Objective To evaluate the feasibility of using a low concentration of contrast medium （Visipaque 270 mgl/mL）, low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography ang...Objective To evaluate the feasibility of using a low concentration of contrast medium （Visipaque 270 mgl/mL）, low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography angiography （CTA）. Methods Forty patients （22 men and 18 women; average age 48.7 ± 14.25 years; average body mass index 23.9 ± 3.7 kg/m^2） undergoing CTA for suspected vascular diseases were randomly assigned into two groups. Group A （n = 20） was administered 370 mgl/mL contrast medium, and group B （n = 20） was administered 270 mgl/mL contrast medium. Both groups were administered at a rate of 4.8 mL/s and an injection volume of 0.8 mL/kg. Images of group A were obtained with 120 kVp and filtered back projection （FBP） reconstruction, whereas images of group B were obtained with 80 kVp and 80% adaptive iterative statistical reconstruction algorithm （ASiR）. The CT values and standard deviations of intracranial arteries and image noise on the corona radiata were measured to calculate the contrast-to-noise ratio （CNR） and signal-to-noise ratio （SNR）. The beam-hardening artifacts （BHAs） around the skull base were calculated. Two readers evaluated the image quality with volume rendered images using scores from 1 to 5. The values between the two groups were statistically compared. Results The mean CT value of the intracranial arteries in group B was significantly higher than that in group A （P 〈 0.001）. The CNR and SNR values in group B were also statistically higher than those in group A （P 〈 0.001）. Image noise and BHAs were not significantly different between the two groups. The image quality score of VR images of in group B was significantly higher than that in group A （P = 0.001）. However, the quality scores of axial enhancement images in group B became significantly smaller than those in group A （P〈 0.001）. The CT dose index volume and dose-length product were decreased by 63.8% and 64%, respectively, in group B （P 〈 0.001 for both）. Conclusion Visipaque combined with 80 kVp and 80% ASiR provided similar image quality in intracranial CTA with 64% radiation dose reduction compared with the use of lopamidol, 120 kVp, and FBP reconstruc-tion.展开更多
目的 探讨能谱CT单能量成像技术联合自适应迭代重建算法在早期胃癌诊断中的价值。方法前瞻性收集河南科技大学第一附属医院经胃镜诊断为胃癌患者25例。采用Revolution CT对患者行能谱扫描,将所有扫描结果行FBP、40-100ke V 7组单能量重...目的 探讨能谱CT单能量成像技术联合自适应迭代重建算法在早期胃癌诊断中的价值。方法前瞻性收集河南科技大学第一附属医院经胃镜诊断为胃癌患者25例。采用Revolution CT对患者行能谱扫描,将所有扫描结果行FBP、40-100ke V 7组单能量重建,测量动、静脉期各患者肿瘤病灶的对比噪声比(CNR),信噪比(SNR),按照评分标准进行图像质量主观评分;选出图像质量组分别与10%-100%ASIR联合进行重建,测量动、静脉相同部位肿瘤病灶的对比噪声比(CNR),信噪比(SNR),按照评分标准进行图像质量主观评分。结果 70ke V联合50%ASIR组图像CNR、SNR及主观评分高于其他组,差异有统计学意义。结论 使用70 ke V单能量联合50%ASIR重建可以得到质量优异的CT图像,可为临床诊断提供有效的信息。展开更多
目的探讨适应性统计迭代算法(ASIR)结合自动管电流调制技术在降低泌尿系CT扫描剂量中的应用价值。方法对2014年9月至2015年3月安徽医科大学第一附属医院25例拟行泌尿系CT平扫患者,设定管电压120 k V,使用自动毫安调制技术,管电流范围10~...目的探讨适应性统计迭代算法(ASIR)结合自动管电流调制技术在降低泌尿系CT扫描剂量中的应用价值。方法对2014年9月至2015年3月安徽医科大学第一附属医院25例拟行泌尿系CT平扫患者,设定管电压120 k V,使用自动毫安调制技术,管电流范围10~400 m A,螺距1.375∶1,球管转速0.5 r/s,先后行常规组及低剂量组扫描,预设常规组噪声指数(NI)为13,低剂量组NI为25。常规组及低剂量组同时使用1.25 mm层厚重建(定义常规组1.25 mm层厚为A组,低剂量组1.25 mm层厚为B组)并分别应用5种不同权重ASIR水平(0、20%、40%、60%、80%)进行图像重建,获得A1~A5、B1~B5共计10组图像,分别测量10个组图像在肝右叶、L1椎弓根水平腹主动脉噪声值及同层面肾门区肾实质CT值(HU),并计算信噪比(SNR)。记录两组扫描患者接受的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)和有效剂量(ED)。并由2名具有5年以上腹部诊断经验的医师采用盲法对图像质量进行评估(5分制),采用Wilcoxon符号秩和检验及配对t检验进行统计学分析。结果常规组CTDIvol为(8.44±1.97)m Gy,ED为(6.13±1.55)m Sv;低剂量组CTDIvol为(2.46±0.70)m Gy,ED为(1.79±0.54)m Sv,两组差异有统计学意义(P<0.05),两组比较平均辐射剂量降低约70%。两组图像质量主观评分≥3分均能满足临床诊断要求。随着ASIR权重系数的增加,图像噪声值逐渐下降,SNR逐渐提高。结论使用ASIR算法结合自动管电流调制技术进行泌尿系低剂量CT扫描,可以在获得满足临床诊断需要的图像质量同时,大幅度降低患者受检的辐射剂量,具有较好的临床可行性。展开更多
