Multiple Projection Images Research Articles

AI-based computer-aided diagnostic system of chest digital tomography synthesis: Demonstrating comparative advantage with X-ray-based AI systems

Background:Compared with chest X-ray (CXR) imaging, which is a single image projected from the front of the patient, chest digital tomosynthesis (CDTS) imaging can be more advantageous for lung lesion detection because it acquires multiple images projected from multiple angles of the patient. Various clinical comparative analysis and verification studies have been reported to demonstrate this, but there is no artificial intelligence (AI)-based comparative analysis studies. Existing AI-based computer-aided detection (CAD) systems for lung lesion diagnosis have been developed mainly based on CXR images; however, CAD-based on CDTS, which uses multi-angle images of patients in various directions, has not been proposed and verified for its usefulness compared to CXR-based counterparts.Background and objective:This study develops and tests a CDTS-based AI CAD system to detect lung lesions to demonstrate performance improvements compared to CXR-based AI CAD.Methods:We used multiple (e.g., five) projection images as input for the CDTS-based AI model and a single-projection image as input for the CXR-based AI model to compare and evaluate the performance between models. Multiple/single projection input images were obtained by virtual projection on the three-dimensional (3D) stack of computed tomography (CT) slices of each patient’s lungs from which the bed area was removed. These multiple images result from shooting from the front and left and right 30/60∘. The projected image captured from the front was used as the input for the CXR-based AI model. The CDTS-based AI model used all five projected images. The proposed CDTS-based AI model consisted of five AI models that received images in each of the five directions, and obtained the final prediction result through an ensemble of five models. Each model used WideResNet-50. To train and evaluate CXR- and CDTS-based AI models, 500 healthy data, 206 tuberculosis data, and 242 pneumonia data were used, and three three-fold cross-validation was applied.Results:The proposed CDTS-based AI CAD system yielded sensitivities of 0.782 and 0.785 and accuracies of 0.895 and 0.837 for the (binary classification) performance of detecting tuberculosis and pneumonia, respectively, against normal subjects. These results show higher performance than the sensitivity of 0.728 and 0.698 and accuracies of 0.874 and 0.826 for detecting tuberculosis and pneumonia through the CXR-based AI CAD, which only uses a single projection image in the frontal direction. We found that CDTS-based AI CAD improved the sensitivity of tuberculosis and pneumonia by 5.4% and 8.7% respectively, compared to CXR-based AI CAD without loss of accuracy.Conclusions:This study comparatively proves that CDTS-based AI CAD technology can improve performance more than CXR. These results suggest that we can enhance the clinical application of CDTS. Our code is available at https://github.com/kskim-phd/CDTS-CAD-P.

Development of 3D tomosynthesis technique for nondestructive technology application using vertically aligned carbon nanotube-based high-resolution cold cathode electron beam

Nondestructive technology (NDT) is the most popular method for detecting defects inside an object without harming it. A 3D tomography algorithm toolbox and an x-ray imaging system are the essential components of NDT. We fabricated a high-resolution cold cathode electron beam (HRC-beam) based on vertically aligned carbon nanotubes to accomplish this objective. Using an HRC-beam, multiple angle projection images were captured in an x-ray imaging system. This x-ray source's horizontal and vertical focal spot sizes were 0.57 and 0.49 mm, respectively. Using the homemade 3D tomography algorithm toolbox, all the multiple projection images were recreated in a 3D volume. This toolbox employs algorithms such as the radon transform and the inverse radon transform to generate the 3D volume. The matlab r2022b program was used to execute the algorithm. This study explains the development of a three-dimensional volume and the inspection of the 3D volume in a slice view using a high-resolution cold cathode electron beam and the 3D tomography algorithm toolbox. A large phantom cable was used to evaluate 3D reconstruction and void inspection inside the large phantom cable.

