High-resolution MRI encoding using radiofrequency phase gradients
High-resolution MRI encoding using radiofrequency phase gradients
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DOI：
10.1002/nbm.3023
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发表时间：
2013-11-01
影响因子：
2.9
通讯作者：
Tomanek, Boguslaw
中科院分区：
文献类型：
--
作者：
Sharp, Jonathan C.;King, Scott B.;Tomanek, Boguslaw
尽管MRI提供了高度诊断性的医学图像，但与x射线或超声相比，全世界患者获得这种方式的机会非常有限。其中一个原因是用于产生核磁共振编码所需的开关磁场的设备的费用和复杂性。这些场梯度也会产生强烈的噪声，并有可能引起神经刺激。我们提出了一种新的MRI编码原理，它完全不使用传统的B-0场梯度。这种新方法-发射阵列空间编码(TRASE) -仅使用谐振射频（RF）场来产生相当于传统MRI的傅里叶空间编码。在自旋回波序列中，通过相位梯度发射场的自旋重聚焦实现k空间遍历（图像编码）。构造了一个由单个发射通道驱动的发射线圈阵列，产生四个相位梯度场，从而实现两个正交空间轴的编码。在0.2 t下获得了手部和手腕的高分辨率二维编码体内MR图像。TRASE利用射频场相位梯度，提供了非常低成本的诊断和利用独特功能的新实验的可能性，例如在不受主B-0磁场干扰的情况下成像。下场成像(
Although MRI offers highly diagnostic medical imagery, patient access to this modality worldwide is very limited when compared with X-ray or ultrasound. One reason for this is the expense and complexity of the equipment used to generate the switched magnetic fields necessary for MRI encoding. These field gradients are also responsible for intense acoustic noise and have the potential to induce nerve stimulation. We present results with a new MRI encoding principle which operates entirely without the use of conventional B-0 field gradients. This new approach - Transmit Array Spatial Encoding' (TRASE) - uses only the resonant radiofrequency (RF) field to produce Fourier spatial encoding equivalent to conventional MRI. k-space traversal (image encoding) is achieved by spin refocusing with phase gradient transmit fields in spin echo trains. A transmit coil array, driven by just a single transmitter channel, was constructed to produce four phase gradient fields, which allows the encoding of two orthogonal spatial axes. High-resolution two-dimensional-encoded in vivo MR images of hand and wrist were obtained at 0.2 T. TRASE exploits RF field phase gradients, and offers the possibility of very low-cost diagnostics and novel experiments exploiting unique capabilities, such as imaging without disturbance of the main B-0 magnetic field. Lower field imaging (