临床型MRI扫描大鼠胰腺技术

Techniques of Clinical Magnetic Resonance Imaging Scanner for the Imaging of Rat Pancreas

目的优化临床型MRI仪扫描大鼠胰腺的成像参数,提高其对大鼠胰腺的成像质量,为大鼠胰腺影像学实验研究提供更优的MRI图像质量和较为经济的研究方案。材料与方法 24只健康雄性Wistar大鼠随机分为常规序列组、调整序列组和优化序列组,每组8只。常规序列组采用临床型MRI仪和常规参数进行扫描。调整序列组参数调整原则为:每次扫描仅变化与T1WI或T2WI成像质量密切相关的6个参数(TR、TE、层厚、激励次数、视野和矩阵)中的1个参数,每个参数在一定范围内设定4个变化值,固定其余参数进行扫描,经2名主治医师评估成像质量,以评估意见一致的成像质量参数作为优化参数,逐步得到所有优化参数,形成优化序列组参数。优化序列组大鼠扫描成像后与常规序列组比较胰腺信号强度和信噪比。结果临床型MRI仪扫描大鼠胰腺的优化参数为,T1WI(M3D/FSPGR/15):TR 6 ms,TE 2.5 ms,层厚2 mm,激励次数8次,视野7 cm×7 cm,矩阵120×120;T2WI(FSE-XL/90):TR 4000 ms,TE 71 ms,层厚2 mm,激励次数1次,视野8 cm×8cm,矩阵192×160。优化序列组T1WI和T2WI序列大鼠胰腺信号强度(t=5.16、3.80,P<0.01)和信噪比(t=5.65、3.26,P<0.01)均显著高于常规序列组。结论优化参数可显著提高临床型MRI仪对大鼠胰腺的成像质量,为开展相关实验研究提供参考。

Purpose To optimize the imaging parameters of clinical MRI scanner in rat pancreas imaging to improve the image quality and to provide better MRI image quality and more economical research method for imaging study of rat pancreas. Materials and Methods Twenty-four healthy male Wistar rats were randomly divided into the conventional sequence（CS） group,the adjustment sequence（AS） group and the optimization sequence（OS） group,with 8 rats in each group. The rats in the CS group were scanned with conventional parameters using a clinical MRI scanner. The principle of parameter adjustment was： parameters associated with T1 WI or T2 WI imaging quality（TR,TE,slice thickness,NEX,FOV and matrix） was set with four changes,and only one of the six parameters was changed in each scan,image quality was evaluated by two senior radiologists,the parameter corresponded the best image quality evaluated consistently by two radiologists were selected as the optimal imaging parameter,all the optimized parameters were set up step by step in this way which formed the imaging parameters in OS group. The pancreatic signal intensity and signal to noise ratio was compared between CS group and OS group after imaging. Results The optimized sequence parameters in clinical MRI scanner were listed below： T1 WI sequence（M3D/FSPGR/15）： TR 6 ms,TE 2.5 ms,slice thickness 2.0 mm,NEX 8,FOV 7 cm×7 cm,Matrix 120×120; T2 WI sequence（FSE-XL/90）： TR 4000 ms,TE 71 ms,slice thickness 2.0 mm,NEX 1,FOV 8 cm×8 cm,Matrix 192×160. The pancreatic SI in T1 WI and T2 WI sequence of the OS group were significantly higher than those in the CS group（t=5.16 and 3.80,P〈0.01）,while the pancreatic SNR in T1 WI and T2 WI sequence of the OS group were significantly higher than those in the CS group（t=5.65 and 3.26,P〈0.01）. Conclusion The optimized parameters can improve the imaging quality of rat pancreas MRI significantly,thus provide a reference for the related experimental study.