Measuring and Modeling Elastography of Human Cornea Using Scanning Laser Doppler Vibrometry

2013 ◽  
Author(s):  
Altaf Khan ◽  
Zoujun Dai ◽  
Thomas J. Royston
Keyword(s):  
Ex Vivo ◽  
Mechanical Vibration ◽  
Laser Doppler Vibrometer ◽  
Viscoelastic Plate ◽  
Laser Doppler ◽  
Scanning Laser ◽  
Human Cornea ◽  
In Vivo Experiments ◽  
Silicone Gels

Our interest is in noninvasively mapping the viscoelastic properties of the human cornea with the aid of a Scanning Laser Doppler Vibrometer (SLDV). Mechanical properties of the cornea can be used to predict early onset of diseases, such as glaucoma and keratoconus. By applying mechanical vibration near the cornea and measuring the dynamic wave propagation across the cornea, an elastographic map can be reconstructed. To effectively reconstruct the data, an appropriate analytical solution is needed to interpret the measured motion; in the present article, we review initial measurements and modeling of phantom cornea models. Several viscoelastic plate phantoms were constructed using silicone gels to simulate corneal structures. Comprehensive frequency sweeps were performed on these phantoms. The material can be represented using a fractional order model of viscoelasticity. Similar experiments have been completed on ex-vivo human cornea from donor eyes. The design shows proof of concept and is now being modified to a more applicable manner for in vivo experiments.

scholarly journals Development of a gel dedicated to gel immersion endoscopy

2021 ◽  
Vol 09 (06) ◽  
pp. E918-E924
Author(s):  
Tomonori Yano ◽  
Atsushi Ohata ◽  
Yuji Hiraki ◽  
Makoto Tanaka ◽  
Satoshi Shinozaki ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Porcine Model ◽  
Ex Vivo ◽  
In Vitro Experiments ◽  
Efficacy And Safety ◽  
Coagulative Necrosis ◽  
Novel Technique ◽  
In Vivo Experiments

Abstract Backgrounds and study aims Gel immersion endoscopy is a novel technique to secure the visual field during endoscopy. The aim of this study was to develop a dedicated gel for this technique. Methods To identify appropriate viscoelasticity and electrical conductivity, various gels were examined. Based on these results, the dedicated gel “OPF-203” was developed. Efficacy and safety of OPF-203 were evaluated in a porcine model. Results  In vitro experiments showed that a viscosity of 230 to 1900 mPa·s, loss tangent (tanδ) ≤ 0.6, and hardness of 240 to 540 N/cm2 were suitable. Ex vivo experiments showed electrical conductivity ≤ 220 μS/cm is appropriate. In vivo experiments using gastrointestinal bleeding showed that OPF-203 provided clear visualization compared to water. After electrocoagulation of gastric mucosa in OPF-203, severe coagulative necrosis was not observed in the muscularis but limited to the mucosa. Conclusions OPF-203 is useful for gel immersion endoscopy.

Identification of pavement material properties using a scanning laser Doppler vibrometer

2016 ◽  
Author(s):  
Navid Hasheminejad ◽  
Cedric Vuye ◽  
Wim Van den Bergh ◽  
Joris Dirckx ◽  
Jari Leysen ◽  
...  
Keyword(s):  
Material Properties ◽  
Laser Doppler Vibrometer ◽  
Laser Doppler ◽  
Scanning Laser ◽  
Scanning Laser Doppler Vibrometer ◽  
Pavement Material

scholarly journals Computed Poststenotic Flow Instabilities Correlate Phenotypically With Vibrations Measured Using Laser Doppler Vibrometry: Perspectives for a Promising In Vivo Device for Early Detection of Moderate and Severe Carotid Stenosis

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Viviana Mancini ◽  
Aslak W. Bergersen ◽  
Kristian Valen-Sendstad ◽  
Patrick Segers
Keyword(s):  
Early Detection ◽  
Carotid Stenosis ◽  
Pressure Fluctuations ◽  
Laser Doppler Vibrometer ◽  
Power Spectra ◽  
Laser Doppler ◽  
Flow Instabilities ◽  
Promising Tool ◽  
The Impact

Abstract Early detection of asymptomatic carotid stenosis is crucial for treatment planning in the prevention of ischemic stroke. Auscultation, the current first-line screening methodology, comes with severe limitations that create urge for novel and robust techniques. Laser Doppler vibrometer (LDV) is a promising tool for inferring carotid stenosis by measuring stenosis-induced vibrations. The goal of the current study was to evaluate the feasibility of LDV for carotid stenosis detection. LDV measurements on a carotid phantom were used to validate our previously verified high-resolution computational fluid dynamics methodology, which was used to evaluate the impact of flowrate, flow split, and stenosis severity on the poststenotic intensity of flow instabilities (IFI). We evaluated sensitivity, specificity, and accuracy of using IFI for stenoses detection. Linear regression analyses showed that computationally derived pressure fluctuations correlated (R2 = 0.98) with LDV measurements of stenosis-induced vibrations. The flowrate of stenosed vessels correlated (R2 = 0.90) with the presence of poststenotic instabilities. Receiver operating characteristic analyses of power spectra revealed that the most relevant frequency bands for the detection of moderate (56–76%) and severe (86–96%) stenoses were 80–200 Hz and 0–40 Hz, respectively. Moderate stenosis was identified with sensitivity and specificity of 90%; values decreased to 70% for severe stenosis. The use of LDV as screening tool for asymptomatic stenosis can potentially provide improved accuracy of current screening methodologies for early detection. The applicability of this promising device for mass screening is currently being evaluated clinically.

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