scholarly journals Learned spectral decoloring enables photoacoustic oximetry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Janek Gröhl ◽  
Thomas Kirchner ◽  
Tim J. Adler ◽  
Lina Hacker ◽  
Niklas Holzwarth ◽  
...  
Keyword(s):  
Photoacoustic Imaging ◽  
Initial Pressure ◽  
Blood Gas Analysis ◽  
Spatial Location ◽  
Gas Analysis ◽  
Blood Oxygenation ◽  
Tissue Properties ◽  
Light Fluence

AbstractThe ability of photoacoustic imaging to measure functional tissue properties, such as blood oxygenation sO$$_2$$ 2 , enables a wide variety of possible applications. sO$$_2$$ 2 can be computed from the ratio of oxyhemoglobin HbO$$_2$$ 2 and deoxyhemoglobin Hb, which can be distuinguished by multispectral photoacoustic imaging due to their distinct wavelength-dependent absorption. However, current methods for estimating sO$$_2$$ 2 yield inaccurate results in realistic settings, due to the unknown and wavelength-dependent influence of the light fluence on the signal. In this work, we propose learned spectral decoloring to enable blood oxygenation measurements to be inferred from multispectral photoacoustic imaging. The method computes sO$$_2$$ 2 pixel-wise, directly from initial pressure spectra $$S_{\text {p}_0}(\lambda , \mathbf {x})$$ S p 0 ( λ , x ) , which represent initial pressure values at a fixed spatial location $$\mathbf {x}$$ x over all recorded wavelengths $$\lambda$$ λ . The method is compared to linear unmixing approaches, as well as pO$$_2$$ 2 and blood gas analysis reference measurements. Experimental results suggest that the proposed method is able to obtain sO$$_2$$ 2 estimates from multispectral photoacoustic measurements in silico, in vitro, and in vivo.

An in vitro study of the effects of isoflurane on oxygen transfer

Perfusion ◽  
2001 ◽  
Vol 16 (4) ◽  
pp. 293-299 ◽  
Author(s):  
Michelle L Muhle ◽  
Alfred H Stammers ◽  
Kimberly D Tremain ◽  
Kevin S Niimi ◽  
Kimberly R Glogowski ◽  
...  
Keyword(s):  
Oxygen Transfer ◽  
Gas Flow ◽  
In Vitro Study ◽  
Blood Gas Analysis ◽  
Gas Analysis ◽  
Anesthetic Technique ◽  
Vitro Model ◽  
The Given

A common anesthetic technique utilized during cardiopulmonary bypass (CPB) includes the use of various inhalation agents, such as isoflurane. The purpose of this study was to evaluate the effects of this agent on oxygen transfer during CPB. An in vitro model was designed using bovine blood. Blood flow was held constant at 2 l/min, while gas flow was manipulated at 1 and 3 l/min. The percentage of inspired oxygen (FiO2) was set at 50 and 100%, and isoflurane was manipulated to 1.0, 3.0 and 5.0%. Blood gas analysis, oxygen transfer, and inlet and outlet isoflurane concentrations were measured at each of the given conditions. A total of 12 trials with four oxygenators were conducted. In the four oxygenators used in our study, no significant differences in oxygenator performance were found. At conditions of 1 l/min gas flow, 50% FiO2 and 1% isoflurane, there were no significant changes in O2 transfer between baseline and measurements taken during isoflurane administration (100.18 ± 12.49 vs 102.35 ± 10.99 ml O2/min, p=0.8031). At 3 l/min gas flow, 100% FiO2 and 5% isoflurane, no significant differences were found (142.35 ± 10.76 vs 154.04 ± 8.95 ml O2/min, p=0.1459). The only significant differences found for oxygen transfer were between 50 and 100% FiO2, all other conditions being set equal (102.35 ± 10.99 vs 137.68 ± 8.62 ml O2/min, p=0.0023). In conclusion, increasing concentrations of isoflurane up to 5% does not affect the efficiency of oxygen transfer in an in vitro circuit. Further studies are necessary to evaluate the effects in an in vivo setting.

scholarly journals In Vitro and In Vivo Multispectral Photoacoustic Imaging for the Evaluation of Chromophore Concentration

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3366
Author(s):  
Aneline Dolet ◽  
Rita Ammanouil ◽  
Virginie Petrilli ◽  
Cédric Richard ◽  
Piero Tortoli ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Photoacoustic Imaging ◽  
Hyperspectral Remote Sensing ◽  
Reference Spectrum ◽  
In Vivo Experiments ◽  
Mouse Tumors ◽  
Chromophore Concentration ◽  
Saturation Rate

