磁共振剪影在显示三叉神经和责任血管关系中的应用与序列优化

目的探索磁共振剪影在显示脑池段三叉神经与周围血管空间关系的应用及相关序列方案的优化。材料与方法 2015年1月至2016年7月,使用3.0T MRI对德阳市人民医院84例疑似三叉神经痛患者行三维时间飞跃法磁共振血管成像(three dimensional time of flight magnetic resonance angiography,3D-TOFMRA)、三维平衡式快速场回波(three dimensional balanced fast field gradient echo,3D-B-FFE)、增强磁共振血管造影(contrast enhanced magnetic resonance angiography,CE-MRA)扫描。然后剪影:用CE-MRA的图像减去3D-B-FFE分别乘以100%、40%、10%系数的图像(剪影法)得到剪影后的A、B、C组图像;3D-TOF-MRA序列的图像减去3D-B-FFE乘以40%系数的图像得到剪影后的D组图像。计算A、B、C、D 4组图像中三叉神经的信噪比(signal to noise ratio,SNR),动静脉血管与三叉神经的对比噪声比(contrast to noise ratio,CNR)和信号强度比(signal intensity ratio,SIR)。对比分析3D-TOF-MRA联合3D-B-FFE与剪影法B组图像判断患侧神经接触血管的情况。结果 A、B、C 3组比较,三叉神经SNR、动静脉与三叉神经CNR、静脉与三叉神经SIR,各组间差异有统计学意义(P0.05),动脉与三叉神经SIR差异无统计学意义(P0.05)。B、D两组比较,三叉神经SNR、动脉与三叉神经CNR和SIR差异无统计学意义(P0.05),而静脉与三叉神经CNR和SIR差异有统计学意义(P0.05)。3D-TOF-MRA联合3D-B-FFE与剪影法B组图像判断血管和神经关系中,两种方法阳性率差异无统计学意义(P0.05)。两种方法诊断同为阳性的患者中,B组图像挤压变形率大于3D-TOF-MRA联合3D-B-FFE(P0.05)。结论 CE-MRA和乘以40%系数的3D-B-FFE剪影,使脑脊液为低信号,神经为等信号,动静脉血管为高信号,其显示三叉神经脑池段与周围血管间的空间关系优势显著。

Application and sequence optimization of MRI subtraction in showing trigeminal nerve and blood vessels

Objective: To explore the application and sequence optimization of MR silhouette in the display of relation between trigeminal nerve of intracisternal segment and surrounding blood vessels. Materials and Methods: From January 2015 to July 2016, 84 patients with suspected trigeminal neuralgia from people's hospital of Deyang city were treated with 3T MRI for 3D-TOF-MRA, 3D-B-FFE and CE-MRA. And then silhouette: the image of CE-MRA minus that of 3D-B-FFE multiplied by the 100%, 40%, 10% coefficient (silhouette method) to obtain the images of group A, B, C after silhouetting, and 3D-TOF-MRA minus 3D-B-FFE multiplied by the image of 40% coefficient to obtain the image of group D. Calculation was done to obtain the singal to noise ratio (SNR) of trigeminal nerve, contrast to noise ratio (CNR) and singal intensity ratio (SIR) of arteries and veins versus trigeminal nerve in the images of group A, B, C and D. The 3D-TOF-MRA combined with 3D-B-FFE and group B of silhouette method were analyzed and compared to determine the affected nerve's contacting with blood vessels. Results: Groups A, B, C were compared, where SNR of trigeminal nerve, CNR of arteries and veins versus trigeminal nerve, and SIR of veins versus trigeminal nerve all had statistical significance (P<0.05), and SIR of arteries and trigeminal nerve had no statistical significance (P>0.05). Groups B, D were compared, where SNR of trigeminal nerve, and CNR and SIR of arteries versus trigeminal nerve had no statistical significance (P>0.05), while CNR and SIR of veins versus trigeminal nerve had statistical significance (P<0.05). In determining the relation between blood vessel and nerve by 3D-TOF-MRA combined with 3D-B-FFE and group B of silhouette method, there was no significant difference in the positive rate of two methods (P>0.05). In the patients diagnosed as positive by both two methods, compressional deformation rate of group B image was greater than that of 3D-TOF-MRA combined with 3D-B-FFE (P<0.05). Conclusion: Silhouette of CE-MRA and 3D-B-FFE multiplied by 40% coefficients make the cerebrospinal fluid low signal, the nerve equal signal, and arteriovenous vessel high signal, which has a strong ability to display the space relation between trigeminal nerve of intracisternal segment and surrounding blood vessel.