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Articoli di riviste sul tema "Oxygenation imaging"

Autore: Grafiati

Pubblicato: 26 ottobre 2023

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1

Costantino, ML, e GB Fiore. "Normalization of experimental results with respect to inlet conditions in membrane oxygenator testing". Perfusion 11, n. 1 (gennaio 1996): 45–51. http://dx.doi.org/10.1177/026765919601100106.

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This study looked at the problem of the excessive variability in oxygenator testing results, induced by variation of inlet parameters, particularly of inlet oxyhaemoglobin saturation. The investigation was carried out in the laboratory. An in vitro circuit was used to perfuse a small oxygenating cell. Blood flow rate (BFR) and film thickness (BFT) were varied to obtain different oxygenation conditions, while the inspired oxygen fraction (FiO 2) and ventilation ratio were kept at constant values. With each test condition, inlet saturation was varied in the range 60-70% and a number of veno-arterial blood samples (at least 20) were withdrawn and analysed for numerical computing and statistical analysis. The generic law relating oxygenation increment to inlet saturation was found. This allowed a useful normalization procedure to be applied to oxygenator testing results and render them comparable, even if obtained at different inlet conditions.

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2

Padhani, Anwar R., Kenneth A. Krohn, Jason S. Lewis e Markus Alber. "Imaging oxygenation of human tumours". European Radiology 17, n. 4 (17 ottobre 2006): 861–72. http://dx.doi.org/10.1007/s00330-006-0431-y.

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3

Benaron, David A., Susan R. Hintz, Arno Villringer, David Boas, Andreas Kleinschmidt, Jens Frahm, Christina Hirth et al. "Noninvasive Functional Imaging of Human Brain Using Light". Journal of Cerebral Blood Flow & Metabolism 20, n. 3 (marzo 2000): 469–77. http://dx.doi.org/10.1097/00004647-200003000-00005.

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Analysis of photon transit time for low-power light passing into the head, and through both skull and brain, of human subjects allowed for tomographic imaging of cerebral hemoglobin oxygenation based on photon diffusion theory. In healthy adults, imaging of changes in hemoglobin saturation during hand movement revealed focal, contralateral increases in motor cortex oxygenation with spatial agreement to activation maps determined by functional magnetic resonance imaging; in ill neonates, imaging of hemoglobin saturation revealed focal regions of low oxygenation after acute stroke, with spatial overlap to injury location determined by computed tomography scan. Because such slow optical changes occur over seconds and co-localize with magnetic resonance imaging vascular signals whereas fast activation-related optical changes occur over milliseconds and co-localize with EEG electrical signals, optical methods offer a single modality for exploring the spatio-temporal relationship between electrical and vascular responses in the brain in vivo, as well as for mapping cortical activation and oxygenation at the bedside in real-time for clinical monitoring.

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4

Kirkham, Brooke M., Susan M. Schultz, Khalid Ashi e Chandra M. Sehgal. "Assessment of Age-related Oxygenation Changes in Calf Skeletal Muscle by Photoacoustic Imaging: A Potential Tool for Peripheral Arterial Disease". Ultrasonic Imaging 41, n. 5 (19 luglio 2019): 290–300. http://dx.doi.org/10.1177/0161734619862287.

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Peripheral artery disease is often asymptomatic, and various imaging and nonimaging techniques have been used for assessment and monitoring treatments. This study is designed to demonstrate the ability of photoacoustic imaging to noninvasively determine changes in tissue oxygenation that occur in mice’s hind limb skeletal muscle as they age. Mice from two age cohorts were scanned bilaterally with a pulsed laser. The photoacoustic signal was unmixed to generate a parametric map of estimated oxygen saturation and then overlaid on grayscale ultrasound images. Tissue oxygenation measured in young and old mice was compared. Photoacoustic imaging visually and quantitatively showed the decrease in skeletal muscle oxygenation that occurs with age. Percent tissue oxygenation decreased from 30.2% to 3.5% ( p < 0.05). This reduction corresponded to reduced fractional area of oxygenation, which decreased from 60.6% to 6.0% ( p < 0.05). The change in oxygenation capacity of the still active vascular regions was insignificant ( p > 0.05). Intrasubject, intra-, and interobserver comparisons showed low variability in measurements, exhibited by high regression and intraclass correlations exceeding 0.81 for all ages. The decrease in oxygenation detected by photoacoustic imaging paralleled the known oxygenation decrease observed in aging tissues, demonstrating that photoacoustic imaging can assess age-related changes in a mouse calf muscle. These intramuscular changes could potentially act as a strong diagnostic marker for peripheral artery disease. This study thus opens the doors for a novel, affordable, noninvasive method of evaluation free of radiation or exogenous material.

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Vivier, Pierre-Hugues, Pippa Storey, Hersh Chandarana, Akira Yamamoto, Kristopher Tantillo, Umer Khan, Jeff L. Zhang et al. "Renal Blood Oxygenation Level–Dependent Imaging". Investigative Radiology 48, n. 7 (luglio 2013): 501–8. http://dx.doi.org/10.1097/rli.0b013e3182823591.

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6

Cies, Jeffrey J., Wayne S. Moore, Nadji Giliam, Tracy Low, Daniel Marino, Jillian Deacon, Adela Enache e Arun Chopra. "Oxygenator impact on voriconazole in extracorporeal membrane oxygenation circuits". Perfusion 35, n. 6 (6 luglio 2020): 529–33. http://dx.doi.org/10.1177/0267659120937906.

