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Iodine Quantification on Spectral Detector-Based Dual-Energy CT Enterography: Correlation with Crohn's Disease Activity Index and External Validation
摘要： Objective: To correlate CT parameters on detector-based dual-energy CT enterography (DECTE) with Crohn’s disease activity index (CDAI) and externally validate quantitative CT parameters. Materials and Methods: Thirty-nine patients with CD were retrospectively enrolled. Two radiologists reviewed DECTE images by consensus for qualitative and quantitative CT features. CT attenuation and iodine concentration for the diseased bowel were also measured. Univariate statistical tests were used to evaluate whether there was a significant difference in CTE features between remission and active groups, on the basis of the CDAI score. Pearson’s correlation test and multiple linear regression analyses were used to assess the correlation between quantitative CT parameters and CDAI. For external validation, an additional 33 consecutive patients were recruited. The correlation and concordance rate were calculated between real and estimated CDAI. Results: There were significant differences between remission and active groups in the bowel enhancement pattern, subjective degree of enhancement, mesenteric fat infiltration, comb sign, and obstruction (p < 0.05). Significant correlations were found between CDAI and quantitative CT parameters, including number of lesions (correlation coefficient, r = 0.573), bowel wall thickness (r = 0.477), iodine concentration (r = 0.744), and relative degree of enhancement (r = 0.541; p < 0.05). Iodine concentration remained the sole independent variable associated with CDAI in multivariate analysis (p = 0.001). The linear regression equation for CDAI (y) and iodine concentration (x) was y = 53.549x + 55.111. For validation patients, a significant correlation (r = 0.925; p < 0.001) and high concordance rate (87.9%, 29/33) were observed between real and estimated CDAIs. Conclusion: Iodine concentration, measured on detector-based DECTE, represents a convenient and reproducible biomarker to monitor disease activity in CD.
关键词： Crohn’s disease,Iodine quantification,Activity index,Dual-energy computed tomography
更新于2025-09-23 15:21:01
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Directed energy deposition of Al 5xxx alloy using Laser Engineered Net Shaping (LENS??)
摘要： Here, we present directed energy deposition (DED) of wrought-like Al 5xxx AlMg alloy by Laser Engineered Net Shaping (LENS?). A transition from an Al 5083 gas atomized powder feedstock to Al 5754 characteristics of the as-deposited material due to selective evaporation of Mg was observed. Density values obtained by X-ray micro-computed tomography (μ-CT) were compared to those obtained by the Archimedes method. The latter indicated a relative density as high as 99.26%. Possible origins of porosity are discussed. The as-deposited material was comprised of both equiaxed and columnar grains with no preferred crystallographic orientation and mean grain size of 36 μm. The Young's modulus, yield stress, ultimate tensile strength, fracture strain, Poisson's ratio, and total ultimate strain energy (toughness) were determined by uniaxial tensile tests combined with digital image correlation (DIC). Fractography complemented the mechanical testing. A pulse-echo ultrasonic non-destructive test was used to obtain more accurate values of the Young's and shear moduli and to adjust the value of the yield strength accordingly. The measured mechanical properties meet the requirements of international standards for wrought Al 5754 in its annealed condition.
关键词： Additive manufacturing (AM),Mechanical properties,Micro-computed tomography (μ-CT),Laser Engineered Net Shaping (LENS?),Directed energy deposition (DED),Aluminum alloys
更新于2025-09-23 15:21:01
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Cardiac Computed Tomography 2.0
摘要： Computed tomography angiography (CTA) is now an established diagnostic option for patients with chest pain. It is a safe alternative to functional testing, provides diagnostic certainty, is a good gatekeeper for downstream invasive angiography, and increases the diagnostic yield when invasive angiography is eventually needed. CTA-driven care is associated with more relief of angina and generates optimal medical therapy associated with reduced death and myocardial infarction. However, CT angiography can lead to more cardiac catheterizations as well as more coronary revascularization. CTA shows good sensitivity, but also suffers from suboptimal specificity; thus, one cannot be sure, lacking other functional test results, that more revascularization procedures are necessary or beneficial compared to operating on lesions with demonstrated ischemia.
