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Objective To establish a neural network model based on enhanced CT for distinguishing ISUP grade of clear cell renal cell carcinoma (ccRCC). Methods We collected 131 cases of ccRCC, with 92 cases of low ISUP grade and 39 cases of high ISUP grade. Patients were divided into training set and validation set according to 5:5 stratified sampling. The enhanced CT images of each ccRCC patient were evaluated by the radiologist. Recursive feature elimination (RFE) was used to reduce the dimension of patients' general features and enhanced CT features, which was used for neural network modeling and validation. Results Patients' general features and enhanced CT features were verified by RFE method and then reduced to 14 features. The top 5 features were growth pattern, necrosis, enlargement of lymph nodes, tumor size and capsule. The AUC of the neural network model based on these 5 features in training set was 0.8844 (95%CI: 0.8062-0.9626), sensitivity was 89.47% and specificity was 82.61%; and those in validation set were 0.7924 (95%CI: 0.6567-0.9280), 75.00% and 86.96%, respectively. Conclusion The neural network model of ccRCC ISUP grade based on enhanced CT has relatively high diagnostic efficiency.
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Objective@#A predictive model of WHO/ISUP grading of renal clear cell carcinoma was constructed based on CT radiomics.@*Methods@#The clinical data of 104 patients with ccRCC confirmed by operation or biopsy from March 2014 to December 2018 in the Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine were retrospectively analyzed. There were 70 males and 34 females, and the age was 61.2±11.7 years. The patients were randomly divided into development cohort (73 cases) and validation cohort (31 cases) by stratified sampling according to 7∶3 ratio. According to the WHO/ISUP pathological grading criteria of renal cancer in 2016, Ⅰ and Ⅱ were defined as low-grade group, Ⅲ and Ⅳ were defined as high-grade group. The radiomics features of ccRCC were calculated in cortical phase images of CT enhanced scanning. LASSO regression was used to reduce the radiomics feature dimensionality in the training group, and to establish radiomics risk scores. The binary logistic regression was used to build the prediction model, which was used in the validation group. Bootstrap method was used to validate the model of training and validation group. AUC, sensitivity and specificity were calculated respectively. Hosmer-Lemeshow goodness-of-fit test was used to evaluate model calibration degree.@*Results@#After dimensionality reduction, the radiomics risk score of ccRCC was established. The low and high-level risk scores of the training group were -2.49±1.73 and 1.23±2.17, with significant difference (t=-7.785, P < 0.01). The binary logistic regression multivariate analysis showed that the radiomics risk score was an independent risk factor in identifying low or high-grade ccRCC with odds ratio of (OR=3.576, 95%CI 1.964~6.513). The predictive model was Y=1/[1+ exp(-Z)], Z=1.274×radiomics risk score+ 0.072. The AUC of radiomics risk score in training group was 0.940 (95%CI 0.883-0.998) with 95.5% sensitivity and 88.2% specificity after internal verification by Bootstrap method, and good Hosmer-Lemeshow goodness-of-fit test (χ2=4.463, P>0.05). The low and high-level risk scores of the Validation group were -2.27±2.02 and 0.82±2.08, with significant difference (t=-3.832, P<0.01). The AUC in validation group was 0.859(95%CI 0.723-0.995) with 77.8% sensitivity and 81.8% specificity, and with good Hosmer-Lemeshow goodness-of-fit test (χ2=14.554, P=0.068) as well.@*Conclusions@#The prediction model based on CT radiomics has high accuracy in predicting high or low grade of ccRCC.
