The diagnosis of a SVCS can be made on a chest radiograph. The most important finding is widening of the right side of the superior mediastinum. Pleural exudative effusion on the right side may occur. A chest computed tomogram (CT) with intravenous contrast medium in the venous phase can be used for the diagnosis of tumor mass size, its localization and SVC diameter and length of SVC stenosis. CT can be useful for the planning of endovascular treatment.

Magnetic resonance imaging (MRI) with MRI phlebocavography and phlebocavography with intravenous contrast injection can be performed. Angiography with syncronous venous pressure gradient measurements and stenting can be carried out. For patients with no known history of malignancy invasive methods, including bronchoscopy, percutaneous needle biopsy, mediastinoscopy, and thoracotomy, can be applied. Biopsies with histological and/or cytological examination can rule out benign causes and determine a specific diagnosis to direct the most appropriate treatment.

Bronchoscopy, can detect endoluminal tumor growth, infiltration of central and peripheral airways, obtain neoplastic tissue or cytological samples with the use of brush, bronchial washing, or bronchoalveolar lavage.

Endobronchial ultrasound and real-time convex-probe endobronchial ultrasound (CP-EBUS)-guided transbronchial needle aspiration (TBNA) offers an alternative and less invasive diagnostic modality for biopsy of mediastinal lymph nodes [10].

Newer techniques of mediastinoscopy such as video-assisted mediastinoscopic lymphadenectomy (VAMLA) and transcervical extended mediastinal lymphadenectomy (TEMLA) allow better visualization and more extensive sampling of mediastinal nodes with the surrounding fatty tissue and can be combined with minimally invasive video-assisted lobectomy [11, 12].

Positron emission tomography provides additional information on nodal status and mediastinal involvement.