关键词： Fractional Flow Reserve,Myocardial Perfusion Imaging,Cardiac Computed Tomography,Coronary Artery Disease,CT Angiography
更新于2025-09-23 15:21:01
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Sparsity-induced dynamic guided filtering approach for sparse-view data toward low-dose X-ray computed tomography
摘要： Iterative reconstruction (IR) methods that can incorporate filtering or regularization techniques have received widespread attention in many situations. Total variation (TV) regularization has proven to be a powerful tool to suppress streak artifacts and noise for sparse-view computed tomography (CT) reconstruction over 360°. However, with under-sampled projection data from limited-view (e.g., half-view) CT scanning, where the projections are further reduced, the edge structures are partly blurred, and some artifacts (such as blocky artifacts) are not effectively suppressed in TV-based results. To further improve the quality of the reconstructed image, a sparsity-induced dynamic guided image filtering reconstruction (SIDGIFR) method is proposed. Intermediate reconstruction results constrained by total difference minimization are taken as the guidance image to filter the results of projection onto convex sets (POCS) by guided image filtering. In the SIDGIFR algorithm, the guidance image is dynamically updated, which can transfer the important features (such as edge and small details) to the filtered image during the iterative process. To confirm the efficiency and feasibility of the SIDGIFR algorithm, simulated experiments and real data studies are performed. The quantitative evaluation shows that the proposed SIDGIFR method has better performance than other classical iterative reconstruction methods. What’s more, the proposed SIDGIFR algorithm can better preserve the edge structures, and suppress noise and artifacts, than the existing iterative reconstruction methods.
关键词： computed tomography,total variation,iterative reconstruction,total difference,guided image filtering,sparse-view
更新于2025-09-23 15:21:01
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Improvement of image quality at CT and MRI using deep learning
摘要： Deep learning has been developed by computer scientists. Here, we discuss techniques for improving the image quality of diagnostic computed tomography and magnetic resonance imaging with the aid of deep learning. We categorize the techniques for improving the image quality as “noise and artifact reduction”, “super resolution” and “image acquisition and reconstruction”. For each category, we present and outline the features of some studies.
关键词： Computed tomography,Image quality improvement,Deep learning,Magnetic resonance imaging
更新于2025-09-23 15:21:01
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Quantitative imaging techniques for the assessment of osteoporosis and sarcopenia
摘要： Bone and muscle are two deeply interconnected organs and a strong relationship between them exists in their development and maintenance. The peak of both bone and muscle mass is achieved in early adulthood, followed by a progressive decline after the age of 40. The increase in life expectancy in developed countries resulted in an increase of degenerative diseases affecting the musculoskeletal system. Osteoporosis and sarcopenia represent a major cause of morbidity and mortality in the elderly population and are associated with a significant increase in healthcare costs. Several imaging techniques are currently available for the non-invasive investigation of bone and muscle mass and quality. Conventional radiology, dual energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound often play a complementary role in the study of osteoporosis and sarcopenia, depicting different aspects of the same pathology. This paper presents the different imaging modalities currently used for the investigation of bone and muscle mass and quality in osteoporosis and sarcopenia with special emphasis on the clinical applications and limitations of each technique and with the intent to provide interesting insights into recent advances in the field of conventional imaging, novel high-resolution techniques and fracture risk.
关键词： sarcopenia,Osteoporosis,photon,magnetic resonance imaging (MRI),absorptiometry,multidetector computed tomography (CT)
更新于2025-09-23 15:21:01
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Early Detection of Cerebral Infarction With Middle Cerebral Artery Occlusion With Functional Near-Infrared Spectroscopy: A Pilot Study
摘要： Background: NIRSIT, a functional near-infrared spectroscopy (fNIRS) device with 204 channels, can measure oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR) in non-pulsatile blood ?ow non-invasively using the absorption difference between HbO2 and HbR at a wavelength of 700–1,000 nm and can display the perfusion status in real time. Objective: We applied NIRSIT to patients with stroke to evaluate the usefulness of NIRSIT as an fNIRS device for the early detection of stroke. Methods: We performed a prospective pilot study in an emergency department (ED). Adult patients who had suspected symptoms and signs of stroke within 12 h of the ?rst abnormal time and who underwent intravenous thrombolysis (IVT) or intra-arterial thrombectomy with acute middle cerebral artery (MCA) or internal carotid artery (ICA) infarction were enrolled. NIRSIT was applied to the patients before the imaging study, and the perfusion status of the brain was displayed in real time at the bedside. We compared the NIRSIT results with the mean transit time (MTT) map from perfusion computed tomography (PCT) and the time-to-peak (TTP) map from perfusion-weighted magnetic resonance imaging (PWI). Results: Six male and three female patients were enrolled, and the median age was 74 years. The most common symptom was unilateral extremity weakness (77.8%), followed by dysarthria (33.3%) and aphasia (11.1%). The median National Institutes of Health Stroke Scale (NIHSS) score was 17. All cases of MCA infarction showed different cerebral oxygen saturation values between bilateral lobes of the brain in fNIRS imaging, and these values matched the PCT and PWI results. Conclusions: The brain hemisphere with low oxygen saturation on fNIRS showed hypoperfusion on PCT or PWI. The fNIRS device could be useful in assessing the perfusion status of the brain and detecting MCA or ICA infarction in real time at the bedside.