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Introduction: To determine the oxygenator impact on alterations of voriconazole in a contemporary neonatal/pediatric (1/4 inch) and adolescent/adult (3/8 inch) extracorporeal membrane oxygenation circuit including the Quadrox-i® oxygenator. Methods: Simulated closed-loop extracorporeal membrane oxygenation circuits (1/4 and 3/8 inch) were prepared with a Quadrox-i pediatric and Quadrox-i adult oxygenator and blood primed. In addition, 1/4- and 3/8-inch circuits were also prepared without an oxygenator in series. A one-time dose of voriconazole was administered into the circuits, and serial pre- and post-oxygenator concentrations were obtained at 5 minutes, 1, 2, 3, 4, 5, 6, and 24 hour time points. Voriconazole was also maintained in a glass vial and samples were taken from the vial at the same time periods for control purposes to assess for spontaneous drug degradation Results: For the 1/4-inch circuit, there was an approximate mean of 64-67% voriconazole loss with the oxygenator in series and mean of 15-20% voriconazole loss without an oxygenator in series at 24 hours. For the 3/8-inch circuit, there was an approximate mean of 44-51% voriconazole loss with the oxygenator in series and a mean of 8-12% voriconazole loss without an oxygenator in series at 24 hours. The reference voriconazole concentrations remained relatively constant during the entire study period demonstrating that the drug loss in each size of the extracorporeal membrane oxygenation circuit with or without an oxygenator was not a result of spontaneous drug degradation. Conclusion: This ex vivo investigation demonstrated substantial voriconazole loss within an extracorporeal membrane oxygenation circuit with an oxygenator in series with both sizes of the Quadrox-i oxygenator at 24 hours and no significant voriconazole loss in the absence of an oxygenator. Further evaluations with multiple dose in vitro and in vivo investigations are needed before specific voriconazole dosing recommendations can be made for clinical application with extracorporeal membrane oxygenation.

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7

Ni, Wendy W., Thomas Christen, Jarrett Rosenberg, Zungho Zun, Michael E. Moseley e Greg Zaharchuk. "Imaging of cerebrovascular reserve and oxygenation in Moyamoya disease". Journal of Cerebral Blood Flow & Metabolism 37, n. 4 (20 luglio 2016): 1213–22. http://dx.doi.org/10.1177/0271678x16651088.

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This study aimed to determine whether measurements of cerebrovascular reserve and oxygenation, assessed with spin relaxation rate R2′, yield similar information about pathology in pre-operative Moyamoya disease patients, and to assess whether R2′ is a better measure of oxygenation than other proposed markers, such as R2* and R2. Twenty-five pre-operative Moyamoya disease patients were scanned at 3.0T with acetazolamide challenge. Cerebral blood flow mapping with multi-delay arterial spin labeling, and R2*, R2, and R2′ mapping with Gradient-Echo Sampling of Free Induction Decay and Echo were performed. No baseline cerebral blood flow difference was found between angiographically abnormal and normal regions (49 ± 12 vs. 48 ± 11 mL/100 g/min, p = 0.44). However, baseline R2′ differed between these regions (3.2 ± 0.7 vs. 2.9 ± 0.6 s−1, p < 0.001), indicating reduced oxygenation in abnormal regions. Cerebrovascular reserve was lower in angiographically abnormal regions (21 ± 38 vs. 41 ± 26%, p = 0.001). All regions showed trend toward significantly improved oxygenation post-acetazolamide. Regions with poorer cerebrovascular reserve had lower baseline oxygenation (Kendall's τ = −0.24, p = 0.003). A number of angiographically abnormal regions demonstrated preserved cerebrovascular reserve, likely due to the presence of collaterals. Finally, of the concurrently measured relaxation rates, R2′ was superior for oxygenation assessment.

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Yamaleyeva, Liliya M., K. Bridget Brosnihan, Lane M. Smith e Yao Sun. "Preclinical Ultrasound-Guided Photoacoustic Imaging of the Placenta in Normal and Pathologic Pregnancy". Molecular Imaging 17 (1 gennaio 2018): 153601211880272. http://dx.doi.org/10.1177/1536012118802721.

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Placental oxygenation varies throughout pregnancy. The detection of early changes in placental oxygenation as pregnancy progresses is important for early identification of preeclampsia or other complications. This invited commentary discusses a recent preclinical study on the application of 3-dimensional photoacoustic imaging (PAI) for assessment of regional variations in placental oxygenation and longitudinal analysis of differences in placental oxygenation throughout normal pregnancy and pregnancy associated with hypertension or placental insufficiency in mice. Three-dimensional PAI more accurately reflects oxygen saturation, hemoglobin concentrations, and changes in oxygen saturation in whole placenta compared to 2-dimensional imaging. These studies suggest that PAI is a sensitive tool to detect different levels of oxygen saturation in the placental and fetal vasculature in pathologic and normal pregnancy in mice.

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9

Yang, Hsin-Jung, Ilkay Oksuz, Damini Dey, Jane Sykes, Michael Klein, John Butler, Michael S. Kovacs et al. "Accurate needle-free assessment of myocardial oxygenation for ischemic heart disease in canines using magnetic resonance imaging". Science Translational Medicine 11, n. 494 (29 maggio 2019): eaat4407. http://dx.doi.org/10.1126/scitranslmed.aat4407.

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Myocardial oxygenation—the ability of blood vessels to supply the heart muscle (myocardium) with oxygen—is a critical determinant of cardiac function. Impairment of myocardial oxygenation is a defining feature of ischemic heart disease (IHD), which is caused by pathological conditions that affect the blood vessels supplying oxygen to the heart muscle. Detecting altered myocardial oxygenation can help guide interventions and prevent acute life-threatening events such as heart attacks (myocardial infarction); however, current diagnosis of IHD relies on surrogate metrics and exogenous contrast agents for which many patients are contraindicated. An oxygenation-sensitive cardiac magnetic resonance imaging (CMR) approach used previously to demonstrate that CMR signals can be sensitized to changes in myocardial oxygenation showed limited ability to detect small changes in signals in the heart because of physiologic and imaging noise during data acquisition. Here, we demonstrate a CMR-based approach termed cfMRI [cardiac functional magnetic resonance imaging (MRI)] that detects myocardial oxygenation. cfMRI uses carbon dioxide for repeat interrogation of the functional capacity of the heart’s blood vessels via a fast MRI approach suitable for clinical adoption without limitations of key confounders (cardiac/respiratory motion and heart rate changes). This method integrates multiple whole-heart images within a computational framework to reduce noise, producing confidence maps of alterations in myocardial oxygenation. cfMRI permits noninvasive monitoring of myocardial oxygenation without requiring ionizing radiation, contrast agents, or needles. This has the potential to broaden our ability to noninvasively identify IHD and a diverse spectrum of heart diseases related to myocardial ischemia.

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Shahidi, Mahnaz, Norman P. Blair, Marek Mori e Ruth Zelkha. "Feasibility of Noninvasive Imaging of Chorioretinal Oxygenation". Ophthalmic Surgery, Lasers and Imaging Retina 35, n. 5 (1 settembre 2004): 415–22. http://dx.doi.org/10.3928/1542-8877-20040901-10.