Coronary tortuosity in patients with acetylcholine-induced coronary microvascular spasm

Abstract Background Angina pectoris in the absence of relevant epicardial stenoses (ANOCA) is frequently caused by coronary microvascular spasm. It has been speculated that the morphology of epicardial coronary arteries is associated with microvascular spasm. One hypothesis is that the vasoconstriction of microvessels leads to intraluminal pressure increase in the vascular segments proximal to the spasm, which may shift the balance of vessel forces toward vessel elongation resulting in coronary tortuosity. Purpose We assessed the relationship between epicardial coronary tortuosity and coronary spasm to elucidate a potential relationship between structural and functional coronary abnormalities. Methods 610 patients (39% male, mean age 61 years) with stable angina yet unobstructed coronary arteries (<50% stenosis) were included in this study. All patients underwent invasive diagnostic coronary angiography followed by intracoronary acetylcholine (ACh) testing according to a standardized protocol. The ACh test was considered “positive” in the presence of (a) angina, ischemic ECG shifts during the test and ≥90% coronary diameter reduction (“epicardial spasm”) or (b) all above without epicardial spasm (“microvascular spasm”). Assessment of coronary tortuosity was performed using left and right coronary images in multiple projections in a blinded fashion. The number and angles of the coronary curves in late diastole determined the severity of coronary tortuosity previously defined by Eleid. Patients were divided into those with at least moderate tortuosity versus those with no or mild tortuosity. Results ACh-testing revealed epicardial spasm in 179 (29%) and microvascular spasm in 172 (28%) patients. The ACh-test was negative/inconclusive in the remaining 259 patients (43%). There were 298 patients (49%) with at least moderate coronary tortuosity. The remaining 312 patients had no or mild coronary tortuosity (51%). Patients with at least moderate tortuosity were more likely to have microvascular spasm (99 patients of 172 with microvascular spasm had at least moderate coronary tortuosity (58%) vs. 76 patients of 179 with epicardial spasm (43%) vs. 126 patients of 259 with negative/inconclusive ACh test (49%), p=0.017). Analysis of coronary tortuosity in patients with positive ACh-test showed that patients with at least moderate coronary tortuosity (n=175) had significantly more microvascular spasm (57%) than epicardial spasm (43%) (p=0.005). We also found that at least moderate coronary tortuosity was significantly more often found in patients with hypertension compared to patients without hypertension (230/438 vs. 71/172, p=0.015). Conclusions In this large cohort of ANOCA patients coronary tortuosity was associated with hypertension and microvascular spasm. Our results provide interesting insights into the relationship of coronary morphology and vasomotor function. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Berthold-Leibinger-Foundation, Ditzingen, Germany

Hyperspectral three-dimensional absorption imaging using snapshot optical tomography.

Hyperspectral imaging (HSI) records a series of two-dimensional (2D) images for different wavelengths to provide the chemical fingerprint at each pixel. Combining HSI with a tomographic data acquisition method, we can obtain the chemical fingerprint of a sample at each point in three-dimensional (3D) space. The so-called 3D HSI typically suffers from low imaging throughput due to the requirement of scanning the wavelength and rotating the beam or sample. In this paper we present an optical system which captures the entire four-dimensional (4D), i.e., 3D structure and 1D spectrum, dataset of a sample with the same throughput of conventional HSI systems. Our system works by combining snapshot projection optical tomography (SPOT) which collects multiple projection images with a single snapshot, and Fourier-transform spectroscopy (FTS) which results in superior spectral resolution by collecting and processing a series of interferogram images. Using this hyperspectral SPOT system we imaged the volumetric absorbance of dyed polystyrene microbeads, oxygenated red blood cells (RBCs), and deoxygenated RBCs. The 4D optical system demonstrated in this paper provides a tool for high-throughput chemical imaging of complex microscopic specimens.

