Comparative study of abdominal CT enhancement in overweight and obese patients based on different scanning modes combined with different contrast medium concentrations.

PURPOSE: To compare image quality, iodine intake, and radiation dose in overweight and obese patients undergoing abdominal computed tomography (CT) enhancement using different scanning modes and contrast medium. METHODS: Ninety overweight and obese patients (25 kg/m2≤body mass index (BMI)< 30 kg/m2 and BMI≥30 kg/m2) who underwent abdominal CT-enhanced examinations were randomized into three groups (A, B, and C) of 30 each and scanned using gemstone spectral imaging (GSI) +320 mgI/ml, 100 kVp + 370 mgI/ml, and 120 kVp + 370 mgI/ml, respectively. Reconstruct monochromatic energy images of group A at 50-70 keV (5 keV interval). The iodine intake and radiation dose of each group were recorded and calculated. The CT values, contrast-to-noise ratios (CNRs), and subjective scores of each subgroup image in group A versus images in groups B and C were by using one-way analysis of variance or Kruskal-Wallis H test, and the optimal keV of group A was selected. RESULTS: The dual-phase CT values and CNRs of each part in group A were higher than or similar to those in groups B and C at 50-60 keV, and similar to or lower than those in groups B and C at 65 keV and 70 keV. The subjective scores of the dual-phase images in group A were lower than those of groups B and C at 50 keV and 55 keV, whereas no significant difference was seen at 60-70 keV. Compared to groups B and C, the iodine intake in group A decreased by 12.5% and 13.3%, respectively. The effective doses in groups A and B were 24.7% and 25.8% lower than those in group C, respectively. CONCLUSION: GSI +320 mgI/ml for abdominal CT-enhanced in overweight patients satisfies image quality while reducing iodine intake and radiation dose, and the optimal keV was 60 keV.

Ergonomic design and evaluation of gemstone polishing workstation.

Objectives. Gemstone polishers suffer from musculoskeletal problems due to constrained working postures, substantially influenced by the poor design of conventional gemstone polishing workstations. The present study investigated the effects of three workstation adjustment parameters (illumination at workstation, polishing height, tool post position) on postural angle, muscle activity and perceived postural discomfort in order to develop recommendations for new gemstone polishing workstations. Methods. Twelve professional gemstone polishers performed the polishing task on a prototype test-rig in 27 different test conditions. Taguchi's L27 orthogonal array was employed to estimate the optimum setting for gemstone polishing workstation design. Results. Study variables had a significant influence on postural angles. Polishing height substantially influenced muscle activity and perceived discomfort in the shoulder and lower back region. Tool post position was found to be the determinant factor for forearm muscle activity and perceived discomfort in the wrist/forearm region. Based on the findings, illumination of 1500 lux, polishing at 15 cm above the elbow height and a 20° tool position was recommended. Conclusions. Our findings present an alternative approach to using Taguchi's design of experiment for workstation improvement, which has received very little attention in ergonomics studies. A confirmation test was conducted to validate the study recommendations.

Cost-effectiveness analysis of sugemalimab vs. placebo, in combination with chemotherapy, for treatment of first-line metastatic NSCLC in China.

Objective: The purpose of this study was to estimate the cost-effectiveness of sugemalimab plus chemotherapy (SC) vs. placebo plus chemotherapy (PC), as the first-line treatment for patients with non-small cell lung cancer (NSCLC) in China. Material and methods: A three-state Markov model with a cycle of 3 weeks was built to assess the incremental cost-effectiveness ratio (ICER) of SC vs. PC as first-line treatment for patients with NSCLC over a 10-year horizon from Chinese health care perspective. Time-dependency transition probability and safety data were derived from a multicenter, randomized, double-blind, phase 3 clinical trial performed in China (GEMSTONE-302). Primary model outcomes included the costs in US dollars and health outcomes in quality-adjusted life-years (QALYs) and the ICER under a willingness-to-pay (WTP) threshold of $37,663/QALYs. Deterministic, scenario and probabilistic sensitivity analysis were employed to investigate the robustness of model outcomes. Results: In base-case analysis, compared with PC, first-line SC for intention-to-treat (ITT) population gained an additional 0.57 QALYs with an incremental cost of $62,404.15, resulting in an ICER of $109,480.97/QALYs gained. When a patient assistance program (PAP) was available, the ICER decreased to $52,327.02/QALYs. In subgroup analysis, the ICER values were above the WTP threshold with or without PAP. Sensitivity analysis results suggested that the model outcomes were reliable. Conclusion: From the perspective of Chinese healthcare system, the SC was not cost-effective in comparison to PC as first-line treatment for NSCLC, regardless of PD-L1 tumor expression level and pathological subtype.

