A comparative study on two scanning techniques of 256 slice spiral CT for diagnosis of Stanford A type aortic root dissection / 中国中西医结合急救杂志

ABSTRACT

Objective To evaluate and compare the imaging quality and diagnostic accuracy of two types of scanning techniques of 256-slice spiral CT angiography, prospective electrocardiogram(ECG)-gated sequence and non ECG-gated high-pitch sequence, used respectively for patients with Stanford type A aortic dissection (AAD) at the root of ascending aorta.Methods A retrospective study was conducted. Sixty-eight patients with AAD were definitely diagnosed by CT angiography were admitted to the Fifth Central Hospital of Tianjin from August 2015 to July 2017, and they were divided into two groups according to different scanning methods: 36 cases of AAD underwent prospective ECG-gated CT angiography (CTA) and 32 patients underwent non ECG-gated high-pitch CTA. A 3-grade scoring system was used to interpret the image quality of the aortic sinus, aortic valve junction zone and coronary artery opening. The CT value and noise value (SD) of aortic root were measured, the image signal to noise ratio (SNR) was calculated and compared with the discovery in exploratory operation; the patients' CTA imaging quality and the coincidence rate of lesion type diagnosis were compared between the two groups.Results All aortic CTA images could meet the diagnostic requirements. The imaging quality scores of aortic sinus, arotic valve junction zone and coronary artery opening images in ECG-gated CTA group were higher than those in non ECG-gated high-pitch CTA group (aortic sinus 2.94±0.23 vs. 1.89±0.67, sinuscanal junction zone 2.94±0.23 vs. 1.83±0.70, coronary artery opening images 2.86±0.35 vs. 1.31±0.52, allP < 0.01); comparisons between the ECG-gated CTA group and non- ECG-gated CTA group in objective indexes, CT value, arotic SD value and SNR at the root of ascending aorta showed there were no statistically significant differences [the value of CT (HU) 425.20±94.38 vs. 439.29±86.78, the SD value of aorta (HU) 22.85±9.40 vs. 26.40±9.41, SNR 21.23±8.16 vs. 19.70±9.98, allP > 0.05]. The coincidence rate between the diagnosis of AAD at the root of ascending aorta and the discovery in the exploratory operation in ECG-gated CTA group was higher than that in non ECG-gated CTA group [94.4% (34/36) vs. 68.8% (22/32),P < 0.01].Conclusion The diagnostic accuracy and image quality of AAD root of ascending aorta in prospective ECG-gated CTA group were significantly higher than those in non ECG-gated CTA group.