双源CT低剂量对比剂肺灌注成像评估肺动脉内血栓与灌注缺损间的关系

目的：应用双源CT低剂量对比剂肺灌注成像评估急性肺动脉栓塞患者血管内血栓与肺灌注缺损间的关系。材料与方法：15例无肺动脉栓塞患者分别行低剂量与常规剂量双能量肺灌注成像，对比分析其图像质量；20例疑肺动脉栓塞患者行低剂量双能量肺灌注成像，同时获得肺动脉CTA（CTPA）及肺灌注图像。用CTPA轴位及三维重建图像分析肺动脉内有无血栓以及血栓的部位、数量、形态特征。用双能量肺灌注分析软件判断有无灌注缺损及缺损的部位、范围。统计肺动脉内血栓与肺灌注缺损间的关系。结果：肺动脉栓塞患者的低剂量与常规剂量双能量肺灌注图像质量无明显差异（P>0.05）。20例患者中，13例肺灌注图像中出现102个肺叶、肺段或亚段灌注缺损，4例共6个灌注缺损无明确血栓。11例患者CTPA轴位及三维重建图像显示43个血栓，2例CTPA显示5个血栓的患者肺内无灌注缺损。9例同时出现血栓与灌注缺损，肺内75个灌注缺损与栓塞肺动脉供血范围一致，21个灌注缺损（8个肺段、13个亚段）与肺动脉供血范围无关。结论：肺动脉内血栓与肺灌注缺损不一定匹配，综合分析双源CT低剂量对比剂双能量肺灌注图像与CTPA，可以提高肺动脉栓塞诊断的准确性。

Relation between intravascular clots of pulmonary artery and lung perfusion defects: assessment with dual source CT low-dose contrast perfusion imaging

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（P0.05）.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.