Application Of ¹⁸F-FDG PET/CT In The Diagnosis And Staging Of Extranodular Natural Killer/T-cell Lymphoma Nasal Type

Extranodal natural killer / T-cell lymphoma nasal type is a kind of rare and aggressive non-hodgkin lymphoma with poor prognosis.Epidemiological survey showed that the incidence of ENKTL was high in developing and underdeveloped countries.The invasion sites were common in the nasal cavity,and other sites had been reported,such as skin,gastrointestinal tract,testis,kidney and respiratory tract.Recently,the standard treatment for ENKTL has not been established.But according to previous studies,ENKTL in early stage had a sensitive response to radiation therapy,and the treatments for advanced ENKTL were based on chemotherapy,so it was important to stage accurately of ENKTL.Conventional radiographic examination methods had relatively low sensitivity,and the capacity of detecting ENKTL was limited,which might affect the staging accurately of ENKTL.¹⁸F-FDG PET / CT imaging is a diagnostic method which contain functional metabolic images combined with CT anatomical images.Two kinds of diagnostic methods can complement each other.¹⁸F-FDG PET / CT can not only identify the location and extent of abnormal metabolism,but also provide timely and accurately imaging evidence for diagnosis and staging.However,the number of ENKTL cases is relatively poor,and the research is relatively limited,and the conclusion is still controversial.Therefore,the application value of ¹⁸F-FDG PET / CT for ENKTL have not been established.ObjectiveThe aim of this study was to determine the value of ¹⁸F-FDG PET / CT in the diagnosis and staging of ENKTL.MethodsIn this study,31patients（19males and 12females）with Nasal-type ENKTL were recruited in our hospital from June 2012 to September 2016.The average age was 39±13.10 years.A total of 775 anatomical sites were scanned by ¹⁸F-FDG PET/CT and conventional enhanced CT,respectively.All anatomical sites were classified as positive and negative according to the malignancy,so as to compare the two methods.Biopsy as the “gold standard” combined imaging examination and clinical follow-up comprehensive analysis were used as a reference standard for diagnosis.SPSS21.0 software was used for statistical analysis and P <0.05 was considered statistically significant difference.Results1.35 nodular lesions and 42 extranodal lesions diagnosed by “gold standard” combined other imaging examination and clinical follow-up comprehensive analysis was confirmed as true positive.And the true positive number of nodular lesions and extranodal lesions detected by ¹⁸F-FDG PET/CT were 34 and 40,while the number detected by conventional enhanced CT were 26 and 36.The sensitivity of ¹⁸F-FDG PET / CT and conventional enhanced CT were 96.10%（74/77）and 80.52%（62/77）respectively,and the specificity of that were 99.86%（697/698）and 99.71%（696/698）respectively.The accuracy of two examination techniques were 99.48%（771/775）、97.81%（758/775）.¹⁸F-FDG PET / CT and conventional enhanced CT had significant difference in diagnostic sensitivity and accuracy（P=0.003、P=0.004）,but the diagnostic specificity had no statistical difference（P=1.00）.2.The effect of staging by ¹⁸F-FDG PET/CT and conventional enhanced CT were 96.77%（30/31）and 74.19%（23/31）respectively.There was a significant difference between ¹⁸F-FDG PET/CT and conventional enhanced CT in the clinical staging（P=0.010）.3.All the 31 patients with ENKTL were examined by ¹⁸F-FDG PET / CT,and the clinical management of 14 patients（14/31,45.16%）were optimized by ¹⁸F-FDG PET/CT images.Conclusion1.The diagnostic efficiency of ¹⁸F-FDG PET / CT imaging for ENKTL were significantly higher than conventional enhanced CT.¹⁸F-FDG PET / CT imaging was a more effective diagnostic method,which could detect the ENKTL timely and accurately.2.¹⁸F-FDG PET / CT imaging could provide reference for staging of ENKTL patients accurately,which could change the treatment regimen of some patients.¹⁸F-FDG PET / CT imaging had a high value in the clinical staging of ENKTL.