Relation between intravascular clots of pulmonary artery and lung perfusion defects: assessment with dual source CT low-dose contrast perfusion imaging
TAN Si-ping, SHEN Bi-xian, CHEN Li-xing, XUE Shui-pei, CHU Er-wei, LIU Kang, WANG Chun-rong, JIA Fei-ge
Department of Imaging, Nanshan Hospital Affiliated to Guangdong Medical College, Shenzhen Guangdong 518052, China
Abstract：Objective: To assess the relation between intravascular clots of pulmonary artery and lung perfusion defects with dual source CT low-dose contrast perfusion imaging. Materials and Methods: Image quality of low-dose and conventional dose dual energy lung perfusion imaging(DEPI) in 15 patients without pulmonary embolism(PE) was analyzed. Twenty consecutive patients with suspected PE underwent dual source CT low-dose contrast perfusion imaging. CT pulmonary angiography(CTPA) and lung perfusion images were analyzed at the same time. Intravascular clots of pulmonary artery were analyzed, including the location, number and morphology by the axial image and three-dimensional reconstruction of CTPA. Lung perfusion defects and its location, extent were evaluated with lung PBV software on the workstation. The relationship between intravascular clots of pulmonary artery and lung perfusion defects were analyzed statistically. Results: No significant difference was found in the image quality of low-dose and conventional dose DEPI of patients without PE(P>0.05). One hundred and two perfusion defects were found in 13 patients by pulmonary perfusion imaging, including lobular, segmental and subsegmental perfusion defects. Six perfusion defects in 4 cases had no clear intravascular clots. Images of axial CTPA and three-dimensional reconstruction showed 43 intravascular clots in 11 patients. Two cases with 5 intravascular clots depicted by CTPA showed no perfusion defects. Nine cases showed both intravascular clots and perfusion defects, with 21 perfusion defects unrelated to the blood supply areas of pulmonary artery(8 segmental and 13 subsegmental), and the remaining 75 perfusion defects consistent with the blood supply areas of pulmonary artery. Conclusion: There is unexpected dissociation between the intravascular clots of pulmonary artery and lung perfusion defects. Analysing the perfusion maps and CTPA of dual source CT low-dose contrast perfusion image will improve the accuracy of diagnosis of PE.
2012, Vol. 23 