Associations between paraspinal muscles fatty infiltration and lumbar vertebral bone mineral density - An investigation by fast kVp switching dual-energy CT and QCT.

Purpose: To investigate the relationship between paraspinal muscles fat content and lumbar bone mineral density (BMD). Methods: A total of 119 participants were enrolled in our study (60 males, age: 50.88 ± 17.79 years, BMI: 22.80 ± 3.80 kg·m-2; 59 females, age: 49.41 ± 17.69 years, BMI: 22.22 ± 3.12 kg·m-2). Fat content of paraspinal muscles (erector spinae (ES), multifidus (MS), and psoas (PS)) were measured at (ES L1/2-L4/5; MS L2/3-L5/S1; PS L2/3-L5/S1) levels using dual-energy computed tomography (DECT). Quantitative computed tomography (QCT) was used to assess BMD of L1 and L2. Linear regression analysis was used to assess the relationship between BMD of the lumbar spine and paraspinal muscles fat content with age, sex, and BMI. The variance inflation factor (VIF) was used to detect the degree of multicollinearity among the variables. P < .05 was considered to indicate a statistically significant difference. Results: The paraspinal muscles fat content had a fairly significant inverse association with lumbar BMD after controlling for age, sex, and BMI (adjusted R 2 = 0.584-0.630, all P < .05). Conclusion: Paraspinal muscles fat content was negatively associated with BMD.Paraspinal muscles fatty infiltration may be considered as a potential marker to identify BMD loss.

Application of metal artifact reduction software in gemstone spectral computed tomography for patients after total knee arthroplasty.

Background: To explore the feasibility and effectiveness of the metal artifact reduction software (MARs) reconstruction algorithm in reducing metal artifacts of knee prostheses and to explore the optimal monochromatic level of virtual monochromatic spectral (VMS) images for artifact reduction to provide high-quality images and reliable diagnosis in patients after total knee arthroplasty (TKA). Methods: A total of 31 patients underwent gemstone spectral computed tomography. VMS images with MARs and without MARs were obtained at different energy levels (80, 100, 120, and 140 keV). Two observers scored each group of images, and interobserver agreement was evaluated. Artificial indices (AIs), percentage500HU and structural similarity index measure (SSIM) values were calculated in the objective analysis to evaluate the image quality and impact of metal artifacts. Results: The consistency of the scores of the 2 observers was good (kappa value =0.78), and the score of the VMS images with MARs was higher than that of VMS images without MARs. AI values and percentage500HU of the MARs group were significantly lower than those of the without MARs group, while SSIM values were significantly higher. In the comparison of different keV images, the AI value decreased with the increase in keV in the range of 80-120 keV, but there was no significant difference between the 120 keV images and 140 keV images. In the group with MARs, the percentage500HU of 100-140 keV images was significantly lower than that of the 80 keV images, but there was no significant difference between 100, 120, and 140 keV images. In the group without MARs, the percentage500HU was significantly different among all keV groups. Conclusions: VMS images combined with the MARs algorithm can significantly reduce the metal artifacts of knee prostheses and improve image quality. At an energy level of 100-120 keV, a good metal artifact removal effect and soft tissue contrast can be achieved, and the best metal artifact removal effect can be achieved at 140 keV.

Preliminary study on the differentiation of vulnerable carotid plaques via analysis of calcium content and spectral curve slope by using gemstone spectral imaging.

