Prostate magnetic resonance imaging at 3 Tesla: Is administration of hyoscine-N-butyl-bromide mandatory?

AIM: To evaluate the value of administration of hyoscine-N-butyl-bromide (HBB) for image quality magnetic resonance imaging (MRI) of the prostate. METHODS: Seventy patients were retrospectively included in the study. Thirty-five patients were examined with administration of 40 milligrams of HBB (Buscopan ; Boehringer, Ingelheim, Germany); 35 patients were examined without HBB. A multiparametric MRI protocol was performed on a 3.0 Tesla scanner without using an endorectal coil. The following criteria were evaluated independently by two experienced radiologists on a five-point Likert scale: anatomical details (delineation between peripheral and transitional zone of the prostate, visualisation of the capsule, depiction of the neurovascular bundles); visualisation of lymph nodes; motion related artefacts; and overall image quality.RESULTS: Comparison of anatomical details between the two cohorts showed no statistically significant difference (3.9 ± 0.7 vs 4.0 ± 0.9, P = 0.54, and 3.8 ± 0.7 vs 4.2 ± 0.6, P = 0.07) for both readers. There was no significant advantage regarding depiction of local and iliac lymph nodes (3.9 ± 0.6 vs 4.2 ± 0.6, P = 0.07, and 3.8 ± 0.9 vs 4.1 ± 0.8, P = 0.19). Motion arte- facts were rated as "none" to "few" in both groups and showed no statistical difference (2.3 ± 1.0 vs 1.9 ± 0.9, P = 0.19, and 2.3 ± 1.1 vs 1.9 ± 0.7, P = 0.22). Overall image quality was rated "good" in average for both cohorts without significant difference (4.0 ± 0.6 vs 4.0 ± 0.9, P = 0.78, and 3.8 ± 0.8 vs 4.2 ± 0.6, P = 0.09). CONCLUSION: The results demonstrated no significant effect of HBB administration on image quality. The study suggests that use of HBB is not mandatory for MRI of the prostate at 3.0 Tesla.     

低剂量64层螺旋CT测定冠状动脉钙化积分的准确性评价

Objective To compare the low- and standard-dose protocols in the evaluation of coronary artery calcification (CAC) scores and in image quality,and to assess the accuracy of low-dose prospective ECG-gated helical CT in CAC measurements.Methods Forty-three patients with CAC were scanned twice using a tube current setting of 100 and 55 mA retrospectively.CAC scores (Agatston) of different branches of coronary artery were recorded.The mean and SD of the CT attenuation values in regions of interest in the aorta were measured,and the value (mean + 2 × SD) were obtained.Results Calcification plaques were found in 105 of the 172 vessels in the 43 subjects.The radiation dose of the 50 mAs group was (0.72 ± 0.04) mSy,significantly lower by 0.6 mSv than that of the 100 mAs group [(1.32 ± 0.08) mSv,P ＜ 0.05].The total calcification score of the 55 mAs group was significantly positively correlated with the routine dose group after performing the square root transformation (r =0.998).A signficant correlation existed in vessel-based calcification between these 2 groups (r= 0.997).Conclusions Low-dose prospective ECG-gated 64-slice CT yields high accuracy on CAC scoring while maintaining the image quality needed to measure CAC.     

足踝部肌腱的多层CT低剂量三维成像研究

目的 探讨足踝部肌腱的低剂量CT扫描三维成像的可行性和合理性.方法 搜集足踝部骨折的连续病例45例,依序分3组:A组(80 kV、100 mAs)、B组(110 kV、60 mAs)、C组(常规组,130 kV、60 mAs),每组各15例,双侧踝部行6层CT扫描,采集模式1.0 mm ×6.分别测量足底部拇展肌CT值及噪声标准差(SD),记录容积CT剂量指数(CTDIvol)值,盲法评价各病例肌腱VR图像质量.对所获数据进行独立样本的单因素方差分析(ANOVA)方法检验或独立样本非参数检验(Kruskal-Wallis H).结果 A组肌肉平均CT值[(71.6±12.0)HU]明显高于B组[(66.8±9.2)HU,P=0.010]和C组[(66.1±7.1)HU,P=0.004];SD值分别为11.9、9.1、7.0 HU,差异有统计学意义(F=37.124,P=0.000),以A组最大,C组最小;CTDIvol平均值分别为(3.01±0.08)、(4.63±0.11)、(7.02±0.24)mGy,差异有统计学意义(H=39.185,P=0.000),A组最小,C组最大;肌腱VR图像评分分别为(2.3±0.5)、(3.7±0.5)、(4.8±0.4)分,差异有统计学意义(H=72.779,P=0.000),图像质量以A组最差,C组最佳,B组图像质量达到诊断标准以上.结论 6层CT的110 kV与60 mAs组合、1 mm准直足踝部肌腱CT成像有良好图像质量而满足诊断需要.

