Sectional Image Reconstruction Research Articles

Breathing motion compensation in chest tomosynthesis: evaluation of the effect on image quality and presence of artifacts.

Chest tomosynthesis (CTS) has a relatively longer acquisition time compared with chest X-ray, which may increase the risk of motion artifacts in the reconstructed images. Motion artifacts induced by breathing motion adversely impact the image quality. This study aims to reduce these artifacts by excluding projection images identified with breathing motion prior to the reconstruction of section images and to assess if motion compensation improves overall image quality. In this study, 2969 CTS examinations were analyzed to identify examinations where breathing motion has occurred using a method based on localizing the diaphragm border in each of the projection images. A trajectory over diaphragm positions was estimated from a second-order polynomial curve fit, and projection images where the diaphragm border deviated from the trajectory were removed before reconstruction. The image quality between motion-compensated and uncompensated examinations was evaluated using the image quality criteria for anatomical structures and image artifacts in a visual grading characteristic (VGC) study. The resulting rating data were statistically analyzed using the software VGC analyzer. A total of 58 examinations were included in this study with breathing motion occurring either at the beginning or end ( ) or throughout the entire acquisition ( ). In general, no significant difference in image quality or presence of motion artifacts was shown between the motion-compensated and uncompensated examinations. However, motion compensation significantly improved the image quality and reduced the motion artifacts in cases where motion occurred at the beginning or end. In examinations where motion occurred throughout the acquisition, motion compensation led to a significant increase in ripple artifacts and noise. Compensation for respiratory motion in CTS by excluding projection images may improve the image quality if the motion occurs mainly at the beginning or end of the examination. However, the disadvantages of excluding projections may outweigh the benefits of motion compensation.

Emerging structural and pathological analyses on the erectile organ, corpus cavernous containing sinusoids.

The corpus cavernosum (CC) containing sinusoids plays fundamental roles for erection. Analysis of pathological changes in the erectile system is studied by recent experimental systems. Various in vitro models utilizing genital mesenchymal-derived cells and explant culture systems are summarized. 3D reconstruction of section images of murine CC was created. Ectopic chondrogenesis in aged mouse CC was shown by a gene expression study revealing the prominent expression of Sox9. Various experimental strategies utilizing mesenchyme-derived primary cells and tissue explants are introduced. Possible roles of Sox9 in chondrogenesis and its regulation by several signals are suggested. The unique character of genital mesenchyme is shown by various analyses of external genitalia (ExG) derived cells and explant cultures. Such strategies are also applied to the analysis of erectile contraction/relaxation responses to many signals and aging process. Erectile dysfunction (ED) is one of the essential topics for the modern aged society. More comprehensive studies are necessary to reveal the nature of the erectile system by combining multiple cell culture strategies.

A Microwave Sensing and Imaging Method for Multiphase Flow Metering of Crude Oil Pipes

This article proposes a microwave sensing and imaging method for multiphase flow monitoring and metering in oil and gas pipes. The ultrawideband (UWB) synthetic aperture radar (SAR) technique is used to create a high-resolution image of the pipe cross section. The image is, then, used to estimate each phase volume by extracting the edge of each phase. Additionally, the generalized impulsization technique is presented and applied to reconstruct a sharp-image, and decrease the error in flow rate estimation. Furthermore, a novel technique to enhance the detectability of weak targets in the images is proposed. Finally, a novel sectional image reconstruction technique is also applied to improve the imaging and metering of the stratified flows. All the proposed techniques are evaluated through experiments. This study demonstrates the ability to accurately estimate the crude oil flow rate with a maximum error of 3.8 ${\%}$ . These results show that UWB SAR is capable of providing a reliable and noninvasive solution for multiphase flow metering.

Microwave Imaging of Breast Tumor Using Time-Domain UWB Circular-SAR Technique.

This paper explores the competency of the time domain ultra-wideband (UWB)-circular synthetic aperture radar (CSAR) to image the breast and detect tumors. The image reconstruction is performed using a time domain global back projection technique adapted to the circular trajectory data acquisition. This paper also proposes a sectional image reconstruction method to compensate for the group velocity changes in different layers of a multilayer medium. Experiments on an advanced breast phantom examines the suitability of this technique for breast tumor imaging. The advanced breast phantom is designed based on a MRI of a real patient, fabricated using 3D printing technology, and filled with liquids that emulate normal and cancerous tissues. The measurement results, compared with MRI imaging of the phantom, demonstrate the suitability of the UWB-CSAR method for breast tumor imaging. This method can be a tool for early diagnosis as well as for treatment monitoring during chemotherapy or radiotherapy.

