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

Objective To study the value of 99Tcm-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 99Tcm-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/nonfracture 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 scintigraphy,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. Key words: Fractures, stress ;  Radionuclide imaging;  Tomography, emission-computed,single-photon ;  Tomography, X-ray computed ;  MDP ;  Rabbits