Objective To evaluate the methods and the factors of affecting imaging quality of 3D CE MRA of carotid arteries.Methods 3D CE MRA in 48 patients were performed using 1.5T super conductive MR scanner,cervical and lumbar combination phased array coils. All patients were examined using intravenous injection Gd-DTPA and breath-hold 3D FLASH sequence. Results Imaging quality was satisfied in 46/48 patients (96%). MIP and MPR could clearly showed normal anatomy. The site,size and stenosis degree of the lesion were also demonstrated. Compared to surgery,DSA and/or ultrasound results , in 23 patients, the sensitivity and specificity of 3D CE MRA were 100% and 100% respeectively for the lesion of carotid arteries. Conclusion High quality images of 3D CE MRA mainly depends on determining the best acquisition delay time,optimizing injection volume and rate of contrast material,using reasonable sequence parameters and skilled level of operators.

Objective To prospectively evaluate the influence of average heart rate,heart rate variability and ECG editing on image quality of 64-slice CT coronary angiography(CTCA)in patients with atrial fibrillation(AF).Methods Fifty patients who were diagnosed with AF underwent respective ECG-gating 64-slice CTCA Image quality(good,moderate,poor)were evaluated on vessel segment level pre-and post ECG editing.Chi-square test was performed to compare the image quality in patients with various average heart rate,heart rate variability,and pre-and post ECC editing.Pearson correlation analysis was performed to test the relationship between the image quality and average heart rate and heart rate variability.Sensitivity,specificity,positive predictive value(PPV)and negative predictive value(NPV)were calculated by using the conventional angiography as the standard reference.Results The average heart rate of the fifty AF patients was(89±23)beat/min,with variability of(18.2±6.1)beat/min.Finally,24(3.4%)segments were considered to have poor image quality in 6(12.0%)patients.Image quality decreased significantly(P＜0.05)at the average heart rate of over 100 beats per minute(11 segments)or the standard deviation of heart rate of over 24 beats per minute(11 segments).There was significant correlation between the mean heart rate and the image quality for all segments,the RCA,and distal section of coronary artery(r=0.50,0.55,0.53,0.49,0.42,0.44;P＜0.05).Heart rate variability was also significant correlated with the image quality.There was significant difference on image quality pre-and post ECG editing(P=0.013).The respective overall sensitivity,specificity,NPV,PPV values were 100%(6/6),93.2%(41/44),100%(41/41),and 66.7%(6/9).Conclusion ECG editing can improve the success rate and the image quality of 64-slice CTCA effectively in patients with AF within a certain range of average heart rates and heart rate variability.

Objective To prospectively evaluate the feasibility and reliablity of low kilovoltage contrast-enhanced multi-slice CT(MSCT)to detect the myocardial viability in chronic myocardial infarcetion.with comparison to magnetic resonance(MR)myocardial perfusion and viability imaging.Methods Thirty-two patients with clinical diagnosed chronic myocardial infarction underwent the first pass and delayenhanced myocardial imaging with 64-slice MSCT and MR Left ventricle was divided into 16 segments.MSCT and MR images of all the patients were blindly analyzed.The size and extent of hypoenhanced regions in first pass phase and hyperenhanced regions in delayed phase were define.The Kappa test was used to assess the ability of identifying the viable myocardium between the two methods.Results In 32 patients with chronic myocardial infarction,MSCT showed hypoenhanced regions in 41 segments and normal in 471 segments during the first phase,while MRI revealed hypoenhanced regions in 47 segments and normal regions in 465 segments.The Kappa value was 0.650 and the concordance rate of the two techniques was 94.5%(484/512).MSCT showed 135 hyperenhanced regions which were non-transmural in 50 segments and transmural in 85 segments.And the other 377 normal segments showed no enhancement in the delayed phase.MRI revealed 120 hyperenhanced regions which were non-transmural in 56 segments and transmural in 64 segments.And the other 392 normal segments showed no enhancement in the delayed phase.The Kappa value of the two techniques was 0.609 and the concordance rate of the two techniques was 80.7% (413/512).Conclusion The study showed that low kilovolrage CE MSCT has a good concordance with MRI and has high feasibility and reliability in evaluating the myocardial viability in chronic myocardial infarction.The radiation dose is still the important aspect of MSCT application.

