This book covers up-to-date evidence of Rapid on-site evaluation (ROSE) for diagnosis of rare disease and used combined with metagenomic sequencing technique in clinical scenarios. ROSE has becoming an efficient interventional diagnostics tool and important reference for lung diseases differentiation, increasing the adequacy rate, diagnostic yield and accuracy of the interventional pulmonary procedures. ROSE has its value in the field of evaluating sampling adequacy for further immunohistochemistry, microbiology studies, flow cytometry analysis, and molecular assays; DNA analysis of biopsy specimens using sequencing technique is performed to provide clue of etiology, which is an emerging pathway for clinical dilemmas. The first part of the book discusses the principals of performing ROSE procedures and reviews the basic concepts and summarized knowledge of key anatomical structures in lung.