重建技术对PET/CT图像空间分辨率影响的模型研究

目的:探讨重建技术对PET/CT中PET图像空间分辨率的影响。方法:采用PET/CT模拟临床条件进行图像数据采集,对分布于椭圆柱分辨率模体长轴方向上的5条线源及6层横断面行PET/CT扫描;选择滤波反投影(FBP)法和VUE Point HD迭代算法进行PET图像重建。迭代算法中增加点扩散函数(PSF)和飞行时间(TOF)两种新技术对图像进行重建,以线源半高宽(FWHM)表示重建图像的空间分辨率,计算5条线源6个层面上径向FWHM,求平均值。结果:在临床采集及重建条件下,使用PSF技术前、后中心位置图像空间分辨率分别为4.95 mm、4.28 mm;TOF技术使用前、后中心位置图像空间分辨率分别为4.95 mm、5.19 mm;FBP算法重建图像空间分辨率为4.63~7.45 mm;VUEPointHD算法空间分辨率为4.07~6.58 mm。结论:PSF技术能够有效提高PET图像空间分辨率,而TOF技术对图像空间分辨率无显著影响。重建算法对PET图像空间分辨率的影响较大,故需依据临床需求和经验选择来辅助决策。

A model research about the effect of reconstruction technique on spatial resolution of PET/CT image

Objective: To investigate the effect of reconstruction technique on the spatial resolution of PET images in PET/CT. Methods: GE Discovery Elite PET/CT was used to simulate clinical condition for collecting image data. The 5 lines sources and 6 transverse sections that distributed on the direction of long axis of resolution model of elliptic column were scanned by PET/CT. The filter back projection(FBP) and VUE Point HD iteration algorithm were selected to reconstruct PET images. And two kinds of new techniques, point spread function(PSF) and time of flight(TOF), were added in iterative algorithm to reconstruct images. And the full width at half maximum(FWHM) of line source was used to express spatial resolution of reconstructed image, and to calculate FWHM on the radial direction of 5 line sources and 6 sections, and then to obtain their means. Results: Under the condition of clinical acquisition and reconstruction, the spatial resolutions of central position images before and after using PSF technique were 4.95 mm and 4.28 mm, respectively. And the spatial resolutions of central position images before and after using TOF technique were 4.95 mm and 5.19 mm, respectively. The spatial resolutions of reconstructed images of FBP algorithm and VUE Point HD algorithm were 4.63~7.45 mm and 4.07~6.58 mm respectively. Conclusion: PSF technique can effectively improve spatial resolution of PET images, while TOF technique has no significant impact on spatial resolution of images. Reconstructed algorithm has greater impact on the spatial resolution of PET images, so it is necessary to assist the decision-making according to clinical needs and experience selection.