Spectral computed tomography(CT)imaging as an advanced and non-invasive technique is of importance in the diagnosis of disease.Therefore,it is significant to develop safe and high-performance contrast agents for spect...Spectral computed tomography(CT)imaging as an advanced and non-invasive technique is of importance in the diagnosis of disease.Therefore,it is significant to develop safe and high-performance contrast agents for spectral CT imaging.Herein,we synthesized a small-molecule erbium chelate(ErDOTA dimeglumine),with the advantages of favorable colloidal and structure stability,good biocompatibility and biosafety,and sensitive spectral CT imaging ability in vitro and in vivo.Erbium chelate exhibits strong X-ray attenuation capability and the energy-dependent attenuation in the range of 40-160 keV due to the high K-edge value of Er(57.5 keV).Especially,the slope of the Hounsfield unit(HU)curve for erbium chelate is 1.5 times that of iohexol at 50 keV,and 5.6 times that of iohexol at130 keV.We then applied erbium chelate in the in vivo spectral CT imaging of healthy mice and DSSinduced colitis mice.It is found that erbium chelate is rapidly metabolized from the intestinal tract in healthy mice within 12 h due to favorable biocompatibility,while it is enriched and displays brighter signals in the inflammatory site of colon in colitis mice.Specifically,the CT value in the large intestines of colitis mice 12 h after erbium chelate administration is 53.0,which is much higher than that of healthy mice(8.3),showing great potential for sensitive and accurate diagnosis of inflammatory bowel disease.Moreover,compared with the clinically used contrast agent iohexol,erbium chelate shows better spectral CT imaging performance in both healthy and colitis mice at low to high energy settings.Superior CT imaging is also observed in CT26 tumor-bearing mice after administration with erbium chelate in comparison to iohexol.In summary,the small-molecule erbium chelate is expected to be a safe and highperfo rmance co ntrast agent for spectral CT imaging to promote the diagnosis of gastrointestinal diseases.展开更多
Objective:To investigate the diagnostic value of spectral CT reconstruction mode for carotid atherosclerotic plaque lesions.Methods:From January 2017 to January 2019,70 patients with carotid atherosclerotic plaque les...Objective:To investigate the diagnostic value of spectral CT reconstruction mode for carotid atherosclerotic plaque lesions.Methods:From January 2017 to January 2019,70 patients with carotid atherosclerotic plaque lesions in our hospita1 were selected as the research object.A11 patients were diagnosed with cervical vascular color Doppler ultrasound and spectral CT scan under spectral cr reconstruction mode.Taking the results of coronaryf angiography as the"gold standard",the clinical value of the two examination methods in the diagnosis of carotid atherosclerotic plaque lesions was compared and analyzed.Results:Coronary angiography diagnosis confirmed that 33 of 70 patients with suspected carotid atherosclerotic plaque lesions had vulnerable plaques and 37 had stable plaques.The accuracy of Spectral CT examination of carotid artery plaque was 87.14%(61/70),sensitivity was 90.91%(30/33),specificity was 83.78%(31/37),and the positive predictive value was 83.33%(30/36),the negative predictive value is 91.76%(31/34),which is higher than that of cervical vascular ultrasonography(61.43%,60.61%,56.76%,57.89%,65.63%),the difference is statistically significant(P<0.05).Conclusion:The application of Spectral CT in the clinical diagnosis and treatment of carotid atherosclerotic plaque lesions with higher accuracy,sensitivity and specificity,is more significant and can provide a more reliable and effective imaging basis.展开更多
Objective: To explore the correlation between the spectral computed tomography(CT) imaging parameters and the Ki-67 labeling index in lung adenocarcinoma.Methods: Spectral CT imaging parameters [iodine concentrations ...Objective: To explore the correlation between the spectral computed tomography(CT) imaging parameters and the Ki-67 labeling index in lung adenocarcinoma.Methods: Spectral CT imaging parameters [iodine concentrations of lesions(ICLs) in the arterial phase(ICLa)and venous phase(ICLv), normalized IC in the aorta(NICa/NICv), slope of the spectral HU curve(λHUa/λHUv)and monochromatic CT number enhancement on 40 keV and 70 keV images(CT40 keVa/v, CT70keVa/v)] in 34 lung adenocarcinomas were analyzed, and common molecular markers, including the Ki-67 labeling index, were detected with immunohistochemistry. Different Ki-67 labeling indexes were measured and grouped into four grades according to the number of positive-stained cells(grade 0, ≤1%;1%<grade 1≤10%;10%<grade 2≤30%;and grade 3, >30%). One-way analysis of variance(ANOVA) was used to compare