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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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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 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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Objective To explore the application of low dose of radiation combined with low concentration of contrast medium in the energy spectrum CT of the coronary artery angiography.Methods 60 patients with suspected diagnosis of coronary heart disease were randomly divided into A,B two groups,30 cases in each group.Group A with 350 mg I/mL contrast agent,undergoing conventional CT scanning;Group B using 300 mg I/mL contrast agent,the gems energy spectrum CT scanning with low-dose.Two groups both adopted forward-looking heart switch control scanning mode.After scanning,group A reconstructed conventional images of 40% ASiR sequence,group B rebuilded axial surface images of single energy 65 keV and 40% ASiR sequence,all the reconstruction images were introduced to AW4.6 workstations used for analysis.Double-blind subjective rating was done by two experienced doctors to measure CT values and SD of aortic sinus (AS),left main (LMA),the left anterior descending branch proximal (LAD-p),left circumflex branch proximal (LCX-p), right coronary artery proximal (RCA-p)and pericardial fat,AS the noise (SD),to calculate the signal-to-noise ratio (SNR)and contrast to noise ratio (CNR),to calculate the effective doses of radiation(ED)by recording CTDI and DLP,and to record iodine intake.By using two independent samples t test to compare two groups of patients’the effective radiation doses,iodine intake,the average CT value,SD,SNR and CNR.Results The subjective image quality score differences and coronary measuring section CT values between the two groups had no statistical significance.In the aspects of effective radiation dose,group B reduced about 29% compared to group A,the difference was statistically significant.Iodine intake in group B decreased about 16% than in group A.Conclusion In coronary artery CT imaging, spectral scanning with low dose of radiation and reconstruction images with single energy can effectively reduce the radiation dose and iodine intake,at the same time it can obtain the approximate image quality like conventional scanning.
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PurposeTo explore the feasibility of personalized energy spectrum scanning in upper abdomen CT by comparing the image quality and radiation dose of optimizing choice spectrum scanning protocol with conventional 120 kVp scan.Material and Methods Sixty patients undergoing abdominal CT scan with and without contrast enhancement were prospectively collected and randomly assigned into two groups. Group A (30 patients) underwent conventional 120 kVp scan and spectral enhancement scanning; group B (30 patients) underwent spectrum scan and 120 kVp enhancement scanning. Spectral scanning protocol was based on individual choice with conventional 120 kVp NI10-5 mm average mAs scan for every patient. The CT dose index of volume (CTDIvol) and effective dose (ED) during non-contrast phase and portal venous phase were recorded. The CT value, standard deviation (SD), signal noise ratio (SNR) and contrast noise ratio (CNR) were measured in the liver parenchyma, spleen parenchyma and portal venous trunk.Results The CTDIvol and ED of spectrum scanning were less than 120 kVp scan but there was no statistical difference (P>0.05). The SD of group B GSI imaging was less than group A 120 kVp (P<0.05), while the SNR was greater than group A. The SD of group A GSI portal venous phase in the liver, spleen and portal vein was less than group B 120 kVp (P<0.05).ConclusionThe optimized energy spectrum scanning protocol can reduce radiation dose with quality of single energy image from the energy spectrum equal to or better than the conventional 120 kVp scanning protocol. Personalized energy spectrum scan protocol provides multi-parameter diagnosis and multi-application platform and can be used routinely in the upper abdomen scan.
