Gd-DTPA磁共振肺灌注成像对猪肺动脉栓塞的诊断价值

目的:通过动物实验摸索磁共振肺灌注成像的最佳剂量,评价灌注成像对肺栓塞的诊断价值.方法:应用5、10、15、20、25ml的Gd-DTPA溶液以3ml/s的流速对6头中华猪进行三维动态增强肺实质灌注成像(机型为 Siemens Vision 1.5T);之后,用明胶海绵颗粒制备猪肺动脉栓塞模型,再以20ml剂量和3ml/s的速度进行肺灌注成像,评价其诊断急性肺栓塞的能力,并与数字减影血管造影(DSA)对照.结果: 0.125、0.25、0.375、0.5、0.625 mmol/kg 5种剂量时肺组织的强化率分别为(29.07±21.67)%、(60.39±12.21)%、(84.89±8.32%)、(87.80±8.49)%和(81.00±9.98)%;后三者与前两者比较差别有非常显著的意义(P<0.001).磁共振肺灌注成像肺栓塞病灶显示率100%(10/10),DSA为80%(8/10),栓塞区表现为楔形低信号灌注缺损,平均信号强度值为137.86±45.32,而正常的灌注区为330.14±46.52,两者差别非常显著(t=8.40,P=0.001).结论:猪肺灌注的满意剂量在0.375～0.5mmol/kg.肺动脉磁共振血管造影结合肺灌注图像显示肺栓塞比DSA好.

Contrast-enhanced MRA of pulmonary artery combined with pulmonary perfusion imaging in pigs: a comparative study with DSA

Objective:To optimize the injection protocol of contrast medium for contrast-enhanced MRA (CEMRA) of pulmonary artery and to evaluate the diagnostic value of CEMRA and pulmonary perfusion imaging (PPI) in an experimental model of acute pulmonary embolism. Methods:CEMRA and PPI were performed in 6 normal pigs with different doses of gadolinium contrast agent (5ml, 10ml, 15ml, 20ml and 25ml) at an injection rate of 3ml/s, and 3 pulmonary embolism models were injected with 20 ml contrast agent at 3 ml/s. DSA was also performed for comparison. Results:The signal intensities and the signal to noise ratios of the pulmonary arteries kept increasing with the dose increase of the contrast agent, but the best angio-pulmonary contrast dose was 10-15ml (0.25-0.375mmol/kg), while the optimal dose for PPI was 15-20ml (0.375-0.5mmol/kg). Although CEMRA demonstrated less obstructed pulmonary arteries than DSA (5/10 vs 8/10)did, it detected all obstructions when combined with PPI. The pulmonary infarction zones showed wedge-shaped perfusion defects on the PPI images, with the signal intensities lower than those of the normal areas (137.86±45.32 vs 330.14±46.52, P<0.001). Conclusion:It is suggested that the optimal dose of the contrast agent is 0.25mmol/kg to 0.375mmol/kg for CEMRA, and 0.375mmol/kg to 0.5mmol/kg for lung perfusion. CEMRA combined with PPI may be better than DSA in demonstrating pulmonary embolism.