the four different grades, and the Bonferroni method was used to correct the P value for multiple comparisons. A Spearman correlation analysis was performed to further research a quantitative correlation between the Ki-67 labeling index and spectral CT imaging parameters.Results: CT40keVa, CT40 keVv, CT70keVa and CT70keVv increased as the grade increased, and CT70keVa and CT70keVv were statistically significant(P<0.05). These four parameters and the Ki-67 labeling index showed a moderate positive correlation with lung adenocarcinoma nodules. ICL, NIC and λHU in the arterial and venous phases were not significantly different among the four grades.Conclusions: The spectral CT imaging parameters CT40keVa, CT40keVv, CT70keVa and CT70keVv gradually increased with Ki-67 expression and showed a moderate positive correlation with lung adenocarcinomas.Therefore, spectral CT imaging parameter-enhanced monochromatic CT numbers at 70 keV may indicate the extent of proliferation of lung adenocarcinomas.展开更多
Objective： This study investigated the capability of dual-energy spectral computed tomography （CT） to quantitatively evaluate lung perfusion defects that are induced by central lung cancer. Methods： Thirty-two pat...Objective： This study investigated the capability of dual-energy spectral computed tomography （CT） to quantitatively evaluate lung perfusion defects that are induced by central lung cancer. Methods： Thirty-two patients with central lung cancer underwent CT angiography using spectral imaging. A univariate general linear model was conducted to analyze the variance of iodine concentration/CT value with three factors of lung fields. A paired t-test was used to compare iodine concentrations and CT values between the distal end of lung cancer and the corresponding area in the contralateral normal lung. Results： Iodine concentrations increased progressively in the far, intermediate and near ground sides in the normal lung fields at 0.60±0.28, 0.93±0.27 and 1.25±0.38 mg/mL, respectively （P〈0.001）. The same trend was observed for the CT values [-（840.64±49.08）, -（812.66±50.85） and -（760.83±89.17） HU, P〈0.001]. The iodine concentration （0.70±0.42 mg/mL） of the lung field in the distal end of lung cancer was significantly lower than the corresponding area in the contralateral normal lung （1.19±0.62 mg/mL） （t=-7.23, P〈0.001）. However, the CT value of lung field in the distal end of lung cancer was significantly higher than the corresponding area in the contralateral normal lung [-（765.29±93.34） HU vs. -（800.07±76.18） HU, t=3.564, P=0.001]. Conclusions： Spectral CT imaging based on the spectral differentiation of iodine is feasible and can quantitatively evaluate pulmonary perfusion and identify perfusion defects that are induced by central lung cancer. Spectral CT seems to be a promising technique for the simultaneous evaluation of both morphological and functional lung information.展开更多
To improve spectral X-ray CT reconstructed image quality, the energy-weighted reconstructed image xbins^W and the separable paraboloidal surrogates（SPS） algorithm are proposed for the prior image constrained compres...To improve spectral X-ray CT reconstructed image quality, the energy-weighted reconstructed image xbins^W and the separable paraboloidal surrogates（SPS） algorithm are proposed for the prior image constrained compressed sensing（PICCS）-based spectral X-ray CT image reconstruction. The PICCS-based image reconstruction takes advantage of the compressed sensing theory, a prior image and an optimization algorithm to improve the image quality of CT reconstructions.To evaluate the performance of the proposed method, three optimization algorithms and three prior images are employed and compared in terms of reconstruction accuracy and noise characteristics of the reconstructed images in each energy bin.The experimental simulation results show that the image xbins^W is the best as the prior image in general with respect to the three optimization algorithms; and the SPS algorithm offers the best performance for the simulated phantom with respect to the three prior images. Compared with filtered back-projection（FBP）, the PICCS via the SPS algorithm and xbins^W as the prior image can offer the noise reduction in the reconstructed images up to 80. 46%, 82. 51%, 88. 08% in each energy bin,respectively. M eanwhile, the root-mean-squared error in each energy bin is decreased by 15. 02%, 18. 15%, 34. 11% and the correlation coefficient is increased by 9. 98%, 11. 38%,15. 94%, respectively.展开更多
