Invasive Pulmonary Adenocarcinoma versus Preinvasive Lesion and Minimally Invasive Adenocarcinoma Appearing as Subsolid Pulmonary Nodules: Differentiation by Using ¹⁸F-FDG PET/CT

Objectives: To retrospectively investigate the value of ¹⁸F-FDG PET/CT for differentiation of preinvasive lesions and minimally invasive adenocarcinomas (MIAs) from invasive pulmonary adenocarcinomas (IPAs) that manifest as subsolid pulmonary nodules.

Methods: This study was approved by the institutional review board. 289 subsolid pulmonary nodules were pathologically confirmed in 289 patients who had undergone ¹⁸F-FDG PET/CT between July 2011 and June 2015. Maximal standardized uptake value (SUVmax) of subsolid pulmonary nodules was evaluated on the PET/CT. Histopathologic diagnoses were made according to the IASLC/ATS/ERS lung adenocarcinoma classification. To evaluate its differentiating accuracy, receiver operating characteristic (ROC) curve analysis was performed.

Results: There were 103 pure ground-glass nodules (GGNs) and 186 part-solid GGNs. Pathologic analysis confirmed 39 preinvasive lesions (14 atypical adenomatous hyperplasias and 25 adenocarcinomas in situ), 41 minimally invasive adenocarcinomas and 209 IPAs. IPAs and preinvasive lesions and MIAs exhibited significant differences in SUVmax (P<0.0001).The area under the ROC curve of SUVmax was 0.938 (95% confidence interval, 0.904-0.963, P<0.0001) for the differentiation of preinvasive lesions and MIAs from IPAs (Figure 1). The optimal cut-off SUVmax for IPAs was more than 1.07 (sensitivity, 84.2%; specificity, 95.0%).

Conclusion: In subsolid pulmonary nodules, ¹⁸F-FDG PET/CT shows excellent accuracy for differentiation of preinvasive lesions and MIAs from IPAs. Research Support: This work was supported in part by a grant (R21CA181885) from the National Cancer Institute of the National Institutes of Health.

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