Growing evidence indicates that vulnerable carotid plaque rupture is an important cause of stroke. However, the role of novel gemstone spectral imaging (GSI) in the assessment of vulnerable carotid plaques has remained to be sufficiently explored. Therefore, the aim of the present study was to provide a comprehensive evaluation of carotid atherosclerotic plaques using both GSI imaging biomarkers and serological biomarkers, and further explore their possible roles in the atherogenic process. The present study analyzed GSI data, including calcium content of carotid atherosclerotic plaques and spectral curve slope, as well as serum high-sensitivity C-reactive protein (Hs-CRP) and monocyte chemotactic protein-1 (MCP-1) levels in patients with a carotid atherosclerotic plaque using GSI-computed tomographic angiography and immunoturbidimetry. Patients with unstable plaque exhibited a significantly lower calcium content and higher spectral curve slope than those of the stable plaque group. In addition, patients with unstable plaque exhibited an increase in Hs-CRP and MCP-1 levels compared with those of the stable plaque and normal control groups. The alteration in GSI calcium content and spectral curve slope reflects a close link between calcification and plaque instability, while aberrant Hs-CRP and MCP-1 expression are involved in the formation or development of vulnerable plaques. Taken together, the present results strongly support the feasibility of using these serological and newly identified imaging parameters as multiple potential biomarkers relevant to plaque vulnerability or stroke progression.

Dual-energy spectral CT imaging of pulmonary embolism with Mycoplasma pneumoniae pneumonia in children.

BACKGROUND: Pulmonary embolism (PE) associated with Mycoplasma pneumoniae pneumonia (MPP) in children has already attracted more attention. CT pulmonary angiography (CTPA) has been the preferred method for diagnosing PE, but it has some limitations, especially for children. Dual-energy spectral CT has been used in diagnosing PE in adults. PURPOSE: To evaluate the application of dual-energy spectral CT in diagnosing PE in children with MPP. MATERIALS AND METHODS: Eighty-three children with MPP and highly suspected PE, underwent CTPA with spectral imaging mode, 25 children were diagnosis with PE. Noise, clot-to-artery contrast-to-noise ratio, image quality and diagnosis confidence were calculated and assessed on nine monochromatic image sets (40 to 80 keV). CTPA images were observed for the presence, localization and embolic degrees of PE. Clots were divided into intra- and extra-consolidation clots. For extra-consolidation clots, iodine concentration (IC) of perfusion defects and normal lung, perfusion defects of four children before and after the treatment were measured and compared. For intra-consolidation clots, IC of consolidation areas with clots and consolidation areas without clot were measured and compared. RESULTS: The optimal energy level for detecting PE in children was 55 keV. 116 clots (29 extra-consolidations) were found, IC of defect regions was 0.69 ± 0.28 mg/mL (extra-consolidations) and 0.90 ± 0.23 mg/mL (intra-consolidations), both significantly lower than the 2.76 ± 0.45 mg/mL in normal lungs and 10.25 ± 1.76 mg/mL in consolidations without clots (P < 0.001). Significant difference was found in the presence or absence of perfusion defects between occlusive clots and nonocclusive clots (P < 0.001). IC of the perfusion defects significantly increased after treatment (P < 0.001). CONCLUSIONS: In dual-energy spectral CTPA, 55 keV images optimize PE detection for children, and MD images quantify pulmonary blood flow of PE, and may help to detect small clots and quantify embolic degrees.

Factors associated with bone erosion in patients with gout: A dual-energy gemstone spectral imaging computed tomography study.

OBJECTIVES: This study aimed to assess the factors influencing bone erosion (BE) in patients with gout using dual-energy gemstone spectral imaging computer tomography. METHODS: We compared the clinical data, laboratory indices, and tissue urate levels at the monosodium urate (MSU) bone interface measured by dual-energy gemstone spectral imaging computed tomography of 87 gout patients with (n = 41) and without (n = 46) BE. Logistic regression analysis was used to investigate the risk factors associated with BE. RESULTS: In total, 47.1% of patients with gout had BE. The disease duration, serum uric acid, tissue urate levels, and the presence of tophi were significantly higher (p < .05) in gout patients with BE than in those without BE. Longer disease duration (odds ratio = 1.11, 95% confidence interval: 1.00-1.24, p < .05) and increased tissue urate levels (odds ratio = 1.01, 95% confidence interval: 1.00-1.02, p < .05) were independently associated with BE. Tissue urate levels at the MSU-bone interface were correlated with the presence of tophi (r = 0.62, p < .001), BE (r = 0.51, p < .001), renal calculus (r = 0.24, p = .03), and serum uric acid levels (r = 0.23, p = .03). CONCLUSIONS: This study found that longer disease duration and elevated tissue urate concentrations at the MSU-bone interface were associated with BE in patients with gout.