Abstract：

Objective To study the feasibility and reasonability of low-dose multi-slice CT(MSCT)with three dimensional rendering of the tendons of foot and ankle. The statistical methods including ANOVA and Kruskal-Wallis H was used. Methods Forty-five consecutive patients with fractures of foot and ankle were enrolled and evenly grouped into A (80 kV, 100 mAs), B(110 k V ,60 mAs) and C (130 kV,60 mAs).The MSCT scanning range was 6 slices of 1.0 mm. The CT value and standard deviation (SD) of the muscle and the CTDIvol were recorded. The image quality of volume rendering of the tendons was blindly evaluated.Results The CT value of muscle in group A (71.6 ± 12.0) HU was significantly higher than group B [(66.8±9.2) HU, P=0.010]and C[(66. 1 ±7. 1) HU, P =0.004]. The SD average values were 11.9, 6. 1 and 7.0 HU for three groups, and there were significant differences among the three groups(F =37. 142, P=0. 0000). Group A had the highest SD value, group C had the lowest SD;CT1DIvol average value were (3.01 ± 0. 08) , (4. 63 ± 0. 11), (7.02 ± 0. 24) mGy respectively, which were significant different among the three groups (H =39. 185, P =0. 000). Group A had the lowest CTDIvol, while group C had the highest CTDIvol. Volume rendering of the tendons was evaluated as 2.3 ± 0. 5、3.7 ± 0. 5、4. 8 ±0. 4, and there were significant differences among the three groups (H = 72. 779, P = 0. 000). Group A had the worst VR images, while group C had the best VR images. All VR images in Group B were good for diagnosis. Conclusion The protocol of 110 kV, 60 mAs, and 1 mm × 6 with three-dimensional volume rendering would be enough for evaluating the tendons of foot and ankle.     

64层螺旋CT肺动脉成像低管电压设置结合个体化对比剂应用的对照研究

Objective To investigate the feasibility of the low tube voltage setting and personalized contrast agent application in 64-row multi-slice spiral CT pulmonary angiography.Methods Ninety patients with high risk of pulmonary artery embolism were sequentially enrolled in the study and divided into 3 groups employing completely randomized design: (1) Regular group included 30 patients using 120 kV and fixed dose of 70 ml contrast agent, (2)Another 30 patients were in 120 kV group, using 120 kV and the contrast amount was determined according to the patient weight (1.0 ml/kg), (3) The remaining 30 patients were included in 100 kV group, using 100 kV and the contrast amount was also determined according to the patient weight(1.0 ml/kg).Administration of contrast agent was completed within 20 seconds for all the patients, followed by 20 ml of saline.The objective and subjective indexes for assessing CT image quality, CT dose index volume (CTDIvol) and effective received dose (ERD) were compared between 120 kV group and 100 kV group; then the contrast media volume, injection rate, objective CT image indexes and subjective indexes for image quality was compared between the 100 kV group and regular group.The variance analysis and post hoc test were employed for the statistical analysis.Results Compared with 120 kV group(3.4± 0.7), the image quality of 100 kV group(5.2±1.8)had higher noise(52.9%), but subjective index for the image quality demonstrated no differences(q=0.272 ,P=0.063)in mediastinum window while CTDIvol and ERD decreased for 34.9%[(9.5±0.0) vs (14.6±0.0) mGy]and 36.8%[(3.8±0.6) vs (2.4± 0.4) mSv].The mean CT values on pulmonary artery of 100 kV group[(269.2±54.7) HU]were 13.4% (31.8/237.4) higher than the 120 kV group[(237.4±62.9) HU], but there was no statistical differences eornpared to normal group(q=0.172,P=0.260).Conclusion Using low kV setting (100 kV) to reduce radiation dose is proved to be effective and feasible in 64-MSCT pulmonary angiography.Personalized contrast agent injection has clinical application value for specific patient group.     

