1 All authors: Department of Radiology and Imaging Science, Indiana University School of Medicine, 950 W Walnut St, R2 E124, Indianapolis, IN 46202.
AJR Am J Roentgenol. 2014 Sep;203(3):W307-14. doi: 10.2214/AJR.13.10791.
The purpose of this article is to evaluate and compare the artifacts caused by metal implants in breast MR images acquired with dual-echo Dixon and two conventional fat-suppression techniques.
Two types of biopsy markers were embedded into a uniform fat-water emulsion. T1-weighted gradient-echo images were acquired on a clinical 3-T MRI scanner with three different fat-suppression techniques-conventional or quick fat saturation, spectrally selective adiabatic inversion recovery (SPAIR), and dual-echo Dixon-and the 3D volumes of artifacts were measured. Among the subjects of a clinical breast MRI study using the same scanner, five patients were found to have one or more metal implants. The artifacts in Dixon and SPAIR fat-suppressed images were evaluated by three radiologists, and the results were compared with those of the phantom study.
In the phantom study, the artifacts appeared as interleaved bright and dark rings on SPAIR and quick-fat-saturation images, whereas they appeared as dark regions with a thin bright rim on Dixon images. The artifacts imaged with the Dixon technique had the smallest total volume. However, the reviewers found larger artifact diameters on patient images using the Dixon sequence because only the central region was recognized as an artifact on the SPAIR images.
Metal implants introduce artifacts of different types and sizes, according to the different fat-suppression techniques used. The dual-echo Dixon technique produces a larger central void, allowing the implant to be easily identified, but presents a smaller overall artifact volume by obscuring less area in the image, according to a quantitative phantom study.
本文旨在评估和比较双回波 Dixon 法与两种传统脂肪抑制技术在乳腺磁共振成像中金属植入物伪影的特点。
将两种类型的活检标记物嵌入均匀的水脂乳液中。在一台临床 3.0T 磁共振扫描仪上使用三种不同的脂肪抑制技术(传统或快速饱和脂肪抑制、频谱选择反转恢复脂肪抑制和双回波 Dixon 法)采集 T1 加权梯度回波图像,并测量伪影的 3D 体积。在使用相同扫描仪的一项临床乳腺磁共振研究中,发现五例患者有一个或多个金属植入物。三位放射科医生评估 Dixon 和 SPAIR 脂肪抑制图像中的伪影,并将结果与体模研究进行比较。
在体模研究中,SPAIR 和快速饱和脂肪抑制图像上的伪影呈交错的亮暗环,而 Dixon 图像上的伪影呈暗区伴有薄亮边。Dixon 技术成像的伪影总体积最小。然而,在使用 Dixon 序列的患者图像上,观察者发现较大的伪影直径,因为 SPAIR 图像仅将中央区域识别为伪影。
根据所使用的不同脂肪抑制技术,金属植入物会产生不同类型和大小的伪影。根据一项定量体模研究,双回波 Dixon 技术产生较大的中央空洞,使植入物更容易识别,但通过使图像中较少的区域模糊,其整体伪影体积较小。