Multispectral photoacoustic imaging is a powerful noninvasive medical imaging technique that provides access to functional information. In this study, a set of methods is proposed and validated, with experimental multispectral photoacoustic images used to estimate the concentration of chromophores. The unmixing techniques used in this paper consist of two steps: (1) automatic extraction of the reference spectrum of each pure chromophore; and (2) abundance calculation of each pure chromophore from the estimated reference spectra. The compared strategies bring positivity and sum-to-one constraints, from the hyperspectral remote sensing field to multispectral photoacoustic, to evaluate chromophore concentration. Particularly, the study extracts the endmembers and compares the algorithms from the hyperspectral remote sensing domain and a dedicated algorithm for segmentation of multispectral photoacoustic data to this end. First, these strategies are tested with dilution and mixing of chromophores on colored 4% agar phantom data. Then, some preliminary in vivo experiments are performed. These consist of estimations of the oxygen saturation rate (sO2) in mouse tumors. This article proposes then a proof-of-concept of the interest to bring hyperspectral remote sensing algorithms to multispectral photoacoustic imaging for the estimation of chromophore concentration.

Bioprinted Nanoparticles for Tissue Engineering Applications

2009 ◽  
Author(s):  
Kivilcim Buyukhatipoglu ◽  
Robert Chang ◽  
Wei Sun ◽  
Alisa Morss Clyne
Keyword(s):  
Tissue Engineering ◽  
Tissue Growth ◽  
Bioactive Components ◽  
Engineering Applications ◽  
Tissue Properties ◽  
Native Tissue ◽  
3D Architecture

Tissue engineering may require precise patterning of cells and bioactive components to recreate the complex, 3D architecture of native tissue. However, it is difficult to image and track cells and bioactive factors once they are incorporated into the tissue engineered construct. These bioactive factors and cells may also need to be moved during tissue growth in vitro or after implantation in vivo to achieve the desired tissue properties, or they may need to be removed entirely prior to implantation for biosafety concerns.

scholarly journals Is the resting rate of oxygen consumption of locomotor muscles in crustaceans limited by the low blood oxygenation strategy?

2001 ◽  
Vol 204 (5) ◽  
pp. 933-940 ◽  
Author(s):  
J. Forgue ◽  
A. Legeay ◽  
J.C. Massabuau
Keyword(s):  
Blood Oxygenation ◽  
Whole Body ◽  
Blood Gas ◽  
Astacus Leptodactylus ◽  
Night Time ◽  
Arterial Blood ◽  
Rate Of Oxygen Consumption ◽  
Locomotor Muscles

Numerous water-breathers exhibit a gas-exchange regulation strategy that maintains O(2) partial pressure, P(O2), in the arterial blood within the range 1–3 kPa at rest during the daytime. In a night-active crustacean, we examined whether this could limit the rate of O(2)consumption (M(O2)) of locomotor muscles and/or the whole body as part of a coordinated response to energy conservation. In the crayfish Astacus leptodactylus, we compared the in vitro relationship between the M(O2) of locomotor muscles as a function of the extracellular P(O2) and P(CO2) and in vivo circadian changes in blood gas tensions at various values of water P(O2). In vitro, the M(O2) of locomotor muscle, either at rest or when stimulated with CCCP, was O(2)-dependent up to an extracellular P(O2) of 8–10 kPa. In vivo, the existence of a night-time increase in arterial P(O2) of up to 4 kPa at water P(O2) values of 20 and 40 kPa was demonstrated, but an experimental increase in arterial P(O2) during the day did not lead to any rise in whole-body M(O2). This suggested that the low blood P(O2) in normoxia has no global limiting effect on daytime whole-body M(O2). The participation of blood O(2) status in shaping the circadian behaviour of crayfish is discussed.

scholarly journals Efficient Photoacoustic Imaging With Biomimetic Mesoporous Silica-Based Nanoparticles

2021 ◽  
Vol 9 ◽  
Author(s):  
Chuangjia Huang ◽  
Xiaoling Guan ◽  
Hui Lin ◽  
Lu Liang ◽  
Yingling Miao ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Near Infrared ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Mesoporous Silica Nanoparticles ◽  
Good Biocompatibility ◽  
Targeting Ability ◽  
Body Clearance

Indocyanine green (ICG), a near-infrared (NIR) fluorescent dye approved by the Food and Drug Administration (FDA), has been extensively used as a photoacoustic (PA) probe for PA imaging. However, its practical application is limited by poor photostability in water, rapid body clearance, and non-specificity. Herein, we fabricated a novel biomimetic nanoprobe by coating ICG-loaded mesoporous silica nanoparticles with the cancer cell membrane (namely, CMI) for PA imaging. This probe exhibited good dispersion, large loading efficiency, good biocompatibility, and homologous targeting ability to Hela cells in vitro. Furthermore, the in vivo and ex vivo PA imaging on Hela tumor-bearing nude mice demonstrated that CMI could accumulate in tumor tissue and display a superior PA imaging efficacy compared with free ICG. All these results demonstrated that CMI might be a promising contrast agent for PA imaging of cervical carcinoma.