64层螺旋CT冠状动脉成像定位像CT值与管电流关系的研究

Objective To characterize the association between the mean CT value on a scout view and the dependent mA selection method, and to evaluate the clinical value of a mA selection method based on scout view mean CT value in obtaining individualized scan protocol and consistent image quality for patient population on 64-row MSCT CT coronary angiography (CTCA).Methods One hundred patients (group A) underwent CCTA consecutively using standard protocol with a fixed mA.The mean CT value of a fixed ROI (region of interest) from the scout AP view and the CTCA image noise (standard deviation on the root of ascending aorta) were measured.The correlation between CT values and noise was studied establish a formula and a list to determine the required mA for obtaining a consistent CTCA image noise based on the measured SV CT value.Another 100 patients (group B) were scanned using the same parameters as group A except the mA and the CT value was also measured.The mA was determined by the list established previously.The CTCA image quality (IQ) as well as the image noise (IN) and the effective dose (ED) from the two groups were statistically analyzed using t-test.The CT findings for the 32 patients in the group B were also compared with the selective coronary angiography (SCA) results.The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of CCTA for detection of significant stenosis were obtained.Results The formula between the required mA and the CT value was : XmA=FmA×[(K1×CTscout + C1)/INa]2.The CCTA images in B group had statistically higher IN (27.66±2.57,22.22±4.17,t=11.33, P=0.000), but no statistical difference between IQ scores for the two groups (3.29±0.66,3.37±0.67,t=0.009, P=0.990), and ED[(8.72±2.51) versus (12.53±0.90) mSv]was 30% lower for the B group (P<0.01).For the 32 patients in the B group who had SCA, the CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.92% (56/59), 92.13% (82/89) ,88.89% (56/63) ,96.47% (82/85) and 93.24% (138/148) wspectively for stenosis greater than 50%.Conclusion The mA selection method based on the SV CT value for CCTA in 64-row MSCT provides individualized protocol to obtain consistent image quality and to optimize dose delivery to patients.     

64层螺旋CT冠状动脉成像定位像CT值与管电流关系的研究

Objective To characterize the association between the mean CT value on a scout view and the dependent mA selection method, and to evaluate the clinical value of a mA selection method based on scout view mean CT value in obtaining individualized scan protocol and consistent image quality for patient population on 64-row MSCT CT coronary angiography (CTCA).Methods One hundred patients (group A) underwent CCTA consecutively using standard protocol with a fixed mA.The mean CT value of a fixed ROI (region of interest) from the scout AP view and the CTCA image noise (standard deviation on the root of ascending aorta) were measured.The correlation between CT values and noise was studied establish a formula and a list to determine the required mA for obtaining a consistent CTCA image noise based on the measured SV CT value.Another 100 patients (group B) were scanned using the same parameters as group A except the mA and the CT value was also measured.The mA was determined by the list established previously.The CTCA image quality (IQ) as well as the image noise (IN) and the effective dose (ED) from the two groups were statistically analyzed using t-test.The CT findings for the 32 patients in the group B were also compared with the selective coronary angiography (SCA) results.The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of CCTA for detection of significant stenosis were obtained.Results The formula between the required mA and the CT value was : XmA=FmA×[(K1×CTscout + C1)/INa]2.The CCTA images in B group had statistically higher IN (27.66±2.57,22.22±4.17,t=11.33, P=0.000), but no statistical difference between IQ scores for the two groups (3.29±0.66,3.37±0.67,t=0.009, P=0.990), and ED[(8.72±2.51) versus (12.53±0.90) mSv]was 30% lower for the B group (P<0.01).For the 32 patients in the B group who had SCA, the CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.92% (56/59), 92.13% (82/89) ,88.89% (56/63) ,96.47% (82/85) and 93.24% (138/148) wspectively for stenosis greater than 50%.Conclusion The mA selection method based on the SV CT value for CCTA in 64-row MSCT provides individualized protocol to obtain consistent image quality and to optimize dose delivery to patients.     

64层螺旋CT冠状动脉成像定位像CT值与管电流关系的研究

Objective To characterize the association between the mean CT value on a scout view and the dependent mA selection method, and to evaluate the clinical value of a mA selection method based on scout view mean CT value in obtaining individualized scan protocol and consistent image quality for patient population on 64-row MSCT CT coronary angiography (CTCA).Methods One hundred patients (group A) underwent CCTA consecutively using standard protocol with a fixed mA.The mean CT value of a fixed ROI (region of interest) from the scout AP view and the CTCA image noise (standard deviation on the root of ascending aorta) were measured.The correlation between CT values and noise was studied establish a formula and a list to determine the required mA for obtaining a consistent CTCA image noise based on the measured SV CT value.Another 100 patients (group B) were scanned using the same parameters as group A except the mA and the CT value was also measured.The mA was determined by the list established previously.The CTCA image quality (IQ) as well as the image noise (IN) and the effective dose (ED) from the two groups were statistically analyzed using t-test.The CT findings for the 32 patients in the group B were also compared with the selective coronary angiography (SCA) results.The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of CCTA for detection of significant stenosis were obtained.Results The formula between the required mA and the CT value was : XmA=FmA×[(K1×CTscout + C1)/INa]2.The CCTA images in B group had statistically higher IN (27.66±2.57,22.22±4.17,t=11.33, P=0.000), but no statistical difference between IQ scores for the two groups (3.29±0.66,3.37±0.67,t=0.009, P=0.990), and ED[(8.72±2.51) versus (12.53±0.90) mSv]was 30% lower for the B group (P<0.01).For the 32 patients in the B group who had SCA, the CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.92% (56/59), 92.13% (82/89) ,88.89% (56/63) ,96.47% (82/85) and 93.24% (138/148) wspectively for stenosis greater than 50%.Conclusion The mA selection method based on the SV CT value for CCTA in 64-row MSCT provides individualized protocol to obtain consistent image quality and to optimize dose delivery to patients.     

