肝脏MR灌注成像技术方法的优化研究

目的优化肝脏MR灌注成像的扫描技术方案.方法采用单层2D FSPGR序列对40例无肝脏疾病和30例肝硬化行MR肝脏灌注扫描.将受检者随机分为4组.A、B组各含5例无肝脏病变受检者,快速团注对比剂(3.5 ml/s)后连续扫描100 s,A组采用经肝门单层横断面扫描,平静呼吸,B组采用单层斜冠状层面(同时包含门静脉主干、腹主动脉、肝实质),屏气状态扫描;C、D组各包含15例无肝脏病变受检者及15例肝硬化患者,均采用单层斜冠状层面扫描,平静呼吸,C组于注射对比剂后连续扫描60 s;D组则连续扫描100 s.分析各组受检者的时间信号强度曲线、峰值时间和肝脏灌注指数.结果A、D组比较,采用单层斜冠位扫描方位可以避免呼吸运动导致的扫描层面的上下移动,并且避免腹主动脉的流入增强效应;B、D组比较,显示采用平静呼吸可以避免屏气后大幅度换气导致的时间信号强度曲线(TIC)大幅度波动.C、D两组正常肝脏及肝硬化患者门静脉和肝实质峰值的时间比较均无统计意义的组间差异(P＞0.05);C组肝实质TIC未显示峰段.D组正常肝脏与硬化患者的TIC峰值时间和肝脏灌注指数之间均有统计意义差异(P＜0.05).结论采用单层2D FSPGR行动态增强MR肝灌注成像时,选用斜冠状层面,平静呼吸,团注对比剂后连续扫描100s更有利于肝脏疾病患者MR灌注量化评估.

Optimization of hepatic MR perfusion imaging protocol

Objective To optimize the protocol of hepatic MR perfusion imaging. Methods Forty cases without liver diseases and 30 cirrhotic patients underwent hepatic MR perfusion imaging by using a single slice 2D FSPGR sequence. These cases were grouped into A, B, C and D, randomly. Group A and B contained 5 normal adults in each and were scanned for 100 s continuously after the bolus injection of Gd-DTPA. A transverse section passing the hepatic porta and quiet breath in group A, an oblique coronal section (containing the abdominal aorta, the portal vein and the right liver lobe) and breath holding in group B. Group C and D contained 15 normal adults and 15 cirrhotic patients in each, and both used an oblique coronal section and quiet breath. 60 s scan time after bolus injection of Gd-DTPA was used in group C and 100s in group D. The time-intensity curve (TIC), peak time and hepatic perfusion index of each group were analyzed. Results Comparing group A and D, the oblique coronal scan plane could avoid the movement artifacts and the in flow enhancement effect of the abdominal aorta. Comparing group B and D, quiet breath could avoid the marked fluctuation of the TIC caused after breath holding. Comparing Group C and D, the 60 s scan time was not enough for the liver TIC to show its peak enhancement in Group C. Conclusion When using a single slice 2D FSPGR sequence, oblique coronal scan plane, quiet breath and 100 s scan time is more suitable for hepatic MR perfusion imaging.