Journal of X-Ray Science and Technology - Volume 30, issue 1

Authors: Wang, Wei | Xia, Xiang-Gen | He, Chuanjiang | Ren, Zemin | Lu, Jian

Article Type: Research Article

Abstract: In this paper, we present an arc based fan-beam computed tomography (CT) reconstruction algorithm by applying Katsevich’s helical CT image reconstruction formula to 2D fan-beam CT scanning data. Specifically, we propose a new weighting function to deal with the redundant data. Our weighting function ϖ ( x _ , λ ) is an average of two characteristic functions, where each characteristic function indicates whether the projection data of the scanning angle contributes to the intensity of the pixel x _ . In fact, for every pixel x _ …, our method uses the projection data of two scanning angle intervals to reconstruct its intensity, where one interval contains the starting angle and another contains the end angle. Each interval corresponds to a characteristic function. By extending the fan-beam algorithm to the circle cone-beam geometry, we also obtain a new circle cone-beam CT reconstruction algorithm. To verify the effectiveness of our method, the simulated experiments are performed for 2D fan-beam geometry with straight line detectors and 3D circle cone-beam geometry with flat-plan detectors, where the simulated sinograms are generated by the open-source software “ASTRA toolbox.” We compare our method with the other existing algorithms. Our experimental results show that our new method yields the lowest root-mean-square-error (RMSE) and the highest structural-similarity (SSIM) for both reconstructed 2D and 3D fan-beam CT images. Show more

DOI: 10.3233/XST-211000

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 1, pp. 145-163, 2022

Authors: Yuan, Xiaohan | Zhu, Xiaomei | Chen, Yang | Liu, Wangyan | Qian, Wen | Xu, Yi | Zhu, Yinsu

Article Type: Research Article

Abstract: BACKGROUND: Energetics alteration plays a crucial role in the myocardial injury process in chronic hypoxia diseases (CHD). 31 P magnetic resonance spectroscopy (MRS) can investigate alterations in cardiac energetics in vivo . OBJECTIVE: To characterize the potential value of 31 P MRS in evaluating cardiac energetics alteration of chronic hypoxic rats (CHRs). METHODS: Twenty-four CHRs were induced by SU5416 combined with hypoxia and divided into four groups according to the modeling time of one, two, three and five weeks, respectively. Control group also contains six rats. 31 P MRS was performed weekly and the ratio of …concentrations of phosphocreatine (PCr) to adenosine triphosphate (ATP) (PCr/ATP) was obtained. In addition, the cardiac structure index and systolic function parameters, including the right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVi), right ventricular end-systolic volume index (RVESVi), and the left ventricular function parameters, were measured. RESULTS: Decreased resting cardiac PCr/ATP ratio in CHRs was observed at the first week, compared to the control group (2.90±0.35 vs. 3.31±0.45, p  = 0.045), while the RVEF, RVEDVi, and RVESVi decreased at the second week (p  < 0.05). The PCr/ATP ratio displayed a significant correlation with RVEF (r  = 0.605, p  = 0.001), RVEDVi, and RVESVi (r  = –0.661, r  = –0.703; p  < 0.001). CONCLUSIONS: 31 P MRS can easily detect the cardiac energetics alteration in a CHR model before the onset of ventricular dysfunction. The decreased PCr/ATP ratio likely reveales myocardial injury and cardiac dysfunction. Show more

Keywords: 31P magnetic resonance spectroscopy (MRS), cardiac energetics, myocardial injury, chronic hypoxia, rat model

DOI: 10.3233/XST-210985

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 1, pp. 165-175, 2022

Authors: Sun, Jihang | Li, Haoyan | Li, Haiyun | Li, Michelle | Gao, Yingzi | Zhou, Zuofu | Peng, Yun

Article Type: Research Article

Abstract: BACKGROUND: The inflammatory indexes of children with Takayasu arteritis (TAK) usually tend to be normal immediately after treatment, therefore, CT angiography (CTA) has become an important method to evaluate the status of TAK and sometime is even more sensitive than laboratory test results. OBJECTIVE: To evaluate image quality improvement in CTA of children diagnosed with TAK using a deep learning image reconstruction (DLIR) in comparison to other image reconstruction algorithms. METHODS: hirty-two TAK patients (9.14±4.51 years old) underwent neck, chest and abdominal CTA using 100 kVp were enrolled. Images were reconstructed at 0.625 mm slice thickness using Filtered …Back-Projection (FBP), 50%adaptive statistical iterative reconstruction-V (ASIR-V), 100%ASIR-V and DLIR with high setting (DLIR-H). CT number and standard deviation (SD) of the descending aorta and back muscle were measured and contrast-to-noise ratio (CNR) for aorta was calculated. The vessel visualization, overall image noise and diagnostic confidence were evaluated using a 5-point scale (5, excellent; 3, acceptable) by 2 observers. RESULTS: There was no significant difference in CT number across images reconstructed using different algorithms. Image noise values (in HU) were 31.36±6.01, 24.96±4.69, 18.46±3.91 and 15.58±3.65, and CNR values for aorta were 11.93±2.12, 15.66±2.37, 22.54±3.34 and 24.02±4.55 using FBP, 50%ASIR-V, 100%ASIR-V and DLIR-H, respectively. The 100%ASIR-V and DLIR-H images had similar noise and CNR (all P  > 0.05), and both had lower noise and higher CNR than FBP and 50%ASIR-V images (all P  < 0.05). The subjective evaluation suggested that all images were diagnostic for large arteries, however, only 50%ASIR-V and DLIR-H met the diagnostic requirement for small arteries (3.03±0.18 and 3.53±0.51). CONCLUSION: DLIR-H improves CTA image quality and diagnostic confidence for TAK patients compared with 50%ASIR-V, and best balances image noise and spatial resolution compared with 100%ASIR-V. Show more

