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
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 p...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
目的探讨双高权重自适应统计迭代重建(ASIR-V)冠状动脉CT血管成像(CCTA)联合人工智能(AI)评估冠心病(CHD)的临床价值。方法前瞻性将124例行CCTA的疑似冠心病(CHD)患者以常规CCTA参数,噪声指数(NI)11,前、后置ASIR-V 50%为对照组,以高权...目的探讨双高权重自适应统计迭代重建(ASIR-V)冠状动脉CT血管成像(CCTA)联合人工智能(AI)评估冠心病(CHD)的临床价值。方法前瞻性将124例行CCTA的疑似冠心病(CHD)患者以常规CCTA参数,噪声指数(NI)11,前、后置ASIR-V 50%为对照组,以高权重后置ASIR-V 90%,前置ASIR-V分别为60%、70%、80%作为实验组。对图像质量进行5分法主观评分,计算信噪比(SNR)、对比噪声比(CNR)、有效剂量(ED),对比各组图像间的主观评分、噪声(SD)、SNR、CNR、ED。优化出图像质量高而ED低的组别进行AI分析,以冠状动脉造影(CAG)结果为金标准,血管狭窄程度≥50%记为阳性,绘制受试者工作特征(ROC)曲线,评估AI的诊断效能。结果对照组与前置ASIR-V 80%组的主观评分(4.61±0.50 vs 4.26±0.58)、SD(36.15±6.82 vs 42.08±7.98)、AR SNR(13.56±3.51 vs 11.26(8.67,13.02))、AR CNR(11.50±3.14 vs 9.52±2.70)、RCA SNR(12.82±3.29 vs 10.40(8.18,12.06))、RCA CNR(10.76±2.93 vs 8.75±2.59)、LCX SNR(12.45±3.26 vs 10.35±2.56)组间差异有统计学意义(P均<0.05),对照组的SD低于前置ASIR-V 80%组,其余参数值高于前置ASIR-V 80%组。优化组为前置ASIR-V 70%组,其AI分析结果对诊断血管狭窄程度≥50%的AUC为0.911,敏感度为0.935,特异度为0.888,阳性预测值为0.811,阴性预测值为0.963,准确率为0.904。结论后置ASIR-V 90%,前置ASIR-V 70%的CCTA参数能够保证图像质量的同时降低辐射剂量,其AI分析结果对诊断CHD有高诊断价值。展开更多
目的探讨低剂量CT结合自适应统计迭代重建技术在泌尿系结石诊断中的价值。方法使用自动管电流调节技术,对临床怀疑泌尿系结石的41例患者同时进行常规剂量及低剂量CT扫描,其中常规组噪声指数(NI)设定为13,低剂量组NI设定为25,运用滤过...目的探讨低剂量CT结合自适应统计迭代重建技术在泌尿系结石诊断中的价值。方法使用自动管电流调节技术,对临床怀疑泌尿系结石的41例患者同时进行常规剂量及低剂量CT扫描,其中常规组噪声指数(NI)设定为13,低剂量组NI设定为25,运用滤过反投影技术(FBP)及自适应统计迭代重建技术(ASIR)对图像进行1.25 mm层厚重建,由两名放射科医师分别对结石(大小、位置、数目)、图像质量(1-5分)、图像噪声(1-3分)及诊断可信度(1-3分)等几个方面进行评估,记录两组扫描的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)并计算有效剂量(ED)。采用Wilcoxon符号秩和检验及配对t检验进行统计学分析。结果低剂量组的平均ED为1.76 m Sv,常规组的平均ED为5.98 m Sv(P〈0.05)。低剂量组使用80%ASIR法处理的图像质量明显高于FBP法处理的图像质量(P〈0.05),而与常规组FBP法处理的图像质量大致相仿,差异无统计学意义(P〉0.05)。结论结合使用自动管电流调节技术及ASIR,可在保证图像质量的前提下,明显降低CT扫描辐射剂量,具有较好的临床可行性。展开更多
摘要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.
摘要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.
摘要目的探讨双高权重自适应统计迭代重建(ASIR-V)冠状动脉CT血管成像(CCTA)联合人工智能(AI)评估冠心病(CHD)的临床价值。方法前瞻性将124例行CCTA的疑似冠心病(CHD)患者以常规CCTA参数,噪声指数(NI)11,前、后置ASIR-V 50%为对照组,以高权重后置ASIR-V 90%,前置ASIR-V分别为60%、70%、80%作为实验组。对图像质量进行5分法主观评分,计算信噪比(SNR)、对比噪声比(CNR)、有效剂量(ED),对比各组图像间的主观评分、噪声(SD)、SNR、CNR、ED。优化出图像质量高而ED低的组别进行AI分析,以冠状动脉造影(CAG)结果为金标准,血管狭窄程度≥50%记为阳性,绘制受试者工作特征(ROC)曲线,评估AI的诊断效能。结果对照组与前置ASIR-V 80%组的主观评分(4.61±0.50 vs 4.26±0.58)、SD(36.15±6.82 vs 42.08±7.98)、AR SNR(13.56±3.51 vs 11.26(8.67,13.02))、AR CNR(11.50±3.14 vs 9.52±2.70)、RCA SNR(12.82±3.29 vs 10.40(8.18,12.06))、RCA CNR(10.76±2.93 vs 8.75±2.59)、LCX SNR(12.45±3.26 vs 10.35±2.56)组间差异有统计学意义(P均<0.05),对照组的SD低于前置ASIR-V 80%组,其余参数值高于前置ASIR-V 80%组。优化组为前置ASIR-V 70%组,其AI分析结果对诊断血管狭窄程度≥50%的AUC为0.911,敏感度为0.935,特异度为0.888,阳性预测值为0.811,阴性预测值为0.963,准确率为0.904。结论后置ASIR-V 90%,前置ASIR-V 70%的CCTA参数能够保证图像质量的同时降低辐射剂量,其AI分析结果对诊断CHD有高诊断价值。
摘要目的探讨低剂量CT结合自适应统计迭代重建技术在泌尿系结石诊断中的价值。方法使用自动管电流调节技术,对临床怀疑泌尿系结石的41例患者同时进行常规剂量及低剂量CT扫描,其中常规组噪声指数(NI)设定为13,低剂量组NI设定为25,运用滤过反投影技术(FBP)及自适应统计迭代重建技术(ASIR)对图像进行1.25 mm层厚重建,由两名放射科医师分别对结石(大小、位置、数目)、图像质量(1-5分)、图像噪声(1-3分)及诊断可信度(1-3分)等几个方面进行评估,记录两组扫描的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)并计算有效剂量(ED)。采用Wilcoxon符号秩和检验及配对t检验进行统计学分析。结果低剂量组的平均ED为1.76 m Sv,常规组的平均ED为5.98 m Sv(P〈0.05)。低剂量组使用80%ASIR法处理的图像质量明显高于FBP法处理的图像质量(P〈0.05),而与常规组FBP法处理的图像质量大致相仿,差异无统计学意义(P〉0.05)。结论结合使用自动管电流调节技术及ASIR,可在保证图像质量的前提下,明显降低CT扫描辐射剂量,具有较好的临床可行性。