Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tuebingen, Germany.
Magn Reson Med. 2013 Jul;70(1):184-92. doi: 10.1002/mrm.24435. Epub 2012 Jul 31.
Off-resonance radiofrequency saturation pulses applied prior to regular excitation in MR sequences can be used to modify signal contrast based on magnetization transfer and direct saturation effects. Clinical applicability and value of ultrashort echo time sequences combined with off-resonance saturation pulses was tested in 16 healthy and 14 tendinopathic as well as paratendinopathic Achilles tendons in vivo at 3 T. A 3D ultrashort echo time sequence in combination with a gaussian off-resonance saturation pulse (frequency offset: 1000-5000 Hz) was used to modify the detectable MR signal intensity from the Achilles tendon. Off-resonance saturation ratio was calculated as the relative reduction in signal intensity under selective off-resonance saturation in relation to a reference measurement without any saturation pulse. Off-resonance saturation ratio in tendons of healthy volunteers ranged from 0.52 ± 0.06 (1000 Hz) to 0.24 ± 0.02 (5000 Hz), whereas symptomatic tendinopathic tendons (0.35 ± 0.04 to 0.17 ± 0.02) and asymptomatic tendinopathic tendons (0.41 ± 0.06 to 0.21 ± 0.02) showed significantly lower mean off-resonance saturation ratio values. Off-resonance saturation ratio values might provide a sensitive and quantitative marker for assessment of pathological microstructure alterations of the Achilles tendon.
在磁共振序列中常规激发之前应用的离频射频饱和脉冲可用于基于磁化传递和直接饱和效应来改变信号对比。在 3T 下，对 16 个健康和 14 个腱病和腱旁腱病的跟腱进行了体内研究，测试了结合离频饱和脉冲的超短回波时间序列的临床适用性和价值。使用三维超短回波时间序列结合高斯离频饱和脉冲（频率偏移：1000-5000Hz）来改变跟腱的可检测磁共振信号强度。离频饱和比是在选择性离频饱和下相对于没有任何饱和脉冲的参考测量的信号强度相对降低来计算的。健康志愿者的肌腱中的离频饱和比范围为 0.52±0.06（1000Hz）至 0.24±0.02（5000Hz），而有症状的腱病性肌腱（0.35±0.04 至 0.17±0.02）和无症状的腱病性肌腱（0.41±0.06 至 0.21±0.02）显示出明显更低的平均离频饱和比值。离频饱和比值可能是评估跟腱病理微观结构改变的敏感和定量标志物。
