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OBJECTIVES@#To explore the difference in CT values between pulmonary thromboembolism and postmortem clot in postmortem CT pulmonary angiography (CTPA) to further improve the application value of virtual autopsy.@*METHODS@#Postmortem CTPA data with the definite cause of death from 2016 to 2019 were collected and divided into pulmonary thromboembolism group (n=4), postmortem clot group (n=5), and control group (n=5). CT values of pulmonary trunk and left and right pulmonary artery contents in each group were measured and analyzed statistically.@*RESULTS@#The average CT value in the pulmonary thromboembolism group and postmortem clot group were (168.4±53.8) Hu and (282.7±78.0) Hu, respectively, which were lower than those of the control group (1 193.0±82.9) Hu (P<0.05). The average CT value of the postmortem clot group was higher than that of the pulmonary thromboembolism group (P<0.05).@*CONCLUSIONS@#CT value is reliable and feasible as a relatively objective quantitative index to distinguish pulmonary thromboembolism and postmortem clot in postmortem CTPA. At the same time, it can provide a scientific basis to a certain extent for ruling out pulmonary thromboembolism deaths.
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Humans , Autopsy , Thrombosis , Pulmonary Embolism/diagnostic imaging , Tomography, X-Ray Computed , Angiography , CadaverABSTRACT
【Objective】 To analyze the influencing factors of the repeat reactive (RR) rates of minipools implicated in minipool (MP) nucleic acid testing(NAT) in Xiamen Blood Center, in order to provide reference for NAT. 【Methods】 Samples of blood donors from January 1, 2019 to October 31, 2022 were collected in Xiamen Blood Center and tested by MP-NAT(pools of six). Statistical analysis and comparison of MP-NAT RR rates was performed among different years, testers, reagent batches, instrument combinations, CT values of MP-NAT reactive pools and sample backgrounds. 【Results】 A total of 234 715 blood samples were tested by MP-NAT, and 428 pools were reactive, in which 248 pools were individual-donor NAT reactive, with a MP-NAT RR rate of 57.9%. The difference of MP-NAT RR rates were not statistically significant among different years, testers, reagent batches, instrument combinations, and sample backgrounds (P> 0.05). The difference of MP-NAT RR rates among different CT values of MP-NAT reactive pools was statistically significant (χ2=69.587, P<0.05). Significantly abnormal RR rate accurred in two months in 2022, and returned to normal after timely handling. 【Conclusion】 The MP-NAT RR rates is one of the important indicators to monitor the quality of NAT. Once there is a significant change in the MP-NAT RR rates, comprehensive analysis and timely handling should be carried out to ensure the quality of blood detection.
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Purpose: Health care workers [HCW] are at a higher risk of infection SARS CoV2 infection due to frequent and close contact to patients with COVID-19. Methods: Serum samples from 500 HCW's were tested for SARS CoV2 IgG antibodies in October 2020. A questionnaire was used to collect demographic and clinical data. All these HCWs were tested for COVID-19, in 2nd week of September 2020, as a hospital policy. Results: Anti SARS CoV2 antibodies were detected in 128/ 500 [25.6%] HCWs. A total of 195/ 500 [39%] enrolled cases had already tested positive for Covid-19 at least once in last six months by RT-PCR. Sixty eight percent of HCWs with previous COVID-19 positivity by RT- PCR tested positive for Anti SARS CoV2 antibodies, whereas only 2.76% of asymptomatic HCWs tested positive. Of 121 anti SARS-CoV-2 IgG positive persons, 70 [57.85%] had CT value < 25. Low CT value and asymptomatic cases had a strong reverse statistically significant association with SARS CoV2 IgG antibody positivity. Conclusions: We report that sero-conversion rate in HCWs is similar to that in general population suggesting that preventive practices used in hospitals are satisfactory. Cases with low viral counts in respiratory sample and asymptomatic cases have lower rate of seroconversion.
