High-resolution CT Analyses of the Relationship between Small Lung Adenocarcinoma and Surrounding Vessels

Background: The relation between pulmonary lung and surrounding vessels in CT images is important. Diagnostic criteria for involved vessels on CT images have not been established. Objective: In order to evaluate the relationship between small lung adenocarcinoma and the surrounding vessels, high -re solution computed tomography (HRCT) was performed for 96 resected small peripheral lesions measuring less than 15 mm in diameter. Methods: The involved vessels in the HRCT images exhibited two characteristic features, namely, branching and penetration into the tumor. We examined whether the appearance of branching of the vessels in the HRCT images reflected the convergence into their lesion. Results: The frequency of branching of the vessels and penetration of the tumor by the vessels, classified according to the tumor size, was 44%and 33%in patients with a tumor the 10 mm or less in diameter, and 50%and 27%in those with a tumor 11-15 mm in diameter, respectively. Thus, it seems reasonable to conclude that vessels are involved if they show branching, even if the lesion is small. The extent of ground glass attenuation (GGA) of the tumor was classified into three grades, group 1 with 100%, group II with 50-100%and group III under 50%opacification. Among these classifications, 38% were classified into group 1 and 52%in groups II + III. The frequency of branching vessels increased as the GGA decreased. Conclusions: Our results suggest that the appearance of branching and penetration of the tumor by the vessels in HRCT images may have significant clinical relevance in small peripheral lung adenocarcinoma, as they indicate the relationship between the tumor and the surrounding vessels.