Comparison between solid component size on thin-section CT and pathologic lymph node metastasis and local invasion in T1 lung adenocarcinoma

To correlate the tumor size and solid component size on thin-section CT (TS-CT) with pathological findings including lymph node (LN) metastasis and local invasion in T1 lung adenocarcinoma. 188 patients with surgically resected T1 lung adenocarcinoma were retrospectively analyzed. Two chest radiologists measured the long-axis and short-axis dimensions of nodules and solid components with a lung and/or a mediastinal window setting (WS) on TS-CT. After analyzing interobserver agreement, average long-axis dimensions of the measured tumors and solid components were correlated with pathological findings. Seven of 188 patients (3.7%) had pathologic LN-positive metastasis. In patients in whom the long axis of the solid component was < 5 mm with a mediastinal WS or < 8 mm with a lung WS on TS-CT, no LN metastases were observed, resulting in a positive predictive value (PPV) for predicting a pathologic LN-negative status of 100% with each WS. Based on the same diagnostic criteria, the PPVs for a pathological local invasion (LI)-negative status were 91 (40/44) and 90% (55/61), respectively. Solid component size on TS-CT may have the potential to predict LN-negative or LI-negative status.