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Objective In the wide clinical practice of liver 3D printing, its related high-dose CT radiation has been somehow neglected and resulted in unnecessary radiation injury to the patients. This study was to explore the feasibility of liver 3D modeling printing with the low-dose radiation CT scanning technique. Methods This retrospective study included 40 patients undergoing liver 3D modeling printing from January 2016 to June 2018, who were equally randomized into a low-dose radiation group (100 kVp, by automated tube current modulation [ATCM] and adaptive statistical iterative reconstruction [ASIR]) and a normal-dose radiation group (120 kVp, 250 mA by filter back projection [FBP]), both with contrast agent Iohexol at 300 mgI/m1. We obtained the values of three-phase enhanced CT scanning of the abdominal aorta, portal vein and liver parenchyma, background noise (BN), volume CT dose index (CTDI), dose length product (DLP), contrast noise ratio (CNR) and effective radiation dose (ED). We input the CT DICOM data into the 3D printer for liver modeling printing and subjectively assessed the results. Results There were statistically significant differences between the low-dose and normal-dose radiation groups in the CTDI, DLP and ED (P 0.05). The ED was decreased about 35.8% in the low-dose group as compared with that in the normal-dose group ([2.58 ± 0.79] vs [4.02 ± 0.26] mSv, P 0.05). Conclusion Low-dose radiation CT scanning technology can meet the clinical requirement of liver 3D modeling printing and significantly reduce the patient’s exposure to CT radiation.
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Objective To explore the application value of virtual monochromatic imaging combined with adaptive statistical iterative reconstruction (ASIR) and automatic spectral imageing mode selection(ASIS) in reducing the radiation dose and contrast dose of CT portal venography.Methods We retrospectively collected 120 cases (80 males and 40 females) who underwent upper abdominal enhancement CT from January 2017 to April 2017.Patients were divided into 3 groups (40 cases in each group) according to the scanning program.Group A used conventional 120 kVp scan,NI =10,contrast agent dosage was 450 mgI/kg of body weight,image was reconstructed with 50％ ASIR technique;Groups B and C used spectral CT mode,NI =10 (Group B),NI =13 (Group C),the amount of contrast agent was 300 mgI/kg of body weight,and the image was reconstructed with 60 keV +50％ ASIR.One-way analysis of variance was used to compare the mean CT values and their differences,image noise,SNR and CNR of portal vein and liver parenchyma in three groups of images.Subjective image quality scores were performed on three groups of images by two senior radiologists.The patient's CTDIvol,DLP were recorded and the E was calculated.Results The amount of contrast agent in group B and C was reduced by about 30％ compared with group A.The portal vein CT values of groups A,B,and C were 168.22± 17.82,209.06±20.07,and 211.03±25.60.The portal vein CT values of group B and C were significantly higher than those of group A,respectively (t =-9.625,-8.680,P ＜ 0.05).The CT value difference between portal vein and liver parenchyma was 60.01± 17.01,106.63±25.83,107.72±25.39,respectively.SNRs were 8.48±1.41,12.64±2.94,10.77±1.94,and CNR were 5.16±1.80,8.13±2.54,7.32±1.84,respectively.The image quality scores were 3.53±0.68,4.75±0.54 and 4.53±0.64,respectively.The CT value difference,SNR,CNR and image quality scores of group B and group C were significantly higher than those in group A(t=-9.536,-9.857,-8.082,-6.064,-6.050,-5.308,-8.912,-6.779,P＜0.05).The CTDIvolof groups A,B and C were (12.15±5.02) mGy,(12.34±4.18) mGy,(10.03±3.13) mGy,DLP were (348.62± 155.99) mGy· cm,(355.56± 131.07) mGy·cm,(287.10±92.25) mGy·cm,respectively,E were (5.23±2.34) mSv,(5.33±1.97) mSv,(4.31±.1.38) mSv,compared with the A and B groups,the CTDI,ol,DLP and E of the C group were significantly lower(t=2.274,2.147,2.147,2.812,2.702,2.702,P＜0.05),and CTDIvol,DLP and E were decreased by 19％.Conclusions In CT portal venography,NI =13,60 keV combined with 50％ ASIR reconstruction and ASIS can be used to personalize the contrast dose and radiation dose of the patient and provide images that meet the diagnostic requirements.
