Department of Electrical Engineering, Stanford University, Stanford, California, USA.
Magn Reson Med. 2010 Mar;63(3):790-6. doi: 10.1002/mrm.22271.
As a noninvasive modality, MR is attractive for in vivo skin imaging. Its unique soft tissue contrast makes it an ideal imaging modality to study the skin water content and to resolve the different skin layers. In this work, the challenges of in vivo high-resolution skin imaging are addressed. Three 3D Cartesian sequences are customized to achieve high-resolution imaging and their respective performance is evaluated. The balanced steady-state free precession (bSSFP) and gradient echo (GRE) sequences are fast but can be sensitive to off-resonance artifacts. The fast large-angle spin echo (FLASE) sequence provides a sharp depiction of the hypodermis structures but results in more specific absorption rate (SAR). The effect of increasing the field strength is assessed. As compared to 1.5 T, signal-to-noise ratio at 3 T slightly increases in the hypodermis and almost doubles in the dermis. The need for fat/water separation is acknowledged and a solution using an interleaved three-point Dixon method and an iterative reconstruction is shown to be effective. The effects of motion are analyzed and two techniques to prevent motion and correct for it are evaluated. Images with 117 x 117 x 500 microm(3) resolution are obtained in imaging times under 6 min.
作为一种非侵入性的方式，磁共振成像（MRI）在体内皮肤成像方面具有吸引力。其独特的软组织对比度使其成为研究皮肤水分含量和分辨不同皮肤层的理想成像方式。在这项工作中，我们解决了体内高分辨率皮肤成像的挑战。定制了三个 3D 笛卡尔序列以实现高分辨率成像，并评估了它们各自的性能。平衡稳态自由进动（bSSFP）和梯度回波（GRE）序列速度快，但可能对离共振伪影敏感。快速大角度自旋回波（FLASE）序列可以清晰地描绘皮下组织结构，但会导致更高的特定吸收率（SAR）。评估了增加磁场强度的效果。与 1.5 T 相比，3 T 时皮下组织的信噪比略有增加，真皮中的信噪比几乎增加了一倍。需要脂肪/水分离，并且使用交错三点 Dixon 方法和迭代重建的解决方案被证明是有效的。分析了运动的影响，并评估了两种防止和校正运动的技术。在不到 6 分钟的成像时间内，获得了具有 117 x 117 x 500 微米（3）分辨率的图像。
