Study On The Qualitative Diagnostic Value Of ¹⁸F-FDG PET/CT For Pulmonary Benign And Malignant Lesions

ObjectiveTo investigate the correlation between the size of benign and malignant pulmonary lesions and SUV_max,whether there has difference between SUV_max and different sizes of benign and malignant lesions,and the best diagnostic cut off value of SUV_max in diagnosis of benign and malignant lesions of different sizes.To improve understanding of malignant lesions in metabolic characteristic,evaluate SUV_maxax diagnostic value of benign and malignant lesions,increase diagnostic accuracy of pulmonary space-occupying lesions.MethodsRetrospective analysis of ¹⁸F-FDG PET/CT examinations for pulmonary space-occupying lesions（nodules or lumps）from June 2012 to December 2016 was performed with clinical and imaging datas of 166 patients.The maximum diameter and SUVmax were measured.The benign and malignant lesions were divided into 5groups according to the maximum diameter of the lesions,including≤1cm group,1²cm group,2³cm group,3⁴cm group and 4⁵cm group.SPSS 20.0 software was used for statistical analysis:two samples were compared using independent samples t-test.Pearson correlation analysis was used for the correlation between maximum lesion size and SUV_max.The ROC curve analysis of SUV_max for benign and malignant lesions was used to evaluate the diagnostic efficacy and the best diagnostic threshold was calculated.Results1.In general,the SUV_max of benign lesions for≤1cm and 1²cm were higher than those of malignant lesions,and the SUVmax of malignant lesions for 2³cm,3⁴cm and 4⁵cm were higher than those of benign lesions.The differences of SUV_max between benign and malignant lesions in≤1cm and 4⁵cm were statistically significant.There were no significant difference for the SUVmax in the other groups.2.The SUV_max of inflammatory granulomas below 3cm were all higher than those of malignant lesions,and the differences were statistically significant.The SUVmax of inflammatory granulomas in 3⁴cm was similar to malignant lesions and the SUV_maxax of inflammatory granulomas was slightly higher,but the difference was not statistically significant.The SUVmax of malignant lesions in 4⁵cm was higher than that of inflammatory granulomas,and the difference was statistically significant.3.Except for group≤1cm,the SUVmax of malignant lesions in the other groups were higher than those of non-inflammatory granulomas and the differences were all statistically significant.4.The correlation coefficient between the maximum diameter of benign lesion and the SUV_max was 0.589,P<0.001.The maximum diameter of benign lesion was significantly correlated with the SUVmax.The correlation coefficient between the maximum diameter of malignant lesion and the SUV_max was 0.751,P<0.001.The maximum diameter of malignant lesion was significantly correlated with the SUV_max.5.The area under the ROC curve of SUV_maxax between inflammatory granulomas and malignant lesions in every group was respectively 0.753,0.776,0.561,0.769.The best diagnostic cut off value was respectively 3.85,6.30,7.50,10.50.The diagnostic sensitivity was respectively 89.2%,87.5%,88.9%,76.9%.The diagnostic specificity was respectively 58.6%,62.1%,33.3%,62.5%.Conclusions1.In general,the size of benign and malignant lesion is significantly correlated with the SUV_max.The larger the lesion,the higher the SUV_max.2.There is a difference in the metabolism between inflammatory granulomas and malignant lesions below 3cm,and the metabolism of inflammatory granulomas is higher than that of malignant lesions.There is no significant difference in the metabolism between inflammatory granulomas and malignant leisons in group 3⁴cm.There is a difference in the metabolism between inflammatory granulomas and malignant lesions in group 4⁵cm,and the metabolism of malignant lesions is higher than that of inflammatory granulomas.3.According to the ROC curve,the best diagnostic cut off value of group 1²cm is3.85.The possibility of inflammatory granuloma is greater when the SUV_maxax is higher than 3.85.The best diagnostic cut off value of group 2³cm is 6.30.The possibility of inflammatory granuloma is greater when the SUV_maxax is higher than 6.30.The best diagnostic cut off value of group 3⁴cm is 7.50.The possibility of inflammatory granuloma is greater when the SUV_maxax is higher than 7.50.The best diagnostic cut off value of group 4⁵cm is 10.50.The possibility of lung cancer is greater when the SUV_maxax is higher than 10.50.4.Except for group≤1cm,the SUV_max between non-inflammatory granulomas and malignant lesions has significant differences in the metabolism.The metabolism of malignant lesions is significantly higher than that of non-inflammatory granulomas.5.The SUVmax is a diagnostic indicator of benign and malignant pulmonary lesions.The relationship between the SUV_max and the size of the lesion must be paid attention to in the clinical diagnosis.At the same time,the diagnostic accuracy can be improved by combining with the signs of HRCT.