Purpose Conventional X-ray CT scanners have limited ability to distinguish low-contrast substances.However,spectral CTs with photon counting detectors can identify photon energy and utilize spectral information,which ...Purpose Conventional X-ray CT scanners have limited ability to distinguish low-contrast substances.However,spectral CTs with photon counting detectors can identify photon energy and utilize spectral information,which is expected to achieve improved contrast.Energy weighting is a kind of reconstruction method for spectral CT.By assigning appropriate weight for each energy channel,the image contrast can be improved.Hence,how to determine the optimal weights is very important.Methods In this paper,we developed an improved projection-based energy weighting model for spectral CT.In this model,the object thickness of low-density materials is assumed as a constant,and the measured spectrum distribution is used to calculate the weight coefficients.Both phantom and tissue experiments were conducted in spectral CT scanner.Results The results showed that the thickness of low-density materials has little influence on the energy weight,so it can be regarded as a constant.For low-contrast phantom,the contrast-to-noise ratio was improved~32%by the proposed projectionbased weighting method.Conclusions The improved projection-based energy weighting model is effective in practice.It can increase the contrast of low-density materials.展开更多
Spectral computed tomography(CT) based on photon counting detectors(PCDs) is a well-researched topic in the field of X-ray imaging. When PCD is applied in a spectral CT system, the PCD energy thresholds must be carefu...Spectral computed tomography(CT) based on photon counting detectors(PCDs) is a well-researched topic in the field of X-ray imaging. When PCD is applied in a spectral CT system, the PCD energy thresholds must be carefully selected, especially for K-edge imaging, which is an important spectral CT application. This paper presents a threshold selection method that yields better-quality images in K-edge imaging. The main idea is to optimize the energy thresholds ray-by-ray according to the targeted component coefficients, followed by obtaining an overall optimal energy threshold by frequency voting. A low-dose pre-scan is used in practical implementations to estimate the line integrals of the component coefficients for the basis functions. The variance of the decomposed component coefficients is then minimized using the Cramer–Rao lower bound method with respect to the energy thresholds. The optimal energy thresholds are then used to take a full scan and gain better image reconstruction with less noise than would be given by a full scan using the non-optimal energy thresholds. Simulations and practical experiments on imaging iodine and gadolinium solutions, which are commonly used as contrast agents in medical applications, were used to validate the method. The noise was significantly reduced with the same dose relative to the non-optimal energy thresholds in both simulations and in practical experiments.展开更多
基金Project supported by the National Natural Science Foundation of China(82304311,81903460)the Sichuan Province Science and Technology Program(2022YFS0616)。
文摘Spectral computed tomography(CT)imaging as an advanced and non-invasive technique is of importance in the diagnosis of disease.Therefore,it is significant to develop safe and high-performance contrast agents for spectral CT imaging.Herein,we synthesized a small-molecule erbium chelate(ErDOTA dimeglumine),with the advantages of favorable colloidal and structure stability,good biocompatibility and biosafety,and sensitive spectral CT imaging ability in vitro and in vivo.Erbium chelate exhibits strong X-ray attenuation capability and the energy-dependent attenuation in the range of 40-160 keV due to the high K-edge value of Er(57.5 keV).Especially,the slope of the Hounsfield unit(HU)curve for erbium chelate is 1.5 times that of iohexol at 50 keV,and 5.6 times that of iohexol at130 keV.We then applied erbium chelate in the in vivo spectral CT imaging of healthy mice and DSSinduced colitis mice.It is found that erbium chelate is rapidly metabolized from the intestinal tract in healthy mice within 12 h due to favorable biocompatibility,while it is enriched and displays brighter signals in the inflammatory site of colon in colitis mice.Specifically,the CT value in the large intestines of colitis mice 12 h after erbium chelate administration is 53.0,which is much higher than that of healthy mice(8.3),showing great potential for sensitive and accurate diagnosis of inflammatory bowel disease.Moreover,compared with the clinically used contrast agent iohexol,erbium chelate shows better spectral CT imaging performance in both healthy and colitis mice at low to high energy settings.Superior CT imaging is also observed in CT26 tumor-bearing mice after administration with erbium chelate in comparison to iohexol.In summary,the small-molecule erbium chelate is expected to be a safe and highperfo rmance co ntrast agent for spectral CT imaging to promote the diagnosis of gastrointestinal diseases.
