胸部增强磁共振血管造影对比剂应用方案的优化

目的：探讨人胸部增强磁共振血管造影(contrast-enhanced MR angiography，CEMRA)的对比剂(钆喷酸葡胺)最佳应用方案。方法：无胸部疾病的自愿者61人，按0.08、0.17、0.25和0.33mmol／kg4种不同剂量分成4组，各组再分别以2、3、4ml／s的流速注射对比剂，应用Siemens Vision Plus 1．5T成像系统进行CEMRA检查，评价不同成像条件对人胸部CEMRA信噪比、信号强度、血管对比度等的影响。结果：从图像的主观评价看，对比剂在0.17mmol／Kg以下无论以何种速度都难以取得理想图像(相同剂量下低流速略好于高流速)，对比剂在0.25mmol／kg以上却无论何种速度都能获得较满意图像。血管的对比度也基本与剂量成正比，但肺动脉在对比剂剂量较大时，由于肺实质的强化，反而会引起血管肺组织对比度的下降。结论：胸部血管的动态三维增强MR血管造影效果主要与对比剂的注射剂量有关，与流速关系不大。推荐胸部增强MRA对比剂剂量为0.25mmol／kg，注射流速为2～3ml／s。

Thoracic contrast-enhanced MR angiography:optimized protocol for contrast medium adoption

Objective: To optimize the contrast medium injection in the thoracic contrast-enhanced MR angiography (CEMRA). Methods: Sixty-one volunteers without thoracic diseases underwent breath-hold 3D CEMRA of the thoracic vessels on a 1. 5T system. The patients were assigned into 12 groups randomly, the contrast medium was injected with 2 ml/s, 3 ml/s and 4 ml/s flow rates at different doses (0. 08 mmol/kg,0. 17 mmol/kg, 0. 25 mmol/kg and 0. 33 mmol/kg), and the effects were compared using the SPSS statistic analysis system. Results: Both the signal intensity and signal to noise ratio of the large vessels in thorax and pulmonary tissues showed positive correlation with the contrast agent dose, but there was no significant relationship with the flow rate. It was very difficult to get qualified MRA images if the dose was less than 0. 17 mmol/kg, while most images were good if the dose was more than 0. 25 mmol/kg(0. 25 mmol/kg). The vessel-pulmonary contrast increased in a limited dose range, if the dose was too high, the vessel contrast would decrease due to the pulmonary enhancement. Conclusion: The best dosage of contrast agent for pulmonary artery 3D CEMRA is 0. 25 mmol/kg, the 3D CEMRA of thoracic vessels mainly correlate with the contrast dose but not with the flow rate. 0. 25 mmol/kg and 2-3 ml/s for vessel 3D CEMRA is recommended.