The application of prospective ECG-gated technique in CT pulmonary angiography

Objective:To study the application value of the prospective ECG-gated 256-slice spiral CT in pulmonary angiography.Methods:90 cases having undergone CTPA on Philips 256-slice spiral CT from July to December 2009 in our hospital were selected and divided randomly into three groups (30 cases each):non ECG-gated helical scan group (non-gated group);prospective ECG-gated group (prospective group);retrospective ECG-gated group (retrospective group).Scan time, scan length,CTDIvol and DLP of each group,together with the patients′ age,gender and heart rate were recorded and computed for an effective radiation dose (ED).Three radiologists with experience estimated the scoring of image quality by double blind method and the coronary artery motion artifacts in scanning range.Results:The scoring of 95.6% of the cases (86/90) in these three groups was greater than or equal to 3.The scoring of image quality,the frequency of the coronary artery motion artifacts,scan time and radiation dose of three groups were significantly different.The scoring of image:the scoring of non-gated group was significantly lower than that of prospective group,equivalent to retrospective group.Coronary motion artifacts:three groups were respectively 88.1%,21.5% and 15.9%.Prospective and retrospective groups were significantly lower than non-gated group.Radiation dose:(7.59+0.87)mSv for prospective group,(7.49+0.80)mSv for non-gated group,having no significant difference but obviously lower than the dose of retrospective group (18.96+1.60)mSv.Scan time:compared with retrospective and non-gated group,the mean scan time of prospective group which was (8.66+0.86)s increased 1 and 5.5 second respectively.Different heart rates didn't influence the image quality of prospective ECG-gated CT pulmonary angiography obviously.Conclusion:Prospective ECG-gated technique on 256-slice spiral CT is a practicable method in performing CT pulmonary angiography,which can improve the image quality in the case of not increasing the radiation dose of patients obviously.