Anatomical variations of pulmonary vessel may cause serious problems during pulmonary segmentectomy. Three-dimensional （3D）computed tomography (CT) presents 3D images of pulmonary vessels and the tracheobronchial tree and may help operative planning. Retrospective studies have identified the importance of 3-dimensional CT in the field of pulmonary segmentectomy. And the aim of this study is to compare the usefulness of 3-dimensional CT with standard chest CT in preoperative planning of video-assisted segmentectomy.

Lung cancer has been the most serious malignancy around the world which has the highest morbidity and mortality amount all the malignant tumors. Due to the wide spread of lung cancer screening, more and more early stage lung cancer patients have been diagnosed. Video-assisted segmentectomy is a standard surgical procedure in treating early stage peripheral non-small cell lung cancer (NSCLC). However, anatomical variations of pulmonary vessel may cause serious problems, for example unexpected bleed during surgery. Three-dimensional computed tomography (CT), which is reconstructed based on the standard chest CT image, presents 3D images of pulmonary vessels and the tracheobronchial tree and therefore helps operative planning. There are several retrospective studies addressed the importance of 3-dimensional CT in the field of pulmonary segmentectomy. And the aim of this multicenter randomized controlled trial is to compare the usefulness of 3-dimensional CT and standard chest CT in preoperative planning of video-assisted segmentectomy.

Inclusion Criteria:

1. Age older than 18 years;

2. Pulmonary nodules or ground glass opacification （GGO） found in chest CT examination, and conform with indications for segmentectomy:

   Peripheral nodule 0.8-2 cm with at least one of the following:

   i. Histology of adenocarcinoma in situ; ii. Nodule has ≥50% ground-glass appearance on CT; iii. Radiologic surveillance confirms a long doubling time (≥400 days). Segmentectomy should achieve parenchymal resection margins ≥2 cm or ≥ the size of the nodule.

3. Adequate cardiac function, respiratory function, liver function and renal function for anesthesia and VATS segmentectomy.

4. American Society of Anesthesiologists (ASA) score: Grade I-III.

5. Patients who can coordinate the treatment and research and sign the informed consent.

Exclusion Criteria:

1. Patients with a significant medical condition which is thought unlikely to tolerate the surgery. For example, cardiac disease, significant liver and renal function disorder.
2. Patients with psychiatric disease who are expected lack of compliance with the protocol.
3. Patients have history of chest trauma or surgery on ipsilateral chest which may cause pleural adhesion.