| ObjectiveTo explore the clinical application of dual-source computed tomography (DSCT) in aortic dissection(AD), and compare the image quality and radiation dosage among non ECG-gated scan, retrospectively ECG-gated spiral scan and prospectively ECG-gated traverse scan. Methods115 patients [age 36-77 years, mean age (45.2±6.4) years, HR 49-107 beats per minute (bpm), mean HR (83.3±6.5) bpm, with a stable HR, variability of HR≤10 bpm, body mass index (BMI):< 30 kg/m2] with suspected aortic dissection underwent CT angiography using dual-source computed tomography (DSCT, Siemens Somatom Definition,2008G). Grouping them into 3 groups, randomly. Group A (35 patients) was scanned with non ECG-gated scan, group B (41 patients) was scanned with retrospectively ECG-gated helical scan (RGH) and group C (39 patients) was scanned with prospectively ECG-gated traverse scan (PGT). All patients were confirmed by operation or conventional aortic angiography. All images were transferred to an external workstation (Leonardo; Siemens Medical Solutions) for further analysis. In addition to the CT axial slices,3D reconstructions (MPR, MIP, CPR and VRT were included) were used to reformat the aorta and coronary artery. Two experienced reviewers assessed the image quality double-blindly. 1.After enhancement scanning, average CT value were used to assess aortic images quality, which were calculated from average CT value of the root of ascending aorta,thoracic aorta at the same level and extremity of aorta. The study considered image quality to be diagnosable if CT value of aorta was≥200Hu.2. All coronary artery segments which met the need of clinical diagnosis in patients were recorded.3. All patients' image noise (IN), CT dose index (CTDIvol) and dose length product (DLP) were recorded. The degree of inter-observer agreement in image quality of aorta was determined by Kappa test, and qualitative image quality of coronary artery was compared with chi-square test. Quantitative image noise and radiation dose were evaluated with q test (SNK) and the rank sun test. Statistical analyses were performed with SPSS version 13.0. A p-value<0.05 was considered to indicate a significant difference.ResultsDSCT aortic angiography in 115 patients was successful. The CT value of all patients were≥200Hu. There was a good agreement (Kappa value=0.76) between 2 readers in aortic image quality. The CT value of group A, B and C were (428.5±27.9) Hu, (337.6±39.4) Hu and (334.9±65.2) Hu, respectively, and there were significant differences between group A and B, group A and C (p<0.05) and there was no significant difference between group B and C (p>0.05). Diagnostic coronary artery segments were 58.40% (306/524),98.70% (610/618), and 97.76% (568/581) respectively, and there were significant differences between group A and B, group A and C (p<0.05) and there was no significant difference between group B and C p=0.2976). Image noise(IN) were (23.31±4.25) Hu, (14.39±3.52) Hu and (15.63±4.18) Hu, respectively, and there were significant differences between group A and B, group A and C (p<0.05) and there was no significant difference between group B and C (p>0.05). The CT dose index (CTDIvol) were (10.15±1.07) mGy, (48.36±7.12) mGy and (18.78±1.17) mGy, and there were significant differences between every two groups (p<0.05). The DLP were (459.02±44.18) mGyxcm, (2182.69±285.99) mGyxcm and (849.37±106.53) mGyxcm, and there were significant differences between every two groups (p<0.05)ConclusionComparing radiation dosage and image quality among the three scanning technique, dual-source CT (DSCT) prospectively ECG-gated traverse scan is a noninvasive, safe and reliable examination in AD diagnosis. |
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