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Objective A predictive model of WHO/ISUP grading of renal clear cell carcinoma was constructed based on CT radiomics.Methods The clinical data of 104 patients with ccRCC confirmed by operation or biopsy from March 2014 to December 2018 in the Mfiliated Hospital of Shaanxi University of Traditional Chinese Medicine were retrospectively analyzed.There were 70 males and 34 females,and the age was 61.2 ± 11.7 years.The patients were randomly divided into development cohort (73 cases) and validation cohort (31 cases) by stratified sampling according to 7∶3 ratio.According to the WHO/ISUP pathological grading criteria of renal cancer in 2016,Ⅰ and Ⅱ were defined as low-grade group,Ⅲ and Ⅳ were defined as high-grade group.The radiomics features of ccRCC were calculated in cortical phase images of CT enhanced scanning.LASSO regression was used to reduce the radiomics feature dimensionality in the training group,and to establish radiomics risk scores.The binary logistic regression was used to build the prediction model,which was used in the validation group.Bootstrap method was used to validate the model of training and validation group.AUC,sensitivity and specificity were calculated respectively.Hosmer-Lemeshow goodness-of-fit test was used to evaluate model calibration degree.Results After dimensionality reduction,the radiomics risk score of ccRCC was established.The low and high-level risk scores of the training group were-2.49 ± 1.73 and 1.23 ± 2.17,with significant difference (t =-7.785,P ＜ 0.01).The binary logistic regression multivariate analysis showed that the radiomics risk score was an independent risk factor in identifying low or high-grade ccRCC with odds ratio of (OR =3.576,95％ CI 1.964 ～ 6.513).The predictive model was Y =1/[1 + exp(-Z)],Z =1.274 × radiomics risk score + 0.072.The AUC of radiomics risk score in training group was 0.940 (95％ CI 0.883-0.998) with 95.5％ sensitivity and 88.2％ specificity after internal verification by Bootstrap method,and good Hosmer-Lemeshow goodness-of-fit test (x2 =4.463,P ＞ 0.05).The low and high-level risk scores of the Validation group were-2.27 ± 2.02 and 0.82 ± 2.08,with significant difference (t =-3.832,P ＜ 0.01).The AUC in validation group was 0.859(95％ CI 0.723-0.995) with 77.8％ sensitivity and 81.8％ specificity,and with good Hosmer-Lemeshow goodness-of-fit test (x2 =14.554,P =0.068) as well.Conclusions The prediction model based on CT radiomics has high accuracy in predicting high or low grade of ccRCC.
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Objective To explore the value of intravoxel incoherent motion DWI (IVIM-DWI) combined with single-voxel MRS in distinguishing osteoporotic fractures from metastatic vertebral compression fractures.Methods Totally 70 patients with vertebral compression fractures,who underwent CT scanner were enrolled.The patients were divided into osteoporotic group or metastatic group based on pathological results or clinical follow-up.All patients underwent conventional sagittal T1W,T2W,STIR,IVIM-DWI and single-voxel MRS scanning.Relative peak areas of the signal of water at 4.7 ppm and lipid at 1.3 ppm were determined.IVIM-DWI parameters (diffusion coefficient [D],pseudo diffusion [D*],perfusion fraction [f]) and MRS parameters (lipid water ratio [LWR],fat fraction [FF]) were also recorded.The diagnostic performance of MRS,IVIM-DWI,as well as MRS combined with IVIM-DWI in distinguishing osteoporotic fractures from metastatic vertebral compression fractures were evaluated by using ROC curve,and the area under curve (AUC) was calculated.Results The f,D and FF in metastatic group were significantly lower than those in osteoporotic group,while D* in metastatic group was significantly higher than that in osteoporotic group (all P＜0.05).The sensitivity,specificity and accuracy in differentiating osteoporotic fractures from metastatic vertebral compression fractures was 87.50％ (28/32),57.89 (22/38) and 71.43％ (50/70) of MRS,78.13％ (25/32),89.47％ (34/38) and 84.28％ (59/70) of IVIM-DWI,90.63％ (29/32),97.37％ (37/38) and 94.29％ (66/70) of MRS combining with IVIM-DWI,respectively.AUC of MRS,IVIM-DWI,as well as MRS combined with IVIM-DWI was 0.73,0.88 and 0.94 (all P ＜0.05),respectively.Conclusion Combination of IVIM-DWI and MRS can improve the diagnostic efficiency of differentiating osteoporotic fractures from metastatic vertebral compression fractures.
