两次激发SE-EPI在肝脏MRI的应用

目的比较两次激发SE-EPI与呼吸门控FSE及SSFSET2WI在肝脏的应用。方法对14名志愿者及21名肝病患者行上腹部呼吸门控FSE及SSFSE和屏气2次激发SE-EPI(TR=5999ms和1999ms)扫描。所有T2WI序列均运用脂肪抑制技术。定量分析肝脏,病灶的信噪比及肝脏-病灶的对比度噪声比,评价各序列的图像质量及伪影。结果两次激发SE-EPI与SSFSE及FSE在肝脏及病灶信噪比,肝脏-病灶对比度噪声比和图像质量方面无明显差别(P>0.05)。SE-EPI的磁敏感伪影及化学位移伪影均较FSE及SSFSE重,其运动伪影较FSE轻(P<0.05)。结论两次激发SE-EPI能够在较短时间里提供较高质量的上腹部T2WI。被检查者在扫描时可自由平静呼吸或屏气,可作为肝脏T2WI选择序列之一。

Two-shot SE-EPI in the hepatic MR imaging

Objective To compare the performance of T2 -weighted two-shot sp in-echo version of echo planar imaging (SE-EPI), respiratory-gating fast spin -echo (FSE) and single-shot fast spin echo (SSFSE) sequences for the evaluatio n of focal hepatic lesions. Methods Breath-hold two-shot SE-EPI (TR=5999ms and 1999ms) of the liver was performed in 14 healthy volunteers and 21 patients, a nd was compared with respiratory-gating T2-weithted FSE and SSFSE. The fat-su ppression technique was used in each sequence. The signal-to-noise ratio (SNR) of the liver and lesion and the contrast-to-noise ratio (CNR) of the l esion-to-liver were quantitatively analyzed. The image quality and artifacts w ere also comparatively studied. Results Quantitatively, SE_EPI, SSFSE and FSE se quences showed non-significant differences (P > 0.05) in liver/lesion CNR, SNR of Liver and lesion and the general image quality. Susceptibility artifacts and chemical shift artifacts on SE-EPI were more than SSFSE and FSE. There were few er motion and ghost artifacts on SE-EPI images compared to FSE images (P< 0.05) . Conclusion SE-EPI of the liver can provide better quality T2-weighted images in shorter acquisition times compared with respiratory-gating FSE and SSFSE. There is no particular requirement for patients to suspend their breath during the aquisition. This technique may be useful in clinical application of hepatic MR imaging.