Journal of X-Ray Science and Technology - Volume 24, issue 2

Authors: Wang, L. | Sixou, B. | Rit, S. | Peyrin, F.

Article Type: Research Article

Abstract: Discrete tomography refers to a class of reconstruction methods adapted to discrete-valued images. Many different approaches have been investigated to address the binary case, when a two-phase object is considered. This reconstruction problem is very important in medical or material applications where it is crucial to reduce the number of projections. In this paper, we address the problem of binary image reconstruction for X-ray CT imaging from a small number of projections. We propose a TV (Total Variation) regularization approach and compare the results obtained with or without an additional box convex constraint. The schemes are applied to a simple …disk image and to more complex bone cross-sections for various noise levels. The minimization of the regularization functional is performed with the state-of-the-art ADMM (Alternate Direction Minimization Method) algorithm. The methods perform equally well on a simple disk image. The additional box convex constraints improves the reconstruction results for complex structures with fine details. Show more

Keywords: X-ray imaging, discrete tomography, inverse problems

DOI: 10.3233/XST-160542

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 177-189, 2016

Authors: Kulkarni, Mayuresh | Dendere, Ronald | Nicolls, Fred | Douglas, Tania S.

Article Type: Research Article

Abstract: BACKGROUND: Digital breast tomosynthesis (DBT) reconstructs planar slices of the breast based on two-dimensional angular projections. Early studies and clinical trials show that DBT is an improvement over full field digital mammography (FFDM) because it provides the radiologist with better image quality and more information. OBJECTIVE: This paper presents a simulation system to model the performance of a slot-scanning FFDM and DBT system. METHODS: A tissue-equivalent three dimensional (3D) breast phantom was constructed, validated for slot-scanning digital mammography and used in simulating digital breast tomosynthesis. The simulation system was validated by comparing images acquired with a …slot-scanning mammography machine with simulated phantom images, using the edge-test method and image quality metrics modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE). Different two-dimensional (2D) projections of the 3D phantom were simulated and the phantom was reconstructed using filtered backprojection. RESULTS: Image quality metrics showed equivalence between simulated and real images. CONCLUSIONS: The simulation tool is suitable for slot-scanning FFDM and DBT and may be used for the design and comparison of mammography systems. Show more

Keywords: Monte-Carlo, slot-scanning, simulation, PENELOPE, DBT, FFDM.

DOI: 10.3233/XST-160543

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 191-206, 2016

Authors: Kazantsev, Daniil | Guo, Enyu | Kaestner, Anders | Lionheart, William R. B. | Bent, Julian | Withers, Philip J. | Lee, Peter D.

Article Type: Research Article

Abstract: X-ray imaging applications in medical and material sciences are frequently limited by the number of tomographic projections collected. The inversion of the limited projection data is an ill-posed problem and needs regularization. Traditional spatial regularization is not well adapted to the dynamic nature of time-lapse tomography since it discards the redundancy of the temporal information. In this paper, we propose a novel iterative reconstruction algorithm with a nonlocal regularization term to account for time-evolving datasets. The aim of the proposed nonlocal penalty is to collect the maximum relevant information in the spatial and temporal domains. With the proposed sparsity seeking …approach in the temporal space, the computational complexity of the classical nonlocal regularizer is substantially reduced (at least by one order of magnitude). The presented reconstruction method can be directly applied to various big data 4D (x , y , z +time) tomographic experiments in many fields. We apply the proposed technique to modelled data and to real dynamic X-ray microtomography (XMT) data of high resolution. Compared to the classical spatio-temporal nonlocal regularization approach, the proposed method delivers reconstructed images of improved resolution and higher contrast while remaining significantly less computationally demanding. Show more

Keywords: Iterative reconstruction, spatio-temporal regularization, time-lapse, nonlocal graphs, p-Laplacian, material science, X-ray microtomography, big data