Multi-Angle Projection Based Blind Omnidirectional Image Quality Assessment

Most of the existing blind omnidirectional image quality assessment (BOIQA) methods are based on data-driven approach where the end-to-end neural network or deep learning tools are mainly used for feature extraction. However, it usually lacks interpretability and is difficult to discover the perceptual mechanism behind. In this paper, from the perspective of perception modeling, we propose a novel multi-angle projection based BOIQA (MP-BOIQA) method. Considering the omnibearing and near eye display characteristics with head mounted display, multiple color cubemap projection images with respect to different viewpoints are grouped as the color omnidirectional distortion (COD) units so as to simulate the user’s viewing behavior in subjective quality assessment. In the designed multi-angle projection based feature extractor, tensor decomposition is implemented on each COD unit for dimensionality reduction, and piecewise exponential fitting is used to get the distribution of mean subtracted contrast normalized coefficients of the unit’s feature matrices in tensor domain. Finally, the extracted features are pooled with random forest. The experimental results on three omnidirectional image quality datasets show that the MP-BOIQA method can deliver highly competitive performance compared with some representative full-reference quality assessment methods, as well as some state-of-the-art BOIQA methods.

Detection of Mandibular Canal in Human Dry Mandibles with Cone Beam Computed Tomography using 270° and 360° Protocols under Continuous and Pulse Modes – A Comparative Study

Background: Cone beam computed tomography (CBCT) enables practitioner to accurately localize and mark the nerve canal. The rotation of the X-ray tube and the detector around the patient's head produces multiple projection images. A high number of projections is associated with increased radiation dose to the patient, higher spatial and contrast resolution. Shorter scan arc results in reduced scan time, reduced dose and smaller file sizes. The pulsed X-ray beam reduces the actual exposure time than the scanning time and the patient radiation exposure. Aim: (1) To assess and compare the diagnostic efficacy between pulse mode and continuous mode (2) To assess and compare the diagnostic efficacy between 270° and 360° CBCT rotational protocols Subjects and Methods: A total of 30 Intact Dentate or Partially dentate dry human mandibles consisting first, second, and third molars were subjected to a total of 4 CBCT scans: 270° rotation scans under continuous and pulse mode, 360° rotation scans under continuous and pulse mode using two CBCT units. Distance from the inferior cortical border of mandible (ICBM) to the roof of the inferior alveolar nerve canal (IANC) was measured at four locations: mental foramen, first, second and third molar. The results were then compared. Results: Comparison of the IANC length measurements for the two modes revealed no significant difference. Conclusion: Shorter scan arc and pulse mode can be adopted in patients finding it difficult to remain stable for prolonged periods of time, while maintaining appreciable clarity and quality of image. This could apply to geriatric patients, children, mentally challenged, in patients with trauma, neurological diseases, anxiety, claustrophobia, wherein the patient's movements might need re-scanning, which would lead to an extra radiation dose to the patient.

Digital Breast Tomosynthesis: an Overview.

The online version contains supplementary material available at 10.1007/s13193-021-01310-y.

Microstructure Analysis and Reconstruction of a Meniscus.