Keywords: Computed Tomography Angiography (CTA), takayasu arteritis, pediatrics, deep learning image reconstruction

DOI: 10.3233/XST-211033

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 1, pp. 177-184, 2022

Authors: Xu, Chengxiao | Zhang, Yue | Zhang, Ning | Sun, Xiaoxuan | Liu, Qingwen | Wang, Qiang | Zhu, Yinsu

Article Type: Research Article

Abstract: BACKGROUND: The morphological alterations of small pulmonary vessels measured by computed tomography (CT) is increasingly used in evaluation of suspected pulmonary hypertension (PH). OBJECTIVE: To investigate the significance alterations of quantitative assessment of small pulmonary vessels on chest CT in distinguishing different types of PH and their severity. METHODS: We retrospectively analyzed a dataset of 120 healthy controls (HCs) and 91 PH patients, including 34 patients with connective tissue diseases-related PH (CTD-PH), 26 patients with idiopathic pulmonary arterial hypertension (iPAH), and 31 patients with chronic obstructive pulmonary disease-related PH (COPD-PH). The CTD-PH patients were …divided into mild to moderate PH (CTD-LM-PH) group (n  = 17) and severe PH (CTD-S-PH) group (n  = 17). A total of 53 CTD patients without PH (CTD-nPH) were enrolled for comparison with the CTD-PH. We measured the cross-sectional area of small pulmonary vessels < 5 mm2 (%CSA <5 ) and between 5–10 mm2 (%CSA5–10 ) as a percentage of total lung area among the populations included above and compared %CSA in different types of PH groups and HCs group. The mean pulmonary arterial pressure (mPAP) was measured by right heart catheterization. RESULTS: The %CSA5–10 of COPD-PH, CTD-PH, and iPAH patients increased (0.21±0.09, 0.49±0.20 and 0.61±0.20, p  < 0.02) sequentially, while the %CSA <5 of CTD-PH, iPAH, and COPD-PH patients decreased (0.79±0.65, 0.65±0.38 and 0.52±0.27, p  < 0.05) sequentially. The %CSA5–10 was significantly higher in CTD-S-PH patients than CTD-LM-PH patients and CTD-nPH patients (0.51±0.21, 0.31±0.15 and 0.28±0.12, p  < 0.01). The %CSA5–10 was positively correlated with mPAP in the CTD-PH group. CONCLUSIONS: The quantitative parameters %CSA <5 and %CSA5–10 assessed by chest CT are useful for distinguishing different types of PH. In addition, the %CSA5–10 can provide information for identification of CTD-PH severity. Show more

Keywords: Small pulmonary vessels, pulmonary hypertension (PH), computed tomography (CT), PH severity classification

DOI: 10.3233/XST-211001

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 1, pp. 185-193, 2022

Authors: Xu, Wenjie | Lu, Rui | Hu, Yun | Cao, Li | Wang, Tao | Tan, Hao | Meng, Xuehuan | Ming, Ye | Zheng, Leilei

Article Type: Research Article

Abstract: OBJECTIVE: To assess reliability of cone-beam CT (CBCT) for nasolabial soft tissue measurements in patients with skeletal class III malocclusion based on 3-dimensional (3D) facial scanner results. METHODS: CBCT and 3D facial scan images of 20 orthognathic patients are used in this study. Eleven soft tissue landmarks and 15 linear and angular measurements are identified and performed. For qualitative evaluation, Shapiro-Wilk test and Bland-Altman plots are applied to analyze the equivalence of the measurements derived from these two kinds of images. To quantify specific deviation of CBCT measurements from facial scanner, the latter is set as a …benchmark, and mean absolute difference (MAD) and relative error magnitude (REM) for each variable are also calculated. RESULTS: Statistically significant differences are observed in regions of nasal base and lower lip vermilion between two methods. MAD value for all length measurements are less than 2 mm and for angular variables < 8°. The average MAD and REM for length measurements are 0.94 mm and 5.64%, and for angular measurements are 2.27° and 3.78%, respectively. CONCLUSIONS: The soft tissue results measured by CBCT show relatively good reliability and can be used for 3D measurement of soft tissue in the nasolabial region clinically. Show more

Keywords: Cone-beam CT, facial scanner, 3-dimensional cephalometry

DOI: 10.3233/XST-211018

Citation: Journal of X-Ray Science and Technology, vol. 30, no. 1, pp. 195-206, 2022