Evaluation of mediastinal lymph nodes using ¹⁸ F-FDG PET-CT scan and its histopathologic correlation

Abstract

AIMS AND OBJECTIVES:To determine the efficacy of integrated 18F-fluorodeoxy glucose positron emission tomography-computed tomography (18F-FDG PET-CT) in the evaluation and characterization of mediastinal lymph nodes into benign and malignant pathology.METHODS:Thirty-five patients with mediastinal lymphadenopathies without primary neoplastic or infective lung pathologies were included in the study. The lymph nodes were detected on contrast-enhanced CT scan of the chest. All patients underwent 18F-FDG PET-CT scan for evaluation of mediastinal lymph nodes. Results of PET-CT were compared with histopathology of the lymph nodes and sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated.STATISTICAL ANALYSIS:The data were collected prospectively and analyzed using (SPSS Inc., Chicago, IL) 11.5 software.RESULTS:Histopathology results in 35 patients revealed tuberculosis in 12, sarcoidosis in 8, and lymphoma in 15. Maximum standardized uptake value (SUVmax) of the benign lymph nodes ranged from 2.3 to 11.8 with a mean±standard deviation (SD) of 5.02±3.26. SUVmax of the malignant lymph nodes ranged from 2.4 to 34 with a mean±SD of 10.8±8.12. There was a statistically significant difference between benign and malignant pathology (P<0.0059). 18F-FDG PET-CT has sensitivity of 93% and specificity of 40% with SUVmax 2.5 as the cutoff. We found the optimal SUVmax cutoff to be 6.2 as determined by the receiver–operator characteristic curve. With 6.2 as cutoff, the sensitivity, specificity, and accuracy were 87%, 70%, and 77%, respectively.CONCLUSIONIn countries where tuberculosis and other granulomatous diseases are endemic, SUVmax cutoff value of 2.5 has low specificity. Increasing the cutoff value can improve the specificity, while maintaining an acceptable sensitivity.

Heterogeneity Analysis of 18F-FDG Uptake in Differentiating Between Metastatic and Inflammatory Lymph Nodes in Adenocarcinoma of the Lung: Comparison with Other Parameters and its Application in a Clinical Setting

“…Hellwig et al [13] preferred to use 2.5 as cutoff value, instead of 4.5 as their best accuracy, in order to reduce the FN results. In our study the cutoff value for SUVmax determined from the ROC curve was 5.96, which was still in the range of the finding from other studies varying from 4.2 to 6.2 [31][32][33][34], although our study only focused on adenocarcinoma of the lung subjects. The accuracy of CV and SUVmax were similar (83.0 vs 80.9), but the correlation between them was only moderate (R 2 0.4237; calculation is not shown), meaning there were cases of pathology-proven metastatic LNs having a negative finding of SUVmax but positive finding of CV, and also benign LNs having a positive finding of SUV but with a negative finding of CV.…”

Role of Diabetes in prevalence of Tuberculosis

“…Bacteria are picked up by dendritic cells, which do not allow the replication of bacteria, but can transport the bacilli to local (mediastinal) lymph nodes [31]. Further spread of the bacilli is through the bloodstream to other tissues and organs where secondary TB lesions can develop in other parts of the lung (particularly the apex of the upper lobes), peripheral lymph nodes, kidneys, brain, and bone [32].…”

The differential diagnostic role of pet-CT in sarcoidosis and lymphoma

“…The SUV max levels cannot differentiate sarcoidosis from malignancy, as PET-CT may be positive in both [6,[11][12][13]. In our study, sarcoidosis patients' average level of SUV max was 10.14 (± 6.11), meanwhile lymphoma was 8.85 (± 5.73) with no statistical difference (p = 0.338).…”

“…Hodgkin lymphoma (HL) and Non-Hodgkin lymphoma (NHL) may both involve mediastinal lymph nodes [1,5]. Positron emission tomography with 18-fluorodeoxyglucose (PET-CT) is widely used in differential diagnosis of MLAPs [6]. High FDG uptake levels may be present in both disease, but additional findings are thought to be helpful in differential diagnosis.…”