256层iCT O-MAR技术运用前后在体模与患者组减除椎弓根螺钉伪影的对照研究

Reducing Metal Artifacts of Pedicle Screw with the Technolgy of 256iCT O-MAR in Phantom and Patients Group

目的运用256层iCT骨科植入物金属去伪影技术（O-MAR）分别对体模及患者椎弓根螺钉伪影去除效果作对比观察,探讨O-MAR技术在减除椎弓根螺钉伪影方面的临床应用价值。方法对体模及35例腰椎内固定进行256层iCT扫描并作O-MAR重组,由2名放射诊断医师对图像质量进行独立评估,运用配对t检验分别对O-MAR技术处理前后体模的螺钉直径、伪影评分及患者组伪影长度、图像质量的去伪影效果指标进行对比评价。结果体模经O-MAR处理后螺钉直径减小,更接近真实直径;O-MAR处理前、后螺钉周围强伪影区CT值标准差（SD）的差异有统计学意义,而弱伪影区和无伪影区SD值则无统计学差异。患者组经O-MAR处理后螺钉腹侧伪影明显减小,处理前、后两者间差异有统计学意义;软组织、界面、椎弓根、椎体及椎管的图像评分O-MAR处理前、后间比较均有统计学差异,其中前3项的O-MAR处理后评分高于处理前,而后2项的处理后评分则低于处理前。结论 O-MAR技术的应用能显著减少CT图像椎弓根螺钉造成的金属伪影,提高图像质量,同时不增加辐射剂量,具有较高临床应用价值。

Objective To evaluate the effect of the technology of 256 iCT O-MAR for reducing metal artifact of pedicle screw in phantom and patients group. Methods Phanton and 35 patients underwent 256 iCT examination with O-MAR reconstruction. Two radiologists scored image quality independently. The diameter of pedicle screw,artifacts level in phantom and the length of pedicle screw artifacts,image quality in patients obtained before and after using O-MAR technology were compared by the two sample paired t test. Results In phantom： The diameter of the pedicle screw is reduced and more closer to the real value after using O-MAR. There was significant difference in the SD value in the strong artifact area around the screw before and after using O-MAR meanwhile there was no significant difference in weak and no artifact area. Patient group： The artifacts of the screw were significiantly reduced. There was significant difference in the length of artifacts before and after using O-MAR. There was statistical significance in image score of soft tissue,the edge of the screw and vertebral body,pedicle,vertebral body and spinal canal was statistically significant before and after using O-MAR. The score of the first three indicators was higher than those before using O-MAR and the score in the latter two indicators was lower than those before using it. Conclusion The artifacts of CT images caused by pedicle screw reduced and image quality improved dramatically after using O-MAR while additional amount of radiation in unnecessary.