Faculty Bibliography

The development of widespread lung cancer screening programs has the potential to dramatically increase the number of thoracic computed tomography (CT) examinations performed annually in the United States, resulting in a greater number of newly detected, indeterminate solitary pulmonary nodules (SPNs). Additional imaging studies, such as fluorodeoxyglucose F 18 (FDG)-positron emission tomography (PET), have been shown to provide valuable information in the assessment of indeterminate SPNs. Newer technologies, such as contrast-enhanced dual-energy chest CT and FDG-PET/CT, also have the potential to facilitate diagnosis of potentially malignant SPNs.

A solitary pulmonary nodule (SPN) is defined as a round opacity that is smaller than 3 cm. It may be solid or subsolid in attenuation. Semisolid nodules may have purely ground-glass attenuation or be partly solid (mixed solid and ground-glass attenuation). The widespread use of multidetector computed tomography (CT) has increased the detection of SPNs. Although clinical assessment of patients' risk factors for malignancy-such as age, smoking history, and history of malignancy-is important to determine appropriate treatment, in the recently published Fleischner guidelines for subsolid nodules, smoking history does not factor into their recommendations for management because there is an increasing incidence of lung adenocarcinoma in younger and nonsmoking patients. At imaging evaluation, obtaining prior chest radiographs or CT images is useful to assess nodule growth. Further imaging evaluation, including CT enhancement studies and positron emission tomography (PET), helps determine the malignant potential of solid SPNs. For subsolid nodules, initial follow-up CT is performed at 3 months to determine persistence, because lesions with an infectious or inflammatory cause can resolve in the interval. CT enhancement studies are not applicable for subsolid nodules, and PET is of limited utility because of the low metabolic activity of these lesions. Because of the likelihood that persistent subsolid nodules represent adenocarcinoma with indolent growth, serial imaging reassessment for a minimum of 3 years and/or obtaining tissue samples for histologic analysis are recommended. In the follow-up of subsolid SPNs, imaging features that indicate an increased risk for malignancy include an increase in size, an increase in attenuation, and development of a solid component. (c)RSNA, 2014.

In this review, we focus on the radiologic, clinical, and pathologic aspects primarily of solitary subsolid pulmonary nodules. Particular emphasis will be placed on the pathologic classification and correlative computed tomography (CT) features of adenocarcinoma of the lung. The capabilities of fluorodeoxyglucose positron emission tomography-CT and histologic sampling techniques, including CT-guided biopsy, endoscopic-guided biopsy, and surgical resection, are discussed. Finally, recently proposed management guidelines by the Fleischner Society and the American College of Chest Physicians are reviewed.

Thoracotomy with lung resection produces postoperative changes that can be challenging for the radiologist. Complications related to anatomic and physiologic changes, infection, and breakdown of surgical anastomoses can significantly increase morbidity and mortality. Prompt and accurate diagnosis of serious postoperative complications is essential.

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.

Rationale: Early COPD is characterized by inflammation leading to lung destruction. Recent data supports that enrichment of the lung microbiome with supraglottic characteristic taxa (SCT) is associated with inflammation. We hypothesize that in subjects with early COPD, areas at higher risk for microaspiration (right) or with greater degree of parenchymal abnormalities will be enriched with SCT or potential pathogenic taxa (PPT) compared to their contralateral lung segment. Methods: Subjects with early emphysema were enrolled for research bronchoscopy from the NYU/EDRN cohort. An independent radiologist semiquantitatively assessed all Chest CT scans: six-point score based on the presence of parenchymal damage in three zones (upper, middle, and lower). Broncho-alveolar lavages (BAL) were obtained from the right middle lobe and lingula segments. Sequencing 16S rDNA performed with 454 pyrosequence. Results: A total of 15 subjects with early COPD were studied. CT scans demonstrated n=7 with normal lower zones and n=8 with symmetrical or asymmetrical emphysema in the lower zones (p=ns). We used Wilcoxon paired comparisons to analyze the microbiome in areas of greater degree of parenchymal abnormalities (if asymmetric) or right compared to the contralateral lung segment. Data showed that the areas of greater abnormalities or right were associated with increased relative abundance (RA) of Haemophilus (RA 0.00170+/-0.002 vs. 0.00084+/-0.001, p=0.04), Neisseria (RA 0.0048+/-0.005 vs. 0.0023+/-0.003, p=0.028), Parvimonas (RA 0.017+/-0.003 vs. 0.0002+/-0.0008, p=0.05), and Serratia (RA 0.0122+/-0.02 vs. 0.0033+/-0.003, p=0.03) compared with the contralateral segment. Streptococcus appeared not to have a predilection for at-risk segments at the genus level. However, at the OTU level, Streptococcus mitis and Streptococcus pneumoniae species were higher in lung segments with more emphysema or right lung segments. Conclusions: Our data shows that areas of greater parenchymal damage or at higher risk for microaspiration (right) are enriched with potentially pathogenic taxa, such as Parvimonas, Neisseria, Haemophilus, Serratia, and Streptococcus. These taxa are known to be in high relative abundance in the oral and supraglottic region. Some of these taxa have been found to be at higher RA after viral infections, suggesting that enrichment of these low relative abundance taxa may play a critical role in disease. However, other supraglottic characteristic taxa such as Prevotella and Veillonella were not increased in these regions. These observations suggest a distinct selection pressure between the upper and lower airway microbiome