Is SUVmax Helpful in the Differential Diagnosis of Enlarged Mediastinal Lymph Nodes? A Pilot Study

To explore the diagnostic value of maximum standard uptake value (SUVmax) from 18F-FDG PET/CT images in enlarged mediastinal lymph nodes of unknown etiology. Methods. We performed a retrospective study of patients with enlarged mediastinal lymph nodes on 18F-FDG PET/CT scans. SUVmax and the short axis and long axis of lymph nodes were recorded. These parameters were compared among the ve commonest causes of mediastinal lymphadenopathy: lymphoma, metastatic disease, sarcoidosis, tuberculosis, and lymphadenitis. Histopathologic diagnosis was recorded as the nal golden standard. Results. A total of 94 patients (62 men and 32 women; age range 7–85 y) were included with nal diagnoses of 42 patients with benign pathology and 52 patients with malignancies. The sensitivity, specicity, and the accuracy of PET/CT in diagnosis of the benign and malignant mediastinal lymph nodes were 94.2%, 73.8%, and 85.1%, respectively. The SUVmax of benign and malignant groups were 13.10 ± 5.21 and 12.59 ± 5.50, respectively, which had no statistical difierence (P > 0.05). However, the long axis and the short axis of lymph nodes in the benign and malignant groups were 2.86 ± 1.02 cm, 1.77 ± 0.60 cm and 6.04 ± 3.83 cm, 3.95 ± 2.08 cm, respectively (P < 0.05). The diagnostic values of PET/CT were higher than those of the long or short axis. However, the specicity of PET/CT was lower (73.8%) than that from the long or short axis (90.5% and 92.9%, respectively), although no statistical difierence existed. Among the ve common causes of mediastinal lymphadenopathy, signicant difierences could be seen in SUVmax and in the long axis and the short axis of lymph nodes (P < 0.05). Conclusions. SUVmax, a commonly used semiquantitative measurement, was not helpful for difierentiation between benign and malignant lesions in patients with enlarged mediastinal lymph nodes in this study. Many benign lesions, such as sarcoidosis and tuberculosis, had high FDG uptake, possibly a trend that the size of the lymph nodes seems to have some diagnostic value.