移植干细胞MRI示踪中呼吸伪影消减方法初探

Study for the reduction of artifacts caused by respiratory movement in magnetic resonance imaging for tracking planted stem cells

目的:探讨磁共振成像(MRI)示踪移植干细胞中消减呼吸伪影的方法。方法:成功制作的急性心肌梗死模型猪共21头,1周后实验组(15头)经冠状动脉植入超顺磁性氧化铁纳米颗粒(SPIOs)标记的骨髓单个核细胞(BM-MNCs);对照组(6头)注入生理盐水。4周后行MRI检查,方法一(n=8,2例来自对照组):戊巴比妥钠全身麻醉,胸带加压固定后行MRI检查;方法二(n=13,4例来自对照组):戊巴比妥钠全身麻醉,气管插管,简易呼吸器控制呼吸,胸带加压固定后行MRI检查。扫描图像分为3个等级:图像对比度、清晰度好,评为优秀;能进行诊断但图像噪声较大,评为良好;噪声大、伪影重影响诊断或不能诊断,评为差。结果:方法一中优秀2例,良好3例,较差3例;方法二中优秀5例,良好6例,较差1例,因气管插管导致皮下气肿而死亡1例。方法二中图像质量优于方法一,等级秩和检验无统计学意义(P>0.05)。结论:利用简易呼吸器控制呼吸可以有效消减MRI中的呼吸伪影,但操作相对复杂,须熟练掌握气管插管术。

Objective To investigate the methods to limit or eliminate in magnetic resonance imaging for tracking planted stem cells. Methods the artifacts caused by respiratory movement Acute myocardial infarction （AMI） models were successfully established in 21 swines. 1 week later, the bone marrow mononuclear cells（BM-MNCs） labeled with superparamagnetic iron oxide nanoparticles（SPIOs） were transplanted via intra-coronary infusion（6 swines was injected with isotonic Na chloride）. MRI was performed with a 3.0 T MR scanner after 4 weeks. Method one（ n = 8, 2 cases were from control group） ：swines were under general anesthesia, fixed with chest bandage before MRI was performed;Method two（n = 13, 4 cases were from control group） ：swines were anaesthetized and fixed as method one. During image acquisition, the swines were controlled apnea with bag respirator. Image quality was classified in three grades： excellent, intermediate or bad. Results In method one, image quality was rated excellent in 2 cases, intermediate in 3 cases, bad in 3 cases; In method two, image quality was rated excellent in 5 cases, intermediate in 6 cases, bad in 1 case, and one swine died because of subcutaneous emphysema. Method two was better than method one obviously. Conclusion Controlled apnea with bag respirator is highly effective in swines for eliminating respiratory motion artifacts, resulting in greatly improved image quality and spatial resolution.