Development of MR elastography using MRI system resonance

磁共振弹性成像(MRE)是一种定量评估组织粘弹性的技术。在大多数MRE研究中，外部驱动器被用来在组织内产生波。已经证明，由成像梯度瓣的脉冲引起的患者床面的振动可以用作MRE的机械驱动机构。该方法受到振动幅值较低的限制。因此，很难测量能够充分分辨体内小组织结构的高分辨率存储模量图(弹性图)。在这项研究中，我们提出了一种方法来改进这种方法，将开关梯度感应振动与传统的磁阻抗脉冲序列相结合。优化开关梯度诱导振动频率，可获得足够的振动幅值。结果表明，该系统可以实现粘弹性的定量测量。

Magnetic resonance elastography (MRE) is a technique for quantitative evaluation of the viscoelasticity of tissue. In most MRE studies an external driver is used to generate waves within tissue. It has been demonstrated that the vibrations of the patient bed that result from the impulse of an imaging gradient lobe can be used as a mechanical driving mechanism for MRE. The method is limited by the low amplitude of the vibrations. Consequently, it is difficult to measure high-resolution storage modulus maps (elastograms) that are able to sufficiently resolve small in vivo tissue structure. In this study, we propose a way to improve this method by using switching-gradient induced vibration in conjunction with a conventional MRE pulse sequence. Sufficient vibration amplitude was available when the switching-gradient induced vibration frequency was optimized. The results indicate that proposed system may enable quantitative measurement of viscoelasticity.