The aim of this pilot study is to evaluate EBUS elastography strain ratio in assessment of mediastinal lymph nodes in patients with suspicion for lung cancer for the first time. Strain ratios of mediastinal lymph nodes will be compared with EBUS B-mode features and with tissue diagnosis as a gold standard.

Evaluation will be performed on consenting consecutive patients at least 18 years old, referred to bronchoscopy with suspicion for lung cancer according to chest CT-scan. Eligible patients should have either enlarged discrete N2/N3 lymph nodes, or central tumor or enlarged N1 lymph nodes with normal mediastinal lymph nodes. Exclusion criteria will be metastatic disease, severe co-morbidity that disqualified surgical treatment, mediastinal infiltration by tumor and small peripheral lung tumor with normal-sized mediastinal lymph nodes.

Outcomes: Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for probability of malignant lymph node diagnosis, determined by elastography strain ratio. Receiver operating characteristic (ROC) analysis will be made to display specificity / sensitivity for different strain ratio cut-off values. Area under the ROC curve will be calculated.

Inclusion Criteria:

• enlarged discrete N2/N3 lymph nodes
• central tumor with normal mediastinal lymph nodes
• enlarged N1 lymph nodes with normal mediastinal lymph nodes

Exclusion Criteria:

• metastatic disease
• severe co-morbidity that disqualified surgical treatment
• mediastinal infiltration by tumor
• small peripheral lung tumor with normal-sized mediastinal lymph nodes

Consecutive patients at least 18 years old, referred to bronchoscopy with suspicion for lung cancer according to chest CT-scan