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Objective:To analyze the imaging changes of patients with monophasic depression based on the changes in CT parameters of each cerebral lobe.Methods:A total of 100 patients with monophasic depression who received treatment in Department of Radiology, Shaoxing 7 th People's Hospital between June 2019 and June 2021 were included in the observation group. An additional 100 healthy individuals who concurrently received physical examination were included in the control group. CT scan of the brain was performed in all participants. CT value of each cerebral lobe was compared between the two groups. Results:CT values of the left frontal lobe and left temporal lobe in the observation group were (40.88 ± 2.01) HU and (40.21 ± 3.01) HU, respectively, which were significantly lower than those in the control group ( tleft frontal lobe = 2.94, P = 0.004; tleft temporal lobe = 3.29, P = 0.001). CT values of the right frontal lobe and right temporal lobe in the observation group were (40.09 ± 2.52) HU and (44.93 ± 3.03) HU, respectively. There were no significant differences in CT values of the right frontal lobe and right temporal lobe between the two groups ( tright frontal lobe = 1.89, P = 0.060; tright temporal lobe = 1.89, P = 0.060). There were no significant differences in CT values of the left and right occipital lobes and the left and right parietal lobes between the two groups (all P > 0.05). One-way analysis of variance revealed that the CT values of the left and right frontal lobes were negatively correlated with age (-0.441, -0.211) and course of disease (-0.445, -0.191) (both P < 0.05); the CT values of the left and right frontal lobes were not significantly correlated with 24-item Hamilton Depression Rating Scale score and the number of attacks (all P > 0.05). The CT values of the left and right temporal lobes (-0.207, -0.213), the left and right occipital lobes (-0.185, -0.195) and the left and right parietal lobes (-0.185, -0.180) were negatively correlated with age (all P < 0.05). The CT values of the left and right temporal lobes, the left and right occipital lobes, and the left and right parietal lobes were not significantly correlated with course of disease, 24-item Hamilton Depression Rating Scale score, and the number of attacks (all P > 0.05). Conclusion:The left and right frontal lobe and the left temporal lobe are atrophic in patients with monophasic depression. The degree of atrophy is closely related to the course of disease. Therefore, these findings can be used as a reference for imaging diagnosis of degenerative diseases of the central nervous system.
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@#<b>Objective</b> To conduct experimental analysis of clinical applicability of a homemade phantom which is equivalent to multiple tissue densities of human body. <b>Methods</b> Materials with densities close to bone, lung, cavity, and soft tissue were manufactured and combined to obtain a homemade in homogeneous phantom. The electron density of equivalent materials was compared with the organs. Ten lung cancer patients in our department were recruited for dose verification of intensity modulated radiation therapy in the homemade phantom and solid-water phantom. The two phantoms were compared for characteristics in dose verification, and the dosimetric differences of the homemade phantom between the calculated values on treatment planning systemand measured values were statistically analyzed by SPSS 21.0 software. <b>Results</b> In the dose verification, the gamma pass rates (3 mm/3%) were more than 90% using both the homemade phantom and solid-water phantom. The measured values in homemade phantom were larger than those in solid-water phantom, and the maximum deviation was 11.5%. The AD and RD values of gamma pass rate in dose verification showed no significant differences between the two phantoms (<i>P</i> > 0.05). <b>Conclusion</b> The homemade phantom meets the accuracy requirement of clinical application and can be used in dose verification of intensity modulated radiation therapy plan.