Modified image fusion technique to remove defocus noise in optical scanning holography

In sectional image reconstruction based on optical scanning holography (OSH) system, tomographic images are always contaminated by defocus noise. Though lots of methods have been proposed to solve this problem, some unsatisfactory results remain. In this article, a modified image fusion method is presented based on wavelet transform and connected component algorithms to deal with the defects in a random-phase OSH system where different sectional images usually have a relative displacement, rotation and loss. The method can fully utilize redundant information and affine transformation to repair the defects, and the defocus noise can be removed well. The final sectional images are more visible.

3D reconstruction of brain section images for creating axonal projection maps in marmosets

BackgroundThe brain of the common marmoset (Callithrix jacchus) is becoming a popular non-human primate model in neuroscience research. Because its brain fiber connectivity is still poorly understood, it is necessary to collect and present connection and trajectory data using tracers to establish a marmoset brain connectivity database. New methodTo visualize projections and trajectories of axons, brain section images were reconstructed in 3D by registering them to the corresponding block-face brain images taken during brain sectioning. During preprocessing, autofluorescence of the tissue was reduced by applying independent component analysis to a set of fluorescent images taken using different filters. ResultsThe method was applied to a marmoset dataset after a tracer had been injected into an auditory belt area to fluorescently label axonal projections. Cortical and subcortical connections were clearly reconstructed in 3D. The registration error was estimated to be smaller than 200 μm. Evaluation tests on ICA-based autofluorescence reduction showed a significant improvement in signal and background separation. Comparison with existing methodsRegarding the 3D reconstruction error, the present study shows an accuracy comparable to previous studies using MRI and block-face images. Compared to serial section two-photon tomography, an advantage of the proposed method is that it can be combined with standard histological techniques. The images of differently processed brain sections can be integrated into the original ex vivo brain shape. ConclusionsThe proposed method allows creating 3D axonal projection maps overlaid with brain area annotations based on the histological staining results of the same animal.

Chest Tomosynthesis: Technical and Clinical Perspectives

The recent implementation of chest tomosynthesis is built on the availability of large, dose-efficient, high-resolution flat panel detectors, which enable the acquisition of the necessary number of projection radiographs to allow reconstruction of section images of the chest within one breath hold. A chest tomosynthesis examination obtains the increased diagnostic information provided by volumetric imaging at a radiation dose comparable to that of conventional chest radiography. There is evidence that the sensitivity of chest tomosynthesis may be at least three times higher than for conventional chest radiography for detection of pulmonary nodules. The sensitivity increases with increasing nodule size and attenuation and decreases for nodules with subpleural location. Differentiation between pleural and subpleural lesions is a known pitfall due to the limited depth resolution in chest tomosynthesis. Studies on different types of pathology report increased detectability in favor of chest tomosynthesis in comparison to chest radiography. The technique provides improved diagnostic accuracy and confidence in the diagnosis of suspected pulmonary lesions on chest radiography and facilitates the exclusion of pulmonary lesions in a majority of patients, avoiding the need for computed tomography (CT). However, motion artifacts can be a cumbersome limitation and breathing during the tomosynthesis image acquisition may result in severe artifacts significantly affecting the detectability of pathology. In summary, chest tomosynthesis has been shown to be superior to chest conventional radiography for many tasks and to be able to replace CT in selected cases. In our experience chest tomosynthesis is an efficient problem solver in daily clinical work.

Depth resolution enhancement in double-detection optical scanning holography

We propose an optical scanning holography system with enhanced axial resolution using two detections at different depths. By scanning the object twice, we can obtain two different sets of Fresnel zone plates to sample the same object, which in turn provides more information for the sectional image reconstruction process. We develop the computation algorithm that makes use of such information, solving a constrained optimization problem using the conjugate gradient method. Simulation results show that this method can achieve a depth resolution up to 1μm.

Deviation influences on sectional image reconstruction in optical scanning holography using a random-phase pupil

In this paper, we analyze the influence of two kinds of deviation errors on sectional image reconstruction for an optical scanning holography system using a random-phase pupil. The first deviation occurs in the lateral pixel position while the second occurs in the pixel value of the decoding function. Theoretical analysis and numerical simulation show that these two deviations may lead to noise in the reconstructed image. Additional discussions include the signal-to-noise ratio of the reconstructed image.