Bone Phenotyping Approaches in Human, Mice and Zebrafish - Expert Overview of the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal traits TranslatiOnal NEtwork").

A synoptic overview of scientific methods applied in bone and associated research fields across species has yet to be published. Experts from the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal Traits translational Network") Working Group 2 present an overview of the routine techniques as well as clinical and research approaches employed to characterize bone phenotypes in humans and selected animal models (mice and zebrafish) of health and disease. The goal is consolidation of knowledge and a map for future research. This expert paper provides a comprehensive overview of state-of-the-art technologies to investigate bone properties in humans and animals - including their strengths and weaknesses. New research methodologies are outlined and future strategies are discussed to combine phenotypic with rapidly developing -omics data in order to advance musculoskeletal research and move towards "personalised medicine".

A Roadmap to Gene Discoveries and Novel Therapies in Monogenic Low and High Bone Mass Disorders.

Genetic disorders of the skeleton encompass a diverse group of bone diseases differing in clinical characteristics, severity, incidence and molecular etiology. Of particular interest are the monogenic rare bone mass disorders, with the underlying genetic defect contributing to either low or high bone mass phenotype. Extensive, deep phenotyping coupled with high-throughput, cost-effective genotyping is crucial in the characterization and diagnosis of affected individuals. Massive parallel sequencing efforts have been instrumental in the discovery of novel causal genes that merit functional validation using in vitro and ex vivo cell-based techniques, and in vivo models, mainly mice and zebrafish. These translational models also serve as an excellent platform for therapeutic discovery, bridging the gap between basic science research and the clinic. Altogether, genetic studies of monogenic rare bone mass disorders have broadened our knowledge on molecular signaling pathways coordinating bone development and metabolism, disease inheritance patterns, development of new and improved bone biomarkers, and identification of novel drug targets. In this comprehensive review we describe approaches to further enhance the innovative processes taking discoveries from clinic to bench, and then back to clinic in rare bone mass disorders. We highlight the importance of cross laboratory collaboration to perform functional validation in multiple model systems after identification of a novel disease gene. We describe the monogenic forms of rare low and high rare bone mass disorders known to date, provide a roadmap to unravel the genetic determinants of monogenic rare bone mass disorders using proper phenotyping and genotyping methods, and describe different genetic validation approaches paving the way for future treatments.

Spectral CT Hybrid Images in the Diagnostic Evaluation of Hypervascular Abdominal Tumors-Potential Advantages in Clinical Routine.

BACKGROUND: This study aimed to investigate the use of spectral computed tomography (SCT) hybrid images combining virtual monoenergetic images (VMIs) and iodine maps (IMs) as a potentially efficient search series for routine clinical imaging in patients with hypervascular abdominal tumors. METHODS: A total of 69 patients with hypervascular abdominal tumors including neuroendocrine neoplasms (NENs, n = 48), renal cell carcinoma (RCC, n = 10), and primary hepatocellular carcinoma (HCC, n = 11) were analyzed retrospectively. Two radiological readers (blinded to clinical data) read three CT image sets (1st a reference set with 70 keV; 2nd a 50:50 hybrid 140 keV/40 keV set; 3rd a 50:50 hybrid 140 keV/IM set). They assessed images subjectively by rating several parameters including image contrast, visibility of suspicious lesions, and diagnostic confidence on five-point Likert scales. In addition, reading time was estimated. RESULTS: Median subjective Likert scores were highest for the 1st set, except for image contrast, for which the 2nd set was rated highest. Scores for diagnostic confidence, artifacts, noise, and visibility of suspicious lesions or small structures were significantly higher for the 1st set than for the 2nd or 3rd set (p < 0.001). Regarding image contrast, the 2nd set was rated significantly higher than the 3rd set (p < 0.001), while the median did not differ significantly compared with the 1st set. Agreement between the two readers was high for all sets. Estimated potential reading time was the same for hybrid and reference sets. CONCLUSIONS: Hybrid images have the potential to efficiently exploit the additional information provided by SCT in patients with hypervascular abdominal tumors. However, the use of rigid weighting did not significantly improve diagnostic performance in this study.

