DIRECT RELATIONSHIP BETWEEN PROTON T2 AND EXERCISE INTENSITY IN SKELETAL-MUSCLE MR IMAGES
DIRECT RELATIONSHIP BETWEEN PROTON T2 AND EXERCISE INTENSITY IN SKELETAL-MUSCLE MR IMAGES
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DOI：
10.1097/00004424-199005000-00003
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发表时间：
1990-05-01
影响因子：
6.7
通讯作者：
POTCHEN, EJ
中科院分区：
文献类型：
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作者：
FISHER, MJ;MEYER, RA;POTCHEN, EJ
在t2加权磁共振（MR）图像中，运动选择性地增加活动肌肉的信号强度（SI）。如果这些SI增加随运动强度分级，则可以使用MR成像识别肌肉恢复模式。本研究的目的是确定运动产生的力量对肌肉T2值的影响。此外，我们还研究了细胞外液容量（ECV）扩张对肌肉T2值的影响。在1.5T GE磁铁中使用标准自旋回波序列收集8名志愿者运动前后的跨轴中小腿图像。运动包括连续三次踝关节背屈，以对抗分级负荷。在运动方案期间和运动方案之外，三名受试者还接受了短暂的下肢静脉阻塞（ECV扩张）。运动后背屈肌的T2值明显升高。运动时产生的平均力越大，运动后T2增加越大（T2 = 29.6 +-）。0.9的同学们。力)。运动和静脉阻塞引起的肌肉横截面积增加相当。这些等量的ECV增加并不伴随着肌肉T2的等量增加；单纯静脉闭塞导致T2增加不到5%，而运动导致T2增加14%至25%。因此，运动后T2升高与ECV升高之间的直接关系尚未确立。然而，运动期间静脉闭塞确实显著增加了前室肌T2和ECV的增加。运动后肌肉在t2加权MR图像中的对比度增强依赖于运动过程中产生的力。因此，可以根据肌肉SI的变化来评估正常和异常的运动模式。虽然ECV的增加是一个因素，但细胞内游离水的增加是运动后肌肉SI增加的主要因素。
Exercise selectively increases the signal intensities (SI) of active muscles in T2-weighted magnetic resonance (MR) images. If these SI increases are graded with exercise intensity, the identification of muscle recruitment patterns may be possible using MR imaging. The purpose of this study was to determine the effect of force generation using exercise on mucsle T2 values. Also, we examined the effects of extracellular fluid volume (ECV) expansion on muscle T2 values. Transaxial midcalf images were collected before and after exercise on eight volunteers in a 1.5T GE magnet using a standard spin echo sequence. Exercise consisted of three consecutive bouts of ankle dorsiflexion against graded loads. Three subjects also underwent brief bouts of lower leg venous occlusion (ECV expansion) during and in addition to the exercise protocol. T2 values for the dorsiflexors significantly increased after exercise. Greater mean force produced during exercise caused greater increases in T2 after exercise (T2 = 29.6 .+-. 0.9 .times. Force). Exercise and venous occlusion caused equivalent increases in muscle cross-sectional area. These equivalent increases in ECV were not accompanied by equivalent increases in muscle T2; venous occlusion alone caused less than a 5% increase in T2 while exercise caused a 14% to 25% increase. Consequently, a direct relationship between increases in T2 and in ECV after exercise was not established. Venous occlusion during exercise, however, did significantly augment the increase in T2 and ECV of the anterior compartment muscles. Contrast enhancement among muscles after exercise in T2-weighted MR images is dependent on generated force during exercise. Normal and abnormal patterns of movement, therefore, may be assessed based on changes in muscle SI. While an increase in ECV is a contributor factor, an increase in free intracellular water is the primary factor underlying an increased muscle SI after exercise.