Abdominal aortic aneurysm (AAA) is a common fatal aortic disease.The rupture of AAA is the procession affected by multiple factors.Besides physiological,pathological and biochemical changes,morphological and biomechanical alteration can also influence this procession.The progress of rupture risk evaluation through morphological and biomechanical characteristics of AAA were reviewed in this article.

Changes in respiratory function before and after CPB in 40 children with state of left-to-right shunt of VSD were studied. Among the cases, 20 of them were with pulmonary hypertension (PH group ) and 20 without PH (control group). Before CPB, resist ante of inspira tion (RI) and resistance of expiration (RE)in PH group (23.87?7.53,42.98?12.1) were significantly higher than those of control group(RI 17.95?7.53,RE 34.95?5.13);compliance of lung-thorax(CLT) in PH group(11.58?4.87) was significantly lower than that of control group(14.32?1.99). After CPB. both RI (30.94?11.89) and RE(46.43?9.9) in PH group were greatly higher than those in control group (28.00?9.29,46.43?9.9);CLT (10.98?4.6) was lower than that of control group (12.3?2.68). In PH group,the PaO_2 decreased and the magnitude of A-aDO2 increased much more than those in control group. The results suggest that respiratory function in the children with PH might not be improved immediately after CPB separation.

Objective To analyse the flow characteristics in the true lumen and false lumen,and the relationship between the flow characteristics and the collapse degree of the true lumen using MRI.Methods Eleven patients with acute Stanford type B aortic dissection were examined by true FISP、3D CE MRA、PC cine MRI on a Siemens Sonata 1.5 T.Not only the quantitative data on the hemodynamics such as peak velocity,average velocity,average flow volume,forward volume,retrograde volume and net volume,and the area of the true lumen and false lumen can be acquired,but also the blood flow model,ie the velocity-mapping.Then we analysed the relationship between the flow characteristics and the collapse degree of the true lumen.Results The average area of the false lumen in the proximal descending aorta(about 2 cm distal to the entry)was(8.10±2.93)cm2,and(2.59±0.93)cm2 of the true lumen in the same slice (P＜0.05).The average velocity in the false lumen,(2.81±0.73)cm/s,was significantly lower than in the true lumen[(15.52±2.84)cm/s,P＜0.01],wheras the average flow(36.32±5.37)ml/s,was not significantly difierent(P＞0.05)from the average flow in the false lumen(37.62±24.58)ml/s.The velocity-mapping curve looked like same in the true and false lumen in this level.And in the abdominal aorta(about the level of the hepatic hilar),the average flow(10.46±5.57)cm/s was significantly lower(P＜0.05)than in true lumen[(4.04±2.96)cm/s].At this level,the direction of blood flow in the true lumen was retrograde(upward)in the mid and late systolic phase in six patients,and normal in the diastolic phase and early systolic phase,that was to say,bidirectional blood flow can be caught in the true lumen of the abdominal aorta.The collapse degree of the true lumen was closely correlated with the the average velocity and the flow volume in the false Iumen,and the coefficient correlation and P value were 0.931 and 0.000,0.926 and 0.000 respectively.Conclusions PC cine MRI can quantitatively measure the peak velocity,average velocity,average flow volume,forward volume,retrograde volume and net volume,and combined with 3D CE MRA can evaluate the collapse degree of the true lumen.It is important for clinical application in the diagnosis,therapeutic management and the therapeutic opportunity choice of the acute Stanford type B aortic dissection.

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 study the value of dual-source CT(DSCT)in assessing aortic mechanical valve with 3D cardiovascular imaging technique.Methods Thirty-four patients with mechanical aortic valve transplantation were enrolled.Nineteen cases transplanted with On-x valve and 15 cases with St jude valre.CT scan was performed in all 34 patients and MRI scan in 30 patients.The CT imaging quality of On-x valve with St jude valve was compared by two independent samples Wilcoxon rank test.Two independent sampies test was used to compare tlle valve angle in the two kinds of valve and also in the same group.The relative functional index of left ventricle in CT and MR analysis by paired-samples t Test. Results The image quality was dirided into three grades.Six hundred and eighty phases in all 34 patients.which included 391 phases with grade 1,171 phases with grade 2 and 118 phases with grade 3.There were no significant different between two kinds of mechanical valve in image quality(image quality of grade 1:Z=-1.084,P=0.286;grade 2:Z=-0.088,P=0.945;grad 3:Z=-1.045,P=0.319).The mean bileaflet angle of 34 cases was 82.0°±4.4°in completely opening and 34.5°±5.7°in completely closing.The mean radian gradient over openess and closure was 47.5°±7.5°.The radian gradient of St iude group(55.0°±1.8°)was obviously larger than On-x group(41.5°±4.1°)(t=-11.732,P=0.000).But,there were no significant difference between dual-source CT and 1.5 T MR when evaluate the left ventrical fuction,including EF[MR.EF(57.2-1-2.8)%,CT-EF(57.9±2.8)%,f:-0.496,P=0.623],EDV[MR-EDV (121.6±9.1)ml,CT-EDV(132.9±11.2)ml,t=-1.198,P:0.240],ESV[MR-ESV(55.1±6.9)ml,CT-ESV(59.5±7.6)ml,t=-1.094,P=0.283],myocardium mass at ED[MR-Myo.mass (155.5 ±12.6)g,CT-Myo.mass(147.9±11.6)g,t=1.823,P=0.079]and CO[MR-CO(5.7±0.4)ml/min,CT-CO(5.9±0.5)ml/min,t=-3.211,P=0.775].Conclusions Dual source CT with 3D cardiovascular imaging technique is valuable and effective for evaluating aortic mechanical valve.The shape of the whole valve and movement of bileaflet reappears well.With the postprocessing software,it allows evaluating aortic mechanical valve function,reliable measurements of opening and closing leaflet angles and left ventrieal function.