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11

Schreml, Stephan, Robert J. Meier, Otto S. Wolfbeis, Tim Maisch, Rolf-Markus Szeimies, Michael Landthaler, Johannes Regensburger, Francesco Santarelli, Ingo Klimant e Philipp Babilas. "2D luminescence imaging of physiological wound oxygenation". Experimental Dermatology 20, n. 7 (28 marzo 2011): 550–54. http://dx.doi.org/10.1111/j.1600-0625.2011.01263.x.

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12

Baker, Clayton A., Nashaat Rasheed, Parag V. Chitnis e Siddhartha Sikdar. "Photoacoustic imaging of muscle oxygenation during exercise". Journal of the Acoustical Society of America 139, n. 4 (aprile 2016): 2176. http://dx.doi.org/10.1121/1.4950463.

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Huong, Audrey, Sheena Philimon e Xavier Ngu. "Multispectral imaging of acute wound tissue oxygenation". Journal of Innovative Optical Health Sciences 10, n. 03 (4 aprile 2017): 1750004. http://dx.doi.org/10.1142/s1793545817500043.

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This paper investigates the appropriate range of values for the transcutaneous blood oxygen saturation (StO2) of granulating tissues and the surrounding tissue that can ensure timely wound recovery. This work has used a multispectral imaging system to collect wound images at wavelengths ranging between 520[Formula: see text]nm and 600[Formula: see text]nm with a resolution of 10[Formula: see text]nm. As part of this research, a pilot study was conducted on three injured individuals with superficial wounds of different wound ages at different skin locations. The StO2 value predicted for the examined wounds using the Extended Modified Lambert–Beer model revealed a mean StO2 of [Formula: see text]% compared to [Formula: see text]% at the surrounding tissues, and [Formula: see text]% for control sites. These preliminary results contribute to the existing knowledge on the possible range and variation of wound bed StO2 that are to be used as indicators of the functioning of the vasomotion system and wound health. This study has concluded that a high StO2 of approximately 60% and a large fluctuation in this value should precede a good progression in wound healing.

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Dmitriev, Ruslan I., Alexander V. Zhdanov, Yvonne M. Nolan e Dmitri B. Papkovsky. "Imaging of neurosphere oxygenation with phosphorescent probes". Biomaterials 34, n. 37 (dicembre 2013): 9307–17. http://dx.doi.org/10.1016/j.biomaterials.2013.08.065.

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Lee, Steven, e Abhishek Chaturvedi. "Imaging adults on extracorporeal membrane oxygenation (ECMO)". Insights into Imaging 5, n. 6 (9 ottobre 2014): 731–42. http://dx.doi.org/10.1007/s13244-014-0357-x.

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Dallefeld, Samantha H., Jennifer Sherwin, Kanecia O. Zimmerman e Kevin M. Watt. "Dexmedetomidine extraction by the extracorporeal membrane oxygenation circuit: results from an in vitro study". Perfusion 35, n. 3 (21 agosto 2019): 209–16. http://dx.doi.org/10.1177/0267659119868062.

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Background: Dexmedetomidine is a sedative administered to minimize distress and decrease the risk of life threatening complications in children supported with extracorporeal membrane oxygenation. The extracorporeal membrane oxygenation circuit can extract drug and decrease drug exposure, placing the patient at risk of therapeutic failure. Objective: To determine the extraction of dexmedetomidine by the extracorporeal membrane oxygenation circuit. Materials and methods: Dexmedetomidine was studied in three closed-loop circuit configurations to isolate the impact of the oxygenator, hemofilter, and tubing on circuit extraction. Each circuit was primed with human blood according to standard practice for Duke Children’s Hospital, and flow was set to 1 L/min. Dexmedetomidine was dosed to achieve a therapeutic concentration of ~600 pg/mL. Dexmedetomidine was added to a separate tube of blood to serve as a control and evaluate for natural drug degradation. Serial blood samples were collected over 24 hours and concentrations were quantified with a validated assay. Drug recovery was calculated at each time point. Results: Dexmedetomidine was highly extracted by the oxygenator evidenced by a mean recovery of 62-67% at 4 hours and 23-34% at 24 hours in circuits with an oxygenator in-line. In contrast, mean recovery with the oxygenator removed was 96% at 4 hours and 93% at 24 hours. Dexmedetomidine was stable over time with a mean recovery in the control samples of 102% at 24 hours. Conclusion: These results suggest dexmedetomidine is extracted by the oxygenator in the extracorporeal membrane oxygenation circuit which may result in decreased drug exposure in vivo.

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Bauer, Jacob Renzo, Arnoud A. Bruins, Jon Yngve Hardeberg e Rudolf M. Verdaasdonk. "A Spectral Filter Array Camera for Clinical Monitoring and Diagnosis: Proof of Concept for Skin Oxygenation Imaging". Journal of Imaging 5, n. 8 (26 luglio 2019): 66. http://dx.doi.org/10.3390/jimaging5080066.

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The emerging technology of spectral filter array (SFA) cameras has great potential for clinical applications, due to its unique capability for real time spectral imaging, at a reasonable cost. This makes such cameras particularly suitable for quantification of dynamic processes such as skin oxygenation. Skin oxygenation measurements are useful for burn wound healing assessment and as an indicator of patient complications in the operating room. Due to their unique design, in which all pixels of the image sensor are equipped with different optical filters, SFA cameras require specific image processing steps to obtain meaningful high quality spectral image data. These steps include spatial rearrangement, SFA interpolations and spectral correction. In this paper the feasibility of a commercially available SFA camera for clinical applications is tested. A suitable general image processing pipeline is proposed. As a ’proof of concept’ a complete system for spatial dynamic skin oxygenation measurements is developed and evaluated. In a study including 58 volunteers, oxygenation changes during upper arm occlusion were measured with the proposed SFA system and compared with a validated clinical device for localized oxygenation measurements. The comparison of the clinical standard measurements and SFA results show a good correlation for the relative oxygenation changes. This proposed processing pipeline for SFA cameras shows to be effective for relative oxygenation change imaging. It can be implemented in real time and developed further for absolute spatial oxygenation measurements.

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Argudo, Eduard, Jordi Riera, Sonia Luque, Ibai Los-Arcos, Manuel López-Meseguer, Alberto Sandiumenge, Xavier Nuvials, Santiago Grau e Ricard Ferrer. "Effects of the extracorporeal membrane oxygenation circuit on plasma levels of ceftolozane". Perfusion 35, n. 3 (7 agosto 2019): 267–70. http://dx.doi.org/10.1177/0267659119864813.

