RS-EPI与SS-EPI序列在眼眶弥散加权成像中的对照研究

目的 探讨分段读出平面回波成像（RS-EPI）在眼眶DWI中应用的可行性，并与单次激发平面回波成像（SS-EPI）对照。方法 选取42名健康受试者，进行眼眶RS-EPI（RS-EPI组）和SS-EPI（SS-EPI组）扫描。对2组图像的正常解剖结构显示能力、脂肪抑制效果、伪影（主要眶尖和颞骨处）及图像综合质量进行评分；定量分析2组图像中玻璃体SNR、眼球前后和左右方向的几何变形率（GDR）、玻璃体和脑桥的ADC值；并进行统计学分析。结果 RS-EPI对正常解剖结构的显示能力（P=0.0090）、减少伪影能力（P<0.0001）及图像的综合质量（P<0.0001）均优于SS-EPI。两者脂肪抑制效果的差异无统计学意义（P=0.7539）。RS-EPI的眼球前后和左右方向GDR（P=0.0014、0.0017）及SNR（P=0.0040）较SS-EPI显著降低；而两组图像玻璃体、脑桥的ADC值差异均无统计学意义（P=0.1438、0.1262）。结论 眼眶3.0TMR成像中，RS-EPI可提供较常规SS-EPI质量更高的DWI图像。

Comparison study of readout-segmented EPI and single-shot EPI in DWI of orbit in healthy adults

Objective To explore the feasibility of the applicatoin of readout-segmented echo-planar imaging (RS-EPI) at 3.0T MR of the orbit DWI and compared with single-shot echo-planar imaging (SS-EPI).Methods Forty-two volunteers underwent both standard SS-EPI and RS-EPI DWI of the orbit at a 3.0T MR unit. Two sets of DWI images were independently qualitatively scored in the number of distinguishable normal structures, fat suppression, ghosting artifact and overall image quality. SNR of the vitreous body, geometric distortion ratio (GDR) in both anterior-posterior (AP) and right-left (RL) direction, and ADC value of the vitreous body and pons were also quantitatively calculated and compared between two sets of DWI images. The statistical analysis was performed. Results For qualitative assessment, the RS-EPI was superior to SS-EPI on the number of distinguishable normal structures (P=0.009 0), ghosting artifact (P<0.000 1), and overall image quality (P<0.000 1), while no significant difference was found on fat suppression (P=0.753 9). For quantitative assessment, RS-EPI had significantly lower GDR than the SS-EPI in both AP and RL direction (P=0.001 4, 0.001 7). The SNR in RS-EPI was significantly lower than that of SS-EPI (P=0.004 0). Meanwhile, there was no significant difference of ADC on vitreous body and pons between RS-EPI and SS-EPI (P=0.143 8, 0.126 2).Conclusion The RS-EPI can provide better image quality than SS-EPI protocol in orbital DWI at 3.0T MR imaging.