DOI: 10.3233/XST-160546

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 207-219, 2016

Authors: Kong, Huihua | Liu, Rui | Yu, Hengyong

Article Type: Research Article

Abstract: Inspired by the Compressed Sensing (CS) theory, it has been proved that the interior problem of computed tomography (CT) can be accurately and stably solved if a region-of-interest (ROI) is piecewise constant or polynomial, resulting in the CS-based interior tomography. The key is to minimize the total variation (TV) of the ROI under the constraint of the truncated projections. Coincidentally, the Split-Bregman (SB) method has attracted a major attention to solve the TV minimization problem for CT image reconstruction. In this paper, we apply the SB approach to reconstruct an ROI for the CS-based interior tomography assuming a piecewise constant …imaging model. Furthermore, the ordered subsets (OS) technique is used to accelerate the convergence of SB algorithm, leading to a new OS-SB algorithm for interior tomography. The conventional OS simultaneous algebraic reconstruction technique (OS-SART) and soft-threshold filtering (STF) based OS-SART are also implemented as references to evaluate the performance of the proposed OS-SB algorithm for interior tomography. Both numerical simulations and clinical applications are performed and the results confirm the advantages of the proposed OS-SB method. Show more

Keywords: Ordered subset Split-Bregman, interior tomography, compressive sensing, total variation minimization, piecewise constant imaging model

DOI: 10.3233/XST-160547

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 221-240, 2016

Authors: Chen, Mianyi | Xi, Yan | Cong, Wenxiang | Liu, Baodong | Wei, Biao | Wang, Ge

Article Type: Research Article

Abstract: For X-ray computed tomography (CT), geometric calibration and rigid patient motion compensation are inter-related issues for optimization of image reconstruction quality. Non-calibrated system geometry and patient movement during a CT scan will result in streak-like, blurring and other artifacts in reconstructed images. In this paper, we propose a locally linear embedding based calibration approach to address this challenge under a rigid 2D object assumption and a more general way than what has been reported before. In this method, projections are linearly represented by up-sampled neighbors via locally linear embedding, and CT system parameters are iteratively estimated from projection data themselves. …Numerical and experimental studies show that images reconstructed with calibrated parameters are in excellent agreement with the counterparts reconstructed with the true parameters. Show more

Keywords: Geometric calibration, rigid patient motion, locally linear embedding (LLE)

DOI: 10.3233/XST-160548

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 241-256, 2016

Authors: Zhang, Lingyan | Li, Shaolin | Hao, Shuai | Yuan, Zhen

Article Type: Research Article

Abstract: The goal for this study was to investigate if proton MRS (1H-MRS) and out-of-phase and in-phase MRI can quantify the fat deposition in bone marrow within the lumbar vertebra that can be used to distinguish well between osteoporosis patients and healthy control subjects. Sixty-eight subjects participated in this study. The diagnostic results from dual-energy x-ray absorptiometry served as the gold standard, which was able to separate the subjects into osteoporosis (38 subjects) and non-osteoporosis group (30 subjects). Then the 68 subjects were further scanned by 1H-MRS and in-phase and out-of-phase MRI and the findings from the imaging methods were also …compared and analyzed. It was found that the measured signal intensity ratio (SIR), lipid-water ratio (LWR) and fat fraction (FF) in L2 vertebra from the two imaging methods were able to identify the fat deposition in bone marrow, which could be used to diagnose osteoporosis. Diagnostic accuracy for osteoporosis based on identified SIR, LRW and FF was analyzed by using ROC curves. Our findings suggested that statistically significant differences were identified between osteoporosis patients and healthy subjects. The sensitivity and specificity equal to 78.9% and 75.9% for SIR, 79.2% and 66.7% for LRW, 71.4% and 72.4% for FF, can be achieved when fat deposition-related parameters in bone marrow from the lumbar vertebra are used as classifiers. Our results showed that fat deposition-related parameters including fat content in bone marrow and water content in the lumbar vertebra are clearly different between the osteoporosis and non-osteoporosis group, suggesting that both 1H-MRS and in-phase and out-of-phase MRI can be used for diagnosing osteoporosis and monitoring its progression. Show more

