Clinical Research Of Low-dose Sequences Of Dual-source CT For Preoperative Evaluation Of Aortic Valve Disease

Objective:To evaluate and compare coronary artery, valve leaflets morphology, aortic valve annulus diameter (AVAD) and left ventricular ejection fraction (LVEF) of aortic valve disease patients by using MinDose sequences of Dual-source CT (MinDose-DSCT), two-dimensional transthoracic echocardiography (2D-TTE) and real-time three-dimensional transthoracic echocardiography (RT-3DE).Materials and Methods:A total of68consecutive patients with aortic valve disease were retrospectively identified at our institution from March2010to January2013. Inclusion criteria:patients with aortic valve disease (aortic stenosis and/or aortic insufficiency) diagnosed by2D-TTE older than60years old or younger than60years old but with poor LVEF (<55%) suspected CAD. Exclusion criteria:body weight>85Kg, severe arrhythmia, after received50or100mg atenolol orally still with heart rate>70beats per minute (bpm), renal insufficiency (serum cretinine>1.5mg/dl), known anaphylactic reactions to iodine-containing contrast material, history of coronary stents and bypass grafts and hemodynamic instability.28patients had to be excluded from study participation, whereas40patients (28male,12female;28only aortic stenosis,7only aortic insufficiency,5aortic stenosis coexisting with moderate to severe valvular regurgitation; mean age61.3±13.6years, range42to77) were included as the experimental group.40patients underwent both2D-TTE, RT-3DE and MinDose-DSCT performed as part of routine clinical evaluation within a1-week period, with no change in clinical status between the studies. With regard to2D-TTE, the LVEF was calculated with the modified Simpson’s method. Parasternal long-axis loops of the aortic root were acquired with zoom mode and the AVAD was measured at the insertion of the leaflets at end-diastole. Observation of origin, proximal morphology, and inside diameter of the coronary artery could be achieved from the short-axis sections of large arteries. RT-3DE was used to measure LVEF directly according to RT-3DE reformation. Of MinDose-DSCT images were reconstructed at70%of the R-R interval, AVADs were measured by using double-oblique reconstruction and LVEFs were calculated by post-processing workstation. MinDose-DSCT had obvious advantages for observation of valvular calcification, number of valve leaflets, and valve prolapse. The study was approved by the local institutional review board and all patients gave written informed consent.Results:The patients in the experimental group completed MinDose sequence of DSCT as well as echocardiographic studies, while the patients in the control group completed the conventional retrospective ECG-gated acquisition. Image quality of all patients underwent echocardiography and MinDose-DSCT could meet the analytical requirements.1. Coronary artory and aortic valve observations:In addition to clearly display coronary arteries MinDose-DSCT could also perfectly reflect the aortic valve lesions by coronal, sagittal and cross-sectional multiplanar reformation (MPR) images, especially showed significant advantages in aortic cross-sectional observation when compared to echocardiography. The observation of a coronary by echocardiography was very limited, the origin of a coronary could be clearly seen only in part of the patients (15/40cases), and the remote status and lumen of blood vessel could not be displayed.2D-TTE could only viewed three aortic valve leaflets through aorta short axis plane but could not make a detailed three-dimensional continuous assessment about leaflet lesions. Although RT-3DE could cut multi-planar planes through different angles of aortic valve leaflets, but the image quality was actually affected by the2D-TTE images and only a minority of patients could clearly show the structure of valve leaflets.2. LVEF observations:There was a strong correlation between LVEFs measured by MinDose-DSCT and2D-TTE (r=0.87, P<0.01) and much stronger correlation between MinDose-DSCT and RT-3DE (r=0.90, P<0.01) was regarded too.3. AVAD observations:As compared with2D-TTE, MinDose-DSCT overestimated AVAD ((24.2±3.2) mm vs.(23.8±2.5) mm, P=0.01) but still was in good agreement with corresponding measurements by2D-TTE (r=0.90, P<0.01).Conclusions:As an one-stop preoperative evaluation, MinDose-DSCT can comprehensively reflect the coronary, AVAD and LVEF of aortic valve disease patients. Objective: To compare the image quality and radiation dose of MinDose sequence of DSCT versus standard retrospective ECG-gated DSCT imaging in aortic valve diseases.Materials and Methods: We retrospectively evaluated73dual-source CT images that were obtained using two different protocols (MinDose sequence [n=40] versus standard retrospective helical ECG-gated [n=33]) in aortic valve disease patients. Subjective evaluation: Two doctors with more than ten years experience in cardiovascular diagnostic imaging blinded to the patient information and scan parameters evaluated all image quality independently. They evaluated the image quality in accordance with the principle of3-or4-point scale, in terms of the visualization of the coronary artery, overall subjective image quality, the stair-step artifacts and the degree of homogeneity of vascular enhancement. Objective evaluation:One radiologist with more than ten years experience in cardiovascular diagnostic imaging evaluated image noise, SNR and CNR. We recorded and compared each examiners radiation dose and the mean score of image quality.We used kappa test to evaluate te diagnostic consistency between two radiologests. A P value<0.05was considered to indicate a significant difference. The study was approved by the local institutional review board and all patients gave written informed consent.Results: The mean overall image quality was perfect and both of MinDose-DSCT and standard retrospective ECG-gated DSCT reached diagnostic criteria, there was no statistically significant difference (P>0.05). The mean score of coronary artery imaging quality of MinDose sequence was1.8±0.2, which was not significantly different from the mean score of image quality of the control group of1.6±0.3(P>0.05). The mean score of the stair-step artifacts of two groups was alse not statistically different from each other (P>0.05). The mean score of the homogeneity of vascular enhancement in the standard retrospective ECG-gated group were better than those scores in the MinDose group (P<0.05).There was no statistical difference of mean vessel attenuation, SNR and CNR between the two groups (all P>0.05).The effective dose in the MinDose-DSCT group ((3.2±0.4) mSv) was60.28%lower than that in the standard retrospective ECG-gated group ((8.7±0.3) mSv)(P=.000).Conclusions: The MinDose sequence of DSCT can be obtained with a low radiation dose and satisfactory image quality, as compared to standard retrospective ECG-gated DSCT, for the evaluation of aortic valve disease patients.