Bae Won C, Malis Vadim, Yamashita Yuichi, Mesa Anya, Vucevic Diana, Miyazaki Mitsue
Department of Radiology, University of California-San Diego, San Diego, CA 92093, USA.
Canon Medical Systems Corporation, Otawara 324-0036, Japan.
J Clin Med. 2024 Aug 6;13(16):4595. doi: 10.3390/jcm13164595.
Computed tomography (CT) is the preferred imaging modality for bone evaluation of the knee, while MRI of the bone is actively being developed. We present three techniques using short-interval delta ultrashort echo time (δUTE), field echo (FE), and FE with high resolution-deep learning reconstruction (HR-DLR) for direct bone MRI. Knees of healthy volunteers ( = 5, 3 females, 38 ± 17.2 years old) were imaged. CT-like images were generated by averaging images from multiple echoes and inverting. The bone signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were determined. The δUTE depicted a cortical bone with high signal intensity but could not resolve trabeculae. In contrast, both the FE and FE HR-DLR images depicted cortical and trabecular bone with high signal. Quantitatively, while δUTE had a good bone SNR of ~100 and CNR of ~40 for the cortical bone, the SNR for the FE HR-DLR was significantly higher ( < 0.05), at over 400, and CNR at over 200. For 3D rendering of the bone surfaces, the δUTE provided better image contrast and separation of bone from ligaments and tendons than the FE sequences. While there still is no MRI technique that provides a perfect CT-like contrast, continued advancement of MRI techniques may provide benefits for specific use cases.
计算机断层扫描（CT）是评估膝关节骨骼的首选成像方式，而骨骼磁共振成像（MRI）也在积极研发中。我们展示了三种使用短间隔增量超短回波时间（δUTE）、场回波（FE）以及具有高分辨率深度学习重建（HR-DLR）的FE技术进行直接骨骼MRI成像。对健康志愿者（n = 5，3名女性，38±17.2岁）的膝关节进行成像。通过对多个回波的图像进行平均并反转来生成类似CT的图像。测定骨骼的信噪比（SNR）和对比噪声比（CNR）。δUTE显示皮质骨具有高信号强度，但无法分辨小梁。相比之下，FE和FE HR-DLR图像均显示皮质骨和小梁骨具有高信号。在定量方面，虽然δUTE对皮质骨的骨骼SNR约为100，CNR约为40，但FE HR-DLR的SNR显著更高（p < 0.05），超过400，CNR超过200。对于骨骼表面的三维渲染，与FE序列相比，δUTE提供了更好的图像对比度以及骨骼与韧带和肌腱之间的分离度。虽然目前仍没有一种MRI技术能提供完美的类似CT的对比度，但MRI技术的持续进步可能会为特定应用场景带来益处。
