The Diagnostic Values Of64-slice Spiral CT Pulmonary Angiography In Pulmonary Embolism

Objective:To evaluate the frequency of embolus of well-visualized pulmonary arteries according to anatomic levels by using different reconstruction slice thickness with64-slice CT pulmonary arteriography and analyze its diagnostic value, and improve the level of diagnosis of pulmonary embolism.Methods:From January2010to October2012, a total of36patients of pulmonary embolism diagnosed by64-slice CT pulmonary angiography were enrolled. The CTPA scan images were devided into four series for each patient:0.75mm thick original transaxial soure images and3series of reconstructed images of1.5mm,3.0mm and5.0mm. Two radiologists independently observed the four series CT images to determine and record if each lobar, segment, subsegmental, fifth artery were well-visualized for presence of pulmonary embolism. Chi-Square test was taken for comparion of the differences among4series of CTPA images for detection of emboli in pulmonary arteries. Kappa test was taken for the agreement of2radiologists for detection of emboli in peripheral pulmonary arterie.Results:The average number of0.75mm,1.5mm,3.0mm,5.0mm thickness imaging was389,192,91, and44, respectively. For detecting the lobar pulmonary artery, the display rate were99%,99%,98%and97%respectively, and there was no statistically significant difference between four slice thickness sets (P>0.05). For detecting the segment, the subsegment and the fifth pulmonary arteries, the resolution of1.5mm thickness was82%、34%、10%respectively, there was a significant difference between0.75mm and1.5mm (P<0.01), while the resolution of1.5mm thickness was better than that of3.0mm and5.0mm thickness sets (P<0.01). For pulmonary emboli in pulmonary arteries, no statistical significant difference was observed between0.75mm and1.5mm thick imagings(P>0.05), The percentage of analyzable emboli was better in1.5mm thick group than3.0mm thick (X2=7.624, P<0.01). interobserver agreement in each serier imagings was good (K value was0.721-0.981).Conclusion:Compared with thick transaxial,1.5mm thick imaging is equally sensitive for deceting emboli in pulimonary arteries, but needs fewer images and less time for image reading.