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Objective To investigate the value of wide-detector helical CT combined with adaptive statistical iterative reconstruction-V (ASIR-V) in the low radiation dose CT examination of upper abdomen in obese patients.Methods In the first phantom experiment part,the optimal percentage of pre-and post-ASIR-V of abdominal scanning (120 kVp,NI =10 HU) were explored.The second human experiment was performed based on the phantom study,and our institutional review board approved this prospective study,each participant provided written informed consent.87 obese patients (body mass index,BMI ≥30 kg/m2) underwent contrast-enhanced abdominal CT scan were randomly divided into two scan protocols [protocol A:n =43,120 kVp,detector coverage of 80 mm,40％ pre-ASIR-V (group A1)and combined with 60％ post-ASIR-V (group A2) respectively;protocol B,n =44,120 kVp,detector coverage of 40 mm,40％ ASIR (group B)].Quantitative parameters [image noise and contrast-to-noise ratio (CNR)] and qualitative visual parameters (overall image quality as graded on a 5-point scale) were compared.Weighted effective dose (E) were assessed.Results The optimal percentage of pre-and post-ASIR-V of abdominal scanning were 40％ and 60％,respectively.The effective radiation dose in protocol A [(4.55 ± 0.95) mSv] was decreased for 53％ as compared with protocol B [(9.58 ± 2.04) mSv](t =-14.773,P ＜ 0.001).During the arterial phase and portal venous phase,except for the CNRs of liver,Group A2 showed higher CNRs (q =2.160-3.209,P ＜ 0.05),lower image noise(q =-4.212--3.202,P＜0.05),and higher overall image quality scores(Z =-5.155--2.561,P ＜0.05) as compared with group A1 and group B.Group A1 showed similar CNRs,similar image noise(P ＞ 0.05),and lower overall image quality scores (Z =-3.298--3.030,P ＜ 0.05) than group B.The overall image quality scores in group A were all greater than 3 point and met the clinical diagnostic level.Conclusions Compared with stand-detector helical CT in obese patients,the wide-detector helical CT combined with 40％ pre-ASIR-V could reduce the radiation dose by 53％,and improve overall image quality by combining post-ASIR-V technique.
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Objective To investigate the impact of prescribed adaptive statistical iterative reconstruction V (Pre-ASiR-V) on imaging quality and radiation dosage of pure ground glass nodules (pGGN) in chest phantom,in order to obtain the optimal level of Pre-ASiR-V.Methods CT scanning for a chest phantom containing 4 artificial pGGNs was performed with Revolution CT,and the Pre-ASiR-V level was set as 0,20％,40％,60％,80％ and 100％ group,respectively.The mean noise,effective dose (ED) and the subjective scores of pGGN imaging were recorded and compared.Results The mean noise of groups (Pre-ASiR-V 0,20％,40％,60％,80％ and 100％) was (17.93±2.20)HU,(17.30±3.68)HU,(18.20± 3.44)HU,(18.80±0.20)HU,(19.87±2.56)HU and (15.90±4.56)HU,respectively (F=0.568,P=0.723).ED of these groups was 7.40 mSv,5.16 mSv,3.36 mSv,1.97 mSv,0.97 mSv and 0.33 mSv,respectively.Compared with imaging of PreASiR-V 0,the reduction percentage of ED was 30.27％,54.59％,73.38％,86.89％ and 95.54％,respectively.The subjective score of the image quality evaluated by the 2 observers had high agreement (Kappa=0.778,P=0.003),and all the scores were greater than 3.The subjective score of Pre-ASiR-V 80％ and 100％ group was slightly lower than those in other groups.Conclusion Different Pre-ASiR-V level slightly impacts the noise of high-resolution CT images of chest phantom,while reduces radiation dosage significantly.Pre-ASiR-V level of 60％ is the optimal protocol.
