目的比较3种高分辨率动态MRI方法评价颞下颌关节盘和髁突运动的图像质量。方法对25例疑似颞下颌关节紊乱病患者进行单次快速自旋回波(SSFSE)检查,采用稳态采集的快速成像(FIESTA),和倾斜矢状位上的损坏的梯度回波(SPGR)。两名放射科医生采用双盲法对图像进行主观和客观评价。主观评价包括下颌髁突信号强度,关节盘,关节盘周围的软组织,和翼外肌,关节盘和髁之间的对比,关节盘和周围软组织之间的对比,髁突运动,和圆盘运动。客观评价指标包括图像信号强度、信噪比(SNR),和对比度噪声比(CNR)。比较了三个序列的图像质量的主观和客观指标。结果SSFSE序列与FIESTA和SPGR序列相比,关节盘信号强度较低,髁突及其周围软组织信号强度较高(均P<0.001)。SPGR序列显示翼外肌的信号强度高于SSFSE和FIESTA序列(P=0.017,P<0.001)。在三个序列中,SSFSE序列显示最清晰的关节盘结构(χ2=41.952,P<0.001),关节盘与髁间对比最强(χ2=35.379,P<0.001),关节盘与周围软组织的对比度最强(χ2=27.324,P<0.001),关节盘运动最清晰(χ2=44.655,P<0.001)。SSFSE和FIESTA序列显示椎间盘移位和减少的比例高于SPGR序列(均P<0.001)。CNR(χ2=21.400,P<0.001),信噪比(χ2=34.880,P<0.001),和髁信号强度(F=337.151,P<0.001)表明SSFSE之间存在差异,FIESTA,和SPGR序列。SSFSE序列的CNR高于FIESTA序列(P<0.001),SSFSE和SPGR序列之间无显著差异(P=0.472)。此外,SSFSE序列的信噪比和信号强度均高于FIESTA和SPGR序列(均P<0.001)。结论SSFSE序列可以观察到最佳的图像质量,可以很好地显示颞下颌关节的结构和运动。因此,SSFSE是检查颞下颌关节运动的首选方法。
Objective To compare the image quality of three high-resolution dynamic MRI methods for evaluating the motion of temporomandibular joint disc and condyle. Methods Twenty-five patients with suspected temporomandibular joint disorders were examined by single-shot fast spin-echo (SSFSE),fast imaging employing steady-state acquisition (FIESTA),and spoiled gradient echo (SPGR) on the oblique sagittal position.Two radiologists performed subjective and objective evaluation on the images with double-blind method.The subjective evaluation included the signal intensity of mandibular condyle,articular disc,soft tissue around articular disc,and lateral pterygoid muscle,the contrast between articular disc and condyle,the contrast between articular disc and surrounding soft tissue,condylar motion,and disc movement.The objective evaluation indexes included image signal intensity,signal-to-noise ratio (SNR),and contrast-to-noise ratio (CNR).The subjective and objective indexes of the image quality were compared between the three sequences. Results The SSFSE sequence had lower signal intensity of articular disc and higher signal intensity of condyle and surrounding soft tissue than FIESTA and SPGR sequences (all P<0.001).The SPGR sequence showed higher signal intensity of lateral pterygoid muscle than the SSFSE and FIESTA sequences (P=0.017,P<0.001).Among the three sequences,SSFSE sequence showed the clearest articular disc structure (χ2=41.952,P<0.001),the strongest contrast between articular disc and condyle (χ2=35.379,P<0.001),the strongest contrast between articular disc and surrounding soft tissue (χ2=27.324,P<0.001),and the clearest movement of articular disc (χ2=44.655,P<0.001).SSFSE and FIESTA sequences showed higher proportion of disc displacement and reduction than SPGR sequence (all P<0.001).The CNR (χ2=21.400,P<0.001),SNR (χ2=34.880,P<0.001),and condyle signal intensity (F=337.151,P<0.001) demonstrated differences among SSFSE,FIESTA,and SPGR sequences.The CNR of SSFSE sequence was higher than that of FIESTA sequence (P<0.001),while it had no significant difference between SSFSE and SPGR sequences (P=0.472).In addition,the SSFSE sequence had higher SNR and signal intensity than FIESTA and SPGR sequences (all P<0.001). Conclusion The best image quality can be observed from SSFSE sequence where both the structure and movement of temporomandibular joint are well displayed.Therefore,SSFSE is preferred for the examination of temporomandibular joint movement.