Nygren Anders T, Greitz Dan
Department of Clinical Physiology, Karolinska Institute, Stockholm Söder Hospital, Stockholm, Sweden.
J Magn Reson Imaging. 2006 Feb;23(2):171-6. doi: 10.1002/jmri.20482.
To detect skeletal muscle ischemia with first-pass gadolinium (Gd) kinetics after exercise.
Eleven subjects with intermittent claudication performed a symptom-limited bilateral plantar flexion exercise in the magnet. Regional ROIs were placed bilaterally in the gastrocnemius and soleus muscles, and a signal intensity (SI) time-curve analysis was performed. Induced ischemia was validated prior to the MRI with the systolic ankle-arm blood pressure index (AAI) measured after a symptom-limited treadmill exercise.
Exercise induced ischemic pain in 16 of 22 legs with a significantly reduced AAI (0.31 +/- 0.15). The time to contrast arrival (TCA) was delayed in symptomatic ischemic legs vs. asymptomatic legs (16.3 +/- 6.9 seconds vs. 11.1 +/- 2.7 seconds, P < 0.05). The maximum SI during recovery was higher in the soleus muscle than in the gastrocnemius muscle in ischemic legs (1.55 +/- 0.1 vs. 1.44 +/- 0.1, P < 0.05). Symptomatic regions had a less steep upslope than asymptomatic regions (43 +/- 15 vs. 63 +/- 14, P < 0.001), with a graded upslope response to ischemia. However, a normal upslope was found in 10 of 29 ischemic regions, and some of the regions showed delayed contrast arrival, suggesting a pseudonormal upslope in ischemic regions.
Exercise-induced ischemia was detected with the use of an SI time-curve analysis. However, disregarding the arterial input function and distribution volume of the tracer may lead to misinterpretation of some ischemic regions.
通过运动后首过钆（Gd）动力学检测骨骼肌缺血情况。
11名间歇性跛行患者在磁共振成像仪中进行症状限制的双侧跖屈运动。在双侧腓肠肌和比目鱼肌放置局部感兴趣区（ROI），并进行信号强度（SI）时间曲线分析。在MRI检查前，通过症状限制的跑步机运动后测量的收缩期踝臂血压指数（AAI）验证诱导性缺血。
22条腿中有16条腿运动诱发缺血性疼痛，AAI显著降低（0.31±0.15）。有症状的缺血腿与无症状腿相比，对比剂到达时间（TCA）延迟（16.3±6.9秒对11.1±2.7秒，P<0.05）。缺血腿中，比目鱼肌恢复期间的最大SI高于腓肠肌（1.55±0.1对1.44±0.1，P<0.05）。有症状区域的上升斜率比无症状区域平缓（43±15对63±14，P<0.001），对缺血有分级上升斜率反应。然而，29个缺血区域中有10个区域上升斜率正常，部分区域显示对比剂到达延迟，提示缺血区域存在假正常上升斜率。
通过SI时间曲线分析检测到运动诱导的缺血。然而，忽略示踪剂的动脉输入函数和分布容积可能导致对某些缺血区域的错误解读。
