RESUMO
OBJECTIVE: To investigate the clinical application of multi-slice computed tomography angiography (MSCTA) low-dose scan in pulmonary veins and left atrium and to reduce the radiation dose. METHOD: 100 middle-sized patients underwent pulmonary veins and left atrium MSCTA were collected and randomly divided into five groups averaged. The tube current were 250 mAs (conventional dose), 200, 150, 100, and 80 mAs (low dose), respectively. The CT scan length (L), volume CT dose index (CTDIvol) and dose length product (DLP) of five groups were recorded automatically, and the effective dose(ED) was measured. The signal to noise ratio (SNR) and the contrast to noise (CNR) of thoracic aorta at the middle level of left atrium were measured to evaluate the image quality objectively. The image quality of pulmonary veins and left atrium MSCTA was evaluated by two experienced radiologists using double-blind method. The results were analyzed by statistics. RESULT: (1) The CTDIvol(mGy), DLP(mGy*cm) and ED decreased evidently with the scan dose reduced, and the difference had statistical significance. (2) The image quality was mainly excellent and good in 100 mAs and the above, and it was mainly good in 80 mAs group. The image quality decreased with mAs reduced. The difference of SNR and CNR within five groups had statistical significance. The satisfaction degree of subjective evaluation on image quality of the five groups was up to 100%. CONCLUSION: On the premise that the image quality confirmed to the clinical diagnosis, the low dose scan in pulmonary veins and left atrium SCTA can obviously reduce radiation dose, and it had important clinical significance.