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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 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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Objective To explore the value of adaptive statistical iterative reconstruction (ASIR) and a sharp recon kernel to obtain high resolution pulmonary images in low-dose pediatric chest CT scans.Methods Totally 42 children underwent low-dose chest CT scans with ASIR were included.Age dependent noise index (NI) was used for dose optimization:NI=12 for 0-12 months old,NI=15 for ＞1 2 years old,NI=17 for 3-6 years old and NI=20 for ≥7 years old.Images were reconstructed to 0.625 mm using different recon kernels:Soft,Standard,Lung,and Chest kernel.ASIR blending was varied from 0 100％ to provide balanced image noise and spatial resolution.Two radiologists independently evaluated images for normal lung structures,abnormal CT findings and image noise on a 5 point scale with 3 being clinically acceptable.The best kernel,as well as the match with the best ASIR weight were analyzed statistically.Results CT images with lung kernel and ASIR 60％ were rated substantially better than those kernel.Conclusion ASIR 60％ with a sharp lung kernel can significantly improve image quality in low dose pediatric chest CT scans.
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Objective To explore the feasibility of reducing radiation dose and iodine contrast medium in 70 kVp abdominal CTA imaging in low-body mass index (BMI;≤22 kg/m2) patients.Methods The 48 patients with suspected abdominal vascular diseases and low BMI (≤22 kg/m2) underwent abdominal CTA.All patients were divided into two groups according to tube voltage and contrast intake randomly.The parameters of group A (n=27) were contrast intake 300 mgI/kg,70 kVp,the conditions of group B (n=21) were contrast intake 500 mgI/kg,120 kVp,and the other conditions were the same in both groups.The image quality of right renal arterial images was evaluated by two observers simultaneously (5-scale).The consistency and difference between the two observers were analyzed.The CT values of abdominal aorta,celiac trunk,superior mesenteric artery,common hepatic artery,pancreatic artery and erector spinae,SD values of erector spinae on the level of right renal hilus were measured respectively in both groups.The CT values of abdominal aorta and its main branches,the CNR of abdominal aorta,the volume CT dose index (CTDIvol),dose-length product (DLP) and overall iodine intake in each group were compared.Results The scoring of right renal arterial images in both groups were 5.00 (1.00),the results showed a good consistency (Kappa=0.932,0.911).The CT values of abdominal aorta,superior mesenteric artery,common hepatic artery and pancreatic artery in group A were all more than those of in group B (all P＜0.05).The CNR of group A was higher than that of group B (P＜0.05).The CTDIvoland DLP in group A decreased by 73.36％ and 74.41％ compared with group B.The overall iodine intakes in group A and group B were (46.33±6.43)ml and (84.31±10.71)rnl,respectively.The overall iodine intake of group A decreased by 45.05％ compared with group B.Conclusion For patients with low BMI (≤22 kg/m2),a 70 kVp tube current abdominal CTA scanning can significantly increase the contrast of images of abdominal artery and its branches.Meanwhile,the radiation dose and overall iodine intake can obviously decrease.
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Objective To explore the impact of pre-setted generation adaptive statistical iterative reconstruction Veo (ASiR-V) on chest CT radiation dose and image quality.Methods The chest model and 120 patients (divided into 6 groups,each n=20) were scanned by GE Revolution CT under the condition of pre-setted ASiR-V weights for 0,20％,40％,60％,80％ and 100％ respectively.The tube voltage was 120 kV,the tube current was automated mAs (Smart mA10-500) technology,the noise index was 11.The dose-length product of each chest model group and patients group were record,the effective dose (ED) of each group was calculated and compared.The image quality among groups through combining the objective CT and standard deviation (SD) values of different organizations (lung tissue,the soft tissue near by spine,the aorta and vertebral body) in chest model and the image subjective rating of patients were compared,and the subjective score of patients' images was also compared among groups.Results With the increase of pre-setted ASiR-V,the ED of chest model and patients reduced as a logarithmic fitting,there are no obvious changes of the CT value and image noise SD value of different organizations in model.The subjective score of mediastinal and pulmonary window was begin to decline at 40％ weighted ASiR-V.The subjective score of mediastinal and pulmonary window descend obviously at 60％ weighted ASiR-V compare to 40％ (P＜0.05).ED of pre-setted 40％ weighted ASiR-V reduced to 57.21％ compared to that of 0 weighted ASiR-V.Conclusion The pre-setted ASiR-V can reduce the radiation dose,and does not affect the objective image quality at the same time.The pre-setted 40 ％ weighted ASiR-V has the highest clinical application value due to the radiation dose can be obviously reduced with ensuring the image quality,which can meet the demand of diagnosis.
