IMR结合O-MAR技术抑制脑动脉瘤术后金属伪影的应用研究

Application of IMR Combined with O-MAR Technique to Inhibit Metal Artifacts After Cerebral Aneurysm Surgery

目的探讨IMR结合O-MAR技术在颅脑术后检查中抑制金属伪影的应用效能。方法选取在我院接受脑内动脉瘤行弹簧圈栓塞术后或动脉瘤夹闭术后行头部平扫复查的60例患者。扫描结束后对患者的颅顶到颅底层面常规原始数据分别进行IMR+O-MAR及iDose4薄层重建。将iDose4重建图像设置为A组,将IMR+O-MAR重建图像设置为B组,图像的层厚和层间距均设置为1 mm。由1名高年资放射技师分别对2组图像瘤体中间层面伪影明显区,选取3处进行CT值及噪声的标准方差值测量,取其平均值(Standard Deviation,SD),分别对比两组金属伪影周围的SD值、对比噪声比(Contrast to Noise Ratio,CNR)、伪影指数(Artifact Index,AI)、伪影的最大直径;然后由2名工作10年以上的影像诊断医师依据金属植入物本身形态及周围软组织的可辨别度,独立对2组图像进行主观评分。结果与iDose4组相比,IMR+O-MAR组噪声、伪影最大直径和AI明显减低(P<0.05),图像质量主观评分和CNR明显增高(P<0.001)。结论采用IMR+O-MAR迭代重建抑制金属伪影技术,能明显减低金属伪影对脑动脉瘤邻近的解剖结构和周围正常组织的影响,对于整体图像质量有明显改善。

Objective To explore the efficacy of IMR combined with OMAR in the inhibition of metal artifact in craniocerebral postoperative examination.Methods A total of 60 patients who received plain head scan for reexamination after coil embolization of intracranial aneurysms or after aneurysm clipping in our hospital were selected.After the scan,conventional raw data were abtained from the cranial top to the cranial base and the original data of the patient was reconstructed respectively in the IMR+O-MAR and iDose4 thin layer.IDose4 reconstructed images were set as Group A,IMR+O-MAR reconstructed images were set as group B,and the layer thickness and layer spacing of the images were set as 1mm..Asenior radiographer measured the CT value and noise of the standard variance(SD)value at 3 locations of the 2 groups of images tumor intermediate layer artifacts obvious area,compared respectively the SD values around the two groups of metal artifacts,compared the noise ratio(CNR),the pseudo-index(AI),the maximum diameter of the pseudo-shadow;Then,two image diagnosticians who worked for more than 10 years independently subjectively graded 2 groups of images based on the shape of the metal implants and the discernment of the surrounding soft tissues.Results Compared with idose4 group,the noise,maximum artifact diameter and AI of IMR+O-MAR group were significantly decreased(P<0.05),while the subjective image quality score and CNR were significantly increased(P<0.001).Conclusion The use of IMR-O-MAR iterative reconstruction to inhibit metal artifacts technology can significantly reduce the effect of metal artifacts on the adjacent anatomical structure and surrounding normal tissues of intracranial aneurysms and improve the overall image quality.