文摘Objective:To investigate the diagnostic value of spectral CT reconstruction mode for carotid atherosclerotic plaque lesions.Methods:From January 2017 to January 2019,70 patients with carotid atherosclerotic plaque lesions in our hospita1 were selected as the research object.A11 patients were diagnosed with cervical vascular color Doppler ultrasound and spectral CT scan under spectral cr reconstruction mode.Taking the results of coronaryf angiography as the"gold standard",the clinical value of the two examination methods in the diagnosis of carotid atherosclerotic plaque lesions was compared and analyzed.Results:Coronary angiography diagnosis confirmed that 33 of 70 patients with suspected carotid atherosclerotic plaque lesions had vulnerable plaques and 37 had stable plaques.The accuracy of Spectral CT examination of carotid artery plaque was 87.14%(61/70),sensitivity was 90.91%(30/33),specificity was 83.78%(31/37),and the positive predictive value was 83.33%(30/36),the negative predictive value is 91.76%(31/34),which is higher than that of cervical vascular ultrasonography(61.43%,60.61%,56.76%,57.89%,65.63%),the difference is statistically significant(P<0.05).Conclusion:The application of Spectral CT in the clinical diagnosis and treatment of carotid atherosclerotic plaque lesions with higher accuracy,sensitivity and specificity,is more significant and can provide a more reliable and effective imaging basis.
基金supported by National Natural Science Foundation of China (No. 91959116)Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (No. ZYLX 201803)+1 种基金“Beijing Hospitals Authority” Ascent Plan (No. DFL20191103)National Key R&D Program of China (No. 2017YFC1309101, 2017YFC1309104).
文摘Objective: To explore the correlation between the spectral computed tomography(CT) imaging parameters and the Ki-67 labeling index in lung adenocarcinoma.Methods: Spectral CT imaging parameters [iodine concentrations of lesions(ICLs) in the arterial phase(ICLa)and venous phase(ICLv), normalized IC in the aorta(NICa/NICv), slope of the spectral HU curve(λHUa/λHUv)and monochromatic CT number enhancement on 40 keV and 70 keV images(CT40 keVa/v, CT70keVa/v)] in 34 lung adenocarcinomas were analyzed, and common molecular markers, including the Ki-67 labeling index, were detected with immunohistochemistry. Different Ki-67 labeling indexes were measured and grouped into four grades according to the number of positive-stained cells(grade 0, ≤1%;1%<grade 1≤10%;10%<grade 2≤30%;and grade 3, >30%). One-way analysis of variance(ANOVA) was used to compare the four different grades, and the Bonferroni method was used to correct the P value for multiple comparisons. A Spearman correlation analysis was performed to further research a quantitative correlation between the Ki-67 labeling index and spectral CT imaging parameters.Results: CT40keVa, CT40 keVv, CT70keVa and CT70keVv increased as the grade increased, and CT70keVa and CT70keVv were statistically significant(P<0.05). These four parameters and the Ki-67 labeling index showed a moderate positive correlation with lung adenocarcinoma nodules. ICL, NIC and λHU in the arterial and venous phases were not significantly different among the four grades.Conclusions: The spectral CT imaging parameters CT40keVa, CT40keVv, CT70keVa and CT70keVv gradually increased with Ki-67 expression and showed a moderate positive correlation with lung adenocarcinomas.Therefore, spectral CT imaging parameter-enhanced monochromatic CT numbers at 70 keV may indicate the extent of proliferation of lung adenocarcinomas.
基金supported by National Natural Science Foundation of China(Grant No.81071129,30970825)the National Basic Research Program of China(973 Program)(Grant No.2011CB707705)
文摘Objective： This study investigated the capability of dual-energy spectral computed tomography （CT） to quantitatively evaluate lung perfusion defects that are induced by central lung cancer. Methods： Thirty-two patients with central lung cancer underwent CT angiography using spectral imaging. A univariate general linear model was conducted to analyze the variance of iodine concentration/CT value with three factors of lung fields. A paired t-test was used to compare iodine concentrations and CT values between the distal end of lung cancer and the corresponding area in the contralateral normal lung. Results： Iodine concentrations increased progressively in the far, intermediate and near ground sides in the normal lung fields at 0.60±0.28, 0.93±0.27 and 1.25±0.38 mg/mL, respectively （P〈0.001）. The same trend was observed for the CT values [-（840.64±49.08）, -（812.66±50.85） and -（760.83±89.17） HU, P〈0.001]. The iodine concentration （0.70±0.42 mg/mL） of the lung field in the distal end of lung cancer was significantly lower than the corresponding area in the contralateral normal lung （1.19±0.62 mg/mL） （t=-7.23, P〈0.001）. However, the CT value of lung field in the distal end of lung cancer was significantly higher than the corresponding area in the contralateral normal lung [-（765.29±93.34） HU vs. -（800.07±76.18） HU, t=3.564, P=0.001]. Conclusions： Spectral CT imaging based on the spectral differentiation of iodine is feasible and can quantitatively evaluate pulmonary perfusion and identify perfusion defects that are induced by central lung cancer. Spectral CT seems to be a promising technique for the simultaneous evaluation of both morphological and functional lung information.