ObjectiveTo analyze the characteristics of menicus microstructure and to reconstruct a microstructure‐mimicing 3D model of the menicus.MethodsHuman and sheep meniscus were collected and prepared for this study. Hematoxylin–eosin staining (HE) and Masson staining were conducted for histological analysis of the meniscus. For submicroscopic structure analysis, the meniscus was first freeze‐dried and then scanned by scanning electron microscopy (SEM). The porosity of the meniscus was determined according to SEM images. A micro‐MRI was used to scan each meniscus, immersed in distilled water, and a 3D digital model was reconstructed afterwards. A three‐dimensional (3D) resin model was printed out based on the digital model. Before high‐resolution micro‐CT scanning, each meniscus was freeze‐dried. Then, micro‐scale two‐dimensional (2D) CT projection images were obtained. The porosity of the meniscus was calculated according to micro‐CT images. With micro‐CT, multiple 2D projection images were collected. A 3D digital model based on 2D CT pictures was also reconstructed. The 3D digital model was exported as STL format. A 3D resin model was printed by 3D printer based on the 3D digital model.ResultsAs revealed in the HE and Masson images, a meniscus is mostly composed of collagen, with a few cells disseminated between the collagen fiber bundles at the micro‐scale. The SEM image clearly shows the path of highly cross‐linked collagen fibers, and massive pores exist between the fibers. According to the SEM images, the porosity of the meniscus was 34.1% (34.1% ± 0.032%) and the diameters of the collagen fibers were varied. In addition, the cross‐linking pattern of the fibers was irregular. The scanning accuracy of micro‐MRI was 50 μm. The micro‐MRI demonstrated the outline of the meniscus, but the microstructure was obscure. The micro‐CT clearly displayed microfibers in the meniscus with a voxel size of 11.4 μm. The surface layer, lamellar layer, circumferential fibers, and radial fibers could be identified. The mean porosity of the meniscus according to micro‐CT images was 33.92% (33.92% ± 0.03%). Moreover, a 3D model of the microstructure based on the micro‐CT images was built. The microscale fibers could be displayed in the micro‐CT image and the reconstructed 3D digital model. In addition, a 3D resin model was printed out based on the 3D digital model.ConclusionIt is extremely difficult to artificially simulate the microstructure of the meniscus because of the irregularity of the diameter and cross‐linking pattern of fibers. The micro‐MRI images failed to demonstrate the meniscus microstructure. Freeze‐drying and micro‐CT scanning are effective methods for 3D microstructure reconstruction of the meniscus, which is an important step towards mechanically functional 3D‐printed meniscus grafts.

Ovine Bone Morphology and Deformation Analysis Using Synchrotron X-ray Imaging and Scattering

Bone is a natural hierarchical composite tissue incorporating hard mineral nano-crystals of hydroxyapatite (HAp) and organic binding material containing elastic collagen fibers. In the study, we investigated the structure and deformation of ovine bone by the combination of high-energy synchrotron X-ray tomographic imaging and scattering. X-ray experiments were performed prior to and under three-point bending loading by using a specially developed in situ load cell constructed from aluminium alloy frame, fast-drying epoxy resin for sample fixation, and a titanium bolt for contact loading. Firstly, multiple radiographic projection images were acquired and tomographic reconstruction was performed using SAVU software, following segmentation using Avizo. Secondly, Wide Angle X-ray Scattering (WAXS) and Small Angle X-ray Scattering (SAXS) 2D scattering patterns were collected from HAp and collagen. Both sample shape and deformation affect the observed scattering. Novel combined tomographic and diffraction analysis presented below paves the way for advanced characterization of complex shape samples using the Dual Imaging and Diffraction (DIAD) paradigm.

High-speed multi-beam X-ray imaging using a lens coupling detector system

We present a high-speed multi-beam X-ray imaging realized using a detector system and the recently developed multi-beam X-ray optics [Voegeli et al., Optica 7, 514 (2020)]. The detector utilized optical relay lenses and mirrors for connecting four scintillator screens to a CMOS camera, enabling the high-speed simultaneous acquisition of multiple projection images. We successfully acquired nine projection images in 0.5 ms with a spatial resolution of 70 μm. Dynamical behaviors of a light-bulb filament and a living ladybug were captured with a temporal resolution of 0.5 ms, demonstrating the potential for high-speed and high-spatial-resolution 4D X-ray tomography.

A Fast Computer-Generated Holographic Method for VR and AR Near-Eye 3D Display

A fast computer-generated holographic method with multiple projection images for a near-eye VR (Virtual Reality) and AR (Augmented Reality) 3D display is proposed. A 3D object located near the holographic plane is projected onto a projection plane to obtain a plurality of projected images with different angles. The hologram is calculated by superposition of projected images convolution with corresponding point spread functions (PSF). Holographic 3D display systems with LED as illumination, 4f optical filtering system and lens as eyepiece for near-eye VR display and holographic optical element (HOE) as combiner for near-eye AR display are designed and developed. The results show that the proposed calculation method is about 38 times faster than the conventional point cloud method and the display system is compact and flexible enough to produce speckle noise-free high-quality VR and AR 3D images with efficient focus and defocus capabilities.

