Yukihiro Ogihara, Presenter: Nothing to Disclose

Kazuto Ashizawa MD, Abstract Co-Author: Nothing to Disclose

Hideyuki Hayashi, Abstract Co-Author: Nothing to Disclose

Akihumi Nishida, Abstract Co-Author: Nothing to Disclose

Naoya Yamasaki, Abstract Co-Author: Nothing to Disclose

Tomoshi Tsuchiya, Abstract Co-Author: Nothing to Disclose

Keitaro Matsumoto, Abstract Co-Author: Nothing to Disclose

Takeshi Nagayasu, Abstract Co-Author: Nothing to Disclose

Tomayoshi Hayashi, Abstract Co-Author: Nothing to Disclose

Sumihisa Honda, Abstract Co-Author: Nothing to Disclose

Masataka Uetani MD, Abstract Co-Author: Nothing to Disclose

A statement from the Fleischer Society suggests that the size of the solid component in lung adenocarcinoma is best measured in its largest dimension visible on axial thin-sections with a mediastinal window setting (WS). Tsutani Y et al. stated that the pathologic lymph node (LN) negative status criteria of a size of the solid component were less than 8mm in its maximum dimension with a lung WS.. The purpose of our study was to correlate the size of solid components on thin-section CT (TS-CT) with pathological findings (LN metastasis and local invasion such as lymphatic or vascular invasion) in T1 lung adenocarcinoma, and to evaluate the predictive value of the size of solid components for pathological status.

From January 2008 to August 2012, 192 patients with surgical resected T1 lung adenocarcinoma were retrospectively analyzed. Two chest radiologists, who were blinded to the results of pathological findings, measured long and short dimensions of the solid components with a lung (WW 1600, WL -600) and/or a mediastinal (WW 320, WL 30) WS. The average sizes of the solid components measured by the two radiologists were correlated with the pathological findings.

7 out of 192 patients (3.6%) had pathological LN metastasis. Patients with a long axis of solid component of less than 5 mm with a mediastinal WS or 8 mm with a lung WS, were observed to have no LN metastasis, resulting in positive predictive value (PPV) for predicting pathologic LN-negative status of 100% with each WS. 62 out of 192 patients (32%) had pathological local invasion. In patients with a long axis of solid component of less than 5 mm with a mediastinal WS or 8 mm with a lung WS, PPV for predicting pathological local invasion-negative status was 91% (40/44) and 90% (55/61), respectively.

The long axis of the solid component with a mediastinal WS bounded by 5mm (Fleischer Society), or that with a lung WS bounded by 8mm was valid for prediction of pathologic LN-negative metastasis.

The patients who meet these predictive criteria may be optimal candidates for limited resection without the systemic LN dissection.

Ogihara, Y, Ashizawa, K, Hayashi, H, Nishida, A, Yamasaki, N, Tsuchiya, T, Matsumoto, K, Nagayasu, T, Hayashi, T, Honda, S, Uetani, M, Classification of T1 Lung Adenocarcinoma by the Size of Solid Components on Thin-section CT: Correlation with Pathological Findings.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13019556.html