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Objective To investigate the CT characteristics of hepatitis B cirrhosis, and to predict the risk of bleeding by establishing a predictive model for upper gastrointestinal bleeding in liver cirrhosis. Methods A retrospective analysis was performed for the clinical data of 101 patients with hepatitis B cirrhosis who were admitted to Tianjin First Central Hospital from January 2015 to June 2021, and these patients were divided into upper gastrointestinal bleeding group and non- bleeding group. The two groups were compared in terms of laboratory findings and CT values in plain scan, arterial phase, portal vein phase, and venous phase measured by contrast-enhanced CT, and the changes in CT values (ΔCT) across different phases were calculated. The t -test or the Mann-Whitney U rank sum test was used for comparison of continuous data between two groups, and the chi-square test was used for comparison of categorical data between two groups. Logistic regression analysis was used to predict the related risk factors; The discrimination of the model was evaluated by calculating the area under the working characteristic curve of the subjects, and the model calibration criteria were determined by Hosmer-lemeshow. Based on the results of multivariate logistic regression analysis, Rstudio4.1.2 R package was used to establish a predictive model, and draws the corresponding ROC curve, calibration curve and clinical decision curve. Results There were significant differences in serum TBil, WBC and PLT levels between the non-bleeding group and the bleeding group (all P < 0.05). There were significant differences in liver-plain, spleen-P-plain and spleen-P-A ΔCT(all P < 0.05). The univariate logistic analysis showed that there were significant differences in leukocytes (odds ratio [ OR ]=0.770, 95% confidence interval [ CI ]: 0.624-0.952, P =0.016), platelets ( OR =0.979, 95% CI : 0.965-0.994, P =0.006), liver plain scan ( OR =1.142, 95% CI : 1.058-1.233, P =0.001), ΔCT value of the spleen from portal vein phase to plain scan ( OR =0.979, 95% CI : 0.959-1.000, P =0.050), and ΔCT value of the spleen from portal vein phase to arterial phase ( OR =0.979, 95% CI : 0.944-0.994, P =0.015) between the hepatitis B cirrhosis patients with upper gastrointestinal bleeding and those without bleeding. The multivariate logistic analysis showed that platelets ( OR =0.968, 95% CI : 0.944-0.993, P =0.011), liver plain phase ( OR =1.148, 95% CI : 1.047-1.259, P =0.003), and ΔCT value of the spleen from portal vein phase to arterial phase ( OR =0.951, 95% CI : 0.908-0.995, P =0.030) were independent risk factors for upper gastrointestinal bleeding. A predictive model for upper gastrointestinal bleeding in hepatitis B cirrhosis was established based on the results of the multivariate logistic analysis, and a calibration curve was plotted. This model had an area under the receiver operating characteristic curve of 0.801 at the cut-off value of 0.433, with a sensitivity of 81.4% and a specificity of 77.6%. The calibration curve of the model fitted well with the ideal curve. Conclusion There are special ΔCT changes in hepatitis B cirrhosis, and the predictive model based on ΔCT has a good predictive ability for upper gastrointestinal bleeding in patients with hepatitis B cirrhosis.
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【Objective】 To analyze the difference of the internal control (IC) Ct value of two sets of blood nucleic acid detection(NAT) systems for individual donation and explore the feasibility of the IC Ct value used as stability evaluation index of NAT system. 【Methods】 A total of 4342 blood samples were randomly selected from our center from June to November 2020, and the IC Ct values of NAT system were classified into three categories: 1) classified by detection items: HBV, HCV and HIV; 2) classified by sample type: negative control (NC), positive control (PC), internal quality control (QC), blood donor sample (S); 3) classified by different instruments: system A and system B, and the differences of IC Ct value were analyzed and compared. 【Results】 A total of 14 196 IC Ct values of NAT were collected, showing a non-normal distribution. 1) classified by detection items: there were differences in the median of overall IC Ct values of HBV, HCV and HIV (H=859.6, P0.05), except for HBV QC (Z=1 635)and S (Z=1 848 560), HCV S (Z=1 957 844), HIV S (Z= 2 217 855) (P<0.01). No difference in IC values (P<0.01) was noted for any detection items (NC, PC, QC and S) in the same set of detection system. 【Conclusion】 Although IC values trended to be different due to types of sample, the NC, PC, and QC samples that come with the original reagents were identical in the two detection systems. The change of IC Ct value may be used as an evaluation index for the stability of the detection system.