Structure Determination by Single-Particle Cryo-Electron Microscopy: Only the Sky (and Intrinsic Disorder) is the Limit.

Traditionally, X-ray crystallography and NMR spectroscopy represent major workhorses of structural biologists, with the lion share of protein structures reported in protein data bank (PDB) being generated by these powerful techniques. Despite their wide utilization in protein structure determination, these two techniques have logical limitations, with X-ray crystallography being unsuitable for the analysis of highly dynamic structures and with NMR spectroscopy being restricted to the analysis of relatively small proteins. In recent years, we have witnessed an explosive development of the techniques based on Cryo-electron microscopy (Cryo-EM) for structural characterization of biological molecules. In fact, single-particle Cryo-EM is a special niche as it is a technique of choice for the structural analysis of large, structurally heterogeneous, and dynamic complexes. Here, sub-nanometer atomic resolution can be achieved (i.e., resolution below 10 Å) via single-particle imaging of non-crystalline specimens, with accurate 3D reconstruction being generated based on the computational averaging of multiple 2D projection images of the same particle that was frozen rapidly in solution. We provide here a brief overview of single-particle Cryo-EM and show how Cryo-EM has revolutionized structural investigations of membrane proteins. We also show that the presence of intrinsically disordered or flexible regions in a target protein represents one of the major limitations of this promising technique.

Edge Fusion Algorithm for Orthogonal Projection of Multiple Overlapping Regions

Stereo projection display technology has become a hot topic in recent years. A edge fusion technology for multiple projection images with multiple overlapping areas is proposed. An edge fusion method is proposed, which can be used for edge fusion of multiple overlapping areas in irregular fusion areas, eliminate the bright band caused by overlapping projection and realize multi-channel seamless Mosaic display. The practical application shows that this method can make the multi-projector display system with multiple planar and different shape and multiple overlapping areas project a seamless vision.

CT and MRI of the Orbit.

Computed Tomography (CT) Imaging for Orbital PathologyCT imaging is produced by obtaining radiographic images in multiple projections using a revolving x-ray tube and x-ray detector. Modern CT technology allows for the rapid acquisition of high-quality data that can be used to create a variety of im

2D hybrid analysis: Approach for building three-dimensional atomic model by electron microscopy image matching

In this study, we develop an approach termed “2D hybrid analysis” for building atomic models by image matching from electron microscopy (EM) images of biological molecules. The key advantage is that it is applicable to flexible molecules, which are difficult to analyze by 3DEM approach. In the proposed approach, first, a lot of atomic models with different conformations are built by computer simulation. Then, simulated EM images are built from each atomic model. Finally, they are compared with the experimental EM image. Two kinds of models are used as simulated EM images: the negative stain model and the simple projection model. Although the former is more realistic, the latter is adopted to perform faster computations. The use of the negative stain model enables decomposition of the averaged EM images into multiple projection images, each of which originated from a different conformation or orientation. We apply this approach to the EM images of integrin to obtain the distribution of the conformations, from which the pathway of the conformational change of the protein is deduced.

Multispectral high-resolution hologram generation using orthographic projection images

We present a new method of synthesizing a digital hologram of three-dimensional (3D) real-world objects from multiple orthographic projection images (OPI). A high-resolution multiple perspectives of 3D objects (i.e., two dimensional elemental image array) are captured under incoherent white light using synthetic aperture integral imaging (SAII) technique and their OPIs are obtained respectively. The reference beam is then multiplied with the corresponding OPI and integrated to form a Fourier hologram. Eventually, a modified phase retrieval algorithm (GS/HIO) is applied to reconstruct the hologram. The principle is validated experimentally and the results support the feasibility of the proposed method.

