正常下肢动脉缺血模型肌肉微循环MR多序列成像研究

Discussing of Cuff-Induced Skeletal Muscle Microvascular Perfusion of Lower Extremity by MR Multiple Sequences

目的探索血氧水平依赖(BOLD)、体素内不相干运动(IVIM)、动脉自旋标记(ASL)磁共振技术研究小腿肌肉缺血灌注的可行性。方法对15名健康志愿者的一侧大腿根部给予不同程度压力,分别在加压前(P_0),收缩压基础上20 mmHg(P_(20))、收缩压基础上40 mmHg(P_(40))和释放压力后(Precovery)在3.0 T磁共振扫描仪上进行双小腿BOLD、IVIM和ASL成像。通过相应后处理软件对加压腿和对侧未加压小腿胫骨前肌、腓骨长肌、比目鱼肌、腓肠肌的BOLD-T_2~*值、IVIM-f值和ASL-BF值进行测量。通过经皮氧分压仪在成像区域测得4种状态下的经皮氧分压(TcPO_2)值作为对比参考。结果 4种不同状态下,加压侧小腿肌肉BF值、f值和T_2~*值都具有统计学意义(P<0.05),但胫骨前肌f值没有统计学意义。在P_(20)和P_(40)这两种状态下,加压侧小腿肌肉BF值和T_2~*值均明显低于加压前(P<0.008)而f值均高于加压前。在P_(40)状态下,加压侧和对照侧相比,除胫骨前肌T_2~*值无统计学意义外,其余肌肉BF值、f值和T_2~*值具有显著性差异。在P_(20)状态下加压侧和对照侧相比,两组腓肠肌的BF值和T_2~*值存在显著性差异。释放压力后所有的值趋向基线值。BF值和T_2~*值与TcPO_2呈正相关(分别ρ=0.465,P=0.001、ρ=0.522,P<0.001〗)。f值与TcPO_2呈负相关(ρ=-0.351,P=0.018)。结论 ASL-BF、BOLDT_2~*、IVIM-f值的变化可以评估小腿肌肉血流灌注情况,BF值和T_2~*值与TcPO_2值具有正相关性而f值与TcPO_2值具有负相关性。

Objective The purpose of this study was to evaluate the skeletal muscle microvascular perfusion changes in the lower extremities under cuff compression paradigm with BOLD、IVIM and ASL MRI techniques. Methods Fifteen healthy young volunteers（seven men and eight women; mean age 21 years） underwent ASL,BOLD and IVIM MR imaging,and transcutaneous oxygen pressure（TcPO2） measurement of the lower extremity at baseline,under cuff compression with pressures of 20 mmHg and 40 mmHg above systolic pressure,and at recovery. All the MRI measurements were carried out on a 3. 0 T MRI unit（HDxt,GE Healthcare） with a cardiac coil. Results Blood flow,T2^＊and f in the experimental side showed significant differences among the 4 statuses in all muscle groups（all P〈0. 05） except f in the anterior muscle group（P = 0. 236）. Whether there existed significant differences or not,blood flow and T2^＊values in the experimental side gradually decreased under 20 mmHg and 40 mmHg cuff compression statuses,while f showed a tendency to increase. Most muscle groups exhibited significant differences in parameter values between experimental and control sides when the cuff compression pressure was lifted to 40 mmHg above systolic pressure. Blood flow and T2^＊showed significant positive correlation with TcPO2 measurements（ρ = 0. 465,P = 0. 001 and ρ = 0. 522,P〈0. 001],respectively）,while f showed significant negative correlation with TcPO2 measurement（ρ =-0. 351,P = 0. 018）. Conclusion Multi-parametric MR techniques including ASL,BOLD and IVIM provide useful and complementary information about tissue perfusion in the lower extremity of healthy humans. Perfusion-related metrics derived from these techniques correlate with TcPO2 measurements.