Objective To evaluate low-dose CT coronary angiography with prospective electrocardiogram (ECG)-triggering using dual-source CT scanner.Methods Sixty-eight patients who underwent coronary CT angiography using a dual-source CT scanner were divided into 2 groups: group A (38 cases) and group B (30 cases).Prospective ECG-triggering sequence scan mode was employed for group A.Inclusion criteria included: heart rate <70 bpm, sinus rhythm, and heart rate fluctuation less than 10 bpm.Data acquisition was set at 70% of the RR-interval.Retrospective ECG-gating helical scan was performed for group B.Inclusion criteria included heart rates < 70 bpm and sinus rhythm.The exclusion criteria included heart failure and serious arrhythmias.In both groups, patients with a BMI≥24 kg/m2 were examined with a tube voltage of 120 kV, whereas patients with a BMI <24 kg/m2 were examined with a tube voltage of 100 kV.All images were transferred to a workstation for further processing and analysis.The imaging quality was evaluated.The imaging quality of coronary artery segments were compared with rank sum test between the two groups, and the radiation dose were compared with t test.Results A total of 476 coronary artery segments were evaluated in group A and 372 segments were evaluated in group B.The mean score of imaging quality for coronary artery segments in group A was 3.48±0.59 and that in group B was 3.53±0.58.There was no statistical difference in imaging quality between the two groups (Z=-1.432, P=0.187).The effective dose was on average (2.51±0.54) mSv (range 1.3--3.3 mSv) in group A, whereas on average (14.55±3.54) rosy (range 7.1--20.2 mSv) in group B.There was a statistical difference between the two groups (t=18.484, P=0.000).Conclusions Low-dose prospective ECG-triggering sequence scan in dual-source CT coronary angiography is feasible in patients with low heart rate and regular cardiac rhythm.This scan mode can substantially reduce radiation doses while preserving good diagnostic image quality.

Objective To investigate the application of low-dose adaptive sequence scan of dual-source CT coronary angiography in patients with high heart rate and evaluate the image quality.Methods Seventy-two patients who underwent coronary CT angiography with heart rate> 70 bpm were divided into 2 groups.Group A was adaptive sequence scan, and Group B was retrospective ECG-gating helical scan.Examinations were performed on a dual-source CT scanner (Somatom Definition) .All images were transferred to a workstation for further processing and analysis.The image quality was evaluated using same criteria.The image quality of coronary artery segments was compared in two groups using rank sum test, and the radiation dose was compared using t test Results A total of 501 coronary artery segments were evaluated in group A and 400 segments in group B.The mean ranks in image quality of coronary artery segments in group A was 475.42, whereas 420.41 in group B.There was a statistical difference in image quality between the two groups (Z= - 3.509,P=0.000).The effective dose was on average (6.2±0.9) mSv in group A, whereas on average (14.7±1.9) mSv in group B, there was a statistical difference between the two groups(t= - 27.011, P=0.000).Conclusions Adaptive sequence scan in dual-source CT coronary angiography is feasible in patients with high heart rates.This scan mode can substantially reduce radiation dose and maintain the diagnostic image quality.

Objective To investigate the feasibility of coronary CT angiography in single cardiac cycle and to analyze the image quality and radiation dose in patients with high heart rate(HR) using 256-row detector CT. Methods Ninety-two consecutive patients between October and November 2015 who were suspected coronary artery disease underwent coronary CT angiography(CCTA) were enrolled, which was performed with a 256-row detector CT(Revolution CT, GE Healthcare) using prospective ECG-triggered volume CCTA within a single cardiac cycle with snapshot freeze(SSF) technique. The patients were grouped by HR during CT scans: group A(80—89 bpm, n=56), group B(90—99 bpm, n=20), and group C(≥100 bpm, n=16). Image quality was compared before and after using SSF technique reconstructions in seventy-four patients. The image quality of coronary artery was evaluated blindly by 2 experienced radiologists using a four-point scale based on the 18-segment model according to the Society of Cardiovascular Computed Tomography guidelines. The differences in age, body mass index, heart rate and CT dose index volume,effective dose(ED) among the three groups were compared by using ANOVA analysis or Kruskal-Wallis test, the image quality and interpretability using χ2 test. Comparisons of image quality between standard and SSF were performed with paired Wilcoxon rank sum test. Kappa coefficient was used to test inter-observer agreement. Results A total of 1 065 coronary artery segments, 98.97%(1 054/1 065) met the requirements for diagnosis. No significant difference was found(χ2=1.274, P=0.563) for the diagnostic image quality of coronary artery segments among the 3 groups with 98.64%(651/660), 99.57%(232/233), 99.42%(171/172), respectively. Significant difference(χ2=68.811, P<0.05) was found for diagnostic image quality before and after using SSF with increase from 90.29%(772/855) to 99.44%(881/886). Image quality was improved with the use of SSF reconstructions and the diagnostic segments were also increased. The median of ED for group A, B and C was 2.03, 1.93, 2.37 mSv, respectively. There was no significant difference in ED among group A, B and group C(H=2.412,P>0.05). Conclusions Single cardiac cycle scan is feasibility for coronary CT angiography in patients with high heart rate using 256-row detector CT. This scan mode can maintain the diagnostic image quality with low radiation dose. SSF technique can improve the image quality.