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Introduction: New antibiotics with bactericidal activity against multi-drug-resistant bacteria are increasingly used in the intensive care units. Here, we aimed to evaluate the influence of the extracorporeal membrane oxygenation on plasma levels of ceftolozane. Case report: A 34-year-old female was admitted to the intensive care unit after bilateral lung transplantation, complicated by primary graft dysfunction and cardiogenic shock needing venoarterial extracorporeal membrane oxygenation. Ceftolozane/tazobactam was started. Plasma ceftolozane levels were monitored on the first and third days of antibiotic treatment. A non-compartment pharmacokinetic analysis was performed and the extraction rate through the oxygenator was calculated. Discussion: The extracorporeal circuit of extracorporeal membrane oxygenation may alter the pharmacokinetics of antibiotics, to varying degrees due to drug sequestration and increased distribution volume. In this case, the extracorporeal membrane oxygenation circuit had little impact on the ceftolozane plasma concentration. Conclusion: Plasma levels of ceftolozane are stable in the extracorporeal membrane oxygenation circuit, suggesting that adjustment of standard doses of ceftolozane in patients with extracorporeal membrane oxygenation support may not be needed.

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Zakhary, Bishoy, Jayne Sheldrake e Vincent Pellegrino. "Extracorporeal membrane oxygenation and V/Q ratios: an ex vivo analysis of CO2 clearance within the Maquet Quadrox-iD oxygenator". Perfusion 35, n. 1_suppl (maggio 2020): 29–33. http://dx.doi.org/10.1177/0267659120906767.

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While hypercapnia is typically well treated with modern membrane oxygenators, there are cases where respiratory acidosis persists despite maximal extracorporeal membrane oxygenation support. To better understand the physiology of gas exchange within the membrane oxygenator, CO2 clearance within an adult Maquet Quadrox-iD oxygenator was evaluated at varying blood CO2 tensions and V/Q ratios in an ex vivo extracorporeal membrane oxygenation circuit. A closed blood-primed circuit incorporating two Maquet Quadrox-iD oxygenators in series was attached to a Maquet PLS Rotaflow pump. A varying blend of CO2 and air was connected to the first oxygenator to provide different levels of pre-oxygenator blood CO2 levels (PvCO2) to the second oxygenator. Varying sweep gas flows of 100% O2 were connected to the second oxygenator to provide different V/Q ratios. Exhaust CO2 was directly measured, and then VCO2 and oxygenator dead space fraction (VD/VT) were calculated. VCO2 increased with increasing gas flow rates with plateauing at V/Q ratios greater than 4.0. Exhaust CO2 increased with PvCO2 in a linear fashion with the slope of the line decreasing at high V/Q ratios. Oxygenator dead space fraction varied with V/Q ratio—at lower ratios, dead space fraction was 0.3-0.4 and rose to 0.8-0.9 at ratios greater than 4.0. Within the Maquet Quadrox-iD oxygenator, CO2 clearance is limited at high V/Q ratios and correlated with elevated oxygenator dead space fraction. These findings have important implications for patients requiring high levels of extracorporeal membrane oxygenation support.

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Howseman, Alistair M., e Richard W. Bowtel. "Functional magnetic resonance imaging: imaging techniques and contrast mechanisms". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 354, n. 1387 (29 luglio 1999): 1179–94. http://dx.doi.org/10.1098/rstb.1999.0473.

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Functional magnetic resonance imaging (fMRI) is a widely used technique for generating images or maps of human brain activity. The applications of the technique are widespread in cognitive neuroscience and it is hoped they will eventually extend into clinical practice. The activation signal measured with fMRI is predicated on indirectly measuring changes in the concentration of deoxyhaemoglobin which arise from an increase in blood oxygenation in the vicinity of neuronal firing. The exact mechanisms of this blood oxygenation level dependent (BOLD) contrast are highly complex. The signal measured is dependent on both the underlying physiological events and the imaging physics. BOLD contrast, although sensitive, is not a quantifiable measure of neuronal activity. A number of different imaging techniques and parameters can be used for fMRI, the choice of which depends on the particular requirements of each functional imaging experiment. The high–speed MRI technique, echo–planar imaging provides the basis for most fMRI experiments. The problems inherent to this method and the ways in which these may be overcome are particularly important in the move towards performing functional studies on higher field MRI systems. Future developments in techniques and hardware are also likely to enhance the measurement of brain activity using MRI.

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Ikuhiro, Kida, K. Maciejewski Paul e Fahmeed Hyder. "Dynamic Imaging of Perfusion and Oxygenation by Functional Magnetic Resonance Imaging". Journal of Cerebral Blood Flow & Metabolism 24, n. 12 (dicembre 2004): 1369–81. http://dx.doi.org/10.1097/01.wcb.0000141501.12558.9b.

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Cerebral blood flow can be measured with magnetic resonance imaging (MRI) by arterial spin labeling techniques, where magnetic labeling of flowing spins in arterial blood water functions as the endogenous tracer upon mixing with the unlabeled stationary spins of tissue water. The consequence is that the apparent longitudinal relaxation time (T1) of tissue water is attenuated. A modified functional MRI scheme for dynamic CBF measurement is proposed that depends on extraction of T1 weighting from the blood oxygenation level–dependent (BOLD) image contrast, because the functional MRI signal also has an intrinsic T1 weighting that can be altered by variations of the excitation flip angle. In the α-chloralose-anesthetized rat model at 7T, the authors show that the stimulation-induced BOLD signal change measured with two different flip angles can be combined to obtain a T1-weighted MRI signal, reflecting the magnitude of the CBF change, which can be deconvolved to obtain dynamic changes in CBF. The deconvolution of the T1-weighted MRI signal, which is a necessary step for accurate reflection of the dynamic changes in CBF, was made possible by a transfer function obtained from parallel laser-Doppler flowmetry experiments. For all stimulus durations (ranging from 4 to 32 seconds), the peak CBF response measured by MRI after the deconvolution was reached at 4.5 ± 1.0 seconds, which is in good agreement with (present and prior) laser-Doppler measurements. Because the low flip angle data can also provide dynamic changes of the conventional BOLD image contrast, this method can be used for simultaneous imaging of CBF and BOLD dynamics.