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【Objective】 To verify the results of HBV DNA and HCV RNA screening under different brands of vacuum collection tubes for blood samples, storage temperature and storage time. 【Methods】 Experiment 1 was conducted as follows: blood samples were collected simultaneously from 52 voluntary blood donors using two brands(divided into group A and group B) of vacuum collection tubes for blood samples. The plasma separation of group A and group B were compared, and the effects of storage time on the NAT yield of HBV DNA and HCV RNA were statistically analyzed. Experiment 2 was conducted as follows: the effects of different storage temperature, time and tubes on the NAT yield of HBV DNA and HCV RNA samples with low viral load in group A and B were verified and compared in the simulated phlebotomy condition. 【Results】 In Experiment 1: After centrifugation, blood plasma layer and cells layer were separated completely in group A(100%, 52/52), but one sample was not well separated in group B(1/52, 1.92%). After 4 to 10 h after collection, blood samples of two groups were centrifuged and screened for HBV DNA, HCV RNA within 24 h. No positive samples were yielded and the Ct values of internal control(IC-DNA and IC-RNA) were uniform. In Experiment 2: Whole blood samples, stored for either 4 h or 6~10 h at 4 ℃ or 25℃ before centrifugation, showed no difference on the NAT-yield of HBV DNA nor HCV RNA samples with low viral load(P>0.05). Ct values of HBV DNA and HCV RNA of group A was similar to those of group B as centrifuged samples were stored for 24 h or 72~104 h at 4℃(P>0.05), but all increased as the storage time prolonged. Ct values of HBV DNA in group A increased from 33.45±0.29(24 h) to 33.82±0.08(72~104 h) and HCV RNA from 35.21±0.20 to 36.12±0.43; HBV DNA from 33.46±0.25 to 34.30±0.60 and HCV RNA from 35.47±0.24 to 36.49±0.51 in group B. 【Conclusion】 Under certain laboratory condition, different storage time, storage temperature and tubes shed few effect on the NAT-yield of HBV DNA and HCV RNA samples with low virus loads. However, it is suggested that the blood sample be detected within 72 h after centrifugation at 4 ℃ storage.
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BACKGROUND: CT scan and differential modeling are used to analyze the fracture end, which is an effective method to judge the degree of bone healing. To obtain the high precision of differential modeling and simulation, how to select the optimal CT scanning parameters needs further research and analysis. OBJECTIVE: To compare the effects of different CT scanning parameters on modeling accuracy in personalized differential modeling analysis, to verify the accuracy and effectiveness of personalized differential modeling in the reduction of simulated target bone segments, and to explore the research value of this method in judging the degree of bone healing of long canals of lower extremities. METHODS: The model of internal fixation was established with porcine femur. Four groups of 80 kV-300 mA (group A-low dose), 120 kV-335 mA (group B-automatic tube current control system), 140 kV-300 mA (group C-manual setting comparison) and 140 kV-80 mA (group D-high kV and low mA) were used to scan the same object with the same pitch, slice thickness and environment. The scanning data of each group were selected, the same CT value range was used, and the differential modeling analysis method was used to model the target bone segment. The average area and maximum area of metal artifacts in CT scanning images, the average CT value, volume and maximum wall thickness peak after differential modeling analysis, the radiation amount under four groups of scanning conditions were compared to determine the reduction of metal artifacts, modeling accuracy and radiation, so as to select the optimal CT scanning parameters. RESULTS AND CONCLUSION: (1) Artifact measurement method results: In group A, there were many metal artifacts, which obviously obstructed bone tissue, and had a possibility of missed diagnosis. In group D, there were minimal metal artifacts, less occlusion around bone tissue, but poor image contrast and high fog. The difference between group B and group C lay in the clarity of images, and the accuracy of diagnosis was basically the same. Therefore, the order of artifact size was as follows: group A > group B > group C > Group D. (2) Differential modeling analysis results: In group B, because of the smaller artifact and less loss of CT value, the simulated model was more close to the reality. Moreover, group B adopted the automatic tube current control system, which could obviously show that the radiation amount was smaller and more protective for patients. (3) It is confirmed that the CT scan under the condition of group B can effectively reduce the interference caused by metal artifacts, better retain the original information of CT gray value, and retain the density information of the target bone segment to the maximum extent. Therefore, when establishing differential modeling, the CT automatic tube current control system is used as the optimal CT scanning parameter, which not only improves the simulation accuracy of personalized differential modeling, but also increases the accuracy of calculation.
