3.0T MR SPACE序列与传统关节软骨三维成像序列比较研究

Comparative Study of FS 3D SPACE Sequence and Conventional 3D Sequences in Articular Cartilage at 3Tesla

目的通过比较软骨信号噪声比(SNR)和对比噪声比(CNR),分析临床三维MR序列显示软骨的效果。资料与方法选取25名健康志愿者进行软骨MRI(年龄21～29岁,平均24岁),使用Siemens Magnetom Trio Tim3.0T超导型磁共振成像仪和膝关节专用线圈。应用:(1)脂肪抑制快速小角度激发(fast low angle shot,FLASH)序列;(2)FLASH序列+水激发(water-excitation,WE);(3)双回波稳态进动(dualecho steady state,DESS)序列;(4)真稳态进动快速成像(true fast imaging with steady-state precession,True-FISP)序列;(5)三维质子加权快速自旋回波(sampling perfection with application-optimized contrast using different flip angle evolutions,SPACE)序列;(6)二维脂肪抑制快速自旋回波质子密度加权成像(fat-suppressed-2D-fast spine cho-proton density weight image,2D-FS-FSE-PD-WI)序列。在股骨髁间凹中央层面分别测量股骨髁软骨、股骨干骺端骨髓、腓肠肌和背景噪声信号强度(SI),计算软骨SNR和软骨-关节液、软骨-骨髓、软骨-肌肉CNR,同时对不同序列显示软骨的能力进行评价。结果3D-FLASH-WE和SPACE序列软骨SNR和软骨/关节液、软骨/脊髓CNR最高(P<0.05),软骨可视度较高。结论在所有三维软骨成像序列中,FLASH和SPACE均能有效显示软骨。而3D-SPACE序列是一种新的MR软骨成像序列,能进行不同加权图像的扫描,对于关节软骨病变的诊断有潜在应用价值。

Objective To investigate the ability of clinical cartilage magnetic resonance imaging through signal noise（SNR） and contrast-noise-Ratio （CNR） analysis.Materials and Methods 25 healthy volunteers （from 21 to 29 years,mean age 24 years） underwent MRI scan of the knee at 3T （Siemens,MAGNETOM Trio,A Tim System） using an 8 channel knee coil. 5 different 3D techniques were used for cartilage imaging：（1）3D FLASH,（2）3D FLASH ＋water-excited,（3） 3D DESS,（4）3D-TrueFISP,（5）3D SPACE （TSE technique with variable flip-angle）,（6）conventional 2D TSE PDWI multi-slice protocol with fat saturation. The signal intensity （SI） of the cartilage in femoral condyle,femoral metaphysic,ossium,gastrocnemius and background noise was measured in femoral condyle fossa,then the cartilage SNR and CNR between cartlage and medulla ossium,synovia and myoideum were calculated,and the ability of different 3D different sequences MR imaging was evaluated.Results 3D SPACE and 3D FLASH WE had a significantly （P0.05） higher SNR for cartilage and higher CNR between cartilage and fluid,marrow than that for other MR sequences.（P0.05）,and also yielded higher cartilage visibility than other sequences （P0.05）.Conclusion 3D-SAPCE sequence is a promising new MR imaging sequence for 3D cartilage diagnosis.