Ground glass nodules: CT-epidemiological analysis of growth patterns

Purpose: To quantify growth patterns of solitary pure ground glass nodules and to relate these pattern to epidemiological factors. Methods and Materials: Between 2008 and 2011, 95 patients were diagnosed on CT with solitary pure ground glass nodule (pGGN) at our hospital. CT features of pGGNs were evaluated at an initial and a follow-up CT. pGGNs were divided into "persisting" or "resolved". Persisting nodules were further classified according to potential changes in total or solid component diameter into "decreased", "unchanged", and "increased". Clinical and demographic data were recorded. Association of data with morphological pGGNs characteristics were tested with Kruskall-Wallis test and logistic regression. Results: After a median follow-up of 16 months, 19/95 (20%) pGGNs resolved and 76/95 (80%) persisted. Of the persisting pGGNs, 51/76 (67.1%) were unchanged, 18/76 (23.7%) increased in size, and 7/76 (9.2%) decreased. Growth was more likely with age 67 years and a diameter 10 mm (OR 4.636; p = 0.016). No significant relation was found between pGGNs growth and gender, history of cancer, or pGGN location. pGGN resolution was more likely with age < 67 (OR 3.28; p = 0.04). No difference in diameter was found between resolved and persisting pGGNs (p = 0.21). Conclusion: As expected, persisting larger pGGNs were more likely to grow than small pGGNs. However, solitary pGGNs were more likely to grow in older than in younger patients. This observation could help to tailor future follow-up recommendations for pGGNs with regard to the seemingly paradoxical influence of patient age.