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Objective:To explore the image quality of 40 keV virtual monoenergetic images (VMI) derived from dual-layer spectral detector CT （DLCT） pancreas dynamic enhanced scanning and its optimal window setting.Methods:From January to July 2019, 28 patients who underwent pancreas enhanced DLCT scan within one week before surgery and pathologically confirmed of pancreatic neuroendocrine tumors (pNETs) were retrospectively enrolled. Conventional polyenergetic images (PI) and 40 keV virtual monoenergetic images （VMI 40 keV） were generated after scanning.CT value of normal pancreatic parenchyma, lesion, abdominal subcutaneous fat, abdominal aorta and portal vein were measured in PI and VMI 40 keV. The contrast-to-noise ratio (CNR) of the pNETs lesion was calculated. All these objective results were compared between VMI 40 keV and PI using paired ttest. Individual window settings （W-Ind, including window width and window level） of VMI 40 keVwere recorded. Calculated window settings （W-Calc） were mathematically calculated via regression analysis and optimized window settings （W-Opt） were obtained.Subjective image quality was assessed with a 5-point scale and compared among VMI 40 keV with different window settings (W-Std, W-Ind, W-Calc and W-Opt) using Friedman test, and compared PI with standard abdominal window setting (W-Std) and VMI 40keV with W-Opt settings using Wilcoxon test.The maximum diameter of lesion was measured and compared with one-way ANOVA analysis among PI and VMI 40 keV with different windows settings. Results:For VMI 40 keV in both arterial phase and portal vein phase, the CT attenuation [(464.0±136.7), (375.4±79.2) HU] of pNETs lesion were statistically significantly higher than those in PI [（168.8±38.0), (140.5±23.5) HU] （ t=-16.107,-22.225, P<0.001）, CNR （16.5±11.1, 10.9±6.1） were also statistically significantly higher than those in PI （4.5±2.9, 3.0±1.9） （ t=-7.838, -9.781， P<0.001）,while with lower image noise in VMI 40 keV[（11.8±1.5),(11.8±1.4) HU] than PI （13.1±1.5,12.9±1.3 HU）（ t=6.356,3.891， P<0.001）. The subjective score for PI with W-Std and VMI 40 keV with W-Std, W-Ind, W-Calc, W-Opt in arterial phase were 4（1）, 1（0）, 5（0）, 5（0.75）, 5（1）, and which in portal vein phase were 3.5（1）, 1（0）, 5（0）, 5（0）, 5（1）.The subjective score of VMI 40 keV with different window settings had statistical differences （χ 2=76.143,76.000， P<0.001）. Compared to the image quality of PI with W-Std settings, VMI 40 keV with W-Opt settings have higher objective score （ Z=4.685, 4.235， P<0.001）. The maximum diameter of lesion has no statistical difference among PI and VMI 40 keV with different window settings （ F=0.008, 0.004， P>0.999） in both arterial phase and portal vein phase. Conclusions:The VMI 40 keV in pancreas dynamic enhancement scanning derived from dual-layer spectral detector CT have higher image quality than PI. Due to changes of CT value of tissue in VMI 40 keV, it is recommended to optimize window settings （window width/window level， 880/230 HU for arterial phase and 840/260 HU for portal vein phase） to obtain the best image quality.
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Objective:To investigate the clinical value of iodine density map and low keV virtual monoenergetic images (VMI) derived from dual-layer spectral detector CT (DLCT) for the pancreatic neuroendocrine tumors (pNETs) detection.Methods:From January to June 2019, data of 23 pathologically confirmed patients of pNETs were retrospectively analyzed. All of the patients underwent pancreas enhanced DLCT scanning within 1 week before surgery. The conventional polyenergetic images (PI), iodine density map and 40, 50, 60, 70 keV VMI were generated. One resident radiologist with 3 years’ experience and one senior radiologist with over 10 years’ experience interpreted the images for the lesion detection independently using the following image series: PI, VMI (40-70 keV), PI combined with iodine density map. Lesion detection rates were recorded and compared among different image series. The CT value and noise of lesion, normal pancreatic parenchyma, and abdominal subcutaneous fat were measured in PI and VMI in both arterial and portal vein phases. The contrast-to-noise ratio (CNR) of lesion was calculated. The CT value of lesion and normal pancreatic parenchyma, CNR of lesion, and image noise were compared using repeated one-way ANOVA test. Subjective image quality was assessed with a 5-point scale and compared with Friedman test.Results:A total of 26 lesions were confirmed from 23 patients. For resident radiologist and senior radiologist, the detection rates of pNETs lesion using PI were 76.9% (20/26) and 84.6% (22/26) respectively, and both improved to 92.3% (24/26) using image series of 40 and 50 keV VMI. For senior radiologist, the pNETs lesion detection rate was further improved to 96.2% (25/26) using image series of PI with iodine map. The CT value of lesion and normal pancreatic parenchyma, CNR, and image noise had statistical differences among PI and VMI (40-70 keV) in both arterial and portal vein phase ( P<0.001). The mean CT attenuation and CNR of lesion in VMI increased significantly as the energy level decreased.The CNR of lesion in all VMI (40-70 keV) was significantly higher than that in PI. The median of subjective scores of image quality in PI and VMI (40-70 keV) were 3, 3, 4, 4, and 5 respectively, and the difference was statistically significant (χ2=66.393, P<0.001). Conclusions:The low keV VMI derived from DLCT can increase the CT value and CNR of pNETs, and the lesion detection rate can be improved combined with iodine density map. The CNR of pNETs is the highest in 40 keV VMI, and image noise is still lower than that of PI, so 40 keV VMI is recommended for clinical application.