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Objective To compare the spatial resolution and density resolution balance algorithm(MBIRSTND)and spatial resolution preference algorithm (MBIRRP20)from new version of model-based iterative reconstruction(MBIRn),and adaptive statistical iterative reconstruction(ASIR) with lung kernel in routine dose about the performance of computer-aided detection (CAD)for quantitative analysis of airway.Methods 30 patients were involved who were scanned for pulmonary disease with spectrum CT.Data with a slice thinkness 0.625 mm were reconstructed with ASIR,MBIRSTNDand MBIRRP20.Airway dimensions from three reconstruction algorithm images were measured using an automated and quantitative software(Dexin-FACT)that was designed to segment and quantify the bronchial tree,and a skeletonization algorithm to extract the center-line of airway trees automatically.For each patient,reconstruction algorithm chose the right middle lobe bronchus,and the bronchial length of the matched airways was measured by this scheme.Two radiologists used a semiquantitative 5 scale (Score 0 stands for its image quality is similar to that with ASIR;Score±1 stand for a little better or a little worse;Score±2 stand for obviously better or obviously worse)to rate subjective image quality of airway trees about images reconstructed with MBIRSTNDand MBIRRP20.Paired t test and Wilcoxon signed-rank test were used.Results Algorithm impacts the measurement variability of bronchus length in chest CT.The bronchial length with MBIRRP20was longer than with MBIRSTND, while the length with ASIR were the shortest(P<0.05).In addition, the optimal reconstruction algorithm was found to affect the subjective noise,the continuity and completeness of bronchial wall,and the show of bronchial end.The subjective noise of MBIRSTNDwas better than that of MBIRRP20.The show of bronchial end of MBIRRP20was better than that of MBIRSTND(P<0.05).There was no significant difference in the continuity and completeness of bronchial wall compared with MBIRRP20and MBIRSTND(P>0.05),which was much better than with ASIR(P<0.05).Conclusion MBIRn can inmprove the analyzing ability of CAD airway.The MBIRSTNDcan significantly reduce the image noise,the MBIRRP20significantly improve the branching of the bronchial arteries,both of which can allow the desired airway quantification accuracy of CAD for chest CT of the bronchial wall.
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Objective To demonstrate the feasibility of high-resolution computed tomography(HRCT)reconstructed with a model-based iterative reconstruction (MBIR)for evaluating early peripheral lung cancer (≤3 cm),by comparing image quality obtained from MBIR,filtered back proj ection reconstruction(FBP)and state of the art adaptive statistical iterative reconstruction(ASIR)algorithm respectively.Methods A total of 30 patients confirmed with lung cancer by postoperative pathology were enrolled in the study.A chest phantom was also used to evaluate image noise,spatial resolution and density resolution.Both patients and chest phantom were received HRCT,and the images were reconstructed using FBP,ASIR(40% ASIR and FBP mix)and MBIR.The objective CT value, standard deviation(SD)and signal noise ratio(SNR)were measured.Two radiologists used a semi-quantitative to rate subjective image quality of lung nodules.Results There was no significant difference in CT value between the three reconstruction algorithms (P>0.05).But significant improvements in objective image noise were observed in MBIR compared with FBP and ASIR (P<0.05):including the SD value in back muscle [(12.63±1.70)with MBIR vs (31.58±5.21)with FBP and (24.55±4.14)with ASIR],and in subcutaneous fat [(12.77±2.53)vs (24.39±5.08)and (19.20±4.11)].Subjective image noise of the three group were also significantly difference:FBP with lowest subjective noise score;and MBIR with highest subjective noise score.The sharpness of small vessels and bronchi and diagnostic acceptability with MBIR were significantly better than with FBP and ASIR (P< 0.05).Conclusion Lung HRCT reconstructed with MBIR provides diagnostically more acceptable images for the detailed analyses of peripheral lung cancer compared with FBP and ASIR.