Reconstruction of sectional images in frequency-domain based photoacoustic imaging

Photoacoustic (PA) imaging is based upon the generation of an ultrasound pulse arising from subsurface tissue absorption due to pulsed laser excitation, and measurement of its surface time-of-arrival. Expensive and bulky pulsed lasers with high peak fluence powers may provide shortcomings for applications of PA imaging in medicine and biology. These limitations may be overcome with the frequency-domain PA measurements, which employ modulated rather than pulsed light to generate the acoustic wave. In this contribution, we model the single modulation frequency based PA pressures on the measurement plane through the diffraction approximation and then employ a convolution approach to reconstruct the sectional image slices. The results demonstrate that the proposed method with appropriate data post-processing is capable of recovering sectional images while suppressing the defocused noise resulting from the other sections.

Fast reconstruction of sectional images in digital holography

Past research has demonstrated that a three-dimensional object scene can be converted into a digital hologram. Subsequently, the object scene can be reconstructed from the hologram with an iterative blind sectional image reconstruction (BSIR) method. However, the computation is extremely intensive, and escalated with the size of holograms. To overcome this problem, we propose a fast BSIR method that reconstructs sectional images with less out-of-focus haze. While the technique proposed here is applicable in general to holography for sectioning, we use holograms acquired by optical scanning holography as examples to show the method's effectiveness.

Sectional image reconstruction and three-dimensional microscopy of small particles by angular spectrum method

In this letter, we demonstrate sectional image reconstruction and three-dimensional microscopy of small particles. We demonstrate sectional image reconstruction and holographic methods to obtain 2D and 3D images of small particles. A single hologram is sufficient to obtain a section containing only the focused parts of the reconstructed image. One can obtain images of different plane sections of a specimen in addition to its 3D display. The reconstruction of a digital hologram is based on the plane-wave expansion of the diffracted wave fields using Fourier optics (this method is also known as the angular spectrum method). With this method, the object-to-hologram distance can be quite small because the minimum-distance requirement does not apply. Furthermore, numerical reconstruction of transparent objects by this method may be interesting for micro-structure measurement.

Sectional image reconstruction in optical scanning holography using a random-phase pupil

A method is presented for the reconstruction of sectional images without the out-of-focus haze from a hologram generated by optical scanning holography. A random-phase pupil is adopted in the process of recovering individual sections from the hologram. The main idea of this approach is to recover a prescribed section while dispersing the energy from other sections into "specklelike patterns," which can be eliminated subsequently by averaging of multiple section images.

Edge-preserving sectional image reconstruction in optical scanning holography

Optical scanning holography (OSH) enables us to capture the three-dimensional information of an object, and a post-processing step known as sectional image reconstruction allows us to view its two-dimensional cross-section. Previous methods often produce reconstructed images that have blurry edges. In this paper, we argue that the hologram's two-dimensional Fourier transform maps into a semi-spherical surface in the three-dimensional frequency domain of the object, a relationship akin to the Fourier diffraction theorem used in diffraction tomography. Thus, the sectional image reconstruction task is an ill-posed inverse problem, and here we make use of the total variation regularization with a nonnegative constraint and solve it with a gradient projection algorithm. Both simulated and experimental holograms are used to verify that edge-preserving reconstruction is achieved, and the axial distance between sections is reduced compared with previous regularization methods.

Three-dimensional reconstruction of CT sectional images of liver tissue based on VTK

Objective Turn the CT sectional image into three-dimensional imaging based on VTK, in or-der to make better treatment programs for patients with liver cancer. Methods Establish visualization toolkit (VTK) visualization development environment based on VC6.0, obtain patient's CT images in DICOM format, use VTK filter and Laplacian sharpening template for pre-treatment of the images, and then use Ray-Casting algo-rithm for three-dimensional reconstruction. Results We can get three-dimensional images with higher resolu-tion and faster imaging speed through this method, which can also be cut, rotated and zoomed. Conclusion Ray-Casting algorithm based on VTK can be used for the three-dimensional imaging of human liver. With the as-sistance of three-dimensional images, doctors can detect the location of diseased tissue more easily and observe the shapes of diseased tissue intuitively. Key words: Liver tissue; Visualization toolkit; Three-dimensional reconstruction; Ray-Casting algorithm

