Fractal analysis of internal and peripheral textures of small peripheral bronchogenic carcinomas in thin-section computed tomography: Comparison of bronchioloalveolar cell carcinomas with nonbronchioloalveolar cell carcinomas

Purpose: To analyze the internal and peripheral textures of small peripheral bronchogenic carcinomas (<2 cm) in thin-section computed tomography (HRCT) images with fractal analysis. Method: Thin-section computed tomography images from 70 patients with bronchogenic carcinomas (61 adenocarcinomas and 9 squamous cell carcinomas) were used. Regions of interest (ROIs) with a matrix size of 32 x 32 (0.326 mm per pixel) were selected manually on the lung-nodule interfaces and within the nodules on HRCT images. Three-dimensional density surfaces based on CT values of ROIs were characterized by fractal dimensions (FDs). Results: When all the bronchogenic carcinomas were divided into bronchioloalveolar cell carcinomas (BACs) and other bronchogenic carcinomas (nonBACs), there were significant differences between BACs and nonBACs in the FDs obtained from the internal textures (mean: 2.38 +/- 0.05 versus 2.19 +/- 0.05; P < 0.0001) and in the FDs obtained from the peripheral textures (mean: 2.16 +/- 0.01 versus 2.06 +/- 0.01; P < 0.0001). Conclusion: The textures of BACs that reveal ground-glass opacities are more complicated than those of nonBACs. The FDs can differentiate between small localized BACs, which have a good prognosis, and nonBACs, which have a poor prognosis. Fractal analysis is promising for characterization of small peripheral pulmonary bronchogenic carcinomas based on radiographic features of HRCT images.