Background Currently there is a trend towards reducing radiation dose while maintaining image quality during computer tomography （CT） examination.This results from the concerns about radiation exposure from CT and t...Background Currently there is a trend towards reducing radiation dose while maintaining image quality during computer tomography （CT） examination.This results from the concerns about radiation exposure from CT and the potential increase in the incidence of radiation induced carcinogenesis.This study aimed to investigate the lowest radiation dose for maintaining good image quality in adult chest scanning using GE CT equipment.Methods Seventy-two adult patients were examined by Gemstone Spectral CT.They were randomly divided into six groups.We set up a different value of noise index （NI） when evaluating each group every other number from 13.0 to 23.0.The original images were acquired with a slice of 5 mm thickness.For each group,several image series were reconstructed using different levels of adaptive statistical iterative reconstruction （ASIR） （30％,50％,and 70％）.We got a total of 18 image sequences of different combinations of NI and ASIR percentage.On one hand,quantitative indicators,such as CT value and standard deviation （SD）,were assessed at the region of interest.The signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） were calculated.The volume CT dose index （CTDI） and dose length product （DLP） were recorded.On the other hand,two radiologists with ＞5 years of experience blindly reviewed the subjective image quality using the standards we had previously set.Results The different combinations of noise index and ASIR were assessed.There was no significant difference in CT values among the 18 image sequences.The SD value was reduced with the noise index＇s reduction or ASIR＇s increase.There was a trend towards gradually lower SNR and CNR with an NI increase.The CTDI and DLP were diminishing as the NI increased.The scores from subjective image quality evaluation were reduced in all groups as the ASIR increased.Conclusions Increasing NI can reduce radiation dose.With the premise of maintaining the same image quality,using a suitable percentage of ASIR can increase the value of NI.To assure image quality,we concluded that when the NI was set at 17.0 and ASlR was 50％,the image quality could be optimal for not only satisfying the requirements of clinical diagnosis,but also achieving the purpose of low-dose scanning.展开更多
文摘Objective To evaluate the feasibility of using a low concentration of contrast medium （Visipaque 270 mgl/mL）, low tube voltage, and an advanced image reconstruction algorithm in head and neck computed tomography angiography （CTA）. Methods Forty patients （22 men and 18 women; average age 48.7 ± 14.25 years; average body mass index 23.9 ± 3.7 kg/m^2） undergoing CTA for suspected vascular diseases were randomly assigned into two groups. Group A （n = 20） was administered 370 mgl/mL contrast medium, and group B （n = 20） was administered 270 mgl/mL contrast medium. Both groups were administered at a rate of 4.8 mL/s and an injection volume of 0.8 mL/kg. Images of group A were obtained with 120 kVp and filtered back projection （FBP） reconstruction, whereas images of group B were obtained with 80 kVp and 80% adaptive iterative statistical reconstruction algorithm （ASiR）. The CT values and standard deviations of intracranial arteries and image noise on the corona radiata were measured to calculate the contrast-to-noise ratio （CNR） and signal-to-noise ratio （SNR）. The beam-hardening artifacts （BHAs） around the skull base were calculated. Two readers evaluated the image quality with volume rendered images using scores from 1 to 5. The values between the two groups were statistically compared. Results The mean CT value of the intracranial arteries in group B was significantly higher than that in group A （P 〈 0.001）. The CNR and SNR values in group B were also statistically higher than those in group A （P 〈 0.001）. Image noise and BHAs were not significantly different between the two groups. The image quality score of VR images of in group B was significantly higher than that in group A （P = 0.001）. However, the quality scores of axial enhancement images in group B became significantly smaller than those in group A （P〈 0.001）. The CT dose index volume and dose-length product were decreased by 63.8% and 64%, respectively, in group B （P 〈 0.001 for both）. Conclusion Visipaque combined with 80 kVp and 80% ASiR provided similar image quality in intracranial CTA with 64% radiation dose reduction compared with the use of lopamidol, 120 kVp, and FBP reconstruc-tion.