双源CT低管电压技术在超重患者冠状动脉成像中的应用

目的 探讨在超重患者双源CT冠状动脉成像中低管电压技术的应用价值,评价其图像质量和辐射剂量.方法 将66例接受双源CT冠状动脉检查,体质量<85 kg、且体质量指数(BMI)为25.0～30.0 ks/m2的患者完全随机化分为A、B 2组.A组30例,管电压为120 kVp;B组36例,管电压为100 kVp.所有患者均采用回顾性心电门控螺旋扫描和四维智能在线剂量调控(CARE Dose 4D)技术,严格控制扫描范围.对2组的扫描数据分别进行多种图像后处理,由影像科副主任医师和副主任技师各1名采用双盲法评估图像质量.测量并计算信噪比(SNR)、对比信噪比(CNR).记录CT容积剂量指数(CTDIvol)和剂量长度乘积(DLP),计算有效辐射剂量(ED).应用两独立样本t检验比较2组患者图像ROI的CT值、噪声、SNR、CNR、辐射剂量及对比剂用量、图像质量评分等.应用X2检验比较两组患者冠状动脉图像质量分级显示段数.应用Kappa检验判断2名评价者评分的一致性.以P<0.05为差异有统计学意义.结果 图像ROI内CT值、噪声(以标准差SD计算)、SNR测量值:A组右冠状动脉(RCA)起始部分别为(429.3±77.4)HU,24.0±8.2、21.8±9.9,左冠状动脉主干(LMA)起始部分别为(436.7±79.0)HU、19.4±7.3、22.3±9.8;B组RCA分别为(503.5±95.4)HU、34.0±12.6、21.0±10.7,LMA分别为(491.7±96.2)HU、33.4±15.5、20.6±11.4;CNR测量值:A组为24.4±10.3,B组为21.9±8.2.2组患者冠状动脉血管腔内强化平均CT值、噪声比较,B组大于A组,差异有统汁学意义(P值均<0.05);2组间SNR、CNR筹异无统计学意义(P值均>0.05);2组CTDIvol比较,A组为(42.2±13.8)mGy,B组为(20.2±6.5)mGy,差异有统计学意义(P<0.05);A组ED为(9.5±3.6)roSy,B组为(4.8±1.7)mSv,差异有统汁学意义(P<0.05);A组图像质量评分为(4.5±1.0)分,B组为(4.7±0.5)分,筹异无统计学意义(P>0.05);A绀评价383段冠状动脉,图像优良者377段(98.4%)B组评价490段冠状动脉,图像优良者483段(98.6%).结论 对于BMI在25.0～30.0 kg/m2的患者,使用100 kVp管电压配合CARE Dose 4D技术进行双源CT冠状动脉检查,可以获得较好的图像质量,并且可以显著降低辐射剂量.

