BACKGROUND: Electromagnetic navigation has improved the diagnostic yield of peripheral bronchoscopy for pulmonary nodules. For these procedures, a thin-slice chest CT scan is performed prior to bronchoscopy at full inspiration and is used to create virtual airway reconstructions that are used as a map during bronchoscopy. Movement of the lung occurs with respiratory variation during bronchoscopy, and the location of pulmonary nodules during procedures may diff er signifi cantly from their location on the initial planning full-inspiratory chest CT scan. Th is study was performed to quantify pulmonary nodule movement from full inspiration to end-exhalation during tidal volume breathing in patients undergoing electromagnetic navigation procedures. METHODS: A retrospective review of electromagnetic navigation procedures was performed for which two preprocedure CT scans were performed prior to bronchoscopy. One CT scan was performed at full inspiration, and a second CT scan was performed at end-exhalation during tidal volume breathing. Pulmonary lesions were identified on both CT scans, and distances between positions were recorded. RESULTS: Eighty-fi ve pulmonary lesions were identifi ed in 46 patients. Average motion of all pulmonary lesions was 17.6 mm. Pulmonary lesions located in the lower lobes moved signifi - cantly more than upper lobe nodules. Size and distance from the pleura did not signifi cantly impact movement. CONCLUSIONS: Signifi cant movement of pulmonary lesions occurs between full inspiration and end-exhalation during tidal volume breathing. Th is movement from full inspiration on planning chest CT scan to tidal volume breathing during bronchoscopy may signifi cantly aff ect the diagnostic yield of electromagnetic navigation bronchoscopy procedures.