Weaver John B, Doyley Marvin, Cheung Yvonne, Kennedy Francis, Madsen Ernest L, Van Houten Elijah E W, Paulsen Keith
Department of Radiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03755, USA.
Clin Biomech (Bristol). 2005 Mar;20(3):312-9. doi: 10.1016/j.clinbiomech.2004.11.010.
Steady state, dynamic MR elastography provides quantitative images of the shear modulus of tissues in vivo. MR elastography was evaluated for its ability to characterize the mechanical properties of the weight bearing plantar soft tissues in vivo.
MR elastography was used to image the heel fat pad and surrounding soft tissues when the subject applied a low pressure on the foot and again when the subject applied high pressure. The placement of the foot was identical for both sets of images.
The results agree well with expected trends. The shear modulus of the tissue under the calcaneus increased from 8 kPa to 12 kPa with increasing pressure while that of peripheral tissues remained constant at 8 kPa which is similar to the shear modulus of fat in breast tissue.
Preliminary results from the steady state MR elastography methods being developed to measure the shear modulus of plantar soft tissues are promising. MR elastography is sufficiently accurate to observe the change in shear modulus with changes in applied pressure and is capable of characterizing the mechanical properties of the plantar soft tissues. Detailed anatomic information can be combined with co-registered mechanical properties. MR elastography could play a significant role in understanding the weight bearing functions of the plantar soft tissues and in evaluating those structures for improved diagnosis and assessment of disease progression.
稳态动态磁共振弹性成像可提供体内组织剪切模量的定量图像。对磁共振弹性成像在体内表征负重足底软组织力学特性的能力进行了评估。
当受试者足部施加低压时，以及再次施加高压时，使用磁共振弹性成像对足跟脂肪垫及周围软组织进行成像。两组图像中足部的放置位置相同。
结果与预期趋势高度吻合。随着压力增加，跟骨下方组织的剪切模量从8千帕增加到12千帕，而周围组织的剪切模量保持在8千帕不变，这与乳腺组织中脂肪的剪切模量相似。
正在开发的用于测量足底软组织剪切模量的稳态磁共振弹性成像方法的初步结果很有前景。磁共振弹性成像足够精确，能够观察到剪切模量随施加压力的变化，并能够表征足底软组织的力学特性。详细的解剖信息可与共同配准的力学特性相结合。磁共振弹性成像在理解足底软组织的负重功能以及评估这些结构以改善疾病诊断和病情评估方面可能发挥重要作用。
