Endoluminal or endoscopic ultrasound (EUS) was first attempted in 1957 by Wild and Reid who placed a mechanical ultrasound transducer in the rectum.¹ It was not until 1975 that the upper gastrointestinal tract was examined when Rasmussen et al² measured the stomach wall thickness with a 6 MHz transducer passed through the biopsy channel of a gastroscope. In the 1980s, with the development of a dedicated endoscope incorporating a mechanical ultrasound transducer, EUS became important in clinical practice. Accurate local and nodal staging of oesophageal, gastric, and pancreatic tumours^3-6 and assessment of stone disease in the biliary tract⁷ established EUS in the investigation of gastrointestinal disease. The accurate detection of mediastinal lymph nodes in oesophageal cancer had obvious implications for patients with lung cancer, and the role of EUS in lung cancer was first described in Japan in 1988.⁸ Further work confirmed the superior accuracy of EUS in the nodal staging of lung . . . [Full text of this article]