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Objective To explore the clinical value of adaptive statistical iterative reconstruction(ASIR)combined with automatic tube current modulation in low dose scan of chest CT.Methods 80 patients who underwent chest CT scan were randomly divided into four groups,with a noise index(NI)of 14,16,18,and 20,respectively.Automatic tube current modulation technique for chest CT scan was adopted for all patients.The standard dose group,with a NI of 14,was reconstructed with FBP.While the low-dose groups,with a NI of 16,18 and 20,were reconstructed with four ASIR levels(20% ASIR,40% ASIR,60% ASIR and 80% ASIR) in each group.The volume CT dose index(CTDIvol),dose length product(DLP)and effective dose(ED)were recorded of the four groups.The signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)were calculated of the different reconstruction groups. Two radiologists with more than five years of work experience blindly scored the subjective image quality.Results Effective dose of the four groups with different NI were(3.29 ± 1.21)mSv,(3.10 ± 1.07)mSv,(2.20 ± 0.82)mSv and(1.97 ± 1.21)mSv,respectively. In all the reconstruction groups,when NI was constant,the greater the ASIR,the lower the SD.When ASIR percentage was constant, the SD was increased and the SNR was reduced along with NI rising up.When the parameters were set as NI 18 and ASIR 60%,the SD would be smaller and SNR would be higher than that of a standard dose group.In aspect of the scores from subjective image quality evaluation,there was no significant difference(P> 0.05).The average ED was decreased by about 33.2% when compared to the standard dose group.Conclusion Combining automatic tube current modulation with ASIR has a certain clinical practicality.When the NI is set at 18 and ASIR is 60%,the image quality can be optimal for not only satisfying the requirements of clinical diagnosis, but also reducing radiation dose in chest CT scanning.
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Objective To evaluate the image quality improvement on abdominal CT imaging by using new model-based iterative reconstruction (MBIRn)in comparison with adaptive statistical iterative reconstruction (ASiR).Methods 40 patients who underwent upper abdominal three-phase contrast-enhanced scan were included.After scanning,all the scans obtained at 180 s later injection were reconstructed by three protocol,including ASiR (combined reconstruction of 40%FBP and 60%ASiR),the MBIRn of the noise reduction settings (MBIRNR40)and the spatinal resolution settings(MBIRSTND).The thickness of the slice was 0.625 mm.The values of CT and SD of the subcutaneous fat,left erector spinae,inferior vena cava and hepatic vein (left and right branches)were measured at the branch level of hepatic vein,and the contrast noise ratio (CNR)between inferior vena cava and hepatic vein were calculated.The subj ective image quality was evaluated by two radiologists according to the noise,smoothness and small branches of the inferior vena cava and hepatic vein using 5-scoring method.The quality images obtained from ASiR method were treated as reference standard.Results For MBIRSTNDand MBIRNR40images,the subjective noise decreased and image quality increased comparing with ASiR images.Among which the MBIRNR40images had the best image with vascular smoothness score and the lowest subjective noise.Conclusion Compared with ASiR,MBIRSTNDand MBIRNR40,especially MBIRNR40improves the quality of CT images of the inferior vena cava and its branches.
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Objective To compare the effect on image quality of low-dose upper abdominal CT reconstructed with the new version of model-based iterative reconstruction (MBIRn) focused on low-contrast resolution (MBIRNR40),conventional model-based iterative reconstruction (MBIRc),adaptive statistical iterative reconstruction (ASIR) and routine-dose CT reconstructed with filtered back projection (FBP).Methods Water plantom at rest was scanned with CT,and spatial resolution and density resolution were compared among FBP,ASIR,MBIRc,and MBIRNR40.Sixty patients with 2 times CT in the upper abdomen within a year were enrolled.The initial examination was acquired at a standard radiation dose (noise index [NI] of 10 HU) and reconstructed with the conventional FBP algorithm.The follow-up scan was acquired at a lowdose (NI=20 HU) and reconstructed with the standard ASIR,MBIRc and MBIRNR40.All images were obtained with 0.625 mm slice thickness.CT values and noise of fat,muscle as well as the liver and kidney parenchyma were measured and CNR of liver and kidney parenchyma using the fat SD as background image noise were calculated.Two radiologists independently graded images for noise,sharpness of details of structures and lesion.The quantitative image quality scores of different reconstructions were analyzed with one-way ANOVA using FBP reconstruction as reference of standard.The degree of interobserver consistency was evaluated using Kappa test.Results The phantom study revealed the highest spatial resolution with MBIRc and highest density resolution with MBIRNR40 among all reconstructions.The dose-length product and radiation dose for the first inspection was (93.18 ± 41.21) mGy · cm,(1.40 ± 0.62) mSv,respectively,and were (368.03 ± 146.25)mGy · cm,(5.52 ± 2.19)mSv for the second inspection,representing an approximate overall dose reduction of 74.68％ and 74.64％.The mean image noise of muscle and fat for MBIRNR40 was significantly lower than that of MBIR,ASIR and FBP(P＜0.05).The mean CNR values of liver and spleen for MBIRNR40 were significantly higher than that of ASIR,MBIRc and FBP (P＜0.05).Two radiologists had a good subjective score consistency.Low-dose MBIRNR40 subjective image noise was the lowest,showing the most detailed on the upper abdominal detail structure and lesion edge,better than MBIRc,MBIRc was superior to routine-dose FBP,low dose ASIR was worst,the difference was statistically significant (P＜0.05).Conclusion With 75％ dose reduction in upper abdominal CT,the MBIRNR40 can provide well objective and subjective image quality than MBIRc and ASIR40,and the routine-dose FBP.