A New Outlook on the Ability to Accumulate an Iodine Contrast Agent in Solid Lung Tumors Based on Virtual Monochromatic Images in Dual Energy Computed Tomography (DECT): Analysis in Two Phases of Contrast Enhancement.

For some time, dual energy computed tomography (DECT) has been an established method used in a vast array of clinical applications, including lung nodule assessment. The aim of this study was to analyze (using monochromatic DECT images) how the X-ray absorption of solitary pulmonary nodules (SPNs) depends on the iodine contrast agent and when X-ray absorption is no longer dependent on the accumulated contrast agent. Sixty-six patients with diagnosed solid lung tumors underwent DECT scans in the late arterial phase (AP) and venous phase (VP) between January 2017 and June 2018. Statistically significant correlations (p ≤ 0.001) of the iodine contrast concentration were found in the energy range of 40-90 keV in the AP phase and in the range of 40-80 keV in the VP phase. The strongest correlation was found between the concentrations of the contrast agent and the scanning energy of 40 keV. At the higher scanning energy, no significant correlations were found. We concluded that it is most useful to evaluate lung lesions in DECT virtual monochromatic images (VMIs) in the energy range of 40-80 keV. We recommend assessing SPNs in only one phase of contrast enhancement to reduce the absorbed radiation dose.

Risk factors associated with musculoskeletal disorders among gemstone polishers in Jaipur, India.

Purpose. Gemstone polishing is a highly repetitive and strenuous job which may lead to musculoskeletal disorders (MSDs) among workers. This study aimed to determine the prevalence of MSDs and their contributing factors among gemstone polishers in Jaipur, India. Materials and methods. A self-reported questionnaire study was conducted among 388 male gemstone polishers. Current working postures of the participants were evaluated using rapid upper limb assessment. Results were considered significant at p ≤ 0.05. Results. MSDs were highly prevalent among gemstone polishers, primarily in the lower back, neck, wrists/forearms and shoulders. Work-related factors including prolonged daily working hours, little recovery time, sustaining a non-neutral working posture, repetitive movements of upper limbs and individual factors including age and job tenure were significantly associated with MSDs in different body regions. Higher education led to a reduction in the occurrence of MSDs. Evaluation of working posture recommended further investigations and immediate changes in working habits of gemstone polishers to avoid serious harm and physical damage. Conclusion. Gemstone polishers in Jaipur are at high risk of developing MSDs in different body regions. Sustaining a non-neutral working posture for a long duration is a major risk factor in the current work setting.

Assessment of Solitary Pulmonary Nodules Based on Virtual Monochrome Images and Iodine-Dependent Images Using a Single-Source Dual-Energy CT with Fast kVp Switching.

With lung cancer being the most common malignancy diagnosed worldwide, lung nodule assessment has proved to be one of big challenges of modern medicine. The aim of this study was to examine the usefulness of Dual Energy Computed Tomography (DECT) in solitary pulmonary nodule (SPN) assessment. Between January 2017 and June 2018; 65 patients (42 males and 23 females) underwent DECT scans in the late arterial phase (AP) and venous phase (VP). We concluded that imaging at an energy level of 65 keV was the most accurate in detecting malignancy in solitary pulmonary nodules (SPNs) measuring ≤30 mm in diameter on virtual monochromatic maps. Both virtual monochromatic images and iodine concentration maps prove to be highly useful in differentiating benign and malignant pulmonary nodules. As for iodine concentration maps, the analysis of venous phase images resulted in the highest clinical usefulness. To summarize, DECT may be a useful tool in the differentiation of benign and malignant SPNs. A single-phase DECT examination with scans acquired 90 s after contrast media injection is recommended.

Assessment of radiation dose and iodine load reduction in head-neck CT angiography using two scan protocols with wide-detector.