Keywords: 1H-MRS, in-phase and out-of-phase MRI, bones, osteoporosis, dual-energy x-ray absorptiometry

DOI: 10.3233/XST-160549

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 257-266, 2016

Authors: Amato, Ernesto | Asero, Grazia | Leotta, Salvatore | Auditore, Lucrezia | Salamone, Ignazio | Mannino, Giovanni | Privitera, Salvatore | Gueli, Anna

Article Type: Research Article

Abstract: BACKGROUND: In computed tomography (CT), the image contrast is given by the difference in X-ray attenuation in the various tissues of the patient and contrast media are used to enhance image contrast in anatomic regions characterized by similar attenuation coefficients. OBJECTIVE: Aim of the present work is to enlarge the range of applicability of the method previously introduced for organ dosimetry in contrast-enhanced CT, by studying the effects of X-ray beam quality on the parameters of the model. Furthermore, an experimental method for the evaluation of the attenuation properties of iodinated solutions is proposed. METHODS: Monte …Carlo simulations of anthropomorphic phantoms were carried out to determine a bi-parametrical (a and b ) analytical relationship between iodine concentration and dose increase in organs of interest as a function of the tube kilo-voltage peak potential (kVp) and filtration. Experimental measurements of increments in Hounsfield Units (HU) were conducted in several CT scanners, at all the kVp available, in order to determine the parameter γ which relates the HU increment with the iodine mass fraction. A cylindrical phantom that can be filled with iodine solutions provided with an axial housing for a pencil ionization chamber was designed and assembled in order to measure the attenuation properties of iodine solutions under irradiation of a CT scanner and to obtain a further validation of Monte Carlo simulations. RESULTS: The simulation-derived parameters of the model, a and b , are only slightly dependent upon the tube kilo-voltage peak potential and filtration, while such scanner-dependent features influence mainly the experimentally-derived γ parameter. Relative dose variations registered by the ionization chamber inside the iodine-filled cylindrical phantom decrease when the X-ray mean energy increases, and reaches about 50% for 10 mg/ml of iodine. CONCLUSIONS: The dosimetric method for contrast-enhanced CT can be applied to all CT scanners by adopting average simulative parameters and by carrying out a simple measurement with a series of iodine contrast solutions. The novel experimental methodology introduced can provide a direct measurement of iodine attenuation properties. Show more

Keywords: Computed tomography, dose, contrast medium, X-ray tube, iodine

DOI: 10.3233/XST-160551

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 267-278, 2016

Authors: Wong, Kelvin K.L. | Wang, Defeng | Liang, Peipeng

Article Type: Editorial

DOI: 10.3233/XST-160554

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 281-283, 2016

Authors: Tan, Zhen | Li, Yongxin | Zang, Dongdong | Zhang, Heye | Zhao, Cailei | Jiang, Haibo | Chen, Yan | Cao, Dezhi | Chen, Li | Liao, Jianxiang | Chen, Qian | Luan, Guoming

Article Type: Research Article

Abstract: Infantile spasm (IS) syndrome is an age-related epileptic encephalopathy that occurs in children. The purpose of this study was to investigate regional homogeneity (ReHo) changes in IS patients. Resting-state fMRI was performed on 11 patients with IS, along with 35 age- and sex-matched healthy subjects. Group comparisons between the two groups demonstrate that the pattern of regional synchronization synchronization in IS patients is changed. Decreased ReHo values were found in default mode network, bilateral motor-related areas and left occipital gyrus of the patient group. Increased ReHo was found in regions of cingulum, cerebellum, supplementary motor area and brain deep nucleus, …such as hippocampus, caudate, thalamus and insula. The significant differences might indicate that epileptic action have some injurious effects on the motor, executive and cognitive related regions. In addition, ReHo values of left precuneus and right superior frontal gyrus were associated with the epilepsy duration in the IS group. The correlation results indicate that the involvement of these regions may be related to the seizure generation. Our results suggest that IS may have an injurious effect on the brain activation. The findings may shed new light on the understanding the neural mechanism of IS epilepsy. Show more