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Yadav, Brijesh Kumar, Uday Krishnamurthy, Sagar Buch, Pavan Jella, Edgar Hernandez-Andrade, Lami Yeo, Steven J. Korzeniewski et al. "Imaging putative foetal cerebral blood oxygenation using susceptibility weighted imaging (SWI)". European Radiology 28, n. 5 (15 dicembre 2017): 1884–90. http://dx.doi.org/10.1007/s00330-017-5160-x.

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Vazquez, Alberto L., Mitsuhiro Fukuda e Seong-Gi Kim. "Evolution of the Dynamic Changes in Functional Cerebral Oxidative Metabolism from Tissue Mitochondria to Blood Oxygen". Journal of Cerebral Blood Flow & Metabolism 32, n. 4 (1 febbraio 2012): 745–58. http://dx.doi.org/10.1038/jcbfm.2011.198.

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The dynamic properties of the cerebral metabolic rate of oxygen consumption (CMRO2) during changes in brain activity remain unclear. Therefore, the spatial and temporal evolution of functional increases in CMRO2 was investigated in the rat somato-sensory cortex during forelimb stimulation under a suppressed blood flow response condition. Temporally, stimulation elicited a fast increase in tissue mitochondria CMRO2 described by a time constant of ~ 1 second measured using flavoprotein autofluorescence imaging. CMRO2-driven changes in the tissue oxygen tension measured using an oxygen electrode and blood oxygenation measured using optical imaging of intrinsic signal followed; however, these changes were slow with time constants of ~ 5 and ~ 10 seconds, respectively. This slow change in CMRO2-driven blood oxygenation partly explains the commonly observed post-stimulus blood oxygen level-dependent (BOLD) undershoot. Spatially, the changes in mitochondria CMRO2 were similar to the changes in blood oxygenation. Finally, the increases in CMRO2 were well correlated with the evoked multi-unit spiking activity. These findings show that dynamic CMRO2 calculations made using only blood oxygenation data (e.g., BOLD functional magnetic resonance imaging (fMRI)) do not directly reflect the temporal changes in the tissue's mitochondria metabolic rate; however, the findings presented can bridge the gap between the changes in cellular oxidative rate and blood oxygenation.

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Christen, T., D. S. Bolar e G. Zaharchuk. "Imaging Brain Oxygenation with MRI Using Blood Oxygenation Approaches: Methods, Validation, and Clinical Applications". American Journal of Neuroradiology 34, n. 6 (2 agosto 2012): 1113–23. http://dx.doi.org/10.3174/ajnr.a3070.

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Dietrich, Maximilian, Berkin Özdemir, Daniel Gruneberg, Clara Petersen, Alexander Studier-Fischer, Maik von der Forst, Felix C. F. Schmitt et al. "Hyperspectral Imaging for the Evaluation of Microcirculatory Tissue Oxygenation and Perfusion Quality in Haemorrhagic Shock: A Porcine Study". Biomedicines 9, n. 12 (3 dicembre 2021): 1829. http://dx.doi.org/10.3390/biomedicines9121829.

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Background: The ultimate goal of haemodynamic therapy is to improve microcirculatory tissue and organ perfusion. Hyperspectral imaging (HSI) has the potential to enable noninvasive microcirculatory monitoring at bedside. Methods: HSI (Tivita® Tissue System) measurements of tissue oxygenation, haemoglobin, and water content in the skin (ear) and kidney were evaluated in a double-hit porcine model of major abdominal surgery and haemorrhagic shock. Animals of the control group (n = 7) did not receive any resuscitation regime. The interventional groups were treated exclusively with either crystalloid (n = 8) or continuous norepinephrine infusion (n = 7). Results: Haemorrhagic shock led to a drop in tissue oxygenation parameters in all groups. These correlated with established indirect markers of tissue oxygenation. Fluid therapy restored tissue oxygenation parameters. Skin and kidney measurements correlated well. High dose norepinephrine therapy deteriorated tissue oxygenation. Tissue water content increased both in the skin and the kidney in response to fluid therapy. Conclusions: HSI detected dynamic changes in tissue oxygenation and perfusion quality during shock and was able to indicate resuscitation effectivity. The observed correlation between HSI skin and kidney measurements may offer an estimation of organ oxygenation impairment from skin monitoring. HSI microcirculatory monitoring could open up new opportunities for the guidance of haemodynamic management.

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Malfertheiner, Maximilian Valentin, Lars Mikael Broman, Leen Vercaemst, Mirko Belliato, Anna Aliberti, Matteo Di Nardo, Justyna Swol et al. "Ex vivo models for research in extracorporeal membrane oxygenation: a systematic review of the literature". Perfusion 35, n. 1_suppl (maggio 2020): 38–49. http://dx.doi.org/10.1177/0267659120907439.

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Abstract (sommario):

With ongoing progress of components of extracorporeal membrane oxygenation including improvements of oxygenators, pumps, and coating materials, extracorporeal membrane oxygenation became increasingly accepted in the clinical practice. A suitable testing in an adequate setup is essential for the development of new technical aspects. Relevant tests can be conducted in ex vivo models specifically designed to test certain aspects. Different setups have been used in the past for specific research questions. We conducted a systematic literature review of ex vivo models of extracorporeal membrane oxygenation components. MEDLINE and Embase were searched between January 1996 and October 2017. The inclusion criteria were ex vivo models including features of extracorporeal membrane oxygenation technology. The exclusion criteria were clinical studies, abstracts, studies in which the model of extracorporeal membrane oxygenation has been reported previously, and studies not reporting on extracorporeal membrane oxygenation components. A total of 50 studies reporting on different ex vivo extracorporeal membrane oxygenation models have been identified from the literature search. Models have been grouped according to the specific research question they were designed to test for. The groups are focused on oxygenator performance, pump performance, hemostasis, and pharmacokinetics. Pre-clinical testing including use of ex vivo models is an important step in the development and improvement of extracorporeal membrane oxygenation components and materials. Furthermore, ex vivo models offer valuable insights for clinicians to better understand the consequences of choice of components, setup, and management of an extracorporeal membrane oxygenation circuit in any given condition. There is a need to standardize the reporting of pre-clinical studies in this area and to develop best practice in their design.