OBJECTIVE: To compare image quality, radiation dose, and iodine intake of head-neck CT angiography (CTA) acquired by wide-detector with the gemstone spectral imaging (GSI) combination with low iodine intake or routine scan protocol. METHODS: Three hundred patients who had head-neck CTA were enrolled and divided into three groups according to their BMI values: group A (18.5 kg/m2 ≦ BMI <24.9 kg/m2), group B (24.9 kg/m2 ≦ BMI <29.9 kg/m2) and group C (29.9 kg/m2 ≦ BMI ≦ 34.9 kg/m2) with 100 patients in each group. Patients in each group were randomly divided into two subgroups (n = 50) namely, A1, A2, B1, B2, C1 and C2. The patients in subgroups A1, B1 and C1 underwent GSI with low iodine intake (270 mgI/ml, 50 ml) and combined with the ASiR-V algorithm. Other patients underwent three dimensional (3D) smart mA modulation with routine iodine intake (350 mgI/ml, 60 ml). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated after angiography. Images were then subjectively assessed using a 5-point scale. CT dose index of volume and dose-length product (DLP) was converted to the effective dose (ED) and then compared. RESULTS: The mean CT values, SNR, CNR and subjective image quality in subgroups A2, B2 and C2 are significantly lower than in subgroups A1, B1, and C1 (P < 0.01), respectively. The ED values in subgroup A1, B1, and C1 are 55.18%, 61.89%, and 69.64% lower than those in A2, B2, and C2, respectively (P < 0.01). The total iodine intakes in subgroups A1, B1, and C1 are 35.72% lower than those in subgroups A2, B2, and C2. CONCLUSIONS: The gemstone spectral imaging with monochromatic images at 53-57 keV combined with ASiR-V algorithm allows significant reduction in iodine load and radiation dose in head-neck CT angiography than those yielded in routine scan protocol. It also enhances signal intensity of head-neck CTA and maintains image quality.

Evaluation of the best single-energy scanning in energy spectrum CT in lower extremity arteriography.

The present study aimed to apply the best single-energy (SE) scanning in energy spectrum computed tomography (CT) to evaluate the usefulness of lower extremity arterial angiography imaging in patients with lower extremity arterial occlusive disease. A total of 64 patients diagnosed with lower extremity arterial occlusive disease were randomly selected and divided into either the experimental group (n=32) or the control group (n=32). The two treatment groups were scanned for lower extremity arteriography using the best SE scanning mode of energy spectrum CT Gemstone imaging (GSI) and mixed energy scanning mode of multi-slice helical CT (MSCT). The CT images, image noise, contrast-to-noise ratio (CNR) and quality scores of the images of lower extremity arteries between the two groups were compared. Image quality of the two experimental groups were independently evaluated by two imaging diagnostic physicians. The CT scores and CNR of the lower extremity arteries were significantly higher in the experimental group compared with the control group (P<0.01). No statistically significant differences in the background noise between the two groups were observed (P<0.05). The image quality scores of two groups, with the differences between the two diagnosticians, were found to be statistically significant (P<0.01). In the lower extremity arterial angiography, the image quality of the best SE in the CT GSI scanning mode was observed to be superior to that taken using MSCT mixed energy scanning mode.

Gemstone spectral imaging dual-energy computed tomography for differentiation of renal cell carcinoma and minimal-fat renal angiomyolipoma.

PURPOSE: To investigate the values of gemstone spectral imaging (GSI)-dual-energy computed tomography (DECT) in differentiation of renal cell carcinoma (RCC) and minimal-fat renal angiomyolipoma (MF-RAML). PATIENTS AND METHODS: Twenty-one patients with ischemic RCC and 19 patients with MF-RAML were enrolled in this study. GSI was performed on them, and the spectrum signs were analyzed. RESULTS: I(H2O), H2O(I), I(fat), and fat(I) concentrations, normalized I concentration, and effective atomic number of corticomedullary phase and parenchymal phase in enhanced GSI-DECT in ischemic RCC group were all significantly lower than those in MF-RAML group (P < 0.05). CT value and absolute slope rate of spectral attenuation curve in two phases in ischemic RCC group were also significantly lower than those in MF-RAML group (P < 0.05). CONCLUSION: GSI-DECT has provided a new idea and method for differential diagnosis of ischemic RCC and MF-RAML, with high-clinical values.