Abstract：

Objective To investigate the image quality and the radiation dose of dual-source computed tomography coronary angiography by using low kilovohage combination with low tube current in overweight patients.Methods Sixty-six patients with body mass inde,(BMI)25.(0-30.0 kg/m2 and a body weight<85 kg were randomized two groups(group A and group B).Thirty patients in group A were examined with 120 kVp,and 36 patients in group B with 100 kVp.ECG-pulsing and care dose 4D for radiation dose reduction were used in all patients.All images were transferred to Siemens workstation for post processing and analysis.Two observers blimted to clinical data independently assessed the image quality of each coronary segment by using a 5-point scoring scale(5:excellent,1:no diagnostic).and measured the different image parameters including image noise,signal-to-noise ratio(SNR)and contrast-to-noise ratio (CNR).The effective dose(ED)was calculated by using CT dose volume index(CTDIvol)and the doselength product (DLP). The mean intraluminal attenuation, image noise, SNR, CNR, radiation dose,volume of contrast medium, and mean image quality scores were compared between the two groups with t test. The grading quantity of coronary artery segment was compared with Chi-square test. The interobserver agreement was determined by Kappa statistics. Results The mean intraluminal attenuation, image noise,SNR in group A were (429. 3±77.4 ) HU, 24.0±8.2, 21.8±9. 9 in right coronary artery ( RCA), and (436. 7±79. 0) HU, 19.4±7.3, 22. 3±9. 8 in left main coronary artery (LMA ), and that in group B were (503.5±95.4) HU, 34.0±12.6, 21.0±10.7 in RCA, and (491.7±96.2) HU, 33.4±15.5,20.6±11.4 in LMA. The CNR were 24.4±10.3 in group A and 21.9±8.2 in group B. The mean intraluminal attenuation and image noise were significantly higher for group B compared with group A ( P <0. 05 ). There were no difference in SNR and CNR between the two groups ( P > 0. 05 ). Estimated ED in group B was significantly lower than that in group A [CTDIvol = (42. 2±13. 8) mGy, ED = (9. 5±3.6)mSv in group A vs. CTDIvol = ( 20. 2±6.5 ) mGy, ED = (4. 8±1.7 ) mSv in group B ; each P < 0. 05 ].Mean image quality scores were not significantly different between two groups ( 4. 5±1.0 in group A vs.4. 7±0. 5 in group B, P > 0. 05 ). A total of 383 coronary artery segments were evaluated in group A and 490 segments in group B. The difference of grading quantity of coronary artery segment was no statistical significant between two groups. Conclusions 100 kVp combination with ECC-pulsing and CARE Dose 4D of dual-source CTCA was valuable for patients with BMI ranging from 25 to 30 kg/m2 which have a better image quality and low radiatiun dose.     

64层螺旋CT冠状动脉成像定位像CT值与管电流关系的研究

Objective To characterize the association between the mean CT value on a scout view and the dependent mA selection method, and to evaluate the clinical value of a mA selection method based on scout view mean CT value in obtaining individualized scan protocol and consistent image quality for patient population on 64-row MSCT CT coronary angiography (CTCA).Methods One hundred patients (group A) underwent CCTA consecutively using standard protocol with a fixed mA.The mean CT value of a fixed ROI (region of interest) from the scout AP view and the CTCA image noise (standard deviation on the root of ascending aorta) were measured.The correlation between CT values and noise was studied establish a formula and a list to determine the required mA for obtaining a consistent CTCA image noise based on the measured SV CT value.Another 100 patients (group B) were scanned using the same parameters as group A except the mA and the CT value was also measured.The mA was determined by the list established previously.The CTCA image quality (IQ) as well as the image noise (IN) and the effective dose (ED) from the two groups were statistically analyzed using t-test.The CT findings for the 32 patients in the group B were also compared with the selective coronary angiography (SCA) results.The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of CCTA for detection of significant stenosis were obtained.Results The formula between the required mA and the CT value was : XmA=FmA×[(K1×CTscout + C1)/INa]2.The CCTA images in B group had statistically higher IN (27.66±2.57,22.22±4.17,t=11.33, P=0.000), but no statistical difference between IQ scores for the two groups (3.29±0.66,3.37±0.67,t=0.009, P=0.990), and ED[(8.72±2.51) versus (12.53±0.90) mSv]was 30% lower for the B group (P<0.01).For the 32 patients in the B group who had SCA, the CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.92% (56/59), 92.13% (82/89) ,88.89% (56/63) ,96.47% (82/85) and 93.24% (138/148) wspectively for stenosis greater than 50%.Conclusion The mA selection method based on the SV CT value for CCTA in 64-row MSCT provides individualized protocol to obtain consistent image quality and to optimize dose delivery to patients.     

64层螺旋CT冠状动脉成像定位像CT值与管电流关系的研究

Objective To characterize the association between the mean CT value on a scout view and the dependent mA selection method, and to evaluate the clinical value of a mA selection method based on scout view mean CT value in obtaining individualized scan protocol and consistent image quality for patient population on 64-row MSCT CT coronary angiography (CTCA).Methods One hundred patients (group A) underwent CCTA consecutively using standard protocol with a fixed mA.The mean CT value of a fixed ROI (region of interest) from the scout AP view and the CTCA image noise (standard deviation on the root of ascending aorta) were measured.The correlation between CT values and noise was studied establish a formula and a list to determine the required mA for obtaining a consistent CTCA image noise based on the measured SV CT value.Another 100 patients (group B) were scanned using the same parameters as group A except the mA and the CT value was also measured.The mA was determined by the list established previously.The CTCA image quality (IQ) as well as the image noise (IN) and the effective dose (ED) from the two groups were statistically analyzed using t-test.The CT findings for the 32 patients in the group B were also compared with the selective coronary angiography (SCA) results.The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of CCTA for detection of significant stenosis were obtained.Results The formula between the required mA and the CT value was : XmA=FmA×[(K1×CTscout + C1)/INa]2.The CCTA images in B group had statistically higher IN (27.66±2.57,22.22±4.17,t=11.33, P=0.000), but no statistical difference between IQ scores for the two groups (3.29±0.66,3.37±0.67,t=0.009, P=0.990), and ED[(8.72±2.51) versus (12.53±0.90) mSv]was 30% lower for the B group (P<0.01).For the 32 patients in the B group who had SCA, the CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.92% (56/59), 92.13% (82/89) ,88.89% (56/63) ,96.47% (82/85) and 93.24% (138/148) wspectively for stenosis greater than 50%.Conclusion The mA selection method based on the SV CT value for CCTA in 64-row MSCT provides individualized protocol to obtain consistent image quality and to optimize dose delivery to patients.     

