Imaging Characteristics in ALK Fusion-Positive Lung Adenocarcinomas by Using HRCT

Objectives: We aimed to identify high-resolution computed tomography (HRCT) features useful to distinguish the anaplastic lymphoma kinase gene (ALK) fusion-positive and negative lung adenocarcinomas. Methods: We included 236 surgically resected adenocarcinoma lesions, which included 27 consecutive ALK fusion-positive (AP) lesions, 115 epidermal growth factor receptor mutation-positive lesions, and 94 double-negative lesions. HRCT parameters including size, air bronchograms, pleural indentation, spiculation, and tumor disappearance rate (TDR) were compared. In addition, prevalence of small lesions (<= 20 mm) and solid lesions (TDR <= 20%) were compared. Results: AP lesions were significantly smaller and had lower TDR (%) than ALK fusion-negative (AN) lesions (tumor diameter: 20.7 mm +/- 14.1 mm vs. 27.4 mm +/- 13.8 mm, respectively, p < 0.01; TDR: 22.8% +/- 24.8% vs. 44.8% +/- 33.2%, respectively, p < 0.01). All AP lesions >20 mm (n = 7, 25.9%) showed a solid pattern. Among all small lesions, AP lesions had lower TDR and more frequent spiculation than AN lesions (p < 0.01). Among solid lesions, AP lesions were smaller than AN lesions (p = 0.01). Conclusion: AP lung lesions were significantly smaller and had a lower TDR than AN lesions. Spiculation was more frequent in small lesions. Non-solid >20 mm lesions may be ALK fusion-negative.