Objectives: We would like to clarify the imaging findings of the main tumor that may omit the requirement for lymph node dissection in clinical IA (cIA) lung adenocarcinoma.

Methods: A total of 336 patients with cIA lung adenocarcinomas with normal preoperative carcinoembryonic antigen (CEA) who underwent surgical resection were analyzed. We investigated the association between various computed tomography (CT) imaging findings or the maximum standardized uptake value (SUVmax) of fluorodeoxyglucose-position emission tomography (FDG-PET) and lymph node metastasis. The maximum tumor diameter was calculated from the CT images using both the lung window setting (LD) and mediastinal window setting (MD). The diameter of the solid component (CD) was defined as consolidation diameter in lung window setting. The solid component ratio (C/T) was defined as CD/LD.

Results: SUVmax, MD, and C/T were independent factors related to lymph node metastasis, but CD was not (p = 0.38). The conditions required for the positive predictive value (PPV) to reach 100% were 10.6 mm for MD, 12.5 mm for CD, and 0.55 for C/T. SUVmax did not reach 100%.

Conclusions: In cIA lung adenocarcinoma with CEA in the normal range, we found that it may be possible for lymph node dissection to be omitted by MD, CD, and C/T.