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Objective To assess image quality of adaptive statistical iterative reconstruction (ASIR),conventional modelbased iterative reconstruction (MBIRc) and a new lung-specific setting (MBIRRP20 and MBIRNR40) from the new version of model-based iterative reconstruction (MBIRn) in submillisievert chest CT comparing with ASIR in standard-dose.Methods Two chest CT examinations were performed with standard-dose and low-dose in 30 patients.Low-dose CT images were reconstructed with ASIR,MBIRc and MBIRn,while standard-dose CT images were reconstructed with ASIR only.Objective image noise and SNR were measured on the same part from the back muscle and subcutaneous fat which located at the level of thoracic entry,trachea carina and hepatic portal.Image quality of lung,mediastinum and upper abdomen structures were evaluated on a 5-point scale.The results were compared with one-way ANOVA and Wilcoxon signed-rank tests.Results The effective dose equivalent for standard-dose CT was (3.01 ± 1.89) mSv,compared with (0.88 ± 0.83) mSv for low dose CT,which decreased by 70.76％.The mean image noise for low-dose MBIRNR40 was significantly lower than that of conventional-dose ASIR,low-dose ASIR and MBIRc (P＜0.05).The mean SNR for low-dose MRIRNR40 was significant ly higher than that of conventional dose ASIR,low-dose ASIR and MBIRc (P＜0.05).The subjective image noise score was significantly lower than that of ASIR and MBIRc,and the score of sharpness of details of the structures score for low dose MBIRn was significantly better than that of the ASIR and MBIRc (P＜0.05).Conclusion MBIRNR40 can significantly reduce image noise and improve SNR compared to ASIR and MBIRc in low-dose,even better than ASIR in standard dose,which reduce radiation dose by about 70％.In low-dose,MBIRPP20 can well display lung structures,and MBIRNR40 can display mediastinal and the upper abdominal structures.
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Objective To assess image quality of adaptive statistical iterative reconstruction (ASIR),conventional modelbased iterative reconstruction (MBIRc) and a new lung-specific setting (MBIRRP20 and MBIRNR40) from the new version of model-based iterative reconstruction (MBIRn) in submillisievert chest CT comparing with ASIR in standard-dose.Methods Two chest CT examinations were performed with standard-dose and low-dose in 30 patients.Low-dose CT images were reconstructed with ASIR,MBIRc and MBIRn,while standard-dose CT images were reconstructed with ASIR only.Objective image noise and SNR were measured on the same part from the back muscle and subcutaneous fat which located at the level of thoracic entry,trachea carina and hepatic portal.Image quality of lung,mediastinum and upper abdomen structures were evaluated on a 5-point scale.The results were compared with one-way ANOVA and Wilcoxon signed-rank tests.Results The effective dose equivalent for standard-dose CT was (3.01 ± 1.89) mSv,compared with (0.88 ± 0.83) mSv for low dose CT,which decreased by 70.76％.The mean image noise for low-dose MBIRNR40 was significantly lower than that of conventional-dose ASIR,low-dose ASIR and MBIRc (P＜0.05).The mean SNR for low-dose MRIRNR40 was significant ly higher than that of conventional dose ASIR,low-dose ASIR and MBIRc (P＜0.05).The subjective image noise score was significantly lower than that of ASIR and MBIRc,and the score of sharpness of details of the structures score for low dose MBIRn was significantly better than that of the ASIR and MBIRc (P＜0.05).Conclusion MBIRNR40 can significantly reduce image noise and improve SNR compared to ASIR and MBIRc in low-dose,even better than ASIR in standard dose,which reduce radiation dose by about 70％.In low-dose,MBIRPP20 can well display lung structures,and MBIRNR40 can display mediastinal and the upper abdominal structures.
