scholarly journals Oxygen Saturation Imaging Using LED-Based Photoacoustic System

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 283
Author(s):  
Rianne Bulsink ◽  
Mithun Kuniyil Ajith Singh ◽  
Marvin Xavierselvan ◽  
Srivalleesha Mallidi ◽  
Wiendelt Steenbergen ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Light Propagation ◽  
Structural Information ◽  
Small Animal ◽  
Clinical Applications ◽  
Propagation Model ◽  
Dual Wavelength ◽  
Imaging Method ◽  
Led Array

Oxygen saturation imaging has potential in several preclinical and clinical applications. Dual-wavelength LED array-based photoacoustic oxygen saturation imaging can be an affordable solution in this case. For the translation of this technology, there is a need to improve its accuracy and validate it against ground truth methods. We propose a fluence compensated oxygen saturation imaging method, utilizing structural information from the ultrasound image, and prior knowledge of the optical properties of the tissue with a Monte-Carlo based light propagation model for the dual-wavelength LED array configuration. We then validate the proposed method with oximeter measurements in tissue-mimicking phantoms. Further, we demonstrate in vivo imaging on small animal and a human subject. We conclude that the proposed oxygen saturation imaging can be used to image tissue at a depth of 6–8 mm in both preclinical and clinical applications.

A Three-Dimensional Registration Method for MicroUS/MicroPET Multimodality Small-Animal Imaging

2007 ◽  
Vol 29 (3) ◽  
pp. 155-166 ◽  
Author(s):  
Ai-Ho Liao ◽  
Li-Yen Chen ◽  
Wen-Fang Cheng ◽  
Pai-Chi Li
Keyword(s):  
Image Registration ◽  
Structural Information ◽  
Multimodality Imaging ◽  
Imaging Techniques ◽  
Small Animal Imaging ◽  
Three Dimensional ◽  
Small Animal ◽  
Imaging Method ◽  
Registration Method ◽  
Animal Imaging

Small-animal models are used extensively in disease research, genomics research, drug development and developmental biology. The development of noninvasive small-animal imaging techniques with adequate spatial resolution and sensitivity is therefore of prime importance. In particular, multimodality small-animal imaging can provide complementary information. This paper presents a method for registering high-frequency ultrasonic (microUS) images with small-animal positron-emission tomography (microPET) images. Registration is performed using six external multimodality markers, each being a glass bead with a diameter of 0.43–0.60 mm, with 0.1 μl of [18F]FDG placed in each marker holder. A small-animal holder is used to transfer mice between the microPET and microUS systems. Multimodality imaging was performed on C57BL/6J black mice bearing WF-3 ovary cancer cells in the second week after tumor implantation and rigid-body image registration of the six markers was also performed. The average registration error was 0.31 mm when all six markers were used and increased as the number of markers decreased. After image registration, image segmentation and fusion are performed on the tumor. Our multimodality small-animal imaging method allows structural information from microUS to be combined with functional information from microPET, with the preliminary results showing it to be an effective tool for cancer research.

Rapid T1rho dispersion imaging for improved characterization of myocardial tissue using synthetic dispersion reconstruction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Gram ◽  
D Gensler ◽  
P Winter ◽  
M Seethaler ◽  
P.M Jakob ◽  
...  
Keyword(s):  
Small Animal ◽  
Dispersion Analysis ◽  
Measurement Time ◽  
Maximum Deviation ◽  
Imaging Method ◽  
Funding Source ◽  
New Approach ◽  
Reference Map ◽  
Quantification Accuracy

