Application Of Dual-Source CT Pulmonary Angiography In Diagnosis Pulmonary Embolism

Objective①To explore the application value of Dual-Source CT (DSCT) prospective electrocardiography(ECG)-gated pulmonary angiography in the diagnosis of pulmonary embolism (PE).②To explore the optimum contrast medium injection protocol of pulmonary angiography by the second generation Dual-Source CT (DSCT) flash mode.Material and Methods①Totally60patients with PE were randomly divided into3groups with20cases in each group. Non ECG-gated thoracic enhanced scan[n=20], retrospective ECG-gated pulmonary angiography[n=20] and Prospective ECG-gated[n=20] was performed to group A, group B and group C respectively. Two radiologists evaluated the image quality of pulmonary arteries. The image quality and radiation dose in group A, B and C were compared.②Eighty cases that were clinically suspected pulmonary embolism underwent CT pulmonary angiography using dual-source computed tomography flash mode. The80patients were randomly divided into4groups (each group containing20patients) using four contrast volume protocols. Protocols A, B, C, D used contrast medium of20ml,30ml,40ml,50ml respectively followed by a saline chaser of50ml with an injection flow rate of5.0ml/s. The region of interest (ROI) of triggering position located in the superior vena cava. Densities of pulmonary arteries and superior vena cava were measured by two radiologists with double blind method. Image quality of pulmonary arteries and artifact of superior vena cava were also analyzed.Result①The total points of image quality score in the3groups was45,58and57respectively. Statistical difference was found between group A and B and between group A and C (all P<0.05), No statistical difference was found between group B and C (P>0.05). The ED was (4.61±1.16) mSv in group A,(15.91±5.01)mSv in group B and (4.95±1.81)mSv in group C respectively. There was statistical difference between group A and B, as well as that between group B and C (all P<0.05). While there was no statistical difference between group A and C (P>0.05).②The percentage of pulmonary arteries exceeding optimal attenuation (>250HU) in group A was less than the groups of B, C and D(P<0.05), while there was no difference between the group B, C and D (P>0.05). The image quality score of:the four groups was4.12±0.38、4.47±0.63、4.43±0.68、4.49±0.54respectively, group A was lower than the others (P<0.05), while there was no significant difference(P>0.05) in the other groups. The artifacts of superior vena in group A was less than that in the other groups (P<0.05, and the values in group D was much more than that in the other groups, No statistical difference was found between group B and C (P>0.05).Conclusion①Prospective ECG-gated pulmonary angiography should be considered as a safe and credible method giving consideration to image quality and radiation dosage in diagnosing PE.②A high flow rate with30ml contrast medium followed by50ml saline could offer the diagnostic images in the second generation Dual-Source CT flash mode for CTPA.