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Objective • To analyze the multidetector CT (MDCT) manifestations of mesenteric venous thrombosis (MVT) and further explore the diagnostic value of MDCT in acute and chronic MVT. Methods • MDCT findings of 47 MVT patients clinically confirmed in Shanghai Sixth People's Hospital, Shanghai Jiao Tong University and Second People's Hospital in Kashgar from January 2012 to October 2018 were retrospectively analyzed. The mean CT value of thrombus on CT axial images of acute and chronic MVT was measured and calculated. According to CT values and CT manifestations, differences between the two groups were statistically analyzed. Results • Among 47 patients with MVT, there were 46 (97.87%) with filling defect of mesenteric vein and its branches, 34 (72.34%) with dilatation of blood vessels at the thrombosis site, 30 (63.82%) with intestinal wall thickening, 9 (19.15%) with enhanced delamination of intestinal wall, 11 (23.40%) with intestinal dilatation, 21 (44.68%) with ascites, and 25 (53.19%) with mesenteric edema. The mean CT value of MVT thrombus in acute group [(42.88±17.77) HU] was higher than that in chronic group [(31.80±6.18) HU] (P<0.05). The proportion of MVT with vasodilation and target sign in acute group was higher than that in chronic group (P<0.05). There was no difference in the ratio of other signs between the two groups. Conclusion • The MDCT findings of MVT patients are characteristic. CT value of thrombus, vasodilation and target sign are valuable in evaluating acute and chronic MVT.
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Objective · To analyze the multidetector CT (MDCT) manifestations of mesenteric venous thrombosis (MVT) and further explore the diagnostic value of MDCT in acute and chronic MVT. Methods · MDCT findings of 47 MVT patients clinically confirmed in Shanghai Sixth People's Hospital, Shanghai Jiao Tong University and Second People's Hospital in Kashgar from January 2012 to October 2018 were retrospectively analyzed. The mean CT value of thrombus on CT axial images of acute and chronic MVT was measured and calculated. According to CT values and CT manifestations, differences between the two groups were statistically analyzed. Results · Among 47 patients with MVT, there were 46 (97.87％) with filling defect of mesenteric vein and its branches, 34 (72.34％) with dilatation of blood vessels at the thrombosis site, 30 (63.82％) with intestinal wall thickening, 9 (19.15％) with enhanced delamination of intestinal wall, 11 (23.40％) with intestinal dilatation, 21 (44.68％) with ascites, and 25 (53.19％) with mesenteric edema. The mean CT value of MVT thrombus in acute group [ (42.88±17.77) HU] was higher than that in chronic group [ (31.80±6.18) HU] (P＜0.05). The proportion of MVT with vasodilation and target sign in acute group was higher than that in chronic group (P＜0.05). There was no difference in the ratio of other signs between the two groups. Conclusion · The MDCT findings of MVT patients are characteristic. CT value of thrombus, vasodilation and target sign are valuable in evaluating acute and chronic MVT.
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Objective To compare the dose difference between the 12-bit and 16-bit CT images containing metallic implants calculated by different algorithms. Methods The titanium alloy rod was inserted into the phantom and subject to CT scan and then the 12-bit and 16-bit CT images were reconstructed. The CT images were online transmitted to the Monaco planning system and a 0° of single field was designed. The dose distribution was calculated by PB (Pencil Beam), CC (Collapsed Cone) and MC (Monte Carlo) algorithms, respectively. The CT-ED curve was expanded and the dose was recalculated. The depth dose curve through the center of the metallic implants along with the direction of the field was obtained by using the Matlab 8. 3 statistical software. The dose distribution curves between 12-bit and 16-bit CT images calculated by different algorithms and the dose difference of varying distances between the incident and the exit surfaces of metallic implants were statistically compared. The dose was measured by thimble chamber. Results The 16-bit CT images accurately read the CT values of the metallic implants. After the CT-ED curve was expanded, the dose on the incident surface of metallic implant was reduced by 5. 43% and that on the exit surface was increased by 25. 56% calculated by PB algorithm compared with MC algorithm. The dose on the posterior exit surface was higher than that of MC algorithm. The dose on the incident surface of metallic surface was decreased by 4. 5%, whereas that on the exit surface was reduced by 4. 31% using CC algorithm. The dose on the posterior exit surface was more significantly reduced. The calculated values by MC algorithm were the most close to the measured values. Conclusions Application of 16-bit CT image, CT-ED curve expansion of the treatment planning system combined with MC algorithm can enhance the accuracy of dose calculation for the patients containing metallic implants during radiotherapy.
