scholarly journals Acoustic Angiography: A New Imaging Modality for Assessing Microvasculature Architecture

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Ryan C. Gessner ◽  
C. Brandon Frederick ◽  
F. Stuart Foster ◽  
Paul A. Dayton
Keyword(s):  
High Resolution ◽  
Imaging Modality ◽  
Dual Frequency ◽  
Contrast Imaging ◽  
3D Images ◽  
Tissue Integration ◽  
Contrast Enhanced ◽  
Imaging Approach ◽  
Microvascular Architecture ◽  
Frequency Ultrasound

The purpose of this paper is to provide the biomedical imaging community with details of a new high resolution contrast imaging approach referred to as “acoustic angiography.” Through the use of dual-frequency ultrasound transducer technology, images acquired with this approach possess both high resolution and a high contrast-to-tissue ratio, which enables the visualization of microvascular architecture without significant contribution from background tissues. Additionally, volumetric vessel-tissue integration can be visualized by using b-mode overlays acquired with the same probe. We present a brief technical overview of how the images are acquired, followed by several examples of images of both healthy and diseased tissue volumes. 3D images from alternate modalities often used in preclinical imaging, contrast-enhanced micro-CT and photoacoustics, are also included to provide a perspective on how acoustic angiography has qualitatively similar capabilities to these other techniques. These preliminary images provide visually compelling evidence to suggest that acoustic angiography may serve as a powerful new tool in preclinical and future clinical imaging.

scholarly journals A robust, semi-automated approach for counting cementum increments imaged with X-ray computed tomography

2021 ◽  
Author(s):  
Elis Newham ◽  
Pamela G Gill ◽  
Kate Robson Brown ◽  
Neil J Gostling ◽  
Ian J Corfe ◽  
...  
Keyword(s):  
Imaging Modality ◽  
Human Vision ◽  
Laboratory Population ◽  
Contrast Imaging ◽  
Thin Sections ◽  
3D Images ◽  
X Ray ◽  
Tissue Sections ◽  
Tooth Roots ◽  
X Ray Computed

Cementum, the tissue attaching mammal tooth roots to the periodontal ligament, grows appositionally throughout life, displaying a series of circum-annual incremental features. These have been studied for decades as a direct record of chronological lifespan. The majority of previous studies on cementum have used traditional thin-section histological methods to image and analyse increments. However, several caveats have been raised in terms of studying cementum increments in thin-sections. Firstly, the limited number of thin-sections and the two-dimensional perspective they impart provide an incomplete interpretation of cementum structure, and studies often struggle or fail to overcome complications in increment patterns that complicate or inhibit increment counting. Increments have been repeatedly shown to both split and coalesce, creating accessory increments that can bias increment counts. Secondly, identification and counting of cementum increments using human vision is subjective, and it has led to inaccurate readings in several experiments studying individuals of known age. Here, we have attempted to optimise a recently introduced imaging modality for cementum imaging; X-ray propagation-based phase-contrast imaging (PPCI). X-ray PPCI was performed for a sample of rhesus macaque ( Macaca mulatta ) lower first molars (n=10) from a laboratory population of known age. A new method for semi-automatic increment counting was then integrated into a purpose-built software package for studying cementum increments. Comparison with data from conventional cementochronology, based on histological examination of tissue sections, confirmed that X-ray PPCI reliably records cementum increments. Validation of the increment counting algorithm suggests that it is robust and provides accurate estimates of increment counts. In summary, we show that our new increment counting method has the potential to overcome caveats of conventional cementochronology approaches, when used to analyse 3D images provided by X-ray PPCI.

A Complete Computational Model of Ultrasound Vibro-Acoustography

2006 ◽  
Author(s):  
Alison E. Malcolm ◽  
Fernando Reitich ◽  
Jiaqi Yang ◽  
Mostafa Fatemi ◽  
James F. Greenleaf
Keyword(s):  
High Resolution ◽  
Optimal Design ◽  
Computational Model ◽  
High Frequency ◽  
Imaging Modality ◽  
Low Frequency ◽  
High Frequency Ultrasound ◽  
Linear Interaction ◽  
Modeling Simulation ◽  
Frequency Ultrasound

Ultrasound vibro-acoustography is a novel medical imaging modality that combines the high resolution of high-frequency ultrasound with the speckle-free images obtained using low-frequency methods. This imaging modality relies on the non-linear interaction of two high frequency beams at slightly different frequencies. We describe the physics of ultrasound vibro-acoustography and outline a strategy for its modeling, simulation, and optimal design.

