一种简单校正PET图像部分容积效应的方法

A Simple Method for Partial Volume Effect Correction in PET Images

部分容积效应使PET图像中的病灶失真,影响临床定量诊断。本文建立一种临床实用的校正病灶失真的方法。方法:根据部分容积效应形成的原理,并基于柱形病灶的模拟实验结果,分析病灶断层图像特征剖线数据和一维病灶图像的关系。由此将二维病灶图像部分容积效应校正问题转化为一维问题,称之为一维校正法。并通过柱型病灶模型的PET实验,对所建校正法进行实验检验。结果:①一维校正法:校正方法的三步骤及数学公式。②实验验证:直径大于分辨率(FWHM)的病灶,得到了很好的直径校正值,偏差在±6%内。直径小于分辨率的病灶,直径校正偏差较大。病灶放射性浓度均值受部分容积效应的影响随病灶变小而加重,对应病灶直径29—3mm,相对偏差从～-17%增加到- 80%以上。经校正后,偏差大幅减少,尤其对直径大于分辨率的病灶,放射性浓度基本得到了完全校正恢复,偏差都在±7%内。对直径小于分辨率的病灶(4.7mm、3mm),虽然没有完全校正恢复,但使偏差平均减小了近一半。结论:提出了一种二维病灶PET图像部分容积效应校正的方法——一维校正法,此方法简单快速,其校正效果令人鼓舞。

The partial volume effects （PVE） make the lesion distorted in PET images, which influences clinical diagnosis. A PVE correction method was set up in this study. According to the principle causing PVE, the relationships between the characteristic profiles of the transversal slice and the image of one dimension lesion were investigated based on a large of simulate experiment results for cylindrical lesions. The PVE correction for two dimension lesion image was simplified to perform with one dimension lesion image. It was named one dimension correction. Then the correction method was evaluated with the phantom study. Results. （1） one dimension correction method, the procedure of PVE correction consisted of three steps and the corrected value of lesion＇ size and radioactivity concentration were formulated- （2） Resuits of evaluation with the phantom study, the lesions＇ sizes and radioactivity concentrations were corrected satisfactorily, and the differences between the corrected and the true values were within 6 % and 7% for the lesions larger than the system resolution （FWHM）. For the smaller lesion, because of the heavier PVE there were much difference between the uncorrected and the true values of lesioff sizes and radioactivity concentrations, it reached more than 80% it was reduced to about half after correction. A PVE correction approach for PET images of two dimension lesions, the one dimension correction, was proposed. It was simple and fast, and the correction results were satisfactory.