背景:最近,开发了一种全身5TMRI扫描仪,以在高场强下打开腹部成像的大门。这项前瞻性研究旨在评估5T肾脏成像的可行性,并比较图像质量。潜在的伪影,和对比度与3T
方法:40名健康志愿者在3T和5T时接受了MRI检查。MRI序列包括T1加权梯度回波(GRE),T2加权快速自旋回波,弥散加权成像,和多回波GRET2*映射。使用四点尺度评估所有序列的图像质量和伪影的存在。对于解剖成像,计算腹部器官组织的信噪比(SNR)和对比度(CR)。此外,对于功能成像,计算皮质/髓质的对比噪声比.使用Wilcoxon符号秩和检验比较3和5T图像之间的视觉评估得分和定量测量值。
结果:与3T检查相比,5T时的T1加权序列显示出明显更好的图像质量,肾静脉和动脉的显著性更高,和类似的文物。T2加权图像上的两种场强之间的图像质量相当,而在5T时观察到明显更高水平的伪影。5TMRI有助于提高腹部器官组织的SNR和CR。对于功能成像,5TMRI显示皮质髓质辨别性改良。3T和5T时肾脏的表观扩散系数差异无统计学意义。而5TMRI导致皮质和髓质的T2*值明显缩短。
结论:5TMRI可提供具有足够图像质量的肾脏解剖和功能图像。
BACKGROUND: Recently, a whole-body 5 T MRI scanner was developed to open the door of abdominal imaging at high-field strength. This prospective
study aimed to evaluate the feasibility of renal imaging at 5 T and compare the image quality, potential artifacts, and contrast ratios with 3 T.
METHODS: Forty healthy volunteers underwent MRI examination both at 3 T and 5 T. MRI sequences included T1-weighted gradient-echo (GRE), T2-weighted fast spin echo, diffusion-weighted imaging, and multi-echo GRE T2* mapping. Image quality and presence of artifacts were assessed for all sequences using four-point scales. For anatomical imaging, the signal-to-noise ratio (SNR) and contrast ratio (CR) of abdomen organ tissues were calculated. Besides, for functional imaging, the contrast-to-noise ratio of cortex/medulla was calculated. Wilcoxon signed rank-sum test was used to compare the visual evaluation scores and quantitative measurements between 3 and 5 T images.
RESULTS: Compared to 3 T examination, T1-weighted sequence at 5 T showed significantly better image quality with higher conspicuity of the renal veins and arteries, and comparable artifacts. Image quality was comparable between both field strengths on T2-weighted images, whereas a significantly higher level of artifacts was observed at 5 T. Besides, 5 T MRI contributed to higher SNR and CR for abdomen organ tissues. For functional imaging, 5 T MRI showed improved corticomedullar discrimination. There was no significant difference between apparent diffusion coefficient of renal at 3 T and 5 T, while 5 T MRI resulted in significantly shorter T2* values in both cortex and medulla.
CONCLUSIONS: 5 T MRI provides anatomical and functional images of the kidney with sufficient image quality.