SPECT／CT融合图像三维半定量分析诊断应力性骨折的实验研究

目的探讨^99Tc^m-MDP骨平面显像结合SPECT／CT融合显像在应力性骨折（SF）早期诊断中的应用价值。方法雄性新西兰大白兔12只，按照随机数字表法分为2组：实验组8只，进行跑跳训练6周；对照组4只，自由活动6周。全部兔均进行^99Tc^m-MDP骨平面显像和SPECT／CT融合显像。将胫骨均分为上、中、下3段，分别在平面图像和SPECT／CT融合图像上勾画各段ROI和三维ROI体积，并计算各自单位面积和体积的平均放射性计数。以对照组兔胫骨总的平均放射性计数为正常均值，计算可疑SF病变骨段放射性计数与正常均值的比值（SF／N），SF／N〉1．46为显像阳性。对显像结果与对应胫骨的病理诊断进行一致性Kappa检验。结果12只兔共24根胫骨，骨平面显像半定量分析诊断SF的灵敏度、特异性及准确性分别为56．25％（9／16）、7／8和66．67％（16／24）；骨平面显像结合SPECT／CT显像三维半定量分析诊断sF的相应指标分别为75．00％（12／16）、8／8和83．33％（20／24）。后者的诊断准确性较前者明显提高。平面显像结合SPECT／CT显像的诊断结果与病理结果的Kappa值为0．667（P〈0．05），两者一致性较好。结论骨平面显像结合SPECT／CT显像诊断sF的灵敏度、特异性和准确性良好。

Three dimensional semi-quantitative analysis of SPECT/CT in the diagnosis of stress fracture

Objective To study the value of ^99Tc^m-MDP planar bone scintigraphy combined with SPECT/CT in the diagnosis of stress fracture （SF）. Methods Twelve male New Zealand white rabbits were randomly divided into two groups by random number table method： 8 in the study group and 4 in the control group. The rabbits in the study group were given electronic stimulation regularly to let them jump in a special device for 6 weeks. All rabbits underwent both ^99Tc^m-MDP bone planar imaging and SPECT/CT. The tibia was divided into three parts （ upper, middle and lower） and the corresponding ROI and volume of interest （VOI） were generated and mean radioactive counts were measured. The average radioactive counts of the control group served as the non-fracture reference. The radioactive counts ratio of suspected SF/non- fracture tibia （SF/N） was calculated. SF/N of 1.46 was the cut-off value for positive SF lesions. Finally, pathological examination was performed in each tibia of the rabbits. Kappa test was used to analyze the consistency between the imaging and histological findings. Results The sensitivity, specificity, accuracy for the diagnosis of SF was 56.25% （9/16）, 7/8, 66.67% （16/24） by planar bone seintigraphy, and 75.00% （ 12/16）, 8/8, 83.33% （20/24） by bone scintigraphy combined with SPECT/CT, respectively. The diagnosis by planar imaging combined with SPECT/CT was significantly more accurate than that of the planar imaging alone. The Kappa value between bone scintigraphy combined with SPECT/CT and pathological findings was 0.667 （P〈0.05）. Conclusion Planar imaging combined with SPECT/CT can improve the diagnostic efficacy of SF.