基金The National Natural Science Foundation of China(No.51575256)the Fundamental Research Funds for the Central Universities(No.NP2015101,XZA16003)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘To improve spectral X-ray CT reconstructed image quality, the energy-weighted reconstructed image xbins^W and the separable paraboloidal surrogates（SPS） algorithm are proposed for the prior image constrained compressed sensing（PICCS）-based spectral X-ray CT image reconstruction. The PICCS-based image reconstruction takes advantage of the compressed sensing theory, a prior image and an optimization algorithm to improve the image quality of CT reconstructions.To evaluate the performance of the proposed method, three optimization algorithms and three prior images are employed and compared in terms of reconstruction accuracy and noise characteristics of the reconstructed images in each energy bin.The experimental simulation results show that the image xbins^W is the best as the prior image in general with respect to the three optimization algorithms; and the SPS algorithm offers the best performance for the simulated phantom with respect to the three prior images. Compared with filtered back-projection（FBP）, the PICCS via the SPS algorithm and xbins^W as the prior image can offer the noise reduction in the reconstructed images up to 80. 46%, 82. 51%, 88. 08% in each energy bin,respectively. M eanwhile, the root-mean-squared error in each energy bin is decreased by 15. 02%, 18. 15%, 34. 11% and the correlation coefficient is increased by 9. 98%, 11. 38%,15. 94%, respectively.
基金the National Key R&D Program of China(Grant No.2016YFC0100400,Ministry of Science and Technology of the People’s Republic of China)the Instrument Developing Project of the Chinese Academy of Sciences(Grant No.YZ201511)the Key Technology Research and Development Team Project of Chinese Academy of Sciences(Grant No.GJJSTD20170005).
文摘Purpose Conventional X-ray CT scanners have limited ability to distinguish low-contrast substances.However,spectral CTs with photon counting detectors can identify photon energy and utilize spectral information,which is expected to achieve improved contrast.Energy weighting is a kind of reconstruction method for spectral CT.By assigning appropriate weight for each energy channel,the image contrast can be improved.Hence,how to determine the optimal weights is very important.Methods In this paper,we developed an improved projection-based energy weighting model for spectral CT.In this model,the object thickness of low-density materials is assumed as a constant,and the measured spectrum distribution is used to calculate the weight coefficients.Both phantom and tissue experiments were conducted in spectral CT scanner.Results The results showed that the thickness of low-density materials has little influence on the energy weight,so it can be regarded as a constant.For low-contrast phantom,the contrast-to-noise ratio was improved~32%by the proposed projectionbased weighting method.Conclusions The improved projection-based energy weighting model is effective in practice.It can increase the contrast of low-density materials.
基金supported by Grants from National key research and development program(No.2016YFF0101304)the National Natural Science Foundation of China(Nos.61771279,11435007)
文摘Spectral computed tomography(CT) based on photon counting detectors(PCDs) is a well-researched topic in the field of X-ray imaging. When PCD is applied in a spectral CT system, the PCD energy thresholds must be carefully selected, especially for K-edge imaging, which is an important spectral CT application. This paper presents a threshold selection method that yields better-quality images in K-edge imaging. The main idea is to optimize the energy thresholds ray-by-ray according to the targeted component coefficients, followed by obtaining an overall optimal energy threshold by frequency voting. A low-dose pre-scan is used in practical implementations to estimate the line integrals of the component coefficients for the basis functions. The variance of the decomposed component coefficients is then minimized using the Cramer–Rao lower bound method with respect to the energy thresholds. The optimal energy thresholds are then used to take a full scan and gain better image reconstruction with less noise than would be given by a full scan using the non-optimal energy thresholds. Simulations and practical experiments on imaging iodine and gadolinium solutions, which are commonly used as contrast agents in medical applications, were used to validate the method. The noise was significantly reduced with the same dose relative to the non-optimal energy thresholds in both simulations and in practical experiments.
