A Retrospective Study Of ⁶⁸Ga-FAPI PET/CT In Differentiating The Nature Of Pulmonary Lesions

Objective:The purpose of this retrospective study was to explore the characteristics of different types of pulmonary lesions on ⁶⁸Ga-FAPI PET/CT,and to evaluate and explore the value of ⁶⁸Ga-FAPI PET/CT in the differentiation of pulmonary lesions.Methods:A retrospective study was performed in 99 patients（52 males,47 females,age（56.8±13.2）years）who met this study’s inclusion criteria and underwent ⁶⁸Ga-FAPI PET/CT in our hospital between January 2020 to August2022.The PET/CT images were analyzed and relevant data were collected.Comparison of the lung lesions’tracer uptake and lymph nodes’tracer uptake value was executed by Kruskal-Wallis test.Comparison of lesions’size and the shape of lesions’margin was executed by chi-square（χ²）test.One-Way ANOVA test was perform to analyze the age differences between groups.Fisher’s precision probability test was perform to analyze the difference of lung lesion’s true positive rate between three groups.Results:The lung lesions’tracer uptake between different groups is different and reached statistical significance（P<0.05）,while the primary-lung-tumor group’s lung lesion tracer uptake is the highest.The mean SUVmax for the lung lesion in benign-non-tumor group was（5.3±5.8）,and the true positive rate was 75.6%.The mean SUVmax for the lung lesion in primary-lung-tumor group was（9.1±4.1）,and the true positive rate was 95.1%.The mean SUVmax for the lung lesion in metastatic-tumor group was（6.1±3.7）,and the true positive rate was 88.0%.In primary-lung-tumor group,the thoracic lymph nodes’tracer uptake positive percentage is 82.9%while the mean SUVmax of those lymph nodes was highest among three groups（5.7±4.8）.The thoracic lymph nodes’tracer uptake of primary-lung-tumor group is different from the another two groups and reached statistical significance（P<0.05）.The proportion of lesion shaped as mass in the primary-lung-tumor group was 24.4%,while this value was 9.1%and 4.0%in the benign-non-tumor group and metastatic-tumor group.The size of lesions in primary-lung-tumor group is statistically significant different from the lesions in metastatic-tumor group（χ²=4.649,P=0.031<0.05）.However,compare primary-lung-tumor group with benign-non-tumor group,benign-non-tumor group with metastatic-tumor group,the size of lesions in lung is not statistically significant different（χ²=2.955,P=0.086>0.05;χ²=0.574,P=0.449>0.05）.The shape of the lung lesions’margin in metastatic-tumor group is different from that in other two groups（χ²=7.094,P=0.008<0.05;χ²=19.371,P<0.05）,and in metastatic-tumor group the ratio of lesions which have a smooth margin is 80%.In benign-non-tumor group and primary-lung-tumor group,only 45.5%and24.4%lung lesions has a smooth margin,and there was no statistically significant difference（χ²=3.626,P=0.057>0.05）.Conclusion:Different lung lesions have different characteristics on⁶⁸Ga-FAPI PET/CT imaging.Take the characteristics of the lesions and lymph nodes’tracer uptake,the morphological characteristics of the lesion and the patient’s medical history into consideration,⁶⁸Ga-FAPI PET/CT imaging has its unique value in judging the nature of lung lesions,especially for the judge of tumor and non-tumor lesions.