Abstract Introduction Over the past decade, CMRI has become the method of choice for characterizing fibrotic scars. Native T1ρ mapping offers an alternative to conventional T1 and T2 quantification techniques due to its high sensitivity to low-frequency processes. In addition, there is the possibility of T1ρ dispersion imaging, which could be used as a sensitive biomarker for assessing myocardial fibrosis [1]. However, due to a very long measurement time, T1ρ dispersion quantification in myocardium can hardly be done in the limited time of a small animal study. In this work we present a concept for rapid T1ρ dispersion quantification based on the new approach of synthetic dispersion reconstruction (SynDR). Theory A T1ρ map is calculated by measuring Nt T1ρ weighted images using different spin lock (SL) times. T1ρ dispersion quantification requires Nf T1ρ maps with different SL amplitudes. Hence the measurement time is very time consuming, because it requires the acquisition of Nt*Nf images (full mapping). With our new approach (SynDR), only a single T1ρ reference map and a series of dispersion weighted images need to be acquired. The T1ρ dispersion can be reconstructed by synthetically generated maps, whereby each map is calculated from the reference map and the dispersion weighted images, only requiring Nt+Nf images. Methods All measurements were performed on a 7T small animal scanner. The method was based on an optional cartesian/radial gradient echo sequence using large flip angles (45°) and an optimized readout sorting. The quantification accuracy of SynDR was compared with full mapping measurements in a phantom experiment and validated in vivo on mice. The synthetic T1ρ maps were used to perform a dispersion analysis in myocardium. Results The comparison between SynDR and the full mapping reference in phantoms showed a very high quantification accuracy with a mean/maximum deviation of 1.1% and 1.7%. Fig. 1 shows synthetic T1ρ maps (a) in healthy mice and the obtained dispersion map (b) using SynDR. In the dispersion analysis (c) a T1ρ slope of 5.6±1.5ms/kHz was obtained for myocardium. Here an acceleration factor of 4 could be realized in comparison to full mapping. In further measurements, an acceleration of 7.4 could be reached using a radial readout with KWIC filter view sharing. Discussion In this work, a novel T1ρ dispersion imaging method was presented that far exceeds the speed of conventional full mapping methods. The acceleration is based on avoiding unnecessary measurements of T1ρ weighted images through more efficient mathematical modeling. Further acceleration could be achieved using an optimized radial data acquisition. The method shows good image quality and high quantification accuracy both in phantom and in vivo. Based on the promising results, further studies in mice are planned to investigate the dispersion character of healthy and diseased tissues. Reference [1] Yin Q et al. Magn Reson Imaging. 2017 Oct; 42:69–73. SynDR method and T1ρ dispersion analysis Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): BRD, Bundesministerium für Bildung und Forschung

scholarly journals An in vivo multimodal feasibility study in a rat brain tumour model using flexible multinuclear MR and PET systems

2020 ◽  
Author(s):  
Chang-Hoon Choi ◽  
Carina Stegmayr ◽  
Aliaksandra Shymanskaya ◽  
Wieland A. Worthoff ◽  
Nuno A da Silva ◽  
...  
Keyword(s):  
Brain Tumour ◽  
Structural Information ◽  
Small Animal ◽  
Optimal Combination ◽  
Small Animal Pet ◽  
Molecular Profile ◽  
Genetic Profile ◽  
Valuable Insight ◽  
Wide Range

Abstract Background: In addition to the structural information afforded by 1H MRI, the use of X-nuclei, such as sodium-23 (23Na) or phosphorus-31 (31P), offers important complementary information concerning physiological and biochemical parameters. By then combining this technique with PET, which provides valuable insight into a wide range of metabolic and molecular processes by using of a variety of radioactive tracers, the scope of medical imaging and diagnostics can be significantly increased. While the use of multimodal imaging is undoubtedly advantageous, identifying the optimal combination of these parameters to diagnose a specific dysfunction is very important and is advanced by the use of sophisticated imaging techniques in specific animal models. Methods: In this pilot study, rats with intracerebral 9L gliosarcomas were used to explore a combination of sequential multinuclear MRI using a sophisticated switchable coil set in a small animal 9.4 T MRI scanner and, subsequently, a small animal PET with the tumour tracer O-(2-[18F]-fluoroethyl)-L-tyrosine ([18F]FET). This made it possible for in vivo multinuclear MR-PET experiments to be conducted without compromising the performance of either multinuclear MR or PET. Results: High-quality in vivo images and spectra including high-resolution 1H imaging, 23Na-weighted imaging, detection of 31P metabolites and [18F]FET uptake were obtained, allowing the characterisation of tumour tissues in comparison to a healthy brain. It has been reported in the literature that these parameters are useful in the identification of the genetic profile of gliomas, particularly concerning the mutation of the isocitrate hydrogenase gene, which is highly relevant for treatment strategy.Conclusions: The combination of multinuclear MR and PET in, for example, brain tumour models with specific genetic mutations will enable the physiological background of signal alterations to be explored and the identification of the optimal combination of imaging parameters for the non-invasive characterisation of the molecular profile of tumours.