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27

An, Hongyu, Qingwei Liu, Cihat Eldeniz e Weili Lin. "Absolute Oxygenation Metabolism Measurements Using Magnetic Resonance Imaging". Open Neuroimaging Journal 5, Suppl 1 (4 novembre 2011): 120–35. http://dx.doi.org/10.2174/1874440001105010120.

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28

J. Muccigrosso, David. "Quantifying Myocardial Oxygenation with Cardiac Magnetic Resonance Imaging". Open Medical Imaging Journal 6, n. 1 (6 aprile 2012): 39–44. http://dx.doi.org/10.2174/1874347101206010039.

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29

Chen, Maomao, Hailey J. Knox, Yuqi Tang, Wei Liu, Liming Nie, Jefferson Chan e Junjie Yao. "Simultaneous photoacoustic imaging of intravascular and tissue oxygenation". Optics Letters 44, n. 15 (24 luglio 2019): 3773. http://dx.doi.org/10.1364/ol.44.003773.

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30

Srinivasan, Vivek J., e Ala Moshiri. "Imaging oxygenation of retinal capillaries with depth resolution". Proceedings of the National Academy of Sciences 117, n. 26 (18 giugno 2020): 14626–28. http://dx.doi.org/10.1073/pnas.2008404117.

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31

Zheng, Jie. "Myocardial Oxygenation Imaging: New Methods for Ischemia Detection". Current Cardiovascular Imaging Reports 4, n. 2 (5 gennaio 2011): 159–64. http://dx.doi.org/10.1007/s12410-010-9063-3.

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32

Thacker, Jon M., Lu-Ping Li, Wei Li, Ying Zhou, Stuart M. Sprague e Pottumarthi V. Prasad. "Renal Blood Oxygenation Level-Dependent Magnetic Resonance Imaging". Investigative Radiology 50, n. 12 (dicembre 2015): 821–27. http://dx.doi.org/10.1097/rli.0000000000000190.

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33

Mcintyre, Michael, Wolfgang Richter, Dara Morden, Anders Wennerberg e Uta Frankenstein. "Blood oxygenation level dependent functional magnetic resonance imaging". Concepts in Magnetic Resonance 16A, n. 1 (2003): 5–15. http://dx.doi.org/10.1002/cmr.a.10049.

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34

Krüger, Gunnar, e Gary H. Glover. "Physiological noise in oxygenation-sensitive magnetic resonance imaging". Magnetic Resonance in Medicine 46, n. 4 (ottobre 2001): 631–37. http://dx.doi.org/10.1002/mrm.1240.

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35

Siero, Jeroen C. W., Alex Bhogal e J. Martijn Jansma. "Blood Oxygenation Level–dependent/Functional Magnetic Resonance Imaging". PET Clinics 8, n. 3 (luglio 2013): 329–44. http://dx.doi.org/10.1016/j.cpet.2013.04.003.

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36

Becker, Axel, Thomas Kuhnt, Hendrik Liedtke, Andreas Krivokuca, Marc Bloching e Jürgen Dunst. "Oxygenation Measurements in Head and Neck Cancers during Hyperbaric Oxygenation". Strahlentherapie und Onkologie 178, n. 2 (1 febbraio 2002): 105–8. http://dx.doi.org/10.1007/s00066-002-0892-0.

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37

Song, Turun, Tao Lin, Zixing Huang, Lei Fu, Shaofeng He, Bin Song e Qiang Wei. "Assessment of Intrarenal Oxygenation in Renal Donor With Blood Oxygenation Level–dependent Magnetic Resonance Imaging". Urology 83, n. 5 (maggio 2014): 1205.e1–1205.e5. http://dx.doi.org/10.1016/j.urology.2014.01.015.

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38

Issitt, R., T. Cumberland, A. Clements e J. Mulholland. "Clinical evaluation of the Admiral 1.35m2 hollow-fibre membrane oxygenator". Perfusion 23, n. 1 (gennaio 2008): 33–38. http://dx.doi.org/10.1177/0267659108093880.

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Abstract (sommario):

This prospective study was designed to evaluate the fundamental clinical performance of a new, small surface area oxygenator. Data were collected from twenty patients undergoing first-time coronary artery bypass grafting using this device. This study focuses on how the reduction of surface area and prime volume affects the essential function of the oxygenator in terms of oxygenation efficiency, heat transference, membrane pressure drops, haemolysis and safety. Oxygenation efficiency was deemed to be well within acceptable margins, even at high flows, over a temperature range of 32-36°C. Heat-exchanger performance was assessed by recording the heater/chiller water temperature compared to retrospective data from a current standard oxygenator. Heater/chiller water temperatures were on average 0.3°C higher with the small surface oxygenator than the standard data. The air handling of the device was excellent and extremely safe. Haemolysis, measured as plasma free haemoglobin, did not increase during bypass (p>0.05). This new oxygenator offers a reduced surface area and priming volume while still ensuring an acceptable safety reserve and performance.

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39

Patel, Kunal S., Mingrui Zhao, Hongtao Ma e Theodore H. Schwartz. "Imaging preictal hemodynamic changes in neocortical epilepsy". Neurosurgical Focus 34, n. 4 (aprile 2013): E10. http://dx.doi.org/10.3171/2013.1.focus12408.

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Abstract (sommario):

Object The ability to predict seizure occurrence is extremely important to trigger abortive therapies and to warn patients and their caregivers. Optical imaging of hemodynamic parameters such as blood flow, blood volume, and tissue and hemoglobin oxygenation has already been shown to successfully localize epileptic events with high spatial and temporal resolution. The ability to actually predict seizure occurrence using hemodynamic parameters is less well explored. Methods In this article, the authors critically review data from the literature on neocortical epilepsy and optical imaging, and they discuss the preictal hemodynamic changes and their application in neurosurgery. Results Recent optical mapping studies have demonstrated preictal hemodynamic changes in both human and animal neocortex. Conclusions Optical measurements of blood flow and oxygenation may become increasingly important for predicting and localizing epileptic events. The ability to successfully predict ictal onsets may be useful to trigger closed-loop abortive therapies.

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40

Durila, Miroslav, Tomas Smetak, Pavel Hedvicak e Jan Berousek. "Extracorporeal membrane oxygenation–induced fibrinolysis detected by rotational thromboelastometry and treated by oxygenator exchange". Perfusion 34, n. 4 (11 gennaio 2019): 330–33. http://dx.doi.org/10.1177/0267659118824218.

