The common methods to check small nodules in the lung are: 1, non-invasive examination: usually with CT, magnetic resonance and positron emission scanning, i.e. PET-CT, all of the above methods can effectively and accurately check small nodules in the lung. Among them, CT chest examination is the fastest method of diagnostic efficiency, and the sensitivity of CT examination can reach 98%-100% and the specificity can reach 54%-93%, so the preferred method is CT examination; 2, invasive examination: invasive examination is divided into minimally invasive electronic thoracoscopy or percutaneous biopsy method by puncture needle. Another is open-chest examination, this method is not commonly used because of the large invasive surface. Usually the first two examination methods are used more often in invasive examination.