scholarly journals Foreword

2002 ◽  
Vol 1 (6) ◽  
pp. 417-417
Author(s):  
Orhan Nalcioglu ◽  
Laurence Clarke
Keyword(s):  
Medical Imaging ◽  
Imaging Techniques ◽  
Small Animal ◽  
Spatial Localization ◽  
Clinical Applications ◽  
Special Issue ◽  
Clinical Investigations ◽  
Measurement Tools ◽  
Important Measurement

In vivo medical imaging has become one of the most important measurement tools in biomedical research and clinical investigations. Medical imaging applications cover a broad spectrum going from small animal research to human studies. This is due to the fact that in vivo medical imaging techniques based on various modalities are capable of providing anatomic, functional, and metabolic information non-invasively with accurate spatial localization enabling longitudinal studies on the same subject. One of the most significant application of such techniques has been in the study of cancer. In this special issue on in vivo medical imaging, we tried to give the readers a flavor of the types of studies that are being done in cancer research and clinical applications. We should emphasize that the topics covered here due to limited space will only provide the readers with a rather limited view. Furthermore, one of the new and upcoming imaging techniques, namely molecular imaging will not be covered here since there have been various extensive reviews of the field have been given in the literature.

scholarly journals In vivo depth-resolved oxygen saturation by dual-wavelength photothermal (DWP) OCT

2011 ◽  
Vol 19 (24) ◽  
pp. 23831 ◽  
Author(s):  
Roman V. Kuranov ◽  
Shams Kazmi ◽  
Austin B. McElroy ◽  
Jeffrey W. Kiel ◽  
Andrew K. Dunn ◽  
...  
Keyword(s):  
Oxygen Saturation ◽  
Dual Wavelength

The Study of Transesophageal Oxygen Saturation Monitoring

2011 ◽  
pp. 173-182
Author(s):  
Zhiqiang Zhang ◽  
Bo Gao ◽  
Guojie Liao ◽  
Ling Mu ◽  
Wei Wei
Keyword(s):  
Standard Deviation ◽  
Oxygen Saturation ◽  
Monitoring System ◽  
Left Ventricular ◽  
Clinical Applications ◽  
Traditional Methods ◽  
Monitoring Technology ◽  
Descending Aorta ◽  
Physiological Information

In this chapter, the transesophageal oxygen saturation (SpO2) monitoring system was proposed based on the early experiments, to provide a new program of SpO2 acquisition and analysis and avoid the limitation of traditional methods. The PPG (photoplethysmographic) signal of descending aorta and left ventricular was monitored in the experiment. The analysis of the peak-to-peak values, the standard deviation and the position of peaks in signal waveforms showed that in vivo signal was more stable and sensitive; and the physiological information was reflected in the left ventricular PPG waveform. Therefore, it can be concluded that the transesophageal SpO2 monitoring technology has better guidance in clinical applications.

The Study of Transesophageal Oxygen Saturation Monitoring

2011 ◽  
pp. 2191-2200
Author(s):  
Zhiqiang Zhang ◽  
Bo Gao ◽  
Guojie Liao ◽  
Ling Mu ◽  
Wei Wei
Keyword(s):  
Standard Deviation ◽  
Oxygen Saturation ◽  
Monitoring System ◽  
Left Ventricular ◽  
Clinical Applications ◽  
Traditional Methods ◽  
Monitoring Technology ◽  
Descending Aorta ◽  
Physiological Information

In this chapter, the transesophageal oxygen saturation (SpO2) monitoring system was proposed based on the early experiments, to provide a new program of SpO2 acquisition and analysis and avoid the limitation of traditional methods. The PPG (photoplethysmographic) signal of descending aorta and left ventricular was monitored in the experiment. The analysis of the peak-to-peak values, the standard deviation and the position of peaks in signal waveforms showed that in vivo signal was more stable and sensitive; and the physiological information was reflected in the left ventricular PPG waveform. Therefore, it can be concluded that the transesophageal SpO2 monitoring technology has better guidance in clinical applications.

scholarly journals High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiang Lan Fan ◽  
Jose A. Rivera ◽  
Wei Sun ◽  
John Peterson ◽  
Henry Haeberle ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Speed ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Fluorescence Signal ◽  
Imaging Method ◽  
Spatiotemporal Resolution ◽  
Two Photon

AbstractUnderstanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.

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