Nygren Anders T
Department of Clinical Physiology, Karolinska Institute, Stockholm Söder Hospital, Stockholm, Sweden.
J Magn Reson Imaging. 2006 Feb;23(2):177-82. doi: 10.1002/jmri.20481.
To detect skeletal muscle ischemia with transverse relaxometry after ischemic exercise.
Ten subjects with intermittent claudication were studied. T2 was measured in the gastrocnemius and soleus muscles (m. gastrocnemius and m. soleus) at rest and repeatedly after exercise during 45 minutes of recovery. Prior to MRI a symptom-limited treadmill exercise was performed, and the ankle-arm blood pressure index (AAI) was measured at rest and after exercise.
In the 14 legs with ischemic pain, a diverging response was found in the calf: T2 increased in m. gastrocnemius by 5.6% +/- 4.9%, but decreased in m. soleus by -1.2% +/- 4.4% (P < 0.001). Moreover, 13 regions in legs with ischemic pain and reduced AAI (from 0.7 +/- 0.2 at rest to 0.31 +/- 0.15 after exercise) had shortened T2 (-3.6% +/- 1.8%) immediately after exercise. This finding was most frequent in m. soleus and two regions of m. gastrocnemius. Recovery was delayed in the latter two regions.
T2 may identify ischemic muscles after hypoxic exercise. Shortened T2 suggests a reduced water content (e.g., distribution volume of water) and may affect the upslope kinetics of an extravascular perfusion tracer. The different responses to ischemia by the soleus and gastrocnemius muscle may be due in part to their different fiber type compositions.
通过缺血运动后的横向弛豫测量法检测骨骼肌缺血情况。
对10名间歇性跛行患者进行研究。在静息状态下以及运动后恢复的45分钟内多次测量腓肠肌和比目鱼肌的T2值。在进行MRI检查之前，先进行症状限制的跑步机运动，并在静息状态和运动后测量踝臂血压指数（AAI）。
在14条有缺血性疼痛的腿中，小腿出现了不同的反应：腓肠肌的T2值增加了5.6%±4.9%，而比目鱼肌的T2值下降了-1.2%±4.4%（P<0.001）。此外，13个有缺血性疼痛且AAI降低（从静息时的0.7±0.2降至运动后的0.31±0.15）的腿部区域在运动后立即出现T2缩短（-3.6%±1.8%）。这一发现最常见于比目鱼肌和腓肠肌的两个区域。后两个区域的恢复延迟。
T2可能有助于识别低氧运动后的缺血肌肉。T2缩短表明含水量降低（例如水的分布容积），可能会影响血管外灌注示踪剂的上坡动力学。比目鱼肌和腓肠肌对缺血的不同反应可能部分归因于它们不同的纤维类型组成。