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 feasibility of comprehensive assessment of the whole aorta and coronary arteries (CA) simultaneously with high-pitch 128-slice dual-source CT ECG-gated FLASH protocol.Methods A total of 48 consecutive patients with suspected aortic diseases underwent CTA examination of the whole aorta and CA using a ECG-gated FLASH CT protocol (pitch =3.2) without heart rate (HR) control.Aorta,aortic valves and CA were shown with different post-processing modalities.The image quality of the aorta,aortic valves and CA was evaluated and compared according to HR (low HR group ≤ 65 bpm,high HR group ＞ 65 bpm).The scan time,effective dose and contrast medium volume were recorded.Inter-observer differences were calculated by Kappa test.Differences between groups were analyzed by Mann-Whitney test with count data and variance test with measurement data.Results All examinations were completed successfully.The image quality was acceptable in the aorta,aortic valve (100％,48/48) and CA (94.0％,551/586).Percentage of diagnostic quality images was slightly higher in low HR group (94.7％,232/245,93.5％,319/341,Z =-2.504,P ＜ 0.05).Inter-reader reproducibility was 95.8％ (46/48) in the aorta and aortic valve,96.6％ (566/586) in CA,yielded good agreement (Kappa =0.81 and 0.89).The mean attenuation of aorta and CA were higher than 300 HU,especially in low HR group (357.0-446.0) HU.Except proximal segment of right CA,the CNR of whole aorta and coronary arteries were significantly higher in the low HR group (24.5-29.0) than that in the high HR group (20.0-23.1,P ＜0.05).SNR of the whole aorta was higher in the low HR group (13.7-17.9) than the high HR group (11.5-13.9,P ＜ 0.05).The mean scan time was (1.56 ± 0.08) s,effective dose was (4.12 ± 1.23) mSv (2.77-6.77 mSv),and contrast medium volume was (72.8 ± 2.1) ml.Conclusions CT angiography of whole aorta and coronary arteries could be performed simultaueously within 2 seconds with CT ECG-gated FLASH protocol.The images were of diagnostic quality for aortic and CA disease with low dose of radiation and contrast media.However,high HR could decrease the image quality of CA.

ObjectiveTo assess the performance of dual-source CT (DSCT) for left atrial volume and function evaluation and compare this performance to that of cardiac cine MR ( CMR ),which was considered as the standard reference technique.Methods Forty-nine patients referred for CT coronary angiography were enrolled in this study.DSCT data sets and FIESTA cines of the vertical long axis covering the left atrium and the short axis covering the left ventricle were obtained on the same day without additional medicine.All images were analyzed to obtain left atrial volume at different time and its function values.All the parameters were corrected by body surface area.Inter-modality agreement was tested through linear regression and Bland-Altman analyses.Repeated measurements were performed to determine inter-observer variation.ResultsThe indexed measurements of DSCT and CMR were (47.4 ± 11.1 ) and (46.2 ± 9.7 )ml/m2 for LAVmax,( 22.2 ± 6.9) and ( 21.3 ± 5.8 ) ml/m2 for LAVmin,( 34.8 ± 8.8 ) and ( 33.6 ± 7.8 )ml/m2 for LAVp,(24.0 ±5.7)and(21.5 ±5.0) ml/m2 for LARV,(11.6 ±3.9)and(10.9 ±3.9) ml/m2 for LAPV,(12.4 ±3.9)and(10.7 ±3.6) ml/m2 for LAAV,(22.6 ±8.4)and(21.0 ±6.4) ml/m2 for LACV,(52.8 ± 7.4) ％ and ( 54.5 ± 6.3 ) ％ for LAEF,respectively.The correlation coefficients between DSCT and CMR measurements for LAVmax,LAVmin,LAVp,LARV,LAPV,LAAV,LACV and LAEF were 0.89,0.90,0.90,0.80,0.82,0.80,0.76 and 0.78,respectively.However,DSCT slightly overestimated LAVmax,LAVmin,LAVp,LARV,LAPV,LAAV and LACV,and the deviation was 1.2,0.9,1.1,0.3,0.1,0.2 and 0.4 ml/m2,respectively.Compared with CMR,DSCT slightly underestimated LAEF of about 0.6％.Interobserver variation was lower in DSCT examination than CMR for the measurements of left atrial function.ConclusionDSCT provided accurateand reproducible measurements of left atrial volume and function.

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 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.