磁共振新的IDEAL序列金属植入物患者脂肪抑制技术的应用价值研究

Explore the Application Value of Fat Suppression Technology in Metal Implants Patients with New IDEAL Sequence of Magnetic Resonance

目的对比频率选择脂肪抑制技术(Frequency-Selective Fat Saturation,FS),探讨非对称回波的最小二程估算法迭代水脂分离(Iterative Dixon of Water-fat with Echo Asymmetry and Least-squares Estimation,IDEAL)技术在金属植入物患者磁共振检查中应用价值。方法选取体内(腰椎、颈椎、骨盆等)含有金属内固定行MRI检查的患者20例,做常规序列扫描及加FS、IDEAL序列扫描,对所得图像通过软件获得感兴趣区信号的强度值分别计算信噪比(Signal to Noise Ratio,SNR)和对比噪声比(Contrast to Noise Ratio,CNR),记录数据结果并做统计学分析;对脂肪抑制均匀性、金属伪影大小应用主观法进行评价。结果FS和IDEAL两种脂肪抑制方法图像SNR分别为:10.9±0.3、20.3±1.2(t=-34.3,P<0.01);图像CNR分别为5.8±0.3、8.3±1.0(t=-11.6,P<0.01);主观评分脂肪抑制均匀性分别为:2.8±0.5、3.6±0.5(t=-6.4,P<0.01);图像金属伪影大小分别为:2.8±0.6,3.7±0.7(t=-5.9,P<0.01)。结论相比于FS,IDEAL脂肪抑制技术能显著减少金属伪影,提供更加均匀的脂肪抑制图像,提高被检部位和周围软组织结构的显示效果,更有利于病灶检出及临床诊断。

Objective To compare the frequency selective fat suppression(FS) technique and explore the iterative dixon of waterfat with echo asymmetry and least-squares estimation(IDEAL) technique with the least two-way estimation of asymmetric echo in magnetic resonance imaging(MRI) of patients with metal implants. Methods Twenty patients with metal internal fixation in the body(such as lumbar spine, cervical spine, pelvis) were selected for MRI examination, and routine sequence scans and FS and IDEAL sequence scans were performed. The intensity of the region of interest signal was obtained by software on the obtained images signal to noise ratio(SNR) and contrast to noise ratio(CNR) were calculated respectively, and the data results were recorded and analyzed statistically. The subjective method was used to evaluate the uniformity of fat suppression and the size of metal artifacts. Results The image SNR of FS and IDEAL were 10.9±0.3, 20.3±1.2(t=-34.3, P<0.01), while the CNR of the images were 5.8±0.3, 8.3±1.0(t=-11.6, P<0.01). The subjective scores for fat suppression uniformity were 2.8±0.5, 3.6±0.5(t=-6.4, P<0.01), and the size of image metal artifacts were 2.8±0.6, 3.7±0.7(t=-5.9, P<0.01). Conclusion Compared with FS, IDEAL fat suppression technology can significantly reduce metal artifacts, provide a more uniform fat suppression image, improve the display effect of the examined part and surrounding soft tissue structure, and is more conducive to the detection of lesions and clinical diagnosis.