FBP 、iDose4和 IMR3种重建算法对低剂量胸部 CT 图像质量的影响

目的：探讨滤波反射投影（FBP）、混合迭代算法（iDose4）和全迭代模型重建（IMR）3种重建技术对低剂量胸部薄层CT图像质量的影响。方法应用飞利浦256层CT ,收集30例怀疑肺部疾病行胸部CT平扫的患者。扫描条件：管电压80 kVp ,管电流80 mAs。所得原始数据采用FBP、iDose4、IMR＿soft（L1＿Body＿Soft＿Tissue）及IMR＿routine（L1＿Body＿Routine）算法进行重建,重建层厚1 mm ,层间距0．5 mm。测量并记录图像噪声、信噪比（SNR）及对比噪声比（CNR）。采用4分法分别对肺窗及纵隔窗进行图像质量的评估。对比分析4组3种不同重建算法的定性及定量参数。结果4组的图像噪声值分别为55．7±20．7,37．0±13．0,13．4±4．9和19．5±7．9。与FBP组相比,iDose4组、IMR＿soft组及IMR＿routine组3组的噪声分别降低了33．5％,75．9％,65％（ P均＜0．001）。IMR＿soft及IMR＿routine 3组的SNR及CNR均明显高于FBP组（P均＜0．001）。iDose4组的SNR及CNR值高于FBP组,但差异无统计学意义（P值分别为0．08,0．91）。IMR＿soft及IMR＿routine 2组的SNR及CNR均高于iDose4组（P均＜0．001）,但2组之间差异无统计学意义（P＞0．05）。IMR＿routine组肺窗图像质量评分高于其他3组,但与IMR＿soft组差异无统计学意义。IMR＿soft组纵隔窗图像质量最高,与FBP、iDose42组差异有统计学意义（P均＜0．01）,但与IMR＿routine组差异无统计学意义（P＞0．05）。结论与FBP重建算法相比较,在低剂量条件下,iDose4及IMR均可明显降低图像噪声及提高图像质量,其中IM R重建算法降噪及提高图像质量效果更为显著。     

Validation of Deep-Learning Image Reconstruction for Low-Dose Chest Computed Tomography Scan: Emphasis on Image Quality and Noise

ObjectiveIterative reconstruction degrades image quality. Thus, further advances in image reconstruction are necessary to overcome some limitations of this technique in low-dose computed tomography (LDCT) scan of the chest. Deep-learning image reconstruction (DLIR) is a new method used to reduce dose while maintaining image quality. The purposes of this study was to evaluate image quality and noise of LDCT scan images reconstructed with DLIR and compare with those of images reconstructed with the adaptive statistical iterative reconstruction-Veo at a level of 30% (ASiR-V 30%).Materials and MethodsThis retrospective study included 58 patients who underwent LDCT scan for lung cancer screening. Datasets were reconstructed with ASiR-V 30% and DLIR at medium and high levels (DLIR-M and DLIR-H, respectively). The objective image signal and noise, which represented mean attenuation value and standard deviation in Hounsfield units for the lungs, mediastinum, liver, and background air, and subjective image contrast, image noise, and conspicuity of structures were evaluated. The differences between CT scan images subjected to ASiR-V 30%, DLIR-M, and DLIR-H were evaluated.ResultsBased on the objective analysis, the image signals did not significantly differ among ASiR-V 30%, DLIR-M, and DLIR-H (p = 0.949, 0.737, 0.366, and 0.358 in the lungs, mediastinum, liver, and background air, respectively). However, the noise was significantly lower in DLIR-M and DLIR-H than in ASiR-V 30% (all p < 0.001). DLIR had higher signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) than ASiR-V 30% (p = 0.027, < 0.001, and < 0.001 in the SNR of the lungs, mediastinum, and liver, respectively; all p < 0.001 in the CNR). According to the subjective analysis, DLIR had higher image contrast and lower image noise than ASiR-V 30% (all p < 0.001). DLIR was superior to ASiR-V 30% in identifying the pulmonary arteries and veins, trachea and bronchi, lymph nodes, and pleura and pericardium (all p < 0.001).ConclusionDLIR significantly reduced the image noise in chest LDCT scan images compared with ASiR-V 30% while maintaining superior image quality.     