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Objective To investigate the relationship between changes in the liver computed tomography (CT) images and the postmortem interval (PMI) of rabbits 129 h after their death due to hemorrhagic shock. Methods CT scanning was used to investigate the hemorrhagic shock death model in 23 rabbits to identify the postmortem cerebral changes from 0 h to 129 h after death. Results The liver or lumbar area in the liver window showed the following characteristic changes: from unchanged, to rapid shrinkage, to slow shrinkage; the mean CT values of the liver initially increased and subsequently decreased. The regression equations for the relationship between the two indices and PMI were established by surgery, and they all had statistical significance (P ＜ 0. 01). Conclusion CT scanning can accurately show changes in the rabbit liver after death. The mean CT value of the liver tissue is more sensitive for inferring early PMI. Furthermore, the liver area/lumbar area ratio parameters are more sensitive for inferring mid-late PMI.
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Objective To investigate the impacts of the CT value-electron density transformation curves on radiotherapy dosage for different scanning sites.Methods The CT value-electron density transformation curves under head,chest and abdomen modes were obtained with CIRS062 nonuniform equivalent phantom,a CT simulator and the same scanning parameters.Totally 8 patients with glioma,lung cancer or gastric cancer had the radiotherapy dosages calculated with Pinnacle 9.8 TPS and CT value-electron density transformation curve under the three modes,so as to analyze the dosage deviation involving in hop value as well as the dose volume histogram (DVH) for the target area and organs at risk (OAR).Results With the scanning parameters kept the same,the head area had no significant differences in the CT value-electron density transformation curve and exposure dosage with the abdomen area (P＞0.05),while the head and abdomen areas had statistical differences in the CT value-electron density transformation curve with the chest area (P＜0.05).CT values varied greatly at the high-density tissue,while the dosage deviations at the target area and OAR were both less than 2％.Conclusion CT value-electron density transformation curve for different scanning sites has influences on radiotherapy dosage,and head and chest tumors should have the dosage calculation based on the CT value-electron density transformation curve with corresponding scanning modes to ensure dosage computation precision during treatment planning.
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Objective To investigate the relationship between the single energy CT value and the tissue density and further evaluate the mass of thyroid.Methods Different substances respectively composed of liquid and solid,liquid and liquid,thyroid gland were selected,and the relationship was investigated between the single energy CT value and the tissue density.Results The CT value was closely related to the content of high atomic number substance.The CT value of thyroid was closely related to the content of iodine.Conclusion It is feasible to measure the thyroid density by the energy spectrum CT.
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Objective According to the CT or MRI images of lumbar disc herniation (LDH),a simple and accurate coordinate partitioning method for describing the size and location of protrusions based on CT value was proposed.This method can provide a reference for the diagnosis and surgical treatment of LDH.Method The system was developed by experienced clinicians and imaging experts.In this system,CT and MR data of patients with LDH was analyzed,and classified by coordinate partition according to the degree of LDH.According to the lumbar disc anatomical and clinical features,the protrusions were located in X axis,Y axis,and Z axis.Results In this system,the position of the protrusions in the spinal canal was respectively partitioned from X axis (horizontal plane),Y axis (sagittal plane) and Z axis (coronal plane),where the X and Y axes were divided into 8 zones (-4 to 4) and the Z axis was divided into 4 zones (1 to 4).The size,i.e.the degree of protrusions,was described by the sum of the absolute values of the corresponding position zones.The greater the value,the more serious of the protrusion is.Conclusion The method of coordinate partitioning based on CT value can well reflect the pathological types,precise position and degree of LDH,and thus provide references for the diagnosis and the selection of surgical methods and surgical occasion of LDH.
