scholarly journals A Review of Ex Vivo X-ray Microfocus Computed Tomography-Based Characterization of the Cardiovascular System

2021 ◽  
Vol 22 (6) ◽  
pp. 3263
Author(s):  
Lisa Leyssens ◽  
Camille Pestiaux ◽  
Greet Kerckhofs
Keyword(s):  
Computed Tomography ◽  
Soft Tissues ◽  
Ex Vivo ◽  
Image Resolution ◽  
Tissue Preparation ◽  
X Ray ◽  
Spatial Image ◽  
Microfocus Computed Tomography

Cardiovascular malformations and diseases are common but complex and often not yet fully understood. To better understand the effects of structural and microstructural changes of the heart and the vasculature on their proper functioning, a detailed characterization of the microstructure is crucial. In vivo imaging approaches are noninvasive and allow visualizing the heart and the vasculature in 3D. However, their spatial image resolution is often too limited for microstructural analyses, and hence, ex vivo imaging is preferred for this purpose. Ex vivo X-ray microfocus computed tomography (microCT) is a rapidly emerging high-resolution 3D structural imaging technique often used for the assessment of calcified tissues. Contrast-enhanced microCT (CE-CT) or phase-contrast microCT (PC-CT) improve this technique by additionally allowing the distinction of different low X-ray-absorbing soft tissues. In this review, we present the strengths of ex vivo microCT, CE-CT and PC-CT for quantitative 3D imaging of the structure and/or microstructure of the heart, the vasculature and their substructures in healthy and diseased state. We also discuss their current limitations, mainly with regard to the contrasting methods and the tissue preparation.

Mineralization of Sialoliths Investigated by Ex Vivo and In Vivo X-ray Computed Tomography

2019 ◽  
Vol 25 (1) ◽  
pp. 151-163 ◽  
Author(s):  
Pedro Nolasco ◽  
Paulo V. Coelho ◽  
Carla Coelho ◽  
David F. Angelo ◽  
J. R. Dias ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Computed Tomography ◽  
Organic Matter ◽  
Ex Vivo ◽  
Correct Selection ◽  
Quantitative Relation ◽  
Helical Computed Tomography ◽  
X Ray ◽  
X Ray Computed

AbstractThe fraction of organic matter present affects the fragmentation behavior of sialoliths; thus, pretherapeutic information on the degree of mineralization is relevant for a correct selection of lithotripsy procedures. This work proposes a methodology for in vivo characterization of salivary calculi in the pretherapeutic context. Sialoliths were characterized in detail by X-ray computed microtomography (μCT) in combination with atomic emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Correlative analysis of the same specimens was performed by in vivo and ex vivo helical computed tomography (HCT) and ex vivo μCT. The mineral matter in the sialoliths consisted essentially of apatite (89 vol%) and whitlockite (11 vol%) with average density of 1.8 g/cm3. In hydrated conditions, the mineral mass prevailed with 53 ± 13 wt%, whereas the organic matter, with a density of 1.2 g/cm3, occupied 65 ± 10% of the sialoliths’ volume. A quantitative relation between sialoliths mineral density and X-ray attenuation is proposed for both HCT and μCT.

scholarly journals Effect of Gold Nanoparticle Size on Their Properties as Contrast Agents for Computed Tomography

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuxi C. Dong ◽  
Maryam Hajfathalian ◽  
Portia S. N. Maidment ◽  
Jessica C. Hsu ◽  
Pratap C. Naha ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agents ◽  
Inductively Coupled Plasma ◽  
Ex Vivo ◽  
Photon Counting ◽  
Optical Emission ◽  
X Ray ◽  
Significant Difference ◽  
Ct Contrast

Abstract Computed tomography (CT) is one of the most commonly used clinical imaging modalities. There have recently been many reports of novel contrast agents for CT imaging. In particular, the development of gold nanoparticles (AuNP) as CT contrast agents is a topic of intense interest. AuNP have favorable characteristics for this application such as high payloads of contrast generating material, strong X-ray attenuation, excellent biocompatibility, tailorable surface chemistry, and tunable sizes and shapes. However, there have been conflicting reports on the role of AuNP size on their contrast generation for CT. We therefore sought to extensively investigate the AuNP size-CT contrast relationship. In order to do this, we synthesized AuNP with sizes ranging from 4 to 152 nm and capped them with 5 kDa m-PEG. The contrast generation of AuNP of different sizes was investigated with three clinical CT, a spectral photon counting CT (SPCCT) and two micro CT systems. X-ray attenuation was quantified as attenuation rate in Hounsfield units per unit concentration (HU/mM). No statistically significant difference in CT contrast generation was found among different AuNP sizes via phantom imaging with any of the systems tested. Furthermore, in vivo imaging was performed in mice to provide insight into the effect of AuNP size on animal biodistribution at CT dose levels, which has not previously been explored. Both in vivo imaging and ex vivo analysis with inductively coupled plasma optical emission spectroscopy (ICP-OES) indicated that AuNP that are 15 nm or smaller have long blood circulation times, while larger AuNP accumulated in the liver and spleen more rapidly. Therefore, while we observed no AuNP size effect on CT contrast generation, there is a significant effect of size on AuNP diagnostic utility.