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Objective To investigate the value of automatic spectral imaging mode selection and adaptive statistical iterative reconstruction(ASIR) in upper abdominal enhanced CT with low contrast agent dose, and to optimize the combination of monochromatic energy level and ASIR percentage.Methods 100 patients underwent upper abdominal enhancement CT were randomly assigned into control group (n=50) and study group (n=50).In the control group, tube voltage of 120 kVp and contrast medium of 450 mg I/kg were used with the images reconstructed using 40% ASIR.In the study group, CT spectral imaging with automatic spectral imaging mode selection and contrast medium of 300 mg I/kg were used,and monochromatic images (40-65 keV,intervals of 5 keV) were reconstructed using 40%-60% ASIR (intervals of 10%), respectively.CT value, image noise and contrast-to-noise ratio of the liver, pancreas, aorta and portal vein and radiation dose were compared using two independent samples t test.Overall image quality was assessed by Mann-Whitney U test.Results All image quality indexes in 60 keV with 40% ASIR, 55-60 keV with 50% ASIR in the study group were equal to or better than the control group.There was no significant difference in radiation dose between control group and study group.Conclusion Combined automatic spectral imaging mode selection with ASIR, upper abdominal enhanced CT with low contrast agent dose could improve image quality compared to 120 kVp with 40% ASIR, without increasing radiation dose.
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OBJECTIVE: To evaluate the impact of iterative reconstruction (IR) on the assessment of diffuse interstitial lung disease (DILD) using CT. MATERIALS AND METHODS: An American College of Radiology (ACR) phantom (module 4 to assess spatial resolution) was scanned with 10–100 effective mAs at 120 kVp. The images were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), with blending ratios of 0%, 30%, 70% and 100%, and model-based iterative reconstruction (MBIR), and their spatial resolution was objectively assessed by the line pair structure method. The patient study was based on retrospective interpretation of prospectively acquired data, and it was approved by the institutional review board. Chest CT scans of 23 patients (mean age 64 years) were performed at 120 kVp using 1) standard dose protocol applying 142–275 mA with dose modulation (high-resolution computed tomography [HRCT]) and 2) low-dose protocol applying 20 mA (low dose CT, LDCT). HRCT images were reconstructed with FBP, and LDCT images were reconstructed using FBP, ASIR, and MBIR. Matching images were randomized and independently reviewed by chest radiologists. Subjective assessment of disease presence and radiological diagnosis was made on a 10-point scale. In addition, semi-quantitative results were compared for the extent of abnormalities estimated to the nearest 5% of parenchymal involvement. RESULTS: In the phantom study, ASIR was comparable to FBP in terms of spatial resolution. However, for MBIR, the spatial resolution was greatly decreased under 10 mA. In the patient study, the detection of the presence of disease was not significantly different. The values for area under the curve for detection of DILD by HRCT, FBP, ASIR, and MBIR were as follows: 0.978, 0.979, 0.972, and 0.963. LDCT images reconstructed with FBP, ASIR, and MBIR tended to underestimate reticular or honeycombing opacities (-2.8%, -4.1%, and -5.3%, respectively) and overestimate ground glass opacities (+4.6%, +8.9%, and +8.5%, respectively) compared to the HRCT images. However, the reconstruction methods did not differ with respect to radiologic diagnosis. CONCLUSION: The diagnostic performance of LDCT with MBIR was similar to that of HRCT in typical DILD cases. However, caution should be exercised when comparing disease extent, especially in follow-up studies with IR.