三维人工智能定位技术在CT胸部扫描中的应用

目的:探讨三维人工智能（AI）定位技术在胸部CT平扫中的应用价值。方法:回顾性分析2020年9月至10月在南京大学医学院附属鼓楼医院因新型冠状病毒肺炎筛查接受胸部平扫CT检查的患者100例,采用区组随机分组法分为人工定位组和三维AI定位组,每组50例。2组患者使用相同的胸部扫描协议。测量2组患者的定位偏离距离、CT剂量...     

个体内对照研究 CT 新技术对胸部低剂量 CT 图像质量的影响

目的：探讨应用高清光子探测器和基于原始数据的迭代重建算法(IR)对胸部低剂量 CT(LDCT)图像质量与结节检出的影响。方法回顾性分析66例行 LDCT 随诊的肺部结节患者,第1次检查采用普通低剂量 CT 扫描,滤波反投影算法(FBP)重建;间隔6个月采用高清光子探测器 CT 扫描机随诊,分别应用 FBP 和 IR 重建,比较普通低剂量组、光子探测器+FBP 组及光子探测器+IR 组的图像质量和结节检出情况。结果普通低剂量组、光子探测器+FBP 组及光子探测器+IR 组图像噪声依次减低、信噪比依次升高,差异均有统计学意义(P 值均<0.001),组间比较差异均有统计学意义(P 值均<0.01)。普通低剂量组、光子探测器+FBP 组及光子探测器+IR 组 CT 图像质量评分依次升高,图像质量评分具有统计学差异(χ2=32.65,P <0.001),组间比较差异均有统计学意义(P 值均<0.001)。3组均发现实性肺结节132个,测量肺结节直径分别为(5.13±1.49)mm、(5.11±1.57)mm、(5.08±1.54)mm,差异无统计学意义(P >0.05);普通低剂量组检出磨玻璃密度结节(GGN)14个,另2组均检出15个,普通低剂量组所测 GGN 直径为(6.44±1.86)mm,光子探测器+FBP 组为(7.23±1.74)mm,光子探测器+IR 组为(7.31±1.68)mm,普通低剂量组对 GGN 的检出效能较另2组低。结论光子探测器和基于原始数据的 IR 可降低 LDCT 图像噪声、改善图像质量,并可提高 GGN 的检出率和测量准确性。     

MinDose技术在CT急性胸痛三联排查中的应用

目的:探讨MinDose技术对急性胸痛三联排查(triple-rule-out,TRO)图像质量和辐射剂量的影响。方法:50例临床症状表现为急性胸痛并行128层CT回顾性心电门控TRO的患者,随机分为A组(常规组)、B组(MinDose组),每组25例。A、B组管电流调节技术窗均采用30%~70%的RR间期,A组窗外曝光剂量为全剂量的20%,B组应用MinDose技术,窗外曝光剂量为全剂量的4%。其余扫描参数相同。分析2组图像质量,记录剂量长度乘积,比较有效剂量。采用t检验比较2组的图像质量和辐射剂量。结果:A、B组图像质量评分分别为(3.06±0.40)分、(2.91±0.44)分,差异无统计学意义(P0.05)。B组辐射剂量为(6.47±1.03)mSv,明显低于A组的(7.25±1.43)mSv,差异有统计学意义(P0.05)。结论:MinDose技术可以在保证图像质量的前提下,降低患者的辐射剂量,在TRO低剂量扫描中具有重要价值。     

前瞻性心电门控 CT 冠状动脉造影手动触发扫描技术的可行性研究

目的：通过CT冠状动脉造影（CTCA）扫描方案的改良以控制对比剂剂量,评价图像质量与辐射剂量,明确该改良方案的临床应用价值。方法患者70例,随机分为2组。A组采用手动触发扫描,CTCA扫描注射10～12 s对比剂药量,B组采用循环时间测试扫描,循环时间测试对比剂剂量20 mL ,CTCA扫描注射14 s对比剂药量。比较2组图像质量、对比剂剂量与辐射剂量。统计学方法采用两独立样本 t检验和χ2检验,检验水准α＝0．05。结果 A、B 2组主观图像质量差异无统计学意义,客观图像质量差异无统计学意义（P＞0．05）。A组对比剂剂量少于B组,差异具有统计学意义（48．14 mL ±3．85 mL vs 86．60 mL ±6．21 mL , t＝－31．142,P＝0．000）。A、B 2组辐射剂量差异无统计学意义（4．94 mSv vs 5．66 mSv ,t＝－1．475,P＝0．145）。结论手动触发扫描可以在大幅度减低对比剂剂量的前提下获得可评估的图像质量。     