Objective To investigate the clinical outcome of fixation and autograft through the pedicle of fractured vertebrae for thoracolumbar burst fracture. Methods 138 cases with thoracolumbar burst fracture were retrospectively analyzed. 30 cases (group A) accepted 4 pedicle screw fixation with autogrft, and other 108 cases (group B) accepted internal fixation through the pedicle of fractured vertebrae with autogrft. All the cases were followed up for 22~72 months. Results The fractured vertebral height and Cobb's angle recovered and the neurological function improved after treatment in both groups (P<0.05), but there was no significant difference between 2 groups. There was significant difference in Visual Analogue Score for back pain (P<0.05). Conclusion Vertebral pedicle screw fixation with transpedicular autograft is an effective operation for thoracolumbar burst fracture, especially on back pain.

Objective:To evaluate the feasibility and diagnostic efficacy of the coronary fractional flow reserve derived from CT (CT-FFR) measurement method based on tracer pharmacokinetic principle.Methods:A total of 130 patients (159 coronary artery vessels) who were admitted to Beijing Anzhen Hospital from January 2015 to March 2019 were included in this study retrospectively. All patients had completed coronary CT angiography (CCTA) and invasive coronary angiography with invasive FFR. Subjective assessment of stenosis degree was performed on CCTA images and non-invasive FFR measurement was performed by using a tracer-kinetics based on CT-FFR measurement method. The Bland-Altman method was used to evaluate the diagnostic consistency of the two methods. Compared with the invasive FFR results, the sensitivity, specificity, positive predictive value, negative predictive value, and area under the ROC curve (AUC) of tracer-kinetics based on CT-FFR results for the diagnosis of coronary ischemic lesions were evaluated. All cases were divided into two heart rate groups:>65 bpm and ≤65 bpm. The diagnostic efficacy of tracer-kinetics based on CT-FFR in different heart rate groups was evaluated. χ 2 test and DeLong test were used to compare diagnostic performance in different evaluation methods and heart rate groups. Logistic regression analysis was used to evaluate the impact of factors such as heart rate, image thickness, image enhancement, and noise on the accuracy of diagnosis. Results:Bland-Altman analysis showed that the average difference between the two methods was -0.01. (-0.11-0.10). Compared with invasive FFR results, the tracer-kinetics based on CT-FFR method had a diagnostic sensitivity of 92.4%, specificity of 82.1%, positive predictive value of 87.6%, negative predictive value of 88.7%, and the area under ROC curve (AUC) value was 0.94. Compared with the diagnostic efficacy of luminal stenosis evaluated based on CCTA images, the difference was significantly statistical ( P<0.05). The diagnostic performance of CT-FFR had no statistically significant difference between the two heart rate groups. Factors such as heart rate, image thickness, image enhancement, and noise had no significant effect on the diagnostic accuracy of the tracer-kinetics based on CT-FFR method. Conclusions:The tracer-kinetics based on CT-FFR method may quickly complete the non-invasive FFR measurement on CCTA images with image quality that meets the needs of clinical diagnosis. It has a good diagnostic performance in the diagnosis of coronary ischemic lesions even for those cases with a faster heart rate. The diagnostic accuracy of tracer-kinetics based on CT-FFR method is not significantly affected by factors such as heart rate, image thickness, image enhancement, and image noise.