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Humans , Diagnosis , Ethics Committees, Research , Follow-Up Studies , Glass , Lung Diseases, Interstitial , Methods , Prospective Studies , Retrospective Studies , Thorax , Tomography, X-Ray ComputedABSTRACT
Objective To discuss the influence to gemstone spectral imagine of low-mA combined with ASIR on simulation phan-tom.Methods 20 simulation phantom-scannings were obtained with GSI-48(260 mA)and 50%ASIR,GSI viewer was used to obtain the optimal CNR monochromatic images,which was as the experimental group;Another 20 simulation phantom-scannings were ob-tained with 120 kVp,3D-auto-mA(NI=10),FBP,which was as the control group.The SD,CNR,SNR,FOM,CTDIVOL and imagine quality score of the control group were compared with that of the experimental group.Results The SD,CNR,SNR,FOM,CTDIVOL and imagine quality score were (5.64±0.49),(14.58 ±1.14),(13.87 ±1.1 9),(29.89 ±5.35),(6.48 ±0),(4.1 1 ±0.59)for the experimental group and (12.62±1.41),(6.70±0.65),(6.87±0.66),(6.62 ±1.32),(6.85 ±0.07),(3.74±0.59)for the control group respectively (P <0.05).Conclusion Gemstone spectral imagine of low-mA combined with ASIR can improve image quality at lower radiation dose.
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Objective To investigate the value of the adaptive statistical iterative reconstruction (ASIR) algorithm for reducing the radiation dose and optimizing the image quality in the low-dose spectral CT scanning in GSl (Gemstone spectral imaging) of the liver.Methods A total of 60 patients who underwent hepatic spectral CT scanning in GSI were enrolled in this study.The patients were randomly divided into two groups according to priority with 30 cases per group.Low-dose spectral CT scanning was used for group A, and images were reconstructed by ASIR 0 and 50％ , marked as A1 and A2.Group B was scanned with conventional dose of spectral CT, and images were reconstructed by Filtered back projection (FBP).Effective doses (E) for each group were calculated.Image quality was assessed by two radiologists, and the radiation doses were compared between groups A and B.Results All image quality of each group were good enough for clinical diagnosis.E for group A and B were (3.2 ±0.2) and (5.8 ± 0.2) mSv, respectively.There was statistical difference with image noise between group A and B(Z =-6.784,P ＜ 0.05).The image noise, SNR and CNR had statistical differences between group A and B (F =24.013, 15.646, 8.285, P ＜0.05).Compared with group A1, the image noise was lower, and the SNR and CNR were higher in groups A2 and B(P ＜ 0.05).There were no statistical differences of image noise, SNR and CNR between groups A2 and B (P ＞ 0.05).There were no statistical differences of the image quality score between groups A1, A2 and B (F =102.38,105.768, P ＜ 0.05).Conclusions ASIR combined with low-dose spectral CT scanning was helpful to reduce radiation dose and could obtain better image quality in hepatic CT examination.
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OBJECTIVE: To evaluate image quality of female pelvic computed tomography (CT) scans reconstructed with the adaptive statistical iterative reconstruction (ASIR) technique combined with low tube-voltage and to explore the feasibility of its clinical application. MATERIALS AND METHODS: Ninety-four patients were divided into two groups. The study group used 100 kVp, and images were reconstructed with 30%, 50%, 70%, and 90% ASIR. The control group used 120 kVp, and images were reconstructed with 30% ASIR. The noise index was 15 for the study group and 11 for the control group. The CT values and noise levels of different tissues were measured. The contrast to noise ratio (CNR) was calculated. A subjective evaluation was carried out by two experienced radiologists. The CT dose index volume (CTDIvol) was recorded. RESULTS: A 44.7% reduction in CTDIvol was observed in the study group (8.18 +/- 3.58 mGy) compared with that in the control group (14.78 +/- 6.15 mGy). No significant differences were observed in the tissue noise levels and CNR values between the 70% ASIR group and the control group (p = 0.068-1.000). The subjective scores indicated that visibility of small structures, diagnostic confidence, and the overall image quality score in the 70% ASIR group was the best, and were similar to those in the control group (1.87 vs. 1.79, 1.26 vs. 1.28, and 4.53 vs. 4.57; p = 0.122-0.585). No significant difference in diagnostic accuracy was detected between the study group and the control group (42/47 vs. 43/47, p = 1.000). CONCLUSION: Low tube-voltage combined with automatic tube current modulation and 70% ASIR allowed the low CT radiation dose to be reduced by 44.7% without losing image quality on female pelvic scan.