scholarly journals Contrast-Enhanced MicroCT for Virtual 3D Anatomical Pathology of Biological Tissues: A Literature Review

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Sébastien de Bournonville ◽  
Sarah Vangrunderbeeck ◽  
Greet Kerckhofs
Keyword(s):  
Soft Tissues ◽  
Ex Vivo ◽  
Functional Characterization ◽  
3D Structure ◽  
Biological Tissues ◽  
X Ray ◽  
Musculoskeletal Tissues ◽  
Contrast Enhanced ◽  
Anatomical Pathology

To date, the combination of histological sectioning, staining, and microscopic assessment of the 2D sections is still the golden standard for structural and compositional analysis of biological tissues. X-ray microfocus computed tomography (microCT) is an emerging 3D imaging technique with high potential for 3D structural analysis of biological tissues with a complex and heterogeneous 3D structure, such as the trabecular bone. However, its use has been mostly limited to mineralized tissues because of the inherently low X-ray absorption of soft tissues. To achieve sufficient X-ray attenuation, chemical compounds containing high atomic number elements that bind to soft tissues have been recently adopted as contrast agents (CAs) for contrast-enhanced microCT (CE-CT); this novel technique is very promising for quantitative “virtual” 3D anatomical pathology of both mineralized and soft biological tissues. In this paper, we provided a review of the advances in CE-CT since the very first reports on the technology to date. Perfusion CAs for in vivo imaging have not been discussed, as the focus of this review was on CAs that bind to the tissue of interest and that are, thus, used for ex vivo imaging of biological tissues. As CE-CT has mostly been applied for the characterization of musculoskeletal tissues, we have put specific emphasis on these tissues. Advantages and limitations of multiple CAs for different musculoskeletal tissues have been highlighted, and their reproducibility has been discussed. Additionally, the advantages of the “full” 3D CE-CT information have been pinpointed, and its importance for more detailed structural, spatial, and functional characterization of the tissues of interest has been shown. Finally, the remaining challenges that are still hampering a broader adoption of CE-CT have been highlighted, and suggestions have been made to move the field of CE-CT imaging one step further towards a standard accepted tool for quantitative virtual 3D anatomical pathology.

scholarly journals Validation of an XCT/fDOT System on Mice

ISRN Optics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Anne Koenig ◽  
Anne Planat-Chrétien ◽  
Kai Hassler ◽  
Martina Bucher ◽  
Jean-Guillaume Coutard ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Imaging System ◽  
Ex Vivo ◽  
Optical Tomography ◽  
Diffuse Optical Tomography ◽  
Cylindrical Geometry ◽  
X Ray ◽  
Dual Modality ◽  
X Ray Computed

In this paper we present systems for dual modality imaging, combining fluorescence-enhanced diffuse optical tomography and X-ray computed tomography. Fluorescence diffuse optical tomography is carried out in a cylindrical geometry, which ensures optimal sampling and a straight forward integration with the X-ray modality. Specific acquisition protocols and reconstruction software have been developed to this end. The X-ray computed tomography serves two purposes. First, it provides the anatomical information in the registered dual modality images. Second, it provides the actual shape and boundaries of the animal as a priori input to the fluorescence reconstruction algorithm. To evaluate the performance of the optical imaging system, experiments have been conducted on phantoms, mice with inserted fluorescing capillaries, and finally on mice bearing tumors, ex-vivo and in-vivo. Experiments on mice with capillaries inserted in different region of interest, allow estimating the detection limits of fluorophore concentrations. The fluorescence reconstructions are shown to be geometrically consistent with the X-ray images. Finally we demonstrate the capability of the bimodal system to localize real tumours in mice in-vivo. These results show that dual modality fluorescence-enhanced diffuse optical tomography and X-ray computed tomography imaging in cylindrical geometry has a high potential for small animal tumour evolution studies.

