腕部无创性三维CT仿真局解在体研究

Three-dimensional digital modeling of human wrist in vivo based on helical CT thin-slice axial images

目的探讨腕部无创性三维CT仿真局解及3D数字化腕模型构建的可行性、技术及价值。方法对52例单侧腕部区域外伤患者行螺旋CT扫描,其中21例增强扫描动、静脉两期,层厚、间距5 mm,1.25 mm层厚及间距重建,在AW4.2影像工作站利用VR Opacity软件进行后处理,采用鼠标自-600Hu逐渐滑升至120Hu调节极小阈值（极大阈值固定设为600 Hu）的方法,分掌面观、背面观和断面观三维体绘制重构局部各层组织结构的三维解剖。结果腕部掌面观、背面观自皮肤至骨骼解剖结构逐层3D显示率为100%,皮肤、皮下静脉、肌腱、关节、骨骼的最佳3D显示极小阈值分别为-300、-200、-100、0、100 Hu。所有伸、屈肌腱、皮下静脉、骨骼清晰3D显示率达100%。所有动脉、深部静脉仅分别显示在基于增强动脉期、静脉期扫描源影像的3D图像上,80~110 Hu极小阈值时,这些动、静脉成像及其与毗邻不透X线异物、骨骼解剖位置关系显示好。腕部韧带、腕管结构在掌面观、背面观3D图像上几无明确显示,在3D断面观上其骨纤维性隧道结构显示率达100%,0 Hu极小阈值显示效果较好。在这些3D图像上,准确测量了所显示结构的大小、长度、深度、间隔等。结论基于序贯阈值的CT体绘制技术无创性逼真展现与观测了活体腕部局部解剖与病变,实现了基于CT断面影像的数字化腕模型的构建,其或可作为解剖教学、模拟手术、术前评估、术中导向与疗效随访等有效腕段。

Objective To investigate the feasibility,methods and value of establishment of 3D digitized wrist model in vivo based on helical CT thin-slice axial images.Methods Fifty-two patients with one wrist injuries by foreign object underwent helical CT（arterial and venous phases contrast-enhanced CT scanning in 21 cases） with scan slice thickness and interval of 5 mm and reconstruction of 1.25 mm.Post-processing on a ADW 4.2 workstation by using VR Opacity software to generate the wrist 3D images of dorsal side,palmar side and cross-section views respectively through sliding mouse slowly to adjust the minimum threshold value from-600 Hu to 120 Hu（the maximum threshold was always set up as 600 Hu）.Results The rate of 3D display layer by layer of from skin surface to bone was 100% in the wrist 3D images of dorsal and palmar side views.The best 3D depiction of skin,subcutaneous vein,muscle tendons,joint and bone was on the VAI with-300,-200,-100,0,100 Hu of the minimum threshold value respectively.And the 3D demonstration rate of the wrist extensor and flexsor tendons,subcutaneous vein,and bone was 100%.All arteries or deep veins were hundred percent depicted distinctly only in the 3D images reconstructed from enhanced arterial or venous phase CT,and the anatomic relationship among these vessels,bones and foreign objects was observed more excellently with from 80 Hu to 110 Hu of the minimum threshold.The wrist retinaculi and carpal tunnel structures were three-dimensionally shown clearly only on the 3D images of cross-section view in particular based on enhanced source data,which the more appropriate threshold was 0 Hu.The size,length,depth,distance of the structures shown on the 3D images were all measured accurately.Conclusion CT volume rendering visualization based on the sequential threshold carry out noninvasively the 3D to show and observation in vivo of the wrist anatomy and disorders and the 3D digital modeling of human wrist based on CT axial images.It may be considered as an effective means of anatomy teaching,operation simulation,pre-operation assessment,operation guidance and following up.