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Abstract (sommario):

Coagulopathy and bleeding is a frequent phenomenon in patients on extracorporeal membrane oxygenation. The cause may be multifactorial and it may change over time. We present a case when bleeding was caused by hyperfibrinolysis induced by oxygenator. The diagnosis was established by comparing thromboelastometry result from blood obtained before and after oxygenator. Hyperfibrinolysis and bleeding could be successfully treated merely by oxygenator exchange.

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41

Sheehan, Jason, Jonathan Sherman, Christopher Cifarelli, Jay Jagannathan, Kasandra Dassoulas, Claire Olson, Jessica Rainey e Shaojie Han. "Effect of trans sodium crocetinate on brain tumor oxgenation". Journal of Neurosurgery 111, n. 2 (agosto 2009): 226–29. http://dx.doi.org/10.3171/2009.3.jns081339.

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Abstract (sommario):

Object Glioblastoma multiforme tumors typically exhibit regions of hypoxia. Hypoxic regions within the tumor make cells less sensitive to radiosurgery and radiation therapy. Trans sodium crocetinate (TSC) has been shown to be a radiosensitizer. The goal of this research was to elucidate the underlying mechanism of TSC's radiosensitizing effect. Methods A rat C6 glioma model was used. The C6 glioma cells were stereotactically injected into the rat brain to create a tumor. Two weeks later, MR imaging was used to confirm the presence of a glioma. Following demonstration on MR imaging of a brain tumor, animals were randomized into 1 of 2 groups: 1) TSC alone (100 μg/kg), or 2) saline control. Licox probes were inserted into the brain tumor and contralateral cerebral hemisphere. Tissue oxygenation measurements were recorded before and after intravenous infusion of either TSC or saline. Results Not surprisingly, tissue oxygenation measurements revealed that the brain tumor was hypoxic relative to the contralateral cerebral hemisphere brain tissue. Two to 8 minutes after TSC was infused, tissue oxygenation measurements in the brain tumor increased above baseline by as much as 60%. After this temporary elevation following TSC infusion, tumor oxygenation measurements returned to baseline. No significant elevations in tissue oxygenation were seen on the contralateral side. Similarly, the saline vehicle was not observed to increase tissue oxygenation in either the brain tumor or the contralateral brain tissue. Conclusions Administration of TSC transiently improves tissue oxygenation in hypoxic gliomas. Such an effect is one potential mechanism for the radiosensitization previously observed after addition of TSC.

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Haddock, Bryan Thomas, Susan T. Francis, Henrik B. W. Larsson e Ulrik B. Andersen. "Assessment of Perfusion and Oxygenation of the Human Renal Cortex and Medulla by Quantitative MRI during Handgrip Exercise". Journal of the American Society of Nephrology 29, n. 10 (11 settembre 2018): 2510–17. http://dx.doi.org/10.1681/asn.2018030272.

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Abstract (sommario):

BackgroundRenal flow abnormalities are believed to play a central role in the pathogenesis of nephropathy and in primary and secondary hypertension, but are difficult to measure in humans. Handgrip exercise is known to reduce renal arterial flow (RAF) by means of increased renal sympathetic nerve activity.MethodsTo monitor medullary and cortical oxygenation under handgrip exercise–reduced perfusion, we used contrast- and radiation-free magnetic resonance imaging (MRI) to measure regional changes in renal perfusion and blood oxygenation in ten healthy normotensive individuals during handgrip exercise. We used phase-contrast MRI to measure RAF, arterial spin labeling to measure perfusion, and both changes in transverse relaxation time (T2*) and dynamic blood oxygenation level–dependent imaging to measure blood oxygenation.ResultsHandgrip exercise induced a significant decrease in RAF. In the renal medulla, this was accompanied by an increase of oxygenation (reflected by an increase in T2*) despite a significant drop in medullary perfusion; the renal cortex showed a significant decrease in both perfusion and oxygenation. We also found a significant correlation (R2=0.8) between resting systolic BP and the decrease in RAF during handgrip exercise.ConclusionsRenal MRI measurements in response to handgrip exercise were consistent with a sympathetically mediated decrease in RAF. In the renal medulla, oxygenation increased despite a reduction in perfusion, which we interpreted as the result of decreased GFR and a subsequently reduced reabsorptive workload. Our results further indicate that the renal flow response’s sensitivity to sympathetic activation is correlated with resting BP, even within a normotensive range.

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Fukuda, Makoto, Asako Tokumine, Kyohei Noda e Kiyotaka Sakai. "Newly Developed Pediatric Membrane Oxygenator that Suppresses Excessive Pressure Drop in Cardiopulmonary Bypass and Extracorporeal Membrane Oxygenation (ECMO)". Membranes 10, n. 11 (21 novembre 2020): 362. http://dx.doi.org/10.3390/membranes10110362.

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Abstract (sommario):

This article developes a pediatric membrane oxygenator that is compact, high performance, and highly safe. This novel experimental approach, which imaging the inside of a membrane oxygenator during fluid perfusion using high-power X-ray CT, identifies air and blood retention in the local part of a membrane oxygenator. The cause of excessive pressure drop in a membrane oxygenator, which has been the most serious dysfunction in cardiovascular surgery and extracorporeal membrane oxygenation (ECMO), is the local retention of blood and air inside the oxygenator. Our designed blood flow channel for a membrane oxygenator has a circular channel and minimizes the boundary between laminated parts. The pressure drop in the blood flow channel is reduced, and the maximum gas transfer rates are increased by using this pediatric membrane oxygenator, as compared with the conventional oxygenator. Furthermore, it would be possible to reduce the incidents, which have occurred clinically, due to excessive pressure drop in the blood flow channel of the membrane oxygenator. The membrane oxygenator is said to be the “last stronghold” for patients with COVID-19 receiving ECMO treatment. Accordingly, the specification of our prototype is promising for low weight and pediatric patients.

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Sivasubramanian, Maharajan, e Leu-Wei Lo. "Assessment of Nanoparticle-Mediated Tumor Oxygen Modulation by Photoacoustic Imaging". Biosensors 12, n. 5 (13 maggio 2022): 336. http://dx.doi.org/10.3390/bios12050336.