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[Abstraet] Purpose To explore the application of noise reduction settings among modelbased iterative reconstruction (MBIRn) on decreasing radiation dose in CTA through experimental study.Materials and Methods Spectral CT was used to scan vessel model which could accommodate 8 tubes under static condition under 120 kVp fixed tube voltage at 10 mA,50 mA,150 mA and 600 mA.The tubes were filled with purified water,1,2,5,10,20 and 30 mgI/ml solutions and 30 mgCa/ml solution.Algorithms of FBP (standard),ASIR40 (combined by 40％ ASIR and FBP),MBIRc and MBIRn with optimized spatial resolution setting as MBIRRP20,MBIRstnd (standard setting),and MBIRNR40 (noise reduction setting) were adopted for original scanning data to reconstruct images of 0.625 mm slice thickness for contrastive analysis.Three fixed layers were chosen and regions of interest were placed on central tube and surrounding ester matrix,and CT value and standard variation (SD) were measured to represent noise.Noise reduction setting MBIRNR40 and solution noise of other reconstruction algorithm images were calculated and compared and average value of contrast noise ratio (CNR) was compared.Results Compared to FBP under different tube currents,ASIR40,MBIRc,MBIRRP20,MBIRstnd and MBIRNR40 reduce noise and increase CNR at different levels.Average noise of MBIRNR40 was the lowest (reduced by 78.33％) and CNR the highest (increased by 241.74％),making it superior to other reconstruction algorithm images (P＜0.05).Meanwhile,the lower the radiation dose was,the more obvious its advantage was.Reconstruction image noise of MBIRNR40 at 10 mA was close to that of FBP and ASIR40 at 600 mA.CNR was obvious greater than that of FBP and ASIR40 at other tube voltage.Conclusion Reconstruction algorithms of MBIRc,MBIRn and ASIR can help enhance CTA image quality and reduce radiation dose.Noise reduction setting MBIRNR40 from MBIRn has the lowest noise and greatest CNR.The lower the radiation dose is,the more obvious its advantage is.
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Objective To explore the clinical application of material decomposition technique on spectral CT imaging and evaluate hemodynamic changes in different liver lobes with liver cirrhosis.Methods 30 patients with liver cirrhosis diagnosed clinically in our hospital were collected and underwent enhanced scanning of abdomen with spectral CT protocol.The monochromatic energy images and iodine-based material decomposition (MD) images were reconstructed after scanning.The iodine concentration (IC) was measured in five liver lobes (the caudate, left lateral, left inner, right anterior and right posterior lobes) and the abdominal aorta of the same axial slice in both the arterial phase (AP) and portal venous phase (VP) on the iodine-water based material decomposition images.The arterial iodine fraction (AIF) and the portal venous iodine concentration (PVIC) as well as the normalized iodine concentration (NIC) during the AP and VP were calculated.The differences of IC,the NIC,the AIF,and the PVIC in five liver lobes in AP and VP were compared by using single factor analysis of variance.Results The IC,the NIC in both AP and VP and the AIF of the caudate liver lobe were higher than those of other four liver lobes, with statistically significant difference (P0.05).The PVIC of the caudate liver lobe was slightly lower than that of the other four liver lobes, however, the difference was not statistically significant (P=0.929).Conclusion The quantitative iodine concentration measurement of liver lobes on spectral CT material decomposition technique can evaluate the hemodynamic changes in liver lobes with liver cirrhosis,and provide more information about the change of blood flow in liver cirrhosis.