关键词： middle cerebral artery,magnetic resonance imaging,computed tomography,perfusion,cerebral infarction
更新于2025-09-23 15:21:01
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[Fundamental Biomedical Technologies] Advanced High-Resolution Tomography in Regenerative Medicine (Three-Dimensional Exploration into the Interactions between Tissues, Cells, and Biomaterials) || Introduction to X-Ray Micro-tomography
摘要： X-ray computed tomography (CT) represents one of the most powerful 3D non-destructive imaging techniques exploited in clinics to help the diagnostic process of many diseases. The progress achieved in the realization of detectors, in x-ray tube technology, and in the computational power of modern hardware has led to its translation toward micrometer and sub-micrometer range resolution applications. Micro-CT and nano-CT systems based on conventional micro-focus x-ray tubes or newest generation liquid-metal-jet anode (MetalJet) systems are, today, available and largely applied in biomedical research for in vitro studies of biomaterials, scaffolds, bones, teeth, etc. as well as for morphologic and functional studies on excised organs and small animals. Absorption-based imaging is the basis for the most common modality of CT scanners; however, the recent developments of x-ray sources based on synchrotron laboratories and capable to reach unprecedented characteristics of brilliance and intensity have allowed the implementation of innovative imaging approaches. These techniques exploit the refraction of x-rays in the matter instead of their absorption, overcoming the intrinsic limitation of conventional techniques and broadening the utility of micro-CT. In this chapter an overview of the basics of micro-CT will be given, starting from the sources characteristics, then describing the x-ray interactions with matter, and finally addressing the image formation principles. In this latter paragraph, particular attention will be reserved to phase-sensitive techniques, highlighting their potentials to improve biomedical research.
关键词： Nano-CT,Micro-CT,Phase-sensitive techniques,Biomedical imaging,X-ray computed tomography
更新于2025-09-23 15:21:01
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Case Report: SPECT/CT as the New Diagnostic Tool for Specific Wrist Pathology
摘要： Introduction: Single photon emission computed tomography has been introduced as a promising new diagnostic tool in orthopaedic pathology since the early 90'. Computed tomography, the combined with SPECT, gives insight in the specific sight of wrist pathology. Literature already supports introduction of SPECT/CT in wrist pathology, but clinical application is lagging. Case Report: A 40yr old patient reported first in 2004 with persisting pain after a right distal radius fracture. Several diagnostics and operative interventions were performed, all unsuccessful. Because of the persisting pain a SPECT-CT was performed which showed a cyst in the hamate bone, which was successfully enucleated. The patient was finally pain free at recent follow-up. With a QDash-score of 43 and a PRW (H) E-DLV-score of 58/150. Discussion: In this case report, SPECT/CT proved a very sensitive diagnostic tool for specific pathology of the wrist. It offered precise localisation and thereby the clinically suspected diagnosis was confirmed and the patient successfully treated.
关键词： Capitate,Proximal row carpectomy,Wrist,SPECT/CT,Hamate,Single-Photon Emission-Computed Tomography
更新于2025-09-23 15:21:01
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Photonic materials for high-temperature applications: Synthesis and characterization by X-ray ptychographic tomography
摘要： Photonic materials for high-temperature applications need to withstand temperatures usually higher than 1000 ?C, whilst keeping their function. When exposed to high temperatures, such nanostructured materials are prone to detrimental morphological changes, however the structure evolution pathway of photonic materials and its correlation with the loss of material’s function is not yet fully understood. Here we use high-resolution ptychographic X-ray computed tomography (PXCT) and scanning electron microscopy (SEM) to investigate the structural changes in mullite inverse opal photonic crystals produced by a very-low-temperature (95 ?C) atomic layer deposition (ALD) super-cycle process. The 3D structural changes caused by the high-temperature exposure were quantified and associated with the distinct structural features of the ceramic photonic crystals. Other than observed in photonic crystals produced via powder colloidal suspensions or sol-gel infiltration, at high temperatures of 1400 ?C we detected a mass transport direction from the nano pores to the shells. We relate these different structure evolution pathways to the presence of hollow vertexes in our ALD-based inverse opal photonic crystals. Although the periodically ordered structure is distorted after sintering, the mullite inverse opal photonic crystal presents a photonic stopgap even after heat treatment at 1400 ?C for 100 h.
关键词： Ptychography X-ray computed tomography,High-temperature applications,3D image analysis,Photonic materials,Low-temperature atomic layer deposition
更新于2025-09-23 15:21:01