Center for Biomedical Imaging/Hospital for Joint Diseases, Department of Radiology, NYU Langone Medical Center, New York, New York, USA.
J Magn Reson Imaging. 2010 Mar;31(3):740-6. doi: 10.1002/jmri.22072.
To determine the feasibility of performing MRI of the wrist at 7 Tesla (T) with parallel imaging and to evaluate how acceleration factors (AF) affect signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image quality.
This study had institutional review board approval. A four-transmit eight-receive channel array coil was constructed in-house. Nine healthy subjects were scanned on a 7T whole-body MR scanner. Coronal and axial images of cartilage and trabecular bone micro-architecture (3D-Fast Low Angle Shot (FLASH) with and without fat suppression, repetition time/echo time = 20 ms/4.5 ms, flip angle = 10 degrees , 0.169-0.195 x 0.169-0.195 mm, 0.5-1 mm slice thickness) were obtained with AF 1, 2, 3, 4. T1-weighted fast spin-echo (FSE), proton density-weighted FSE, and multiple-echo data image combination (MEDIC) sequences were also performed. SNR and CNR were measured. Three musculoskeletal radiologists rated image quality. Linear correlation analysis and paired t-tests were performed.
At higher AF, SNR and CNR decreased linearly for cartilage, muscle, and trabecular bone (r < -0.98). At AF 4, reductions in SNR/CNR were:52%/60% (cartilage), 72%/63% (muscle), 45%/50% (trabecular bone). Radiologists scored images with AF 1 and 2 as near-excellent, AF 3 as good-to-excellent (P = 0.075), and AF 4 as average-to-good (P = 0.11).
It is feasible to perform high resolution 7T MRI of the wrist with parallel imaging. SNR and CNR decrease with higher AF, but image quality remains above-average.
确定在 7 特斯拉（T）下使用并行成像进行腕关节 MRI 的可行性，并评估加速因子（AF）如何影响信噪比（SNR）、对比噪声比（CNR）和图像质量。
本研究获得了机构审查委员会的批准。我们自行构建了一个四发射八接收通道阵列线圈。9 名健康受试者在 7T 全身磁共振扫描仪上进行了扫描。获得了软骨和小梁骨微观结构的冠状面和轴面图像（3D-Fast Low Angle Shot（FLASH），有和没有脂肪抑制，重复时间/回波时间=20ms/4.5ms，翻转角=10°，0.169-0.195×0.169-0.195mm，0.5-1mm 层厚），并使用 AF 1、2、3、4 进行采集。还进行了 T1 加权快速自旋回波（FSE）、质子密度加权 FSE 和多回波数据图像组合（MEDIC）序列。测量了 SNR 和 CNR。三位肌肉骨骼放射科医生对图像质量进行了评分。进行了线性相关分析和配对 t 检验。
在更高的 AF 下，软骨、肌肉和小梁骨的 SNR 和 CNR 呈线性下降（r<−0.98）。在 AF 4 时，SNR/CNR 的降低分别为：52%/60%（软骨），72%/63%（肌肉），45%/50%（小梁骨）。放射科医生对 AF 1 和 2 的图像评分近乎优秀，对 AF 3 的图像评分良好到优秀（P=0.075），对 AF 4 的图像评分平均到良好（P=0.11）。
在并行成像的帮助下，在 7T 下进行腕关节高分辨率 MRI 是可行的。随着 AF 的增加，SNR 和 CNR 会降低，但图像质量仍保持在平均水平以上。