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Purpose To explore the value of spectral coronary CT angiography (CCTA) in reducing radiation dose and contrast dose using individualized optimal monochromatic imaging.Materials and Methods Sixty patients with suspected coronary disease were recruited in the study,who were randomly divided into two groups:group A (n=30) using conventional CT protocol with 350 mgI/ml contrast agent;group B (n=30) using low dose spectral CT imaging mode with 300 mgI/ml contrast agent.The images of group A were reconstructed with conventional process,and the images of group B were reconstructed with Optimal CNR to obtain the optimal monochromatic energy images.The images of both groups were transferred to an Advanced Workstation for analysis.Double-blinded method was carried out to qualify the images.CT values of coronary artery segments,as well as standard deviations (SD),the signal-to-noise ratio (SNR),contrast-to-noise ratio (CNR) of aortic sinus were measured.Radiation doses and iodine intake were compared between the two groups.The optimal keV distribution in group B was analyzed.Results There was no significant difference for the subjective scoring of image quality,CT value of each coronary artery segment,SD,SNR,and CNR values between the two groups (P＞0.05).The effective radiation dose and total iodine load in group B were less than that in group A (P＜0.05).The optimal energy distribution for group B was 60-75 keV,average at (66.50+3.91) keV.Conclusion Compared with the conventional CT protocol,spectral CT imaging at optimal energy levels combined with iterative reconstruction can effectively reduce the radiation dose and iodine load,and obtain better images than usual protocol.
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Objective To explore the value of the spectral CT iodine-based material decomposition technique in differential diagnosis of central pulmonary carcinoma from obstructive pneumonia and atelectasis.Methods 25 cases with central pulmonary carcinoma complicating with obstructive pneumonia and atelectasis underwent CT plain scan and spectral contrast scan including pulmonary-arterial-phase (PAP) and bronchial-arterial-phase(BAP).Conventional CT images and iodine base images were generated in each phase by GSI viewer.The 4 groups of images differences between the tumor and the obstructive pneumonia and atelectasis were analyzed.Results The margin of the tumor was ill-defined in plain scan.The cases that showed difference between the tumor and the obstructive pneumonia and atelectasis in 4 groups of images were respectively as follows,10 in conventional CT images of PAP,1 6 in conventional CT images of BAP,1 9 in iodine base images of PAP,and 23 in iodine base images of BAP.The difference of the 4 groups was significant (χ2 =16.54,P0.05),but were better than that of the conventional CT images of PAP(χ2 =6.65,P <0.05).Conclusion Spectral CT iodine-based material decomposition technique is helpful to improve subjective diagnosis of central pulmonary carcinoma complicating with obstructive pneumonia and atelectasis,especially in iodine base images of BAP,it can provide accurate information for clinical stage and treatment.
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Purpose To explore the correlation between normal pancreas and abdominal aorta in the peak enhancement (PE) and the shift time at the peak by applying the multislices spiral CT perfusion imaging.Materials and Methods Prospectively analyzed 62 patients who received enhancement CT examination for the superior or the middle abdomen,underwent optimum level CT perfusion imaging after plain scanning.These data were processed on a Vitreal 2.0 worker-station by using Toshiba body software package.The time-density curves (TDC) of the normal pancreas and the abdominal aorta were drawn,the PE and the shift time of PE were recorded and their correlation was analyzed.Results Compared with abdominal aorta,the mean value of PE of the normal pancreas was lower,and the difference was statistically significant [(111.94± 14.42)HU vs (351.83 ± 74.93)HU,P＜0.05],the mean difference was (246.10± 65.86)HU.Compared with abdominal aorta,the mean shift times of PE of the normal pancreas was latter,and the difference was statistically significant [(37.56±6.90) s vs (30.82±6.73) s,P＜0.05],the mean difference was (6.54±2.97)s.The PE and shift time of PE of the normal pancreas were positively and linearly correlated with that of abdominal aorta (r=0.438,r=0.379).Conclusion The PE of the normal pancreas is not synchronous with that of the abdominal aorta.The shift time of the former is usually 6～8 seconds slower than that of the latter.This provides a basis to find the PE of the normal pancreas in enhanced scan.