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Objective To explore the feasibility of the virtual non-contrast images derived from dual-layer spectral detector CT (SDCT) substitute for true non-contrast images.Methods From July 2017 to September 2017,40 patients under-went pre-and arterial-venous dual-phase post-contrast abdominal imagining on a SDCT in Shanghai Jiaotong University School of Medicine Affiliated Ruijin Hospital.The images were retrospectively analyzed.The arterial VNC images (VNC-a) and venous VNC images (VNC-v)were derived from spectral based image (SBI) datasets of arterial and portal venous phase using a dedicated software respectively.Then mean CT attenuation,mean image noise,signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared with one-way ANOVA analysis among TNC,VNC-a,VNC-v images in liver,spleen,pancreas,abdominal aorta,inferior vena cava,psoas muscle,L4 vertebra and perirenal fat.And Bland-Altman plots was used to analyze the CT attenuation equivalence between TNC and VNC.Subjective image quality was assessed with a 5-point scale and compared with Friedman H test.The dose length product (DLP) of pre-and post-contrast scans were recorded.Results The CT attenuation of abdominal aorta,perirenal fat,L4.vertebra among three kinds of images had significant differences (P＜0.05)which overestimated the CT attenuation of perirenal fat and underestimated CT attenuation of abdominal aorta and vertebra compared to TNC,VNC.Except for pancreas,the image noise of all other tissues among three kinds of images had significant differences,images noise of VNC images were lower than TNC images (P＜0.05).The SNR of liver,spleen,psoas muscle and inferior vena cava and CNR of pancreas,abdominal aorta,inferior vena cava,L4 vertebra and perirenal fat were statistically significant among the three images (P＜0.05).Except for vertebra and perirenal fat,good equivalence between VNC and TNC images were observed in all relevant tissues with Bland-Altman analysis.Image quality subjective scoring of TNC,VNC-a,and VNC-v were 5.00(1.00),5.00(0.75),5.00(1.00) respectively which had no significant differences (P=0.20).The DLP of TNC,arterial and venous phase scan were (255.2±62.0),(258.9±62.9),(252.0±61.2)mGy·cm,and the total DLP of dual-phase contrast enhanced scan was (766.2± 185.3) mGy· cm.The DLP of TNC accounted for 33.3％(255.2/766.2) of the total DLP,and effective dose of TNC was (3.83±0.90)mSv.Conclusions CT attenuation in VNC image which exhibited lower image noise was identical to TNC images in the majority of abdomen tissues except for vertebra and perirenal fat.and the VNC image.The VNC image which reduces radiation dosage derives from SDCT enhanced image might be used as a substitute for the TNC image.
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Objective To explore the value of CT spectral imaging in the demonstration of pancreatic ductal adenocarcinoma (PDAC).Methods 113 patients were scanned by CT spectral,and gemstone spectral imaging (GSI) was performed in late arterial phase (AP) and portal venous phase (PP).All diagnosis were pathologically confirmed.The ROIs were placed on the lesion and on the pancreatic parenchyma.The ROI files including the CTmono values and the normalized CTmono values (normalized to pancreatic parenchyma) were saved.The works were performed three times repeatedly.CNR values ranged from 40 keV to 140 keV and the optimal keV in AP and PP were calculated.The differences of CTmono values, normalized CTmono values,and CNR were compared between the optimal keV and 70 keV(equivalent to conventional 120 kVp energy level).Paired t-test and Wilcoxon signed rank test were performed.P<0.05 was considered statistically significant.Results The optimal monochromatic energy of PDAC were 40 keV in both AP and PP.The optimal CNR values(mean±standard) were 2.31±1.02 and 2.38±1.02 in AP and PP,while the corresponding values of 70 keV were 2.08±0.98 and 2.12±0.96.The CNR of 40 keV was higher than that of 70 keV in both AP and PP.The CTmono values of PDAC were (58±13) HU and (71±19) HU at 70 keV and were (111±44) HU and (155±57) HU at 40 keV in AP and PP.The CTmono value in PP was higher than in AP.The median of normalized CTmono values of PDAC at 40 keV were 47.0% and 53.9% in AP and PP, and were lower than those of 70 keV,which were 57.7% and 61.8%.The differences of normalized CTmono values between 40 keV and 70 keV were significant.Conclusion CT spectral imaging manifests that PDAC is hypovascular both in AP and PP and is progressively enhanced form AP to PP.There is maximal conspicuity of tumor in AP, and the optimal monochromatic imaging can improve the conspicuity of PDAC lesion.
