A 62-year-old woman with a 40 pack-year smoking history presents with hoarseness and facial swelling. Imaging reveals a left-sided central lung mass with superior vena cava (SVC) compression and left supraclavicular lymphadenopathy. Bronchoscopy shows an endobronchial lesion. Which investigation is most appropriate to confirm histological diagnosis and assess for distant metastases in a single imaging modality?