Development of MR elastography using MRI system resonance

磁共振弹性成像（MRE）是一种定量评价组织粘弹性的技术。在大多数MRE研究中，外部驱动器用于在组织内产生波。已经证明，由成像梯度波瓣的脉冲引起的患者床的振动可以用作MRE的机械驱动机制。该方法受到低振幅振动的限制。因此，难以测量能够充分分辨小的体内组织结构的高分辨率储能模量图（弹性图）。在这项研究中，我们提出了一种方法来改善这种方法，通过使用开关梯度诱导振动结合传统的磁共振脉冲序列。当开关梯度诱导振动频率优化时，可获得足够的振动幅值。结果表明，所提出的系统可以实现定量测量的粘弹性。

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.