Spatially resolved diffuse optical correlation spectroscopy (SR-DOCS) for quantitative assessment of skin tissue perfusion matrix

2018 ◽  
Author(s):  
Sujatha Narayanan Unni ◽  
Vysakh Vasudevan ◽  
Kavyakantha R.S.
Keyword(s):  
Quantitative Assessment ◽  
Tissue Perfusion ◽  
Correlation Spectroscopy ◽  
Skin Tissue ◽  
Optical Correlation ◽  
Spatially Resolved

Initial experience with a new quantitative assessment tool for fluorescent imaging in peripheral artery disease

VASA ◽  
2017 ◽  
Vol 46 (5) ◽  
pp. 383-388 ◽  
Author(s):  
Henrik Christian Rieß ◽  
Anna Duprée ◽  
Christian-Alexander Behrendt ◽  
Tilo Kölbel ◽  
Eike Sebastian Debus ◽  
...  
Keyword(s):  
Indocyanine Green ◽  
Quantitative Assessment ◽  
Tissue Perfusion ◽  
Fluorescent Imaging ◽  
Peripheral Artery ◽  
Peripheral Bypass ◽  
Before And After ◽  
Artery Disease ◽  
Green Fluorescent ◽  
Peripheral Bypass Grafting

Abstract. Background: Perioperative evaluation in peripheral artery disease (PAD) by common vascular diagnostic tools is limited by open wounds, medial calcinosis or an altered collateral supply of the foot. Indocyanine green fluorescent imaging (ICG-FI) has recently been introduced as an alternative tool, but so far a standardized quantitative assessment of tissue perfusion in vascular surgery has not been performed for this purpose. The aim of this feasibility study was to investigate a new software for quantitative assessment of tissue perfusion in patients with PAD using indocyanine green fluorescent imaging (ICG-FI) before and after peripheral bypass grafting. Patients and methods: Indocyanine green fluorescent imaging was performed in seven patients using the SPY Elite system before and after peripheral bypass grafting for PAD (Rutherford III-VI). Visual and quantitative evaluation of tissue perfusion was assessed in an area of low perfusion (ALP) and high perfusion (AHP), each by three independent investigators. Data assessment was performed offline using a specially customized software package (Institute for Laser Technology, University Ulm, GmbH). Slope of fluorescent intensity (SFI) was measured as time-intensity curves. Values were compared to ankle-brachial index (ABI), slope of oscillation (SOO), and time to peak (TTP) obtained from photoplethysmography (PPG). Results: All measurements before and after surgery were successfully performed, showing that ABI, TTP, and SOO increased significantly compared to preoperative values, all being statistically significant (P < 0.05), except for TTP (p = 0.061). Further, SFI increased significantly in both ALP and AHP (P < 0.05) and correlated considerably with ABI, TTP, and SOO (P < 0.05). Conclusions: In addition to ABI and slope of oscillation (SOO), the ICG-FI technique allows visual assessment in combination with quantitative assessment of tissue perfusion in patients with PAD. Ratios related to different perfusion patterns and SFI seem to be useful tools to reduce factors disturbing ICG-FI measurements.

scholarly journals Kinetic differences between macro- and microvascular measures of reactive hyperemia

2020 ◽  
Vol 129 (5) ◽  
pp. 1183-1192
Author(s):  
Miles F. Bartlett ◽  
Andrew Oneglia ◽  
Manall Jaffery ◽  
Shayla Manitowabi-Huebner ◽  
Dennis M. Hueber ◽  
...  
Keyword(s):  
Doppler Ultrasound ◽  
Near Infrared ◽  
Perfusion Pressure ◽  
Mechanical Energy ◽  
Reactive Hyperemia ◽  
Tissue Perfusion ◽  
Experimental Manipulation ◽  
Correlation Spectroscopy ◽  
Diffuse Correlation Spectroscopy

NEW & NOTEWORTHY We extend our understanding of macro- versus microvascular hemodynamics in humans, by using near-infrared diffuse correlation spectroscopy (micro-) and Doppler ultrasound (macro-) to characterize reperfusion hemodynamics following experimental manipulation of the ischemic stimulus and tissue perfusion pressure. Our results suggest kinetic differences between macro- and microvascular reperfusion are largely determined by differences in fluid mechanical energy (i.e., pressure, gravitational, and kinetic energies) between the two compartments, rather than inherent differences between the macro- and microvasculature.

scholarly journals Diffuse Correlation Spectroscopy at Short Source-Detector Separations: Simulations, Experiments and Theoretical Modeling