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PurposeSupport vector machine (SVM) is a machine learning method based on statistical learning theory of Vapnik-Chervonenkis (VC) dimension structure and risk minimization theory. We analyzed the gem spectrum CT scan data of patients with thyroid nodules and established the SVM diagnostic model. The experimental targets were then reduced and the forecast analysis was carried out based on SVM model. The diagnostic model and experimental methods were proved to provide guidance for clinical diagnosis of thyroid nodules.
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Objective To compare the virtual non-enhanced chest CT (VNCT)generated from spectral CT with conventional non-enhanced chest CT in patients with lung disease in terms of CT number accuracy and image quality.Methods A total of 30 patients with lung disease proved by pathology underwent the conventional non-enhanced thoracic CT and contrast enhanced CT with spectral imaging mode in arterial phase (AP)and venous phase (VP).The VNCT images were reconstructed based on the enhanced spectral CT imaging data.The mean CT number,signal to noise ratio (SNR)for the lesions and image quality score were obtained and compared between the true non-contrast CT (TNCT)and the VNCT (including AP and VP)with paired t test.Results The mean±standard deviation for CT number were (38.74±5.17)HU,(39.08±5.07)HU and (38.96± 5.18)HU for TNCT,VNCT at AP and VNCT at VP,respectively, with no statistical difference (P>0.05).All 3 sets of images demonstrated acceptable image quality,even though there were statistically significant differences in the SNR value and image quality score.The mean ± standard deviation values for SNR were 4.74±0.42 with TNCT, 3.79 ± 0.5 1 with VNCT at AP and 3.77 ± 0.39 with VNCT at VP (P <0.05),and the image quality scores were 5.00 ±0.00 with TNCT,4.17±0.65 with VNCT at AP and 4.17±0.53 with VNCT at VP (P<0.05).Conclusion In patients with lung disease,the vir-tual non-enhanced CT images generated from spectral CT provide accurate CT numbers for lesions and acceptable image quality com-pared with the true non-contrast CT.VNCT may be used to replace TNCT to improve work flow and reduce radiation dose.
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Objective To evaluate the clinical value of spectral CT monochromatic imaging in improvement of imaging quality of bronchial arteries.Methods We retrospevtively analyzed the chest CT images in 38 patients who underwent the contrast-enhanced spectral CT.These images included a set of 140 kVp polychromatic images and default 70 keV monochromatic images.Using a standard Gemstone Spectral Imaging (GSI)viewer at an advanced workstation (AW4.6),an optimal energy level (in keV)for obtai-ning the best CNR of the bronchial artery could be automatically obtained.The SNR,CNR and objective imaging quality score for these 3 imaging sets (140 kVp,70 keV and optimal energy level)were obtained and compared with one-way ANOVA .Results The optimal energy levels for obtaining the best CNR were (62.58±2.74)keV.The SNR of the 140 kVp polychromatic images,70 keV monochromatic images,and the optimal keV monochromatic images were 1 6.44±5.85,20.96 ±8.32 and 24.91 ±9.91,the CNR were 13.30±5.45,1 7.25±6.97 and 20.67±8.62,and the subjective imaging quality scores were 1.97 ±0.82,3.24±0.75 and 4.47±0.60,respectively,exhibiting significant differences among groups (F =10.1 7,10.1 7 and 1 1 1.12,P <0.00).The optimal monochromatic group was superior to the 70 keV group and the 140 kVp mixed-energy group.Conclusion Monochromatic images at approximately 62 keV in dual-energy spectral CTA yields the best CNR and highest diagnostic confidence for imaging bronchial ar-teries,which may improve imaging quality for imaging bronchial arteries.
ABSTRACT
The teaching material library of nutrition and food hygiene was established based on the concept of integrable ware.This paper discussed on the methods and the experiences.The establishing principle must be clear,knowledge points should be separated into parts accurately,courseware and other computerized teaching materials should be made into full use and convenient and efficient retrieval method must be established.In the future,teaching material library and platform construction should be improved and study of educational technology should be strengthened to improve teaching quality and adapt to modern teaching requirements.