无心率控制第二代双源CT前门控序列扫描冠状动脉造影的临床评价

目的：分析无心率控制下的患者不同采集窗设置,明确前瞻性心电门控序列扫描对图像质量与辐射剂量的影响。方法前瞻性选取75例患者行CT冠状动脉造影(CTCA)扫描,中位年龄55岁。所有患者均无心率控制。心率≤65次/min采集期相设置为65%~75%,65次/min<心率≤80次/min采集期相设置30%~75%,心率>80次/min采集期相设置为35%~45%。分析患者辐射剂量与冠状动脉图像质量主观评分。结果75例患者有效剂量(ED)为(2.44±1.21)mSv,其中A组为(1.54±0.41)mSv,B组为(3.57±0.53)mSv,C组为(1.64±0.27)mSv;A组vs B组P=0.000,A组vs C组P=0.854,B组 vs C组P=0.000。75例患者共评价1043段冠状动脉节段,平均显示13.9段,(3.66±0.51)分。其中A组(3.75±0.44)分;B组(3.60±0.54)分;C组(3.38±0.67)分;A组vs B组P=0.000,A组vs C组P=0.004,B组vs C组P=0.032。结论前瞻性心电门控序列扫描通过适应不同心率修改采集窗范围可以获得可评估的图像质量,并且避免不必要的辐射剂量产生,值得进一步研究与应用。     

64层螺旋CT肺动脉成像低管电压设置结合个体化对比剂应用的对照研究

目的 探讨低kV设置及个体化对比剂应用在64层MSCT肺动脉成像(MSCTPA)中应用的可行性.方法 连续选取具有发生肺动脉栓塞可能的高危患者90例,按完全随机设计分为3组:(1)常规组30例,管电压120 kV,对比剂总量70ml;(2)120 kV组30例,管电压120 kV,对比剂总量根据患者体质量进行个体化设置(1.0 ml/kg);(3)100 kV组30例,管电压100 kV,对比剂总量根据患者体质量进行个体化设置(1.0 ml/kg).3组患者的对比剂均在20 s注射完毕,并以相同流率追加生理盐水20ml.对120 kV组和100 kV组CT图像的客观指标、主观图像质量评价、GT容积剂量指数(CTDIvol)和有效吸收剂量(ERD)进行比较;对100 kV组和常规组的对比剂用量、对比剂注射流率、CT图像的客观指标和主观图像质量评价进行比较,以评价64层MSCT低kV设置联合个体化对比剂应用在MSCTPA中应用的可行性.使用方差分析及post hoc检验对3组数据进行统计学分析.结果 图像噪声水平:100 kV组(5.2±1.8)与120 kV组(3.4±0.7)比较增加了52.9%,纵隔窗图像主观图像质量评价差异无统计学意义(q=0.272,P=0.063);CTDIvol:100 kV组[(9.5±0,0)mGy]与120 kV组[(14,6±0,0)mGy]比较下降34,9%;ERD:100 kV组[(2,4±0.4)mSv]与120 kV组[(3.8±0.6)mSv]比较下降36.8%;肺动脉平均CT值:100 kV组[(269.2±54.7)HU]相对于120 kV组[(237.4±62.9)HU]平均增加了13.4%,与常规组比较差异无统计学意义(q=0.172,P=0.260).结论 64层MSCTPA应用低kV设置(100 kV)降低辐射剂量是可行和有效的,个体化对比剂注射方案对特殊人群有一定临床价值.     

下呼吸道非金属异物的定位诊断(附150例分析)

目的　探讨下呼吸道非金属异物的X线定位诊断。方法　回顾性分析 15 0例X线诊断与纤维支气管镜检查所见相符合的下呼吸道非金属异物患者。均在透视下以不同角度观察呼吸两相时心影、纵隔、肺野透亮度以及横膈的变化情况 ,以此判断异物所在的位置。结果　 15 0例患者 ,气管异物 3 8例 ,右侧支气管异物 81例 (包括右主支气管 2 5例 ,右上叶支气管 4例 ,右中叶支气管 5例 ,右下叶及段支气管 47例 ) ,左侧支气管异物 3 1例 (包括左主支气管 13例 ,左上叶支气管 2例 ,左下叶支气管 16例 )。由于存在着解剖上的差异 ,右下叶支气管异物较左侧的多。结论　凡疑有下呼吸道异物的病例 ,均应行X线检查 ,透视应作为常规 ,其具有更高的定位诊断准确性