2019 ◽  
Vol 9 (15) ◽  
pp. 3047 ◽  
Author(s):  
Karthik Vishwanath ◽  
Sara Zanfardino
Keyword(s):  
Diffusion Theory ◽  
Small Animal ◽  
Tissue Perfusion ◽  
Flow Channel ◽  
Correlation Spectroscopy ◽  
Diffuse Correlation Spectroscopy ◽  
Non Invasive ◽  
Yield Information ◽  
Theoretical Analyses

Diffuse correlation spectroscopy (DCS) has widely been used as a non-invasive optical technique to measure tissue perfusion in vivo. DCS measurements are quantified to yield information about moving scatterers using photon diffusion theory and are therefore obtained at long source-detector separations (SDS). However, short SDS DCS could be used for measuring perfusion in small animal models or endoscopically in clinical studies. Here, we investigate the errors in analytically retrieved flow coefficients from simulated and experimental data acquired at short SDS. Monte Carlo (MC) simulations of photon correlation transport was programmed to simulate DCS measurements and used to (a) examine the accuracy and validity of theoretical analyses, and (b) model experimental measurements made on phantoms at short SDS. Experiments consisted of measurements from a series of optical phantoms containing an embedded flow channel. Both the fluid flow rate and depth of the flow channel from the liquid surface were varied. Inputs to MC simulations required to model experiments were obtained from corrected theoretical analyses. Results show that the widely used theoretical DCS model is robust for quantifying relative changes in flow. We also show that retrieved flow coefficients at short SDS can be scaled to retrieve absolute values via MC simulations.

Perfusion kinetics from clinical DCE mris increase the accuracy of predictions of tumor response to chemotherapy.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e12651-e12651
Author(s):  
John A Cole ◽  
Joseph R Peterson ◽  
Tyler M Earnest ◽  
Micahel J Hallock ◽  
John R Pfeiffer ◽  
...  
Keyword(s):  
Exchange Rates ◽  
Tumor Response ◽  
Tissue Perfusion ◽  
Response To Treatment ◽  
Vascular Density ◽  
Modeling Framework ◽  
Spatially Resolved ◽  
Response To Chemotherapy ◽  
Tumor Modeling ◽  
Extravascular Volume

e12651 Background: Nutrient and drug penetration into any solid tumor are critical determinants of the tumor's response to treatment. They depend on both the density of microvasculature within the tumor microenvironment, as well as the exchange rates of nutrients between the microvasculature and the extracellular space. But these parameters are heterogenous, varying considerably from location to location within the tumor and surrounding tissues. The Toft's model and its analogues date back to the early 1990s, and have been used to estimate vascular density, exchange rates, and extracellular-extravascular volume in a spatially-resolved manner using dynamic contrast enhaced (DCE) MRI's. Unfortunately, accurately extracting kinetic parameters from a DCE time-series requires the images to have a time-resolution of just a few seconds, which is rarely done in clinical practice. Methods: We employ a custom designed parallel algorithm to fit DCE MRI data to an exactly-solved ODE model of tissue perfusion kinetics. Results: Here we describe a simplified model of tissue perfusion that can be fit to DCE time traces with temporal resolutions of 90 seconds or more. We show that for many breast tumors, the vascular density and tissue-vascular exchange rate are such that they give rise to a halo of fast-perfusing tissue on the tumor periphery, and slower-perfusing tissue inside. We then use this model as part of a more comprehensive tumor simulation methodology to predict how different patients will respond to neoadjuvant chemotherapy (NACT). We find that the incorporation of our microvascular model gives rise to significantly more accurate predictions of post-treatment tumor volume. Conclusions: Performing perfusion kinetics analyses on clinical MRIs is both challenging, but critical for accurately predicting how a patient will respond to treatment. Our model, which relaxes the requirement for fine DCE temporal resolution, allows for these analyses to be performed on a larger swath of patients without the need for small volumes of interest, or ultra-fast MRI techniques. Moreover, when used within a broader tumor-modeling framework, our model increases the accuracy of predictions of tumor response to NACT.

Remote sensing of methane with broadband laser and optical correlation spectroscopy on the Q-branch of the 2ν3 band

2013 ◽  
Vol 291 ◽  
pp. 3-8 ◽  
Author(s):  
Benjamin Thomas ◽  
Grégory David ◽  
Christophe Anselmo ◽  
Elodie Coillet ◽  
Katja Rieth ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Correlation Spectroscopy ◽  
Optical Correlation ◽  
Broadband Laser
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