Atherosclerotic plaque imaging using phase-contrast X-ray computed tomography

2008 ◽  
Vol 294 (2) ◽  
pp. H1094-H1100 ◽  
Author(s):  
Masakazu Shinohara ◽  
Tomoya Yamashita ◽  
Hideto Tawa ◽  
Masafumi Takeda ◽  
Naoto Sasaki ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Atherosclerotic Plaque ◽  
Phase Contrast ◽  
Soft Tissues ◽  
Ex Vivo ◽  
Mass Density ◽  
Specific Mass ◽  
X Ray ◽  
Coronary Syndrome ◽  
Luminal Narrowing

Reliable, noninvasive imaging modalities to characterize plaque components are clinically desirable for detecting unstable coronary plaques, which cause acute coronary syndrome. Although recent clinical developments in computed tomography (CT) have enabled the visualization of luminal narrowing and calcified plaques in coronary arteries, the identification of noncalcified plaque components remains difficult. Phase-contrast X-ray CT imaging has great potentials to reveal the structures inside biological soft tissues, because its sensitivity to light elements is almost 1,000 times greater than that of absorption-contrast X-ray imaging. Moreover, a specific mass density of tissue can be estimated using phase-contrast X-ray CT. Ex vivo phase-contrast X-ray CT was performed using a synchrotron radiation source (SPring-8, Japan) to investigate atherosclerotic plaque components of apolipoprotein E-deficient mice. Samples were also histologically analyzed. Phase-contrast X-ray CT at a spatial resolution of 10–20 μm revealed atherosclerotic plaque components easily, and thin fibrous caps were detected. The specific mass densities of these plaque components were quantitatively estimated. The mass density of lipid area was significantly lower (1.011 ± 0.001766 g/ml) than that of smooth muscle area or collagen area (1.057 ± 0.001407 and 1.080 ± 0.001794 g/ml, respectively). Moreover, the three-dimensional assessment of plaques could provide their anatomical information. Phase-contrast X-ray CT can estimate the tissue mass density of atherosclerotic plaques and detect lipid-rich areas. It can be a promising noninvasive technique for the investigation of plaque components and detection of unstable coronary plaques.

scholarly journals Optimization of X-ray Investigations in Dentistry Using Optical Coherence Tomography

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4554
Author(s):  
Ralph-Alexandru Erdelyi ◽  
Virgil-Florin Duma ◽  
Cosmin Sinescu ◽  
George Mihai Dobre ◽  
Adrian Bradu ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Radiation Dose ◽  
Imaging Techniques ◽  
Image Resolution ◽  
Optical Coherence ◽  
X Rays ◽  
High Quality ◽  
X Ray

The most common imaging technique for dental diagnoses and treatment monitoring is X-ray imaging, which evolved from the first intraoral radiographs to high-quality three-dimensional (3D) Cone Beam Computed Tomography (CBCT). Other imaging techniques have shown potential, such as Optical Coherence Tomography (OCT). We have recently reported on the boundaries of these two types of techniques, regarding. the dental fields where each one is more appropriate or where they should be both used. The aim of the present study is to explore the unique capabilities of the OCT technique to optimize X-ray units imaging (i.e., in terms of image resolution, radiation dose, or contrast). Two types of commercially available and widely used X-ray units are considered. To adjust their parameters, a protocol is developed to employ OCT images of dental conditions that are documented on high (i.e., less than 10 μm) resolution OCT images (both B-scans/cross sections and 3D reconstructions) but are hardly identified on the 200 to 75 μm resolution panoramic or CBCT radiographs. The optimized calibration of the X-ray unit includes choosing appropriate values for the anode voltage and current intensity of the X-ray tube, as well as the patient’s positioning, in order to reach the highest possible X-rays resolution at a radiation dose that is safe for the patient. The optimization protocol is developed in vitro on OCT images of extracted teeth and is further applied in vivo for each type of dental investigation. Optimized radiographic results are compared with un-optimized previously performed radiographs. Also, we show that OCT can permit a rigorous comparison between two (types of) X-ray units. In conclusion, high-quality dental images are possible using low radiation doses if an optimized protocol, developed using OCT, is applied for each type of dental investigation. Also, there are situations when the X-ray technology has drawbacks for dental diagnosis or treatment assessment. In such situations, OCT proves capable to provide qualitative images.

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