Small Pulmonary Nodules: Detection at Chest CT and Outcome

PURPOSE: To determine the outcome of pulmonary nodules less than 1 cm in diameter detected at chest computed tomography (CT). MATERIALS AND METHODS: Reports of chest CT performed during 6 months were reviewed to find patients with pulmonary nodules smaller than 1 cm in long axis for which repeat CT was recommended. Records were studied to determine whether follow-up had been performed, the initial nodules had changed in size, or nodules had been resected. RESULTS: A total of 3,446 chest CT examinations were performed, with 334 patients meeting inclusion criteria. Three patients underwent nodule resection and had pathologic examination results positive for cancer; 185 underwent follow-up, of whom 13 had results excluded as indeterminate. In the remaining 172 patients, 88 had incomplete characterization because of follow-up of less than 2 years, which left 84 with nodule characterization at follow-up. When these 84 patients were combined with the three patients with nodule resection, the number yielded was 87 patients. Seventy-seven of 87 had benign nodules because of resolution or 2-year stability, and 10 of 87 had malignant nodules because of growth or positive histologic examination results. Nine of 10 with malignant nodules had a known primary neoplasm. CONCLUSION: CT commonly helped identify small nodules. Increase in size occurred infrequently and almost exclusively in patients with a known malignancy.