Current readings: radiologic interpretation of the part-solid nodule: clinical relevance and novel technologies

Persistent subsolid nodules, part-solid or pure ground-glass attenuation, are associated with primary lung adenocarcinoma, recently redefined by the International Association for the Study of Lung Cancer-American Thoracic Society-European Respiratory Society in 2011 and include newly categorized entities of adenocarcinoma in situ, minimally invasive adenocarcinoma, and lepidic-predominant adenocarcinoma. Awareness of the relationship of the subsolid nodule with adenocarcinoma has emerged in the era of high-resolution multidetector computed tomography (CT). This article highlights the role of noninvasive CT for subsolid nodules with an emphasis on the potential for quantitative measures to predict adenocarcinoma subtypes and their longitudinal behavior. Of particular importance is the knowledge that an increase in solid components on CT is an indication of progression. Continued experience in evaluating quantitative measures in combination with morphologic features, including margin contour, internal architecture, and nodule size, will further aid in guiding crucial decisions pertaining to the use of CT surveillance vs more invasive approaches including biopsy and surgical resection.