Endobronchial ultrasound-guided transbronchial needle aspiration of hilar and mediastinal lymph nodes detected on 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Evaluation of hypermetabolic mediastinal-hilar lymph nodes determined by PET/CT with EBUS-TBNA and calculation of SUVmax cutoff values in differentiation of malignancy

Computed tomography (CT) and positron emission tomography (PET) are the most commonly used methods for diagnosis and staging in both malignant and benign diseases of the lung parenchyma and mediastinum. Endobronchial ultrasonography (EBUS) guided transbronchial needle aspiration biopsy (TBNA) has become widespread in recent years because it allows minimally invasive tissue sampling. PET-CT has high sensitivity in the diagnosis of malignancy but has low specificity. The false positive rate is high with the SUVmax 2.5 cutoff value, which is widely used in studies about malignancy. In our study, we evaluated lymph nodes with high F18-fluorodeoxyglucose (FDG) uptake on PET/CT and sampled by EBUS-TBNA. We aimed to calculate the new SUVmax cutoff values in the differentiation of malignancy. Our study included 103 patients who were examined for any reason and who underwent biopsy with EBUS-TBNA due to mediastinal or hilar lymph node enlargement on PET-CT. The relationship between PET-CT findings and EBUS findings, EBUS-TBNA results was evaluated. Biopsies were taken from 140 lymph nodes in 103 patients included in our study, and 39 (27.8%) were diagnosed as malignant. In our study, when the SUVmax cutoff value in PET-CT is taken as 2.54, the sensitivity is 98%, but the specificity remains at the level of 12%. When the SUVmax cutoff value in PET-CT was taken as 4.58, the sensitivity was 92% and the specificity was 49%. When this value was accepted as 5.25, and 6.09 the sensitivity was respectively 90% and 85%, the specificity was respectively 52% and 60%. In evaluations, we conducted in order to determine different SUVmax cutoff values that can be used for higher sensitivity and specificity in malignancy studies, the cutoff values were 4.58, 5.25, and 6.09. It is thought that these cutoff values will be useful both for diagnosing malignancy and for distinguishing benign pathologies.

Cytologic Evaluation of Positron Emission Tomography-Computed Tomography-Positive Lymph Nodes Sampled by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: Experience at a Large Cancer Center

CONTEXT.—

Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is routinely used to evaluate mediastinal lymph nodes (LNs), especially for cancer staging. There are limited large studies evaluating the cytologic, radiologic, and clinical features of ¹⁸F-fluorodeoxy glucose positron emission tomography-computed tomography-positive (PET-CT+) LNs.

OBJECTIVE.—

To compare cytologic, radiologic, and clinical features of PET-CT+, cytology-malignant (PET-CT+/Cyto+) and PET-CT+, cytology-benign (PET-CT+/Cyto-) LNs.

DESIGN.—

The pathology database was searched for cases of mediastinal LNs obtained by EBUS-TBNA from January 1, 2015 to December 31, 2015. The cytologic, radiologic, and clinical features were collected for all PET-CT+ LNs.

RESULTS.—

Of 2267 mediastinal LNs obtained by EBUS-TBNA during this period, 577 LNs met the criteria. Of the latter, 263 (46%) were PET-CT+/Cyto+ and 314 (54%) were PET-CT+/Cyto-. All of the patients with PET-CT+/Cyto+ results had a prior or concurrent diagnosis of malignancy as compared to 89% of patients with PET-CT+/Cyto- results. Of the 224 patients with PET-CT+/Cyto+ LNs, 177 (79%) had metastases from lung primary, 43 (19%) had metastases from nonlung primaries, and 7 (3%) had lymphoma. Average LN size was larger in the PET-CT+/Cyto+ group than in the PET-CT+/Cyto- group (14.6 mm versus 9.58 mm), and mean standardized uptake value in PET-CT+/Cyto+ LNs was higher than that of PET-CT+/Cyto- LNs (10.05 versus 5.99). Significant cytologic findings in PET-CT+/Cyto- cases were necrosis and granulomatous inflammation, including 3 cases with fungal organisms.

CONCLUSIONS.—

PET-CT positivity alone was nonspecific for malignancy and insufficient to guide management of patients with mediastinal adenopathy, but specificity could be improved when combined with LN size and standardized uptake value.