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Abstract (sommario):

Photoacoustic imaging (PAI) is an invaluable tool in biomedical imaging, as it provides anatomical and functional information in real time. Its ability to image at clinically relevant depths with high spatial resolution using endogenous tissues as contrast agents constitutes its major advantage. One of the most important applications of PAI is to quantify tissue oxygen saturation by measuring the differential absorption characteristics of oxy and deoxy Hb. Consequently, PAI can be utilized to monitor tumor-related hypoxia, which is a crucial factor in tumor microenvironments that has a strong influence on tumor invasiveness. Reactive oxygen species (ROS)-based therapies, such as photodynamic therapy, radiotherapy, and sonodynamic therapy, are oxygen-consuming, and tumor hypoxia is detrimental to their efficacy. Therefore, a persistent demand exists for agents that can supply oxygen to tumors for better ROS-based therapeutic outcomes. Among the various strategies, NP-mediated supplemental tumor oxygenation is especially encouraging due to its physio-chemical, tumor targeting, and theranostic properties. Here, we focus on NP-based tumor oxygenation, which includes NP as oxygen carriers and oxygen-generating strategies to alleviate hypoxia monitored by PAI. The information obtained from quantitative tumor oxygenation by PAI not only supports optimal therapeutic design but also serves as a highly effective tool to predict therapeutic outcomes.

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Zeller-Plumhoff, B., T. Roose, G. F. Clough e P. Schneider. "Image-based modelling of skeletal muscle oxygenation". Journal of The Royal Society Interface 14, n. 127 (febbraio 2017): 20160992. http://dx.doi.org/10.1098/rsif.2016.0992.

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Abstract (sommario):

The supply of oxygen in sufficient quantity is vital for the correct functioning of all organs in the human body, in particular for skeletal muscle during exercise. Disease is often associated with both an inhibition of the microvascular supply capability and is thought to relate to changes in the structure of blood vessel networks. Different methods exist to investigate the influence of the microvascular structure on tissue oxygenation, varying over a range of application areas, i.e. biological in vivo and in vitro experiments, imaging and mathematical modelling. Ideally, all of these methods should be combined within the same framework in order to fully understand the processes involved. This review discusses the mathematical models of skeletal muscle oxygenation currently available that are based upon images taken of the muscle microvasculature in vivo and ex vivo . Imaging systems suitable for capturing the blood vessel networks are discussed and respective contrasting methods presented. The review further informs the association between anatomical characteristics in health and disease. With this review we give the reader a tool to understand and establish the workflow of developing an image-based model of skeletal muscle oxygenation. Finally, we give an outlook for improvements needed for measurements and imaging techniques to adequately investigate the microvascular capability for oxygen exchange.

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Faraco, Carlos C., Megan K. Strother, Jeroen CW Siero, Daniel F. Arteaga, Allison O. Scott, Lori C. Jordan e Manus J. Donahue. "The Cumulative Influence of Hyperoxia and Hypercapnia on Blood Oxygenation and R2*". Journal of Cerebral Blood Flow & Metabolism 35, n. 12 (15 luglio 2015): 2032–42. http://dx.doi.org/10.1038/jcbfm.2015.168.

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Abstract (sommario):

Cerebrovascular reactivity (CVR)-weighted blood-oxygenation-level-dependent magnetic resonance imaging (BOLD-MRI) experiments are frequently used in conjunction with hyperoxia. Owing to complex interactions between hyperoxia and hypercapnia, quantitative effects of these gas mixtures on BOLD responses, blood and tissue R2∗, and blood oxygenation are incompletely understood. Here we performed BOLD imaging (3T; TE/TR = 35/2,000 ms; spatial resolution = 3×3×3.5 mm3) in healthy volunteers ( n = 12; age = 29±4.1 years) breathing (i) room air (RA), (ii) normocapnic-hyperoxia (95% O2/5% N2, HO), (iii) hypercapnic-normoxia (5% CO2/21% O2/74% N2, HC-NO), and (iv) hypercapnic-hyperoxia (5% CO2/95% O2, HC-HO). For HC-HO, experiments were performed with separate RA and HO baselines to control for changes in O2. T2-relaxation-under-spin-tagging MRI was used to calculate basal venous oxygenation. Signal changes were quantified and established hemodynamic models were applied to quantify vasoactive blood oxygenation, blood–water R∗2, and tissue-water R∗2. In the cortex, fractional BOLD changes (stimulus/baseline) were HO/RA = 0.011 ± 0.007; HC-NO/RA = 0.014±0.004; HC-HO/HO = 0.020±0.008; and HC-HO/RA = 0.035 ±0.010; for the measured basal venous oxygenation level of 0.632, this led to venous blood oxygenation levels of 0.660 (HO), 0.665 (HC-NO), and 0.712 (HC-HO). Interleaving a HC-HO stimulus with HO baseline provided a smaller but significantly elevated BOLD response compared with a HC-NO stimulus. Results provide an outline for how blood oxygenation differs for several gas stimuli and provides quantitative information on how hypercapnic BOLD CVR and R∗2 are altered during hyperoxia.

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Krishna, Murali C., Shingo Matsumoto, Keita Saito, Masayuki Matsuo, James B. Mitchell e Jan H. Ardenkjaer-Larsen. "Magnetic resonance imaging of tumor oxygenation and metabolic profile". Acta Oncologica 52, n. 7 (19 agosto 2013): 1248–56. http://dx.doi.org/10.3109/0284186x.2013.819118.

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48

Ayala, Leonardo, Fabian Isensee, Sebastian J. Wirkert, Anant S. Vemuri, Klaus H. Maier-Hein, Baowei Fei e Lena Maier-Hein. "Band selection for oxygenation estimation with multispectral/hyperspectral imaging". Biomedical Optics Express 13, n. 3 (3 febbraio 2022): 1224. http://dx.doi.org/10.1364/boe.441214.

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49

Calin, Mihaela Antonina, Ileana Carmen Boiangiu, Sorin Viorel Parasca, Sorin Miclos, Dan Savastru e Dragos Manea. "Blood oxygenation monitoring using hyperspectral imaging after flap surgery". Spectroscopy Letters 50, n. 3 (16 marzo 2017): 150–55. http://dx.doi.org/10.1080/00387010.2017.1297957.

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Padhani, Anwar R. "Where are we with imaging oxygenation in human tumours?" Cancer Imaging 5, n. 1 (2005): 128–30. http://dx.doi.org/10.1102/1470-7330.2005.0103.

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