fibrosis-associated microvascular changes in tissue. Data were collected from murine hind limbs 6 months after 40-Gy single-dose irradiation and compared with nonirradiated contralateral tissues of the same animals. OCT-derived vascular density and average vessel diameter metrics were compared to quantitative vascular analysis of stained histological slides. Results indicate that RIF manifests significant microvascular changes at this time point posttreatment. Abnormal microvascular changes visualized by OCT in this preclinical setting suggest the potential of this label-free high-resolution noninvasive functional imaging methodology for RIF diagnosis and assessment in the context of clinical RT

Colorization and Automated Segmentation of Human T2 MR Brain Images for Characterization of Soft Tissues

Characterization of tissues like brain by using magnetic resonance (MR) images and colorization of the gray scale image has been reported in the literature, along with the advantages and drawbacks. Here, we present two independent methods; (i) a novel colorization method to underscore the variability in brain MR images, indicative of the underlying physical density of bio tissue, (ii) a segmentation method (both hard and soft segmentation) to characterize gray brain MR images. The segmented images are then transformed into color using the above-mentioned colorization method, yielding promising results for manual tracing. Our color transformation incorporates the voxel classification by matching the luminance of voxels of the source MR image and provided color image by measuring the distance between them. The segmentation method is based on single-phase clustering for 2D and 3D image segmentation with a new auto centroid selection method, which divides the image into three distinct regions (gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) using prior anatomical knowledge). Results have been successfully validated on human T2-weighted (T2) brain MR images. The proposed method can be potentially applied to gray-scale images from other imaging modalities, in bringing out additional diagnostic tissue information contained in the colorized image processing approach as described

Low-coherence photonic method of electrochemical processes monitoring

Abstract We present an advanced multimodality characterization platform for simultaneous optical and electrochemical measurements of ferrocyanides. Specifically, we combined a fiber-optic Fabry–Perot interferometer with a three-electrode electrochemical setup to demonstrate a proof-of-principle of this hybrid characterization approach, and obtained feasibility data in its monitoring of electrochemical reactions in a boron-doped diamond film deposited on a silica substrate. The film plays the dual role of being the working electrode in the electrochemical reaction, as well as affording the reflectivity to enable the optical interferometry measurements. Optical responses during the redox reactions of the electrochemical process are presented. This work proves that simultaneous opto-electrochemical measurements of liquids are possible

Physics in Medicine and Biology 52 6 1659 1674 IOP PUBLISHING LTD BRISTOL; DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND

In an effort to understand dynamic optical changes during laser interstitial thermal therapy ( LITT), we utilize the perturbative solution of the diffusion equation in heterogeneous media to formulate scattering weight functions for cylindrical line sources. The analysis explicitly shows how changes in detected interstitial light intensity are associated with the extent and location of the volume of thermal coagulation during treatment. Explanations for previously reported increases in optical intensity observed early during laser heating are clarified using the model and demonstrated with experimental measurements in ex vivo bovine liver tissue. This work provides an improved understanding of interstitial optical signal changes during LITT and indicates the sensitivity and potential of interstitial optical monitoring of thermal damage.CR: AMIN Z, 1993, INVEST RADIOL, V28, P1148 ANDERSON CD, 2004, J GASTROINTEST SURG, V8, P660, DOI 10.1016/j.gassur.2004.04.009 BEVAN PD, 2001, ULTRASOUND MED BIOL, V27, P809 BOWN SG, 1983, WORLD J SURG, V7, P700 BREMER C, 2001, INVEST RADIOL, V36, P327 CHENG HLM, 2003, J MAGN RESON IMAGING, V18, P585, DOI 10.1002/jmri.10388 CHEONG WF, 1995, OPTICAL THERMAL RESP, P275 CHIN LCL, 2001, PHYS MED BIOL, V46, P2407 CHIN LCL, 2003, PHYS MED BIOL, V48, P543 CHIN LCL, 2004, OPT LETT, V29, P959 CHUNG AH, 1999, MED PHYS, V26, P2017 DAVIDSON SRH, 2005, LASER SURG MED, V36, P297 HAZLE JD, 2002, J MAGN RESON IMAGING, V15, P185 IIZUKA MN, 2000, PHYS MED BIOL, V45, P1335 KAK AC, 1988, PRINCIPLES COMPUTERI LARIN KV, 2005, J PHYS D APPL PHYS, V38, P2645, DOI 10.1088/0022-3727/38/15/017 MALONE DE, 1994, INVEST RADIOL, V29, P915 MCNICHOLS RJ, 2004, LASER SURG MED, V34, P48, DOI 10.1002/lsm.10243 MINHAJ AM, 2002, PHYS MED BIOL, V47, P2987 NTZIACHRISTOS V, 2000, P NATL ACAD SCI USA, V97, P2767 OLEARY M, 1996, THESIS U PENNSYLVANI OLEARY MA, 1995, OPT LETT, V20, P426 OSTERMEYER MR, 1997, J OPT SOC AM A, V14, P255 PEARCE J, 1995, OPTICAL THERMAL RESP PUCCINI S, 2003, MAGNET RESON MED, V49, P351, DOI 10.1002/mrm.10357 RITZ JP, 2001, LASER SURG MED, V29, P205 ROGGAN A, 2001, MED LASER APPL, V16, P65 TERENJI A, 2005, LASER SURG MED, V36, P365, DOI 10.1002/lsm.20178 VERHEY JF, 2003, PHYS MED BIOL, V48, P3595 WHELAN WM, 1995, MED PHYS, V22, P105 WHELAN WM, 2005, INT J THERMOPHYS, V26, P23

Media 1: Rapid time-gated polarimetric Stokes imaging using photoelastic modulators

Originally published in Optics Letters on 15 August 2013 (ol-38-16-2997

Media 2: Rapid time-gated polarimetric Stokes imaging using photoelastic modulators

Originally published in Optics Letters on 15 August 2013 (ol-38-16-2997