Catheter-mounted dual-frequency ultrasound transducers for intravascular contrast-enhanced superharmonic imaging

2019 ◽  
Vol 146 (4) ◽  
pp. 3031-3031
Author(s):  
Jinwook Kim ◽  
Sandeep Kasoji ◽  
Eric Markley ◽  
xiaoning jiang ◽  
Paul Dayton
Keyword(s):  
Ultrasound Transducers ◽  
Dual Frequency ◽  
Contrast Enhanced ◽  
Frequency Ultrasound

“High Resolution High Voltage Electron Microscopy”

1968 ◽  
Vol 26 ◽  
pp. 326-327
Author(s):  
Benjamin M. Siegel
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Voltage ◽  
Full Potential ◽  
Contrast Imaging ◽  
High Voltage Electron Microscopy ◽  
Low Contrast ◽  
Voltage Electron ◽  
Critical Areas ◽  
High Voltage Electron

The potential advantages of high voltage electron microscopy for extending the limits of resolution and contrast in imaging low contrast objects, such as biomolecular specimens, is very great. The results of computations will be presented showing that at accelerating voltages of 500-1000 kV it should be possible to achieve spacial resolutions of 1 to 1.5 Å and using phase contrast imaging achieve adequate image contrast to observe single atoms of low atomic number.The practical problems associated with the design and utilization of the high voltage instrument are, optimistically, within the range of competence of the state of the art. However, there are some extremely important and critical areas to be systematically investigated before we have achieved this competence. The basic electron optics of the column required is well understood, but before the full potential of an instrument capable of resolutions of better than 1.5 Å are realized some very careful development work will be required. Of great importance for the actual achievement of high resolution with a high voltage electron microscope is the fundamental limitation set by the characteristics of the high voltage electron beam that can be obtained from the accelerator column.

Functional information from magnetic resonance imaging

1995 ◽  
Vol 53 ◽  
pp. 84-85
Author(s):  
Alan P. Koretsky ◽  
Afonso Costa e Silva ◽  
Yi-Jen Lin
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Cancer Biology ◽  
Imaging Modality ◽  
Magnetic Resonance Images ◽  
Great Success ◽  
Functional Information ◽  
Resonance Imaging ◽  
High Resolution Mri

Magnetic resonance imaging (MRI) has become established as an important imaging modality for the clinical management of disease. This is primarily due to the great tissue contrast inherent in magnetic resonance images of normal and diseased organs. Due to the wide availability of high field magnets and the ability to generate large and rapidly switched magnetic field gradients there is growing interest in applying high resolution MRI to obtain microscopic information. This symposium on MRI microscopy highlights new developments that are leading to increased resolution. The application of high resolution MRI to significant problems in developmental biology and cancer biology will illustrate the potential of these techniques.In combination with a growing interest in obtaining high resolution MRI there is also a growing interest in obtaining functional information from MRI. The great success of MRI in clinical applications is due to the inherent contrast obtained from different tissues leading to anatomical information.

Recent applications of TEM to the study of interfaces

1990 ◽  
Vol 48 (4) ◽  
pp. 308-309
Author(s):  
C. Barry Carter
Keyword(s):  
High Resolution ◽  
Sample Preparation ◽  
Grain Boundaries ◽  
Diffuse Scattering ◽  
Imaging Techniques ◽  
Amorphous Material ◽  
Contrast Imaging ◽  
Current State ◽  
Actual Nature ◽  
High Resolution Images

This paper will review the current state of understanding of interface structure and highlight some of the future needs and problems which must be overcome. The study of this subject can be separated into three different topics: 1) the fundamental electron microscopy aspects, 2) material-specific features of the study and 3) the characteristics of the particular interfaces. The two topics which are relevant to most studies are the choice of imaging techniques and sample preparation. The techniques used to study interfaces in the TEM include high-resolution imaging, conventional diffraction-contrast imaging, and phase-contrast imaging (Fresnel fringe images, diffuse scattering). The material studied affects not only the characteristics of the interfaces (through changes in bonding, etc.) but also the method used for sample preparation which may in turn have a significant affect on the resulting image. Finally, the actual nature and geometry of the interface must be considered. For example, it has become increasingly clear that the plane of the interface is particularly important whenever at least one of the adjoining grains is crystalline.A particularly productive approach to the study of interfaces is to combine different imaging techniques as illustrated in the study of grain boundaries in alumina. In this case, the conventional imaging approach showed that most grain boundaries in ion-thinned samples are grooved at the grain boundary although the extent of this grooving clearly depends on the crystallography of the surface. The use of diffuse scattering (from amorphous regions) gives invaluable information here since it can be used to confirm directly that surface grooving does occur and that the grooves can fill with amorphous material during sample preparation (see Fig. 1). Extensive use of image simulation has shown that, although information concerning the interface can be obtained from Fresnel-fringe images, the introduction of artifacts through sample preparation cannot be lightly ignored. The Fresnel-fringe simulation has been carried out using a commercial multislice program (TEMPAS) which was intended for simulation of high-resolution images.