Subject(s)
Adult , Aged , Female , Humans , Middle Aged , Body Mass Index , Feasibility Studies , Genital Diseases, Female/diagnosis , Pelvis/diagnostic imaging , Radiation Dosage , Radiographic Image Interpretation, Computer-Assisted , Signal-To-Noise Ratio , Tomography, X-Ray ComputedABSTRACT
OBJECTIVE: To assess the performance of adaptive statistical iterative reconstruction (ASIR)-applied ultra-low-dose CT (ULDCT) in detecting small lung nodules. MATERIALS AND METHODS: Thirty patients underwent both ULDCT and standard dose CT (SCT). After determining the reference standard nodules, five observers, blinded to the reference standard reading results, independently evaluated SCT and both subsets of ASIR- and filtered back projection (FBP)-driven ULDCT images. Data assessed by observers were compared statistically. RESULTS: Converted effective doses in SCT and ULDCT were 2.81 +/- 0.92 and 0.17 +/- 0.02 mSv, respectively. A total of 114 lung nodules were detected on SCT as a standard reference. There was no statistically significant difference in sensitivity between ASIR-driven ULDCT and SCT for three out of the five observers (p = 0.678, 0.735, < 0.01, 0.038, and < 0.868 for observers 1, 2, 3, 4, and 5, respectively). The sensitivity of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT in three out of the five observers (p < 0.01 for three observers, and p = 0.064 and 0.146 for two observers). In jackknife alternative free-response receiver operating characteristic analysis, the mean values of figure-of-merit (FOM) for FBP, ASIR-driven ULDCT, and SCT were 0.682, 0.772, and 0.821, respectively, and there were no significant differences in FOM values between ASIR-driven ULDCT and SCT (p = 0.11), but the FOM value of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT and SCT (p = 0.01 and 0.00). CONCLUSION: Adaptive statistical iterative reconstruction-driven ULDCT delivering a radiation dose of only 0.17 mSv offers acceptable sensitivity in nodule detection compared with SCT and has better performance than FBP-driven ULDCT.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Lung/pathology , Lung Neoplasms/diagnostic imaging , ROC Curve , Radiation Dosage , Radiographic Image Enhancement , Radiographic Image Interpretation, Computer-Assisted , Rectal Neoplasms/pathology , Retrospective Studies , Tomography, X-Ray ComputedABSTRACT
Objective To investigate the best weighting of adaptive statistical iterative reconstruction (ASIR) algorithm and optimized low-dose scanning parameters in thoracic aorta CT angiography(CTA).Methods Totally 120 patients with the body mass index (BMI) of 19-24 were randomly divided into 6 groups.All patients underwent thoracic aorta CTA with a GE Discovery CT 750 HD scanner (ranging from 290-330 mm).The default parameters (100 kV,240 mAs) were applied in Group 1.Reconstructions were performed with different weightings of ASIR (10％-100％ with 10％),and the signal to noise ratio (S/N) and contrast to noise ratio (C/N) of images were calculated.The images of series were evaluated by 2 independent radiologists with 5-point-scale and lastly the best weighting were revealed.Then the mAs in Group 2-6 were defined as 210,180,150,120 and 90 with the kilovoltage 100.The CTDIvoland DLP in every scan series were recorded and the effective dose (E) was calculated.The S/N and C/N were calculated and the image quality was assessed by two radiologists.Results The best weighing of ASIR was 60％ at the 100 kV,240 mAs.Under 60％ of ASIR and 100 kV,the scores of image quality from 240 mAs to 90 mAs were(4.78 ±0.30)-(3.15 ±0.23).The CTDIvol and DLP were 12.64-4.41 mGy and 331.81-128.27 mGy,and the E was 4.98-1.92 mSv.The image qualities among Group 1-5 were nor significantly different (F =5.365,P ＞ 0.05),but the CTDIvol and DLP of Group 5 were reduced by 37.0％ and 36.9％,respectively compared with Group 1.Conclusions In thoracic aorta CT Angiography,the best weighting of ASIR is 60％,and 120 mAs is the best mAs with 100 kV in patients with BMI 19-24.