比较优化STIR和IDEAL两种脂肪抑制技术在金属植入物MRI的应用价值

Comparison of the Value of Optimized STIR and IDEAL Fat Suppression Techniques in MRI of Patients with Metal Implants

目的比较优化短反转恢复(Short TI Inversion Recovery,STIR)和三点非对称法脂肪抑制技术(Iterative Dixon of Water-fat with Echo Asymmetry and Least-squares Estimation,IDEAL)对金属植入物磁共振成像(Magnetic Resonance Imaging,MRI)图像质量的影响。方法选取腰椎金属内固定术后需行MRI检查的患者30例,行常规序列以及优化STIR、IDEAL序列扫描,通过对感兴趣区信号的强度值分别计算信噪比(Signal to Noise Ratio,SNR)和信噪比(Contrast to Noise Ratio,CNR),对数据结果做统计学分析;对脂肪抑制均匀性、金属伪影大小进行主观评价。结果优化STIR和IDEAL两种方法图像信噪比分别为:19.26±0.96、20.26±1.24(t=-2.94,P<0.01);图像噪声比分别为:7.03±0.94、8.28±0.97(t=-6.07,P<0.01);主观评分脂肪抑制的均匀性分别为:3.47±0.51、3.63±0.50(t=1.37,P>0.05);金属伪影的大小分别为:3.68±0.67,3.74±0.65(t=-0.57,P>0.05)。结论IDEAL技术在脂肪抑制均匀性、金属伪影、图像信噪比等图像质量方面和优化STIR脂肪抑制技术相当,并且可以得到更好的SNR和CNR。因此在机器条件允许的情况下,对于金属植入物的患者可以选择IDEAL脂肪抑制技术进行检查。

Objective To compare the effects of optimized short TI inversion recovery(STIR)and iterative dixon of water-fat with echo asymmetry and least-squares estimation(IDEAL)fat suppression technique on MRI image quality of metal implants.Methods Thirty patients requiring MRI examination after lumbar metal fixation were selected for routine,optimized STIR and IDEAL sequence scan.The signal to noise ratio(SNR)and contrast to noise ratio(CNR)of region of interests signal intensity were calculated and statistically analyzed.The uniformity of fat inhibition and the size of metal artifact were subjectively evaluated.Results The SNR of optimized STIR and IDEAL fat suppression methods were:19.26±0.96,20.26±1.24(t=-2.94,P<0.01);The CNR of the images were:7.03±0.94,8.28±0.97(t=-6.07,P<0.01).Subjective scoring uniformity of fat suppression were:3.47±0.51,3.63±0.50(t=1.37,P>0.05);the size of image metal artifacts were:3.68±0.67,3.74±0.65(t=-0.57,P>0.05).Conclusion IDEAL technology is comparable to STIR fat suppression technology in terms of fat suppression uniformity,metal artifacts,image signal-to-noise ratio,and results in better SNR and CNR.Therefore,if the machine conditions allows,patients with metal implants can choose IDEAL fat transplantation technology for examination.