3．0TMR腕关节软骨多序列成像实验研究

3.0T multiple MR sequences imaging in wrist joint cartilage

目的观察不同扫描序列及参数对腕关节软骨成像质量的影响,优化获取3D-FSPGR序列最佳扫描参数。方法选择成人尸体腕关节3个,用GE SIGNA EXITE II 3.0T磁共振扫描仪检查,MRI序列包括自旋回波T1加权像(SE T1WI)、自旋回波T2加权像(SE T2WI)、质子密度加权像(PDWI)、脂肪抑制质子加权像(FS PDWI)及三维脂肪抑制扰像梯度回波像(3D-FSPGR),其中后者采用不同的TE时间[minimum(2.2 ms)、minfull(6.6 ms)、outphase(3.2 ms)]结合不同翻转角(Flip,5°、10°2、0°、30°、60°)进行扫描,分别得到每一序列的相同层面图像并计算不同参数成像关节软骨的信噪比(SNR),软骨与骨髓、软骨与肌腱的对比噪声比(CNR)。结果①FS PD序列、3D-FSPGR序列软骨信号-噪声比较高;3D-FSPGR序列在TE/Flip(6.6 ms/30°)时具有最好的软骨与骨髓、软骨与肌腱的对比噪声比;②PDWI、FS PDWI、及3D-FSPGR序列间关节软骨的SNR对比,差异无统计学意义(P>0.05);3D-FSPGR序列软骨与骨髓、软骨与肌腱的CNR较PDWI、FS PDWI序列软骨与骨髓、软骨与肌腱的CNR差异有统计学意义(P<0.01);③SE T1WI、SE T2WI序列关节软骨SNR、软骨与骨髓、软骨与肌腱的CNR均较低,差异无统计学意义(P>0.05);与PDWI、FS PDWI3、D-FSPGR序列比较,差异有统计学意义(P<0.01)。结论3D-FSPGR在TE/Flip(6.6 ms/30°)时关节软骨显示最清晰,为关节软骨检查的最佳扫描序列;FS PDWI序列关节软骨显示较清晰,可作为关节软骨检查的常规扫描序列。

Objective To explore the effects of different scan sequences and parameters on image quality, and to obtain the optimal different 3D-FSPGR parameter sequences. Methods Three normal cadaver wrists were imaged with GE SIGNA EXITE Ⅱ 3.0TMR system. SE T1WI, FSE T2WI, PDWI, FS PDWI and 3D-FSPGR were determined, and the 3D-FSPGR sequences were achieved by varying flip angles （5,10,20,30, 60°） and combining each flip angle with different echo fime（TE） [minimum （2.2 ms）, minfull（6.6 ms）, inphase（2.2 ms） and outphase（3.2 ms）]. This gave the same layer imaging parameters for each scan sequence, Then the contrast-to-noise（C/N） ratios for cartilage versus bone marrow and the cartilage versus tendon were calculated. Results （1） The highest CNR and better SNR between cartilage and adjacent tissues were found in the 3D-SPGR T1 [TE/minfidl（6.6 ms）, Flip（30′）] sequence; （2） The SNR of articular cartilage was not statistically different among PDWI, FS PDWI and 3D-FSPGR sequences; CNR of articular cartilage with adjacent tissues in the 3D-FSPGR sequence showed significant differences compared with the PDWI and the FS PDWI sequences. There were no significant differences in all groups of 3D- FSPGR sequences; （3） In the SE T1WI and the FSE T2WI sequences, both （signal to noise ratio）SNR of articular cartilage and（contrast to noise）CNR between cartilage and adjacent tissues were decreased but significant differences were not found between them（ P 〉 0.05 ）. Compared with the other sequences, SE T1WI and FSE T2WI sequences showed statistical significances. Conclusions Among the five sequences, the optimal parameters are the 3D-FSPGR TE/flipl（6.6 ms/30°） sequence. The sequences have significant advantages compared with the other series in imaging normal cartilage of the wrist, and the 3D-FSPGR sequence is the optimal sequence for assessment of cartilage. As a conventional scan sequence, FS PDWI sequence can do a good job in imaging articular cartilage.