Minor components of micropapillary and solid subtypes in lung invasive adenocarcinoma (≤ 3 cm): PET/CT findings and correlations with lymph node metastasis

Objective To investigate the PET/CT findings in lung invasive adenocarcinoma with minor components of micropapillary or solid contents and its association with lymph node metastasis. Materials and methods A total of 506 lung invasive adenocarcinoma (≤ 3 cm) patients who underwent a PET/CT examination and resection surgery were included. According to the proportion of solid/micropapillary components, the patients were classified into three groups: solid/micropapillary-negative (SMPN) ( n = 258), solid/micropapillary-minor (SMPM; > 5% not predominant) ( n = 158) and solid/micropapillary-predominant (SMPP; > 5% most dominant) ( n = 90). The patients’ PET/CT findings, including SUVmax, MTV, TLG and CT characteristics, and other clinical factors were compared by one-way ANOVA test. Logistic regression analysis was done to identify the most predictive findings for lymph node metastasis. Results The value of SUVmax, MTV, TLG and tumor size was highest in SMPP group, followed by SMPM and SMPN group ( P