Evaluation of an infrared laser-Doppler blood flowmeter

1987 ◽  
Vol 252 (6) ◽  
pp. G832-G839 ◽  
Author(s):  
A. P. Shepherd ◽  
G. L. Riedel ◽  
J. W. Kiel ◽  
D. J. Haumschild ◽  
L. C. Maxwell
Keyword(s):  
Rotational Velocity ◽  
Rotating Disk ◽  
Tissue Perfusion ◽  
Infrared Laser ◽  
Blood Oxygenation ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Flow Signal

Several laser-Doppler blood flowmeters are now commercially available; however, only one utilizes an infrared laser diode (Laserflo, TSI, St. Paul, MN). Because of this and other unique features such as its microprocessor-based signal analyzer, we evaluated this device's ability to measure tissue perfusion. Initially, we determined whether laser illumination directly affected the microvasculature. Intravital microscopic observations in the hamster cremaster muscle indicated that neither He-Ne nor infrared laser light affected the diameters of arterioles that were responsive to vasoactive agents. To test the flowmeter for linearity and repeatability, we used a rotating disk to simulate a light-scattering, flowing medium. The "flow" signal was highly correlated (r = 0.99) with the rotational velocity of the disk, was consistent among flow probes, and showed a high degree of reproducibility. The second model consisted of microsphere suspensions pumped through cuvettes. The laser-Doppler velocimeter (LDV) flow signal was linear with respect to pump output. With red blood cells in the perfusate, we examined the effects of blood oxygenation on the flowmeter's performance. The LDV flow signal was unaffected by changes in blood oxygenation. We evaluated linearity in vivo in isolated, perfused rat livers and in isolated canine gastric flaps. We observed linear relationships between total flow and laser-Doppler flow measured on the surface of the liver (r = 0.98) and in the gastric mucosa (r = 0.98), but the slopes of the relationships between total and local LDV flow showed considerable variability not noted in the in vitro studies.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Photoacoustic Imaging of Tattoo Inks: Phantom and Clinical Evaluation

2020 ◽  
Vol 10 (3) ◽  
pp. 1024 ◽  
Author(s):  
Eftekhar Rajab Bolookat ◽  
Laurie J. Rich ◽  
Gyorgy Paragh ◽  
Oscar R. Colegio ◽  
Anurag K. Singh ◽  
...  
Keyword(s):  
Photoacoustic Imaging ◽  
Imaging Modality ◽  
Preoperative Evaluation ◽  
Healthy Human ◽  
Non Invasive ◽  
Diagnostic Applications ◽  
Yellow Pigments ◽  
Tattoo Inks

Photoacoustic imaging (PAI) is a novel hybrid imaging modality that provides excellent optical contrast with the spatial resolution of ultrasound in vivo. The method is widely being investigated in the clinical setting for diagnostic applications in dermatology. In this report, we illustrate the utility of PAI as a non-invasive tool for imaging tattoos. Ten different samples of commercially available tattoo inks were examined for their optoacoustic properties in vitro. In vivo PAI of an intradermal tattoo on the wrist was performed in a healthy human volunteer. Black/gray, green, violet, and blue colored pigments provided higher levels of PA signal compared to white, orange, red, and yellow pigments in vitro. PAI provided excellent contrast and enabled accurate delineation of the extent of the tattoo in the dermis. Our results reveal the photoacoustic properties of tattoo inks and demonstrate the potential clinical utility of PAI for intradermal imaging of tattoos. PAI may be useful as a clinical adjunct for objective preoperative evaluation of tattoos and potentially to guide/monitor laser-based tattoo removal procedures.

Comprehensive Identification of Tibiofemoral Joint Anatomy and Mechanical Response: Pathway to Multiscale Characterization

2012 ◽  
Author(s):  
Snehal Chokhandre ◽  
Craig Bennetts ◽  
Jason Halloran ◽  
Robb Colbrunn ◽  
Tara Bonner ◽  
...  
Keyword(s):  
Knee Joint ◽  
Mechanical Response ◽  
Model Development ◽  
Fe Analysis ◽  
Tissue Response ◽  
Tissue Properties ◽  
Multiscale Mechanics ◽  
Human Knee Joint

The human knee joint is a complex multi-body structure, whose substructures greatly affect its mechanical response. An understanding of the multiscale mechanics of the joint is essential for the prevention and treatment of knee joint injuries and pathologies. Due to the limitations associated with in vivo experimentation, mechanical characterization of the knee joint has commonly relied on in vitro experimentation [1,2]. Predictive and descriptive studies of the mechanical function of the knee and its substructures have commonly employed computational modeling, in particular finite element (FE) analysis, which can be driven by experimental data. With the recent focus on the use of FE models of the knee joint for scientific and clinical purposes [3–5], data for model development, verification, and validation became increasingly important, especially when relying on FE analysis for decision making. An adequate representation of a joint not only depends on the specimen-specific anatomy but may also need to be informed by specimen-specific tissue properties for model development, and specimen-specific joint/tissue response to confirm model response.

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