Effect of heat treatment on the luminescence properties of natural apatite.

Regarding gemstone identification, the effect of heat treatment under reduction condition to optical and luminescence properties of natural green apatite (Ca5(PO4)3OH, F, Cl) from Madagascar has been investigated. Although electron microprobe analysis (EPMA) shows a luminescence defect of rare earth element such as Ce (0.47%), Pr (0.22%) and Nd (0.15%), however original sample does not show luminescence properties. With consecutive heating process, the color alteration from green to colorless of samples, and also the enhancement of luminescence properties of Ce3+ in natural apatite was observed. Mechanism of fluorescence enhancement and color changes during heating process were discussed using optical spectra and emission spectra. Optical spectra of heated apatite point out that green and blue color assigned to the existence of a photochromic center of Ce3+-SiO3- radical and SO3-, respectively. Consequently, the vanishing of these both bands resulted in the colorless heated apatite at 800 °C. Heated apatite showed emission band at 365 nm because of the deactivation of electron from 4f of Ce3+ to 5d. Optical spectra reveal that the correlation of luminescence enhancement and the fading of yellow tint of heated apatite by means of the descending of Ce3+ to Ce4+ charge transfer process. The ultimate contribution of this work is the finding of the difference of luminescence properties between non-heated and heated apatite which can be used as an effective tool for gem identification. This identification tool is remarkable because it is rapid and non-destructive.

[Clinical value of spectral CT imaging in preoperative evaluation of pathological grading of esophageal squamous cell carcinoma].

Objective: To investigate the value of spectral computed tomography quantitative parameters in the assessment of pathological grade of esophageal squamous cell carcinoma before operation. Methods: The imaging findings of 52 patients with confirmed esophageal squamous cell carcinoma by surgery and pathology were prospectively analyzed in Henan Provincial People's Hospital from June 2016 to May 2017.There were 43 males and 9 females, aged 49-76 years, with an average age of (66±8) years.All the patients were divided into three groups based on the pathological finding: well-differentiated group (n=12), moderately-differentiated group (n=20), poorly-differentiated group (n=20). All the patients received chest plain scan and double phase enhanced scan of gemstone spectral computed tomography.The enhancement attenuation (HU), the average of the slope of the spectral Hounsfield Unit curve (λ(HU)), normalized iodine concentration (NIC), normalized effective atomic number (Z(eff-a)) were measured and calculated.The difference in HU, λ(HU), NIC, Z(eff-a) among different grades were statistically analyzed.The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficiency of single and combined parameters in the differentiation of poorly-differentiated and well-moderately differentiated esophageal squamous cell carcinoma. Results: There were significant differences in HU, λ(HU), NIC, Z(eff-a) among different pathological grading of the esophageal squamous cell carcinoma in arterial phase and venous phase (F=4.496-9.056, H=23.204, 20.724, all P<0.05). The best single parameter to differentiate poorly-differentiated from well-moderately differentiated esophageal squamous cell carcinoma was NIC in arterial phase with areas under the ROC curve (AUC), the cutoff value, sensitivity, specificity, accuracy of 0.860, 0.197, 65.0%, 96.9%, 84.6%, respectively; the best combination of parameters was HU+ NIC+ λ(HU) in arterial phase with AUC, the threshold of predicted probability, sensitivity, specificity, accuracy of 0.913, 0.380, 85.0%, 81.3%, 82.7%, respectively. Conclusion: Gemstone spectral imaging quantitative parameters can be used to evaluate the pathological grading of esophageal squamous cell carcinoma, the NIC and HU+ NIC+ λ(HU) in arterial phase have the highest differential diagnostic efficiency.

Dual-Energy Computed Tomography: Physical Principles, Approaches to Scanning, Usage, and Implementation: Part 1.

There are increasing applications of dual-energy computed tomography (CT), a type of spectral CT, in neuroradiology and head and neck imaging. In this 2-part review, the fundamental principles underlying spectral CT scanning and the major considerations in implementing this type of scanning in clinical practice are reviewed. In the first part of this 2-part review, the physical principles underlying spectral CT scanning are reviewed, followed by an overview of the different approaches for spectral CT scanning, including a discussion of the strengths and challenges encountered with each approach.