High-resolution z-contrast imaging of semiconductor interfaces

1989 ◽  
Vol 47 ◽  
pp. 468-469
Author(s):  
S. J. Pennycook
Keyword(s):  
High Resolution ◽  
Phase Contrast ◽  
Contrast Imaging ◽  
Compositional Modulation ◽  
Semiconductor Interfaces ◽  
Complex Figure ◽  
Thin Region ◽  
Stem Image ◽  
Annular Detector ◽  
Z Contrast

Using a high-angle annular detector on a high-resolution STEM it is possible to form incoherent images of a crystal lattice characterized by strong atomic number or Z contrast. Figure 1 shows an epitaxial Ge film on Si(100) grown by oxidation of Ge-implanted Si. The image was obtained using a VG Microscopes' HB501 STEM equipped with an ultrahigh resolution polepiece (Cs ∽1.2 mm, demonstrated probe FWHM intensity ∽0.22 nm). In both crystals the lattice is resolved but that of Ge shows much brighter allowing the interface to be located exactly and interface steps to be resolved (arrowed). The interface was indistinguishable in the phase-contrast STEM image from the same region, and even at higher resolution the location of the interface is complex. Figure 2 shows a thin region of an MBE-grown ultrathin super-lattice (Si8Ge2)100. The expected compositional modulation would show as one bright row of dots from the 2 Ge monolayers separated by 4 rows of lighter Si columns. The image shows clearly that strain-induced interdiffusion has occurred on the monolayer scale.

Contrast-Enhanced Ultrasound: a Simple and Effective Tool in Defining a Rapid Diagnostic Work-up for Small Nodules Detected in Cirrhotic Patients during Surveillance

2016 ◽  
Vol 25 (2) ◽  
pp. 205-211 ◽  
Author(s):  
Antonio Giorgio ◽  
Luca Montesarchio ◽  
Piero Gatti ◽  
Ferdinando Amendola ◽  
Paolo Matteucci ◽  
...  
Keyword(s):  
Predictive Value ◽  
Imaging Modality ◽  
Dynamic Imaging ◽  
Contrast Enhanced Ultrasound ◽  
Histologic Diagnosis ◽  
Therapeutic Work ◽  
Contrast Enhanced ◽  
Arterial Vascularization ◽  
Cirrhotic Patients ◽  
Work Up

  Background & Aims: Disappearance of portal blood flow and arterial vascularization is the hallmark of hepatocarcinogenesis. The capability of a dynamic imaging modality detecting arterial hypervascularization of small nodules is crucial to promote a rapid diagnostic and therapeutic work-up improving survival. We aimed to evaluate the capability of CEUS to detect arterial vascularization of ≤ 2 cm HCC nodules arising during surveillance so as to shorten the diagnostic and therapeutic work-up. Methods: From October 2009 to September 2014, among 1757 consecutive cirrhotic patients under surveillance with ultrasound (US), 243 patients had new single nodules 7-20 mm; 229/243 had a conclusive histologic diagnosis and comprised the study group. All patients underwent CEUS followed by enhanced MRI and US guided percutaneous 18G needle core biopsy of the nodules. Of the 229 nodules, 27 were hyperechoic, 171 hypoechoic and 31 isoechoic lesions. Results: The histology results revealed that 199/229 nodules were HCC and 30 were benign. Of 199 HCC, CEUS evidenced arterial hypervascularity in 190 nodules (95.5%) (sensitivity 94.48 %, specificity 100%, PPV 100%, NPV 76.92 %). Of the 39 CEUS arterial-unenhanced nodules, 30 were benign and 9 (23%) were well-differentiated HCC. eMRI showed arterial hypervascularity in 199 nodules (86,9%). Of these, only 193 (97%) were histologically HCCs while 6 were benign (sensitivity: 97%, specificity: 80%, PPV: 97%, NPV: 80%). Conclusions: CEUS has a great capability to detect arterial hypervascularity of small HCC. Because only 4.5% of new nodules escape the demonstration of arterial hyervascularity, CEUS must be performed immediately after conventional US to contrast the malignant fate of small lesions arising in a cirrhotic liver.. Abbreviations: CEUS: contrast-enhanced ultrasound; CT: computed tomography; HCC: hepatocellular carcinoma;MRI: magnetic resonance; NPV: negative predictive value; PPV: positive predictive value; US: ultrasonography.

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