Keywords: Epilepsy, resting-state fMRI, regional homogeneity, infantile spasm, thalamus, DMN

DOI: 10.3233/XST-160559

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 285-295, 2016

Authors: Liu, Liansheng | Wu, Yuefeng | Zheng, Jiayi | Lai, Xinsheng | Zeng, Daohui | Li, Hengguo | Shi, Changzheng | Yang, Minjie | Liang, Changhong

Article Type: Research Article

Abstract: OBJECTIVE: This study aimed to observe the cerebral activation effects of acupuncturing the Zusanli (ST36) plusYanglingquan (GB34) points in young healthy volunteers based on Regional Homogeneity (ReHo) indices. METHODS: Ten healthy volunteers were enrolled, including 4 males and 6 females between the ages 20 and 34 years with a median age of 23 years. Magnetic resonance imaging (GE Signa HDxt 3.0T) was performed in four groups: Before acupuncture (Control Group), after acupuncture at Zusanli (ST36 Group), after acupuncture at Yanglingquan (GB34 Group) and after acupuncture at both Zusanli and Yanglingquan (Compatibility Group). Differences in the brain ReHo indices …of the 4 groups were analyzed by statistical parametric mapping (SPM8) and ReHo data processing methods. The significantly different brain regions were obtained using a false discovery rate correction (FDR-Corrected). RESULTS: The ReHo indices revealed that the main significant effect was in the Compatibility Group. Compared with the resting state of the Control Group, the ReHo values of the Compatibility Group increased in the right middle frontal gyrus (BA8, 9), left superior temporal areas (BA22), ventral anterior cingulate area (BA24) and right inferior parietal lobe (BA40); in contrast, the ReHo values decreased in the left thalamus, right insular cortex (BA13), left inferior frontal lobe (BA9) and right dorsal anterior cingulate area (BA32). Our analysis showed that the Compatibility Group had higher ReHo values than the left inferior parietal lobule (BA40) and right frontal cortex (BA6) of the ST36 Group and the posterior lobe of the right cerebellum, dorsal anterior cingulate (BA32), left and right middle frontal gyrus (BA46, BA9), left precuneus (BA7), right inferior parietal love (BA40) of the GB34 Group. CONCLUSION: The results of our neuroimaging study suggest that the combination of acupoints could more widely activate areas of the brain compared to a single acupoint. Additionally, the combination of acupoints can activate some new brain areas and generate new curative effects. Show more

Keywords: Acupuncture, Zusanli (ST36), Yanglingquan (GB34), Regional Homogeneity (ReHo) indices, functional magnetic resonance imaging

DOI: 10.3233/XST-160557

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 297-308, 2016

Authors: Gong, Xuehao | Mao, Xuhua | Chen, Yan | Huang, Leidan | Liu, Weizong | Huang, Xian | Tan, Zheng | Wang, Xianming | Wu, Wanqing | Chen, Qian | Li, Rong

Article Type: Research Article

Abstract: In this study, we examine the potential of heart rate variability (HRV) as an efficient tool for predicting the onset of epilepsy in children. We totally collected 53 seizures EEG and ECG data using Video - EEG - ECG monitoring system. We then separated the ECG data into three segments: ten-minute before onset of each seizure, five-minute before onset of each seizure, and five-minute from the onset of each seizure. After the HRV parameters in all segments were calculated, we compared the differences between pre-ictal period and ictal period. We found that the values of meanHR, LF and LF/HF were …greater in onset period. And the values of meanRR and the HF were less in ictal period. And it presented the similar changes when seizures occurred in the daytime and seizures occurred in the nighttime. In brief, we found that the sympathetic nervous system was under a more active status during onset period. We speculated that the HRV parameters such as the LF, HF or LF/HF could have potential to predict the seizures in children with epilepsy. Show more

