猪关节软骨损伤MR成像实验研究

Experimental study on MR diagnosis of articular cartilage injury in porcine knee joint

目的观察MR三维重建图像显示关节软骨损伤病变的能力及测量病变大小的准确性。方法采用新鲜猪膝关节,以外科方法制作2～4级的关节软骨损伤标本并进行MR扫描,最后在工作站对图像进行二维和三维重建并测量,与标本的实际测量结果相对照。结果按照1、1.5、3mm扫描层厚分组,3、4级损伤的SSD三维重建图像测量值的平均百分误差比较,P<0.01。SSD和MIP2种三维重建方式测量误差的差异具有统计学意义(P<0.05)。3组测量值比较差异具有显著的统计意义(P<0.01)。SSD三维重建图像对4级损伤测量的百分误差最小。3、4级损伤测量值差异具有统计意义(P<0.05)。测量关节软骨病变大小在1mm扫描层厚的SSD三维重建图像上较二维磁共振图像更为准确(P<0.05)。结论三维重建测量误差的大小与MR扫描层厚、三维重建方式、损伤区的大小和关节软骨损伤的程度等有关。关节软骨的三维重建图像能够较真实的反映关节软骨表面的不规则形态。

Objective To assess the accuracy of three-dimensional reconstruction based on 3D-FISP-FS sequence magnetic resonance images of articular cartilage lesions. Methods Five frestdy slaughtered porcine knees were used in this study. Articular cartilage injuries of grade-2, grade-3 and grade-4 were created on articular surfaces of the five porcine knee joints. The five porcine knees were scanned using a Siemens symphony magnetic resonance imaging system and a flex coil. Using an Advantage Workstation 3.1 of General Electric Medical System, the MR images of FS-3D-FISP sequence were reconstructed into two and three dimeosional images. Results According to the MR scan thickness, all the specimens were divided into three groups（ 1 mm, 1.5 mm, 3 mm）, and Friedman Test was performed （P 〈 0.01 ） . Friedman Test was performed to evaluate the difference between SSD and MIP, which showed a statistical difference（ P 〈 0. 05）. With the SSD reconstruction image the lesions could be measured more accurately in case of higher SNR. The percentage error of the measurement on surface reconstruction image was related to the lesions dimensions. Analysis of variance was performed for three groups, which showed a significant statistical difference （P 〈 0.01） .Mann-Whitney U test was performed in tow groups （articular cartilage grade 3 and 4）, which showed a statistical difference （P 〈 0.05） . Using three dimensional reconstruction images of 1mm to measure cartilage lesion dimensions was more accurately than using tow dimensional MR images. Friedman Test was performed （ P 〈 0. 05）. Conclusion The percentage error of the measurement on three-dimensional reconstruction image is related to the MR scan thickness, the method of three-dimensional reconstruction, the lesion＇ s dimensions and the lesion＇ s degree. The three-dimensional reconstruction of cartilage from thin-section MR imaging can show irregadarities of cartilage surface.