文摘目的 探讨能谱CT单能量成像技术联合自适应迭代重建算法在早期胃癌诊断中的价值。方法前瞻性收集河南科技大学第一附属医院经胃镜诊断为胃癌患者25例。采用Revolution CT对患者行能谱扫描,将所有扫描结果行FBP、40-100ke V 7组单能量重建,测量动、静脉期各患者肿瘤病灶的对比噪声比(CNR),信噪比(SNR),按照评分标准进行图像质量主观评分;选出图像质量组分别与10%-100%ASIR联合进行重建,测量动、静脉相同部位肿瘤病灶的对比噪声比(CNR),信噪比(SNR),按照评分标准进行图像质量主观评分。结果 70ke V联合50%ASIR组图像CNR、SNR及主观评分高于其他组,差异有统计学意义。结论 使用70 ke V单能量联合50%ASIR重建可以得到质量优异的CT图像,可为临床诊断提供有效的信息。
文摘目的研究自动管电流调制扫描及50%权重自适应性统计迭代重建算法（adaptive statistical iterative reconstruction,ASIR）重建时,不同噪声指数（noise index,NI）的设定对胸部CT扫描图像质量的影响,探索合适的NI以降低辐射剂量。方法前瞻性地连续纳入193例行胸部CT扫描的患者,随机分为6组,各组NI预设为15、18、21、24、27、30,并进一步根据患者的体质量指数（Body Mass Index,BMI）分为三个亚组：偏瘦及正常组（BMI≤23.9）、超重组（24≤BMI≤27.9）、肥胖组（BMI≥28）。所有患者均采用自动管电流调制技术扫描,50%权重的ASIR重建。由2位放射科医师采用盲法分别对图像质量进行主观评分（〈13分,良好;13~15分,临界;〉15分,不能接受）,测量肺重建及纵隔重建图像的噪声（脂肪）、信噪比（大血管-脂肪）、对比噪声比（大血管-脂肪）。记录各患者CT容积剂量指数（CT does index volume,CTDIvol）、剂量长度乘积（dose length product,DLP）、有效剂量（effective dose,ED）。另外记录每位患者纵隔重建图像管电流小于50m A的层面占所有层面的百分比。结果随着NI的升高,图像主观评分增高（质量下降）,信噪比及对比噪声比降低。各NI预设条件下胸部CT图像主观评分均≤15分,仅NI=30时,4例（4/34）患者图像主观评分为13~15分。NI=30时图像主观评分显著高于、信噪比低于NI为15~27图像（P〈0.05）。NI为24~30的辐射剂量显著低于NI为15~21（P〈0.05）。NI为27及30时,随着BMI增加,出现电流低于50m A层面百分比降低（P〈0.05）。在NI为30时,随着BMI增加,辐射剂量显著增加（P〈0.05）。结论自动管电流调制扫描及50%ASIR重建下,胸部CT扫描可以预设NI为30,在大幅降低辐射剂量的同时,图像质量也能满足诊断要求。
文摘Background Currently there is a trend towards reducing radiation dose while maintaining image quality during computer tomography （CT） examination.This results from the concerns about radiation exposure from CT and the potential increase in the incidence of radiation induced carcinogenesis.This study aimed to investigate the lowest radiation dose for maintaining good image quality in adult chest scanning using GE CT equipment.Methods Seventy-two adult patients were examined by Gemstone Spectral CT.They were randomly divided into six groups.We set up a different value of noise index （NI） when evaluating each group every other number from 13.0 to 23.0.The original images were acquired with a slice of 5 mm thickness.For each group,several image series were reconstructed using different levels of adaptive statistical iterative reconstruction （ASIR） （30％,50％,and 70％）.We got a total of 18 image sequences of different combinations of NI and ASIR percentage.On one hand,quantitative indicators,such as CT value and standard deviation （SD）,were assessed at the region of interest.The signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） were calculated.The volume CT dose index （CTDI） and dose length product （DLP） were recorded.On the other hand,two radiologists with ＞5 years of experience blindly reviewed the subjective image quality using the standards we had previously set.Results The different combinations of noise index and ASIR were assessed.There was no significant difference in CT values among the 18 image sequences.The SD value was reduced with the noise index＇s reduction or ASIR＇s increase.There was a trend towards gradually lower SNR and CNR with an NI increase.The CTDI and DLP were diminishing as the NI increased.The scores from subjective image quality evaluation were reduced in all groups as the ASIR increased.Conclusions Increasing NI can reduce radiation dose.With the premise of maintaining the same image quality,using a suitable percentage of ASIR can increase the value of NI.To assure image quality,we concluded that when the NI was set at 17.0 and ASlR was 50％,the image quality could be optimal for not only satisfying the requirements of clinical diagnosis,but also achieving the purpose of low-dose scanning.