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Objective To explore the quantitative characteristics of pancreatic ductal adenocarcinoma(PDAC) in single-source dual energy spectral CT imaging. Methods From January 2013 to December 2014, 113 patients underwent dual phase contrast-enhanced gemstone spectral imaging(GSI) on Discovery CT 750 HD. All diagnoses were pathologically confirmed by surgery or biopsy. The spectral HU curves of PDAC were observed, the monochromatic CT values, the effective atomic number(Zef ), the iodine concentration(IC), water concentration(WC), and the corresponding normalized values(normalized monochromatic CT values, normalized Zef , normalized IC, normalized WC)of the lesion and the pancreatic parenchyma in late arterial phase(AP) and portal venous phase(PP) were recorded . The measurements were performed three times repeatedly. Paired t test (normal distribution) or Wilcoxon test (non-normal distribution) were used for analyzing the differences between the two phases and between PDAC and pancreatic parenchyma. Results The monochromatic CT values of PDAC in AP were lower than in PP at each energy level and the difference was more marked at lower energy. The normalized monochromatic CT values increased with the increase of energy level in both AP and PP and the difference was more distinct at lower energy. The Zef , IC and normalized IC of PDAC all had significant differences(P<0.05), while the WC, normalized Zef , and normalized WC had no difference between AP and PP. The Zef and IC of pancreatic parenchyma had significant differences(P<0.05), while the WC had no difference between AP and PP. The differences of Zef , IC, and WC between PDAC and pancreatic parenchyma were significant in both two phases (P<0.05). Conclusions Dual phase CT spectral imaging showed characteristic quantitative parameters of pancreatic ductal adenocarcinoma. The monochromatic CT values, Zef , and iodine concentration of PDAC were lower than those of pancreatic parenchyma in both AP and PP. The monochromatic CT values, Zef , and iodine concentration of PDAC in late arterial phase were lower than those in portal venous phase. The differences were all more distinct at lower energy.
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Objective To explore the effect of different scan parameters and algorithm on detection of iron deposition with coexsiting fat by dual soure CT.Methods One ml homogenate of normal rat liver tissues and 1 ml iron dextran solution with different concentrations (50.000,25.000,12.500,6.250,3.125,and 1.560 mg/ml) were fully mixed respectively.The 6 test tubes were scanned by dual source CT in the mode of dual energy to gain the iron specific slope.Different concentrations of dextran iron(50,40,30,20,10,and 5 mg/ml),triglyceride(volume percent were 60％,30％,and 10％,respectively),and homogenate of normal rat liver tissues were mixed.All 18 tubes were scanned by dual source CT with 80-140 kVp and 100-140 kVp,and all these images were reconstructed by filtered back projection (FBP) and singogram affirmed iterative reconstruction(SAFIRE).Raw data were reconstructed by filtering and iterative method.△H value (△H =CT value low kVp-CT valuehigh kVp) and overlay value of three substances decomposition algorithm were measured and analyzed by t test.The Spearmen correlation was applied in iron concentration and measured values.Results Iron specific slope was found to be 1.9392.When 80-140 kVp and 100-140 kVp were applied,△H values were (198 ± 28) and (152 ± 18) HU by using FBP reconstruction,and △H values were (191 ± 23) and (149 ± 17) HU by using SAFIRE reconstruction.The differences were statistically significant(t =-2.934 and-3.492,P =0.032 and 0.017).Overlay values were (381 ±54) and (236 ±31) HU by using FBP reconstruction,and overlay values were (399 ±53) and (276 ± 43) HU by using SAFIRE reconstruction.The differences were also statistically significant (t =-5.739 and-7.949,P =0.002 and 0.001).Under the same energy portfolio but different reconstruction,both △H and overlay value showed no differences (P ＞ 0.05).Except for the conditions with 100-140 kVp tube voltage,△H had no correlation with iron solution concentration (P ＞ 0.05) under either FBP or SAFIRE reconstruction.When other reconstruction methods and tube voltage combination were used,overlay or △H value showed correlation with iron solution concentrations (r value ranged from 0.959 to 0.997,P values ＜ 0.01).Conclusions Different energy portfolios of dual source CT will act on the measured value of iron deposition.The measured values will not be affected by ways of reconstruction.For the detection of iron coexisting in fat,overlay values of material decomposition algorithm is better.
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This paper describes the design process and implementation process of electronic film system. The establishment of electronic film system allowed us to aggressively reduce film use and costs and to demonstrate a positive return.
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Medical Records Systems, Computerized , Radiology Information Systems , X-Ray FilmABSTRACT
In this paper, by describing and comparing different implementations of electronic film combined with the actual application of the electronic film in the imaging department and the clinical departments. We elaborate electronic film for optimizing the imaging department workflow to improve service quality and patient satisfaction and other aspects of value.