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Objective To measure the CT Hounsfield Unit ( HU) and relative stopping power ( RSP) conversion curve. Methods In this study, the RSPs of 12 different tissue equivalent rods were measured with proton and carbon beam in the Shanghai Proton and Heavy Ion Center ( SPHIC) . The same tissue equivalent materials were scanned with CT scanner to acquire the HU. Results Conversion curve for the transformation of HU into RSP was generated for both proton and carbon ion beam. Differences between RSPs measured using proton and carbon beam were ≤0. 64%except lung material. Conclusions A RSP versus HU conversion curve was generated for both protons and carbon ions.
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Objective To measure the CT Hounsfield Unit ( HU) and relative stopping power ( RSP) conversion curve. Methods In this study, the RSPs of 12 different tissue equivalent rods were measured with proton and carbon beam in the Shanghai Proton and Heavy Ion Center ( SPHIC) . The same tissue equivalent materials were scanned with CT scanner to acquire the HU. Results Conversion curve for the transformation of HU into RSP was generated for both proton and carbon ion beam. Differences between RSPs measured using proton and carbon beam were ≤0. 64%except lung material. Conclusions A RSP versus HU conversion curve was generated for both protons and carbon ions.
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Ojective To investigate the clinical application value of low dose contrast agent in computerized tomography pulmonary angiography (CTPA) with spectral CT imaging.Methods Totally 52 patients suspected with pulmonary embolism underwent multi-slice spiral CT pulmonary angiography,and were randomly divided into a control group (n =27) and a research group (n=25).The research group used spectral CT with 35 ml of contrast medium and the control group used 64-slice CT with conventional 80 to 90 ml of contrast medium.The CT values of the pulmonary trunk,left pulmonary artery (LPA),right pulmonary artery (RPA),pulmonary vein and ascending aorta were measured.The contrast to noise ratio (CNR) of the pulmonary artery was also calculated.In addition,the image quality of CTPA was evaluated independently by two experienced radiologists.Results The CT values (HU) of the pulmonary trunk,left pulmonary artery(LPA),right pulmonary artery (RPA) in the research group were (432.2±63.4),(373.5±48.8),(381.4±53.6) and (62.5-±6.4),respectively,and significantly higher than those in the control group,showing statistical differences (P＜0.05).The evaluation results of the CTPA images by two radiologists showed that the image quality in the research group was better than that in the control group (P＜0.05).Conclusion The image quality of pulmonary angiography with spectral CT using low contrast medium dose can be improved compared with the conventional spiral CT.
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BACKGROUND: We evaluated the performance of the BD MAX StaphSR Assay (SR assay; BD, USA) for direct detection of Staphylococcus aureus and methicillin resistance not only in S. aureus but also in coagulase-negative Staphylococci (CNS) from positive blood cultures. METHODS: From 228 blood culture bottles, 103 S. aureus [45 methicillin-resistant S. aureus (MRSA), 55 methicillin-susceptible S. aureus (MSSA), 3 mixed infections (1 MRSA+Enterococcus faecalis, 1 MSSA+MRCNS, 1 MSSA+MSCNS)], and 125 CNS (102 MRCNS, 23 MSCNS) were identified by Vitek 2. For further analysis, we obtained the cycle threshold (Ct) values from the BD MAX system software to determine an appropriate cutoff value. For discrepancy analysis, conventional mecA/mecC PCR and oxacillin minimum inhibitory concentrations (MICs) were determined. RESULTS: Compared to Vitek 2, the SR assay identified all 103 S. aureus isolates correctly but failed to detect methicillin resistance in three MRSA isolates. All 55 MSSA isolates were correctly identified by the SR assay. In the concordant cases, the highest Ct values for nuc, mecA, and mec right-extremity junction (MREJ) were 25.6, 22, and 22.2, respectively. Therefore, we selected Ct values from 0-27 as a range of positivity, and applying this cutoff, the sensitivity/specificity of the SR assay were 100%/100% for detecting S. aureus, and 97.9%/98.1% and 99.0%/95.8% for detecting methicillin resistance in S. aureus and CNS, respectively. CONCLUSIONS: We propose a Ct cutoff value for nuc/mec assay without considering MREJ because mixed cultures of MSSA and MRCNS were very rare (0.4%) in the positive blood cultures.