Three-dimensional microscopy and sectional image reconstruction using optical scanning holography

Fast acquisition and high axial resolution are two primary requirements for three-dimensional microscopy. However, they are sometimes conflicting: imaging modalities such as confocal imaging can deliver superior resolution at the expense of sequential acquisition at different axial planes, which is a time-consuming process. Optical scanning holography (OSH) promises to deliver a good trade-off between these two goals. With just a single scan, we can capture the entire three-dimensional volume in a digital hologram; the data can then be processed to obtain the individual sections. An accurate modeling of the imaging system is key to devising an appropriate image reconstruction algorithm, especially for real data where random noise and other imaging imperfections must be taken into account. In this paper we demonstrate sectional image reconstruction by applying an inverse imaging sectioning technique to experimental OSH data of biological specimens and visualizing the sections using the OSA Interactive Science Publishing software.

Blind sectional image reconstruction for optical scanning holography

Optical scanning holography is a powerful holographic recording technique in which only a single two-dimensional scan is needed to record three-dimensional information. As in standard digital holography, for the reconstruction of a sectional image, the resulting data must then be postprocessed to obtain sectional content. We propose a blind sectional image reconstruction technique to automate the data processing. This reconstruction uses edge information to determine the appropriate Fresnel zone plates automatically and applies inverse imaging to recover the sectional images with significant suppression of the defocus noise. The experimental data used to verify the algorithm are measured from a physical implementation of the optical scanning holography system.

Reconstruction of sectional images in holography using inverse imaging

This paper discusses the reconstruction of sectional images from a hologram generated by optical scanning holography. We present a mathematical model for the holographic image capture, which facilitates the use of inverse imaging techniques to recover individual sections. This framework is much more flexible than existing work, in the sense that it can handle objects with multiple sections, and possibly corrupted with white Gaussian noise. Simulation results show that the algorithm is capable of recovering a prescribed section while suppressing the other ones as defocus noise. The proposed algorithm is applicable to on-axis holograms acquired by conventional holography as well as phase-shifting holography.

Improvement of image resolution and quantitative accuracy in clinical Single Photon Emission Computed Tomography

Clinical Single Photon Emission Computed Tomography (SPECT) is a scanning technique which acquires gamma-camera images (‘projections’) over a range of angles around a patient. These projections allow the reconstruction of cross sectional (‘tomographic’) images of the gamma-radiating pharmaceutical distribution in the patient, thus providing interesting information about the functioning of organs and tissues. SPECT images are seriously affected by a variety of image degrading processes. Restrictions on the amount of radio-pharmaceutical that can be administered to a patient cause noise in the projections and the limited spatial resolution of the gamma-camera results in blurring of the projections. In addition to these image degradations, the reconstruction of cross-sections is complicated by Compton scattering of γ-photons in tissue, which causes attenuation of the photon flux received by the gamma-camera and causes improper detection of photons which have been scattered in tissue. This results in some additional blurring and loss of accuracy of the SPECT images in predicting activity concentrations. Tremendous efforts have been made to improve the quantitative accuracy and the spatial resolution of SPECT, and to reduce the noise in the reconstructed images. These efforts have resulted in corrective reconstruction algorithms, which are generally based on incorporation of accurate models of the main image degrading factors. Improvements of the data acquisition hardware can further increase image quality. In this paper, the image formation process of SPECT, including image-degrading factors, is explained. In addition, reconstruction algorithms and hardware modifications are reviewed, and their effects on image quality are illustrated with physical phantom and simulation experiments.

Image-enhanced thermal-wave slice diffraction tomography with numerically simulated reconstructions

Thermal-wave slice diffraction tomography (TSDT) is a photothermal imaging technique for non-destructive evaluation (NDE), leading to the detection of subsurface cross sectional defects in opaque solids in the very-near-surface region ( - mm). An exact, Green's-function based mathematical model that represents the behaviour of a three-dimensional thermal wave is developed and correlated with a numerical reconstruction technique. The computational technique utilizes the well known Tikhonov regularization method to invert almost singular matrices resulting from the ill-posedness of the inverse thermal-wave problem for the reconstruction of thermal diffusivity cross sectional images in materials. Numerical calculations of the inverse problem are carried out using the Born approximation and simulated reconstructions in back scattering and transmission are presented.