基于MR模板的PET/MRI衰减校正方法

Attenuation correction method of PET/MRI based on MR template

目的设计并对比基于MRI的衰减校正模板对PET图像的衰减校正效果,寻找衰减校正效果最佳模板。方法采集30名志愿者的18 F-FDG PET图像,根据性别或不同头部尺寸创建MRI模板,包括女性组(fmg)、男性组(mmg)、小尺寸头部组(smg)、大尺寸头部组(bmg)和基础组(gmg),与PET透射模板结合后获得个体化衰减图,并最终用于18F-FDG PET图像的衰减校正;测量并对比经不同模板校正的PET图像ROI内的放射性活度值和与原始PET图像相比的相对偏差值。结果女性受试者经衰减校正的PET图像中,其ROI内放射性活度的最小差值为4Bq/ml,来源于fmg与gmg模板间,而男性受试者放射性活度的最小差值为1Bq/ml,来源于mmg与fmg模板间。经5个不同模板校正后与经PET透射扫描所获得的衰减数据之间均存在差异,相对偏差值范围为-6.31%～6.32%。gmg模板与其他4个模板的相对偏差值范围为-3.44%～5.34%。结论基于MR模板的衰减校正方法对于受试者个体不存在明显的性别差异,一般情况下,gmg模板即可满足要求。

Objective To design and compare the effect of attenuation correction(AC)based on different MR templates for PET images,and to find out the template with best attenuation correction results.Methods PET images of 30 subjects were collected.MR templates were established according to different gender or head sizes,including female group(fmg),male group(mmg),small head group(smg),big head group(bmg)and the general group(gmg),which were co-registrated with the PET transmission template to obtain individual attenuation map,then the data were used in AC for PET images.The radioactivity values within ROI of the corrected PET images and the relative deviations from original PET images were measured and compared.Results On PET images after AC of females,the minimum difference of radioactivity in ROI was 4 Bq/ml,which was derived from the fmg and gmg templates.The minimum difference in the radioactivity of males was 1 Bq/ml,which was derived from the mmg and fmg templates.There was a difference between each of the attenuation data obtained from 5 different template corrections and PET transmission scans with the relative deviation range from-6.31%to 6.32%.The relative deviation between the gmg template and the other 4 templates ranged from-3.44%to 5.34%.Conclusion There is no obvious gender difference based on MR template AC method.Under normal circumstances,the gmg template can meet the requirements.