运用模体定量评价三维DSA距离测量的准确性

Quantitative Evaluation of Distance Measurements Accuracy for Three-dimensional Angiography System Using Phantoms

目的运用模体定量评估三维DSA距离测量的准确性,以指导临床工作。方法应用模拟动脉瘤模体和动脉狭窄模体,改变不同的扫描野、重建矩阵、模体方向来研究三维空间距离测量的准确性。通过对模体中球体和圆柱体三维容积重建图像尺寸测量与模体实际尺寸进行对比评估。结果在三维图像重建中不同的扫描野、重建矩阵、模体方向均能清晰显示圆柱体、球体影像及模拟狭窄的程度。随着扫描野的缩小,对球体直径和狭窄直径的测量精度提高,对于圆柱体长度测量无变化。重建矩阵加大,球体直径测量误差减少(1283最大为0.36mm,2563最大为0.12mm)。圆柱体狭窄百分率测量误差大约为3%。结论当选用合适的图像成像参数和后处理方法时,利用重建后的三维图像测量动脉瘤的大小和动脉狭窄的程度是相当可靠的。

Objective To quantitativly evaluate the accuracy of three-dimensional （3D） distance measurements performed with 3D angiography using various phantoms.Methods In order to investigate the accuracy of 3D distance measurements, aneurysm phantoms and stenusis phantoms were used. The field of view （FOV） size, reconstruction matrix, and direction of the phantom were changed. The dimensions of the spheres and cylinders were measured on volume rendering （VR） images and compared with the phantoms actual size. Results In different FOV, reconstruction matrixes and directions of the phantom, the reconstructed 3D images could clearly show the cylinder or the sphere imaging and simulation narrow level. With reducing the FOV, the measurement accuracy of the sphere diameter and narrow diameter improved and the measurement of the cylinder length did not change. With increasing the reconstruction matrix, the measurement error of the sphere diameter decreased（in 1283 reconstruction ,the maximum measurement error of sphere diameter was 0.36 mm ; in 2563 reconstruction, the maximum measurement error of sphere diameter was 0.12 mm ）.The measurement error of Cylinder percent stenosis was about 3%. Conclusion When using proper imaging parameters and pestprocessing methods, measurements of aneurysm size and percent stenosis on the reconstructed 3D angiograms are substantially reliable.