Objective To discuss the clinical value of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT imaging performance and metabolic parameters in distinguishing extranodal natural killer/T-cell lymphoma, nasal type (ENKTCL) from nasopharyngeal carcinoma.

Methods The imaging and clinical data of 11 ENKTCL patients and 22 nasopharyngeal carcinoma petients confirmed by histopathological examination from April 2020 to June 2023 at the Third Hospital of Mianyang were included. The patients included 19 males and 14 females, aged (50.6±16.8) years. The ¹⁸F-FDG PET/CT imaging performance and metabolic parameters of patients with ENKTCL and nasopharyngeal carcinoma were compared for differential diagnosis between ENKTCL and nasopharyngeal carcinoma. Factors for differential diagnosis between ENKTCL and nasopharyngeal carcinoma patients were screened. Intergroup comparisons of measurement data were performed using independent sample t-test. Intergroup comparisons of counting data were performed using chi-square test or Fisher's exact probability method. Multivariate Logistic regression analysis was applied to screen and identify the imaging performance and metabolic parameters of the two diseases. The efficacy of ¹⁸F-FDG PET/CT in differential diagnosis between ENKTCL and nasopharyngeal carcinoma was assessed on the basis of the receiver operating characteristic (ROC) curve.

Results The ¹⁸F-FDG PET/CT imaging performance of patients with ENKTCL and nasopharyngeal carcinoma revealed nasopharyngeal soft tissue thickening. The proportion of diffuse growth of lesions in ENKTCL patients was higher than that in nasopharyngeal carcinoma patients (63.6% vs. 18.2%), and nasopharyngeal carcinoma was more likely to invading the skull base bone (59.1% vs. 9.1%) compared to ENKTCL, differences were statistically significantly (χ²=9.219, 10.812; both P<0.05). The metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of ENKTCL and nasopharyngeal carcinoma patients ((122.64±29.29) cm³ vs. (29.05±8.16) cm³, (311.06±66.73) g vs. (73.69±18.75) g) were statistically significantly different (t=3.078, 3.424; both P<0.05). Multivariate Logistic regression analysis demonstrated that skull base bone invasion and TLG could distinguish ENKTCL from nasopharyngeal carcinoma (OR=94.513, 0.988; 95%CI: 1.102–8 104.704, 0.980–0.996; both P<0.05). The ROC curve to evaluate the diagnostic efficacy of ¹⁸F-FDG PET/CT between ENKTCL and nasopharyngeal cancer showed that the area under curve was 0.971 (95%CI: 0.933–1.000) with a sensitivity of 90.9% and specificity of 81.8%.

Conclusion ¹⁸F-FDG PET/CT, by combining imaging performance and metabolic parameters, is of certain value in distinguishing ENKTCL and nasopharyngeal carcinoma.