Markerless tumor tracking using short kilovoltage imaging arcs for lung image-guided radiotherapy

The ability to monitor tumor motion without implanted markers is clinically advantageous for lung image-guided radiotherapy (IGRT). Existing markerless tracking methods often suffer from overlapping structures and low visibility of tumors on kV projection images. We introduce the short arc tumor tracking (SATT) method to overcome these issues. The proposed method utilizes multiple kV projection images selected from a nine-degree imaging arc to improve tumor localization, and respiratory-correlated 4D cone-beam CT (CBCT) prior knowledge to minimize the effects of overlapping anatomies. The 3D tumor position is solved as an optimization problem with prior knowledge incorporated via regularization. We retrospectively validated SATT on 11 clinical scans from four patients with central tumors. These patients represent challenging scenarios for markerless tumor tracking due to the inferior adjacent contrast. The 3D trajectories of implanted fiducial markers were used as the ground truth for tracking accuracy evaluation. In all cases, the tumors were successfully tracked at all gantry angles. Compared to standard pre-treatment CBCT guidance alone, trajectory errors were significantly smaller with tracking in all cases, and the improvements were the most prominent in the superior-inferior direction. The mean 3D tracking error ranged from 2.2–9.9 mm, which was 0.4–2.6 mm smaller compared to pre-treatment CBCT. In conclusion, we were able to directly track tumors with inferior visibility on kV projection images using SATT. Tumor localization accuracies are significantly better with tracking compared to the current standard of care of lung IGRT. Future work involves the prospective evaluation and clinical implementation of SATT.

Straightforward computer-generated Fresnel hologram from multiple angular orthogonal projection images

By the multiple angular orthogonal projection images, a novel method for a straightforward computer-generated Fresnel hologram is demonstrated. With the angular orthogonal projection images at various viewpoints obtained from a computer designed three-dimensional object, an incoherent Fresnel hologram can be synthesized. After the shifted angular orthogonal projection images are multiplied by the constant phase factors and integrated, a two-dimensional complex matrix including three-dimensional information is achieved. The proposed Fresnel hologram is verified to be equivalent to an optical coherent Fresnel hologram. Since the diffraction and Fourier transform calculations are not necessary, the calculation complexity of the Fresnel hologram synthetic process can be greatly simplified.

X-ray Nano- and Micro-tomography in an SEM

X-ray microfocus computer tomography (μ-CT) is a non-destructive experimental technique that reveals the 3D internal microstructure of the sample under study. The experimental set-up consists of an X-ray source, an X-ray detector, and set in between is a sample that is placed on a rotation stage. With this set-up multiple X-ray projection images can be obtained from the sample at different angles. In between the acquisition of two successive images, the sample is rotated over a small angle, typically between 0.2° and 1°. This set of projection images is then used as input for the reconstruction algorithm, which calculates a reconstruction of the internal microstructure of the sample with (sub-) micrometer sensitivity.

Three-dimensional Čerenkov tomography of energy deposition from ionizing radiation beams.

Since its discovery during the 1930s the Čerenkov effect (light emission from charged particles traveling faster than the local speed of light in a dielectric medium) has been paramount in the development of high-energy physics research. The ability of the emitted light to describe a charged particle's trajectory, energy, velocity, and mass has allowed scientists to study subatomic particles, detect neutrinos, and explore the properties of interstellar matter. However, to our knowledge, all applications of the process to date have focused on the identification of particles themselves, rather than their effect upon the surroundings through which they travel. Here we explore a novel application of the Čerenkov effect for the recovery of the spatial distribution of ionizing radiation energy deposition in a medium and apply it to the issue of dose determination in medical physics. By capturing multiple projection images of the Čerenkov light induced by a medical linear accelerator x-ray photon beam, we demonstrate the successful three-dimensional tomographic reconstruction of the imparted dose distribution.