The study is aimed to evaluate the sensitivity, specificity, positive predictive value, negative predictive value and accuracy rate of endobronchial ultrasound (EBUS) image features in diagnosing peripheral pulmonary lesions (PPLs).

The study is designed as a single center prospective trial. The participating center is Department of Ultrasound, Shanghai chest Hospital, Shanghai Jiao Tong University, China. The study is expected to enroll 200 patients. The investigator evaluates the sensitivity, specificity, positive predictive value, negative predictive value and accuracy rate of EBUS image features in diagnosing PPLs. EBUS is performed using an endoscope ultrasound system, which is equipped with a 20-MHz mechanical radial-type probe (UM-S20-17S;Olympus) with an external diameter of 1.4 mm.

Inclusion Criteria:

1. Patients who are older than 18 year-old.
2. Chest CT shows PPLs suspected to be malignant that need to be confirmed by pathology. The lesion is surrounded by lung parenchyma and invisible in standard bronchoscopy.
3. Patients who agree to undergo bronchoscopy without any contraindications.
4. Patients who have good compliance and sign informed consent.

Exclusion Criteria:

1. Absence of bronchus leading to or adjacent to the lesion from CT scan.
2. Refusal of participation.
3. Severe cardiopulmonary dysfunction and other indications that can't receive bronchoscopy.
4. Presence of concomitant endobronchial lesion during the bronchoscopy procedure