Diagnostic Value Of ^99mTc-MDP Three-phase Bone Imaging Combined With SPECT/CT Fusion Imaging In Giant Cell Tumor Of Bone

Objective:The clinical data,imaging features of three-phase bone imaging and SPECT/CT fusion imaging of patients with giant cell tumor of bone（GCTB）were retrospectively analyzed.Semi-quantitative analysis was used to quantitatively process the three-phase bone imaging images to determine the optimal threshold of semi-quantitative parameters that could predict the pathological grade,imaging grade and Ki-67 expression of proliferating cell antigen,providing a new feasible method for accurate development of clinical diagnosis and treatment plans and preoperative noninvasive assessment of whether the tumor was invasive.Methods:Clinical data of patients with GCTB in limbs and long bones confirmed by pathology were collected by retrospective analysis method from January 2015 to August 2022 in the Second Hospital of Jilin University.Collect the imaging information,age,gender,lesion location,symptoms,and signs of 99m Tc-MDP three-phase bone imaging combined with SPECT/CT fusion imaging and other general patient information,as well as relevant laboratory tests:erythrocyte sedimentation rate,C-reactive protein,alkaline phosphatase,calcium ions,phosphorus ions.The characteristics of SPECT/CT fusion imaging of GCTB lesions and the measurement of tumor volume were summarized by the PACS system;the radioactivity-time curve of the lesion was obtained by delineating the region of interest in the blood flow phase of the lesion using Siemens MI post-processing software,and the slope of the curve,area under the curve,rapid perfusion time,and time to peak were obtained by semi-quantitative analysis,and the ratio of radioactivity uptake between the blood pool phase and delayed phase lesions and the unaffected side was calculated,and pathological grade（Jaffe grade）,the imaging grade（Campanacci grade）,and Ki-67 expression of GCTB lesions were detected by more than two specialists in the imaging and pathology departments.The significant differences in each semi-quantitative parameters among different Jaffe grades,Campanacci grades and Ki-67 expression groups were analyzed,and the optimal threshold was determined by receiver operating characteristic curve（ROC）to predict the imaging and pathological grades of giant cell tumor of bone and Ki-67 expression.SPSS 26 and Medcalc 12 were used for statistical analysis,and P<0.05 was considered statistically significant.Use Power Point to make relevant images.Results:1.A total of 46 patients（46 lesions）were included,including 30 males and 16females,with a mean age of 41.17±13.65 years.Lesions were more common in the distal femur and proximal tibia（70%）.In SPECT/CT imaging,24 patients（52%）showed eccentric growth and 22 patients（48%）showed central growth;12 patients（26%）had no invasion of the adjacent bone cortex and 34 patients（74%）had varying degrees of invasion and thinning or discontinuity of the adjacent bone cortex;26 patients（56%）showed the presence of bone ridges inside the lesion and 20patients（44%）showed no bone ridges inside the lesion;12 patients（26%）had pathological fractures and 32 patients（74%）had no fractures.2.There were significant differences in the slope of the radiation-time curve,area under the curve,and ratio of radioactivity uptake in the blood flow phase among different imaging grades,and when the slope of the radiation-time curve was>10.7,the sensitivity of diagnosing GCTB as Campanacci grade II or III was 77.8%,the specificity was 100%,and the area under the ROC curve was 0.917.3.There were significant differences in the slope and area under the radiation-time curve among different pathological grades,and when the area under the radiation-time curve was>22711.96,the sensitivity of diagnosing GCTB as pathological grade III was 100%,the specificity was 100%,and the area under the ROC curve was 1.00.4.There was a significant difference in the time to peak between Ki-67 groups with different degrees of expression,and when the time to peak was≤0.234 s,the sensitivity of diagnosing GCTB as having high Ki-67 expression（≥15%）was 60.0%,the specificity was 100%,and the area under the ROC curve was 0.789.Conclusions:1.^99mTc-MDP three-phase bone imaging and SPECT/CT fusion imaging can not only show the morphological changes of the lesion,but also show the blood supply of the lesion and the level of bone salt metabolism in the diagnosis of GCTB.2.Semi-quantitative analysis of ^99mTc-MDP three-phase bone imaging can reflect the degree of tumor cell proliferation,quantify the tumor blood supply and the degree of adjacent soft tissue congestion,and then non-invasively evaluate the invasiveness of giant cell tumor of bone;and can guide the clinical development of appropriate treatment through the prediction of pathological grade,imaging grade and Ki-67 expression.