Keywords: Seizure, HRV, children

DOI: 10.3233/XST-160558

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 309-317, 2016

Authors: Chen, Dan | Liu, Bin | Jin, Chuanbing | Cao, Yongsheng | Han, Hui | Deng, Xuefei

Article Type: Research Article

Abstract: BACKGROUND: During surgical procedures, the basal vein in the posterior incisural space is susceptible to obstruction. In such circumstances, venous infarction can occur along with venous damage. OBJECTIVE: The aim of this study was to correlate the microanatomy of the basal vein in the posterior incisural space with the digital subtraction angiography (DSA) and computed tomographic venography (CTV). METHODS: Twenty cadavers and 42 patients were examined in this study. The head of each cadaver was injected with blue-colored gelatin via the internal jugular veins. Venograms for each patient were obtained from the venous phases of DSA …or CTV. RESULTS: Compared to the cadavers, in the patients, DSA and CTV revealed 90% and 95% of the basal vein, respectively. According to difference of entrance, three types of basal veins were identified. No statistical difference of typing was found among the cadavers, DSA images and CTV images. On three sides of the cadavers and one side of the CTV images, the basal vein entered the straight sinus through the meningeal vein in the tentorium cerebelli. CONCLUSIONS: Preoperative DSA and CTV are useful in the design of individualized surgical approaches and the preservation of the basal vein in the posterior incisural space. Show more

Keywords: Basal vein, posterior incisural space, microanatomy, digital subtraction angiography, computed tomographic venography

DOI: 10.3233/XST-160555

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 319-327, 2016

Authors: Wang, Zhiqun | Zhang, Min | Han, Ying | Song, Haiqing | Guo, Rongjuan | Li, Kuncheng

Article Type: Research Article

Abstract: The amygdala is an important brain area involved in cognitive procession and emotional regulation. Previous studies have typically considered the amygdala as a single structure, which likely masks contribution of individual amygdala subdivisions. Actually, the amygdala is heterogeneous and composed of structurally and functionally distinct nuclei, which may present different connectivity patterns and predict to relevant cognitive deficits in Alzheimer’s disease (AD). However, little is known about functional connectivity of amygdala subregions in the resting state in AD subjects. Here, we employed resting-state functional MRI (fMRI) to examine functional connectivity changes of subregions comparing the AD patients with the age-matched …control subjects. Thirty-two AD and 38 control subjects were analyzed. We defined three subregions of the amygdala according to probabilistic cytoarchitectonic atlases and mapped the whole-brain resting-state functional connectivity for each subregion: The central medial nucleus (CM) of amygdala exhibited connections with the lentiform nucleus, parahippocampus and lateral temporal gyrus; the lateral basal nucleus (LB) of amygdala functionally connected with the parahippocampus, lateral temporal gyrus, middle occipital gyrus and medial prefrontal cortex; and the superficial nucleus (SF) of amygdala had connection with the parahippocampus, lentiform nucleus, lateral temporal gyrus, insula, middle occipital gyrus, precentral and postcentral gyrus. Comparing with the controls, the AD patients presented disrupted connectivity patterns in the LB of amygdala, which predicted disconnection with the left uncus, right insula, right precentral gyrus, the left superior temporal gyrus and right claustrum. These findings in a large part supported our hypothesis and provided a new insight in understanding the pathophysiological mechanisms of AD. Show more

Keywords: Amygdala, functional connectivity, functional MRI, Alzheimer disease

DOI: 10.3233/XST-160556

Citation: Journal of X-Ray Science and Technology, vol. 24, no. 2, pp. 329-342, 2016