Imaging Features of Lung Cancers Detected By Low-Dose Helical Computed Tomography

Objective To investigate the imaging features of lung cancers detected by low-dose helical CT scanning in order to improve the understanding of early lung cancers. Methods A total of consecutive 13099 patients who had received low-dose helical CT screening were collected. The patients included 8362 males( 63. 8%) and 4737 females( 36. 2%) with a mean age of( 52 ± 10) years( range 40- 105 years). The patients with suspected lung cancer were followed up. The imaging features of the nodules and masses which turned out to be lung cancer were analyzed. Results Among the 13099 subjects,suspicious lung cancer was considered in 73( 0. 56%),and a total of 74 nodules( 3 cm) and mass( 3 cm) were detected,the mean diameter of the lesions was 2. 1 cm( range 0. 8- 8. 1 cm). The 74 lesions included 16( 21. 6%) non-solid nodules,21( 28. 4%) solid nodules,19( 25. 7%) mixed nodules,5( 6. 8%) mixed masses and 13( 17. 6%) solid masses. Of the 73 cases,diagnosis of lung cancer was confirmed in 61( 83. 6%),among them a total of 50 cancer lesions were detected in 49 cases,including central lung cancer( n = 11,22%) and peripheral lung cancer( n = 39,78%),and the mean diameter was 1. 6 cm( range 0. 8- 2. 9 cm). Pathologically,squamous cancer was seen in 4 cases( 8. 2%),adenocarcinoma in 44 cases( 89. 8%) and small cell lung cancer in one case( 2. 0%). CT scanning demonstrated that type Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ and Ⅵ of lung cancer was observed in 15( 30%),10( 20%),4( 8%),7( 14%),4( 8%) and 10( 20%) cases respectively. The nodules that had inner and marginal signs were significantly larger than the nodules that had no inner and marginal signs( 1. 9 cm vs. 1. 2 cm,P 0. 001). Conclusion In pulmonary cancers confirmed by low-dose spiral CT screening,the lesions taking nodular form are more frequently seen than those taking mass form. The cancerous nodules have certain CT features.