The Diagnostic Value Of ¹⁸F-FDG PET/CT Imaging In Primary Bone Lesions

Objective:This article aimed to analyze the differential diagnostic value of ¹⁸F-FDG PET/CT in primary bone lesions by comparing the morphological signs and metabolic parameters of ¹⁸F-FDG PET/CT between benign and malignant bone lesions,and furthermore analyzed the morphological and metabolic parameters of primary malignant bone tumors（PMBT）between different malignant pathological types.Methods（1）One hundred and thirty-five patients with primary bone lesions underwent ¹⁸F-FDG PET/CT in Tianjin Medical University Cancer Hospital from January 2013 to May 2018 and met the inclusion criteria were collected.The original images of all patients were reviewed on PACS,and the morphological features,location,edge of lesions,presence of a sclerotic margin,bone destruction,periosteal reaction and surrounding soft tissue mass,were analyzed and recorded.Further,all of the original images were reviewed on the AW4.6 workstation.If the lesion only involved isolated bone,we drew the area of the isolated lesion as the region of interest（ROI）or if the lesions involved multiple bones,we drew the area of the highest standardized maximum uptake value（SUVmax）as ROI,using PET VACA software delineated the ROI with a threshold of 42%SUVmax,and obtained five metabolic indicators,including SUVmax,mean standardized uptake value（SUVmean）,peak standardized uptake value（SUVpeak）,tumor metabolic volume（MTV）and total lesion glycolysis（TLG）.Aχ2 test was used to compare the categorical variables and a t test was used to compare the continuous variable.Then the receiver-operating characteristic curve（ROC）was used to analyze the differential diagnostic ability of all parameters including morphology,metabolism,morphological scores and metabolic scores.（2）Eighty-five patients with PMBT underwent ¹⁸F-FDG PET/CT in Tianjin Medical University Cancer Hospital from January 2013 to May2018 and met the inclusion criteria were collected.According to the pathological results,they were divided into sarcoma group（n=46）,myeloma group（n=17）,lymphoma group（n=14）and other groups（n=8）.The distribution of SUVmax was analyzed.Variance analysis was used to analyze the metabolic parameters of each group.Fourty-six sarcomas were further divided into osteosarcoma（n=25）,chondrosarcoma（n=9）,Ewing sarcoma（n=4）and undifferentiated sarcoma（n=8）,and were analyzed.Results:（1）The metabolic parameters of the malignant group were significantly higher than those of benign lesions,and all the morphological signs and metabolic parameters between the benign and malignant groups were statistically significant（P<0.05）.In the low-metabolism group,the areas under the curve（AUC）obtained by using the morphological score≥2 as the standard for diagnosing PMBT were slightly higher than the AUCs obtained by using the morphological score≥3 as the diagnostic criteria and the AUCs obtained by single morphological features（0.788⁰.826 vs.0.611-0.818 vs.0.637-0.776）;AUCs obtained by using the metabolic score≥2 points were higher than AUCs obtained from single metabolic index in the group with good lesion boundary,no bone destruction and no soft tissue around（0.767⁰.891 vs.0.732⁰.851）.Among all the individual variables,TLG has the highest AUC=0.851.（2）In 85 cases of PMBT,the SUVmax of 61.2%of tumors was concentrated between3.00g/ml and 12.00g/ml.The metabolic level of lymphoma was the highest,and significantly higher than that of sarcomas,myelomas and others groups（P<0.05）,but there was no significant difference in metabolic parameters between sarcomas,myelomas and others groups（P>0.05）;in the sarcomas subgroup analysis,SUV of the undifferentiated sarcoma>osteosarcoma>chondrosarcoma>Ewing sarcoma,but MTV and TLG of Ewing sarcoma>Undifferentiated sarcoma>Osteosarcoma>Chondrosarcoma.Conclusions:（1）¹⁸F-FDG PET/CT palyed role in differential diagnosis of primary bone lesions.Combined with morphological signs and metabolic parameters,the detection rate of primary malignant bone tumors can be improved.And combined index surpassed any single parameter.（2）Different pathological types of PMBT had the different distribution range of SUVmax.Lymphoma tends to be concentrated at a high level,and all metabolic parameters of lymphoma were higher than others.Therefore,¹⁸F-FDG PET/CT has a good diagnostic value in the differential diagnosis of primary bone lesions and has value in the diagnosis of pathological subtypes of PMBT.