Objective To investigate the effects of different contrast injection schemes on the image quality of triple-rule-out com-puted tomography angiography(TRO-CTA).Methods A total of 691 patients with acute chest pain who underwent TRO-CTA exami-nation from multiple centers were prospectively selected and randomly divided into mixed group and unmixed group according to dif-ferent contrast injection methods.The image quality of aorta,pulmonary artery and coronary artery in the two groups was evaluated subjectively and objectively and the radiation dose was calculated.Results There were no significant differences in subjective image quality scores,aorta and coronary CT values,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)between the two groups(P>0.05),while there were significant differences in pulmo-nary CT values,SNR,CNR and radiation dose between the two groups(P<0.05).Conclusion The utilization of a mixed contrast injection scheme in TRO-CTA can satisfy diagnostic require-ments while ensuring a low proportional dosage and reduced radiation dose,which has clinical application value.

Objective To investigate the effects of different contrast injection schemes on the image quality of triple-rule-out com-puted tomography angiography(TRO-CTA).Methods A total of 691 patients with acute chest pain who underwent TRO-CTA exami-nation from multiple centers were prospectively selected and randomly divided into mixed group and unmixed group according to dif-ferent contrast injection methods.The image quality of aorta,pulmonary artery and coronary artery in the two groups was evaluated subjectively and objectively and the radiation dose was calculated.Results There were no significant differences in subjective image quality scores,aorta and coronary CT values,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)between the two groups(P>0.05),while there were significant differences in pulmo-nary CT values,SNR,CNR and radiation dose between the two groups(P<0.05).Conclusion The utilization of a mixed contrast injection scheme in TRO-CTA can satisfy diagnostic require-ments while ensuring a low proportional dosage and reduced radiation dose,which has clinical application value.

Objective To develop a prediction model for microvascular invasion(MVI)and its risk classification in hepatocellular carcinoma(HCC)based on gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid(Gd-EOB-DTPA)enhanced MRI.Methods Patients who underwent preoperative MRI examination and surgical pathological confirmation of HCC were included.The patients were divided into MVI-negative(M0),MVI-low-risk(M1)and MVI-high-risk(M2)groups,and their clinical data,laboratory test results and MRI signs were compared.Univariate and multivariate logistic regression analyses were used to determine the independent risk factors for MVI and high-risk MVI,and the nomograms for predicting MVI and high-risk MVI were established based on the logistic regression analysis results.Results Significant differences in alpha-fetoprotein(AFP),pathological grade,tumor diameter,tumor margin,peri-tumoral enhancement in arterial phase and peri-tumoral hypo-intensity in hepatobiliary phase were observed among the three groups.Logistic regression analysis showed that larger tumor diameter,non-smooth tumor margin and peri-tumoral hypo-intensity in hepatobiliary phase were independent risk factors for predicting high-risk MVI(P＜0.05),meanwhile the above factors,as well as AFP≥400 ng/mL and peri-tumoral enhancement in arterial phase,were associated with the occurrence of MVI(P＜0.05).The predicted MVI and high-risk MVI nomograms were developed based on the above factors,and the C-index was 0.838 and 0.764,respectively.Conclusion Gd-EOB-DTPA enhanced MRI signs are correlated with the status and classification of MVI,and nomograms developed on the basis of the above features is helpful to predict the individual's risk of MVI before surgery.

Objective To develop a prediction model for microvascular invasion(MVI)and its risk classification in hepatocellular carcinoma(HCC)based on gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid(Gd-EOB-DTPA)enhanced MRI.Methods Patients who underwent preoperative MRI examination and surgical pathological confirmation of HCC were included.The patients were divided into MVI-negative(M0),MVI-low-risk(M1)and MVI-high-risk(M2)groups,and their clinical data,laboratory test results and MRI signs were compared.Univariate and multivariate logistic regression analyses were used to determine the independent risk factors for MVI and high-risk MVI,and the nomograms for predicting MVI and high-risk MVI were established based on the logistic regression analysis results.Results Significant differences in alpha-fetoprotein(AFP),pathological grade,tumor diameter,tumor margin,peri-tumoral enhancement in arterial phase and peri-tumoral hypo-intensity in hepatobiliary phase were observed among the three groups.Logistic regression analysis showed that larger tumor diameter,non-smooth tumor margin and peri-tumoral hypo-intensity in hepatobiliary phase were independent risk factors for predicting high-risk MVI(P＜0.05),meanwhile the above factors,as well as AFP≥400 ng/mL and peri-tumoral enhancement in arterial phase,were associated with the occurrence of MVI(P＜0.05).The predicted MVI and high-risk MVI nomograms were developed based on the above factors,and the C-index was 0.838 and 0.764,respectively.Conclusion Gd-EOB-DTPA enhanced MRI signs are correlated with the status and classification of MVI,and nomograms developed on the basis of the above features is helpful to predict the individual's risk of MVI before surgery.

Objective To evaluate the perfusion findings of solitary brain metastasis using MR arterial spin labeling (ASL)imaging,and make a comparison with dynamic susceptibility contrast (DSC)imaging.Methods Twenty-three patients with pathologically proven solitary brain metastasis from lung cancer underwent ASL and DSC imaging.The ASL cerebral blood flow (CBF),DSC regional CBF (rCBF)and DSC regional cerebral blood volume (rCBV)were measured and compared between the tumor and the contralateral brain parenchyma.Pearson correlation test was performed to assess the relations between ASL and DSC measurements.Results Brain metastasis showed ring-like hyper-perfusion on ASL and DSC mappings.ASL CBF values of the tumor and the contralateral brain parenchyma were(54.872±21.131)mL·min-1·100 g-1and (21.109±4.788)mL·min-1·100 g-1,respectively (P<0.01).DSC rCBF values of the tumor and the contralateral brain parenchyma were (1.094 8±0.309 3)mL·min-1·100 g-1and (0.495 7±0.154 1)mL· min-1·100 g-1,respectively (P<0.01).DSC rCBV values of the tumor and the contralateral brain parenchyma were (1.753 1±0.545 5)mL/100 g and (0.729 9±0.215 8)mL/100 g,respectively (P<0.01).There was a strong correlation between ASL CBF and DSC rCBF (r=0.898,P<0.01),and there was no correlation between ASL CBF and DSC rCBV.Conclusion ASL can evaluate the CBF of brain metastasis as DSC dose. It requires no contrast agent administration and can be used in daily clinical practice.