Evaluation of solitary pulmonary nodule detected during computed tomography examination

Abstract

The solitary pulmonary nodule (SPN) has always been a diagnostic challenge for the radiologists. Currently, with increased utilization of computed tomography (CT) greater number of nodules is being discovered, with numerous indeterminate lesions, which frequently cannot be immediately classified into benign or malignant category.In this article we review the imaging features of benign and malignant round opacities; we demonstrate currently used standards and also more advanced techniques that are helpful in evaluating SPNs such as contrast-enhanced CT, PET/CT imaging and also pathologic sampling with biopsy or surgical resection.We also summarize the methods of evaluating and managing SPNs based on the latest guidelines from the Fleischner Society and American College of Chest Physicians.

Keywords: indeterminate nodule; multi-detector computed tomography (MDCT); solitary pulmonary nodule (SPN); transthoracic needle biopsy (TNB).

Figure 1

The differential diagnosis for a solitary pulmonary nodule [3,4].

Figure 2

Well-circumscribed pulmonary nodule with smooth margins.

Figure 3

Pulmonary nodule with irregular margins.

Figure 4

Pulmonary nodule with lobulated margins.

Figure 5

Pulmonary nodule with spiculated margins and „halo sign”.

Figure 6

Benign granuloma with characteristic laminated pattern of calcification.

Figure 7

Benign pulmonary nodule with central calcification due to prior histoplasma infection.

Figure 8

Histoplasmosis. Pulmonary nodule in CT and PET-CT. Note that the nodule is non FDG avid.

Figure 9

Pulmonary nodule with malignant pattern of calcification.

Figure 10.

Benign hamartoma.

Figure 11

Benign cavity with relatively smooth, thin walls. This infectious lesion nearly resolved on follow-up imaging.

Figure 12

Metastatic cavitary nodule due to squamous cell carcinoma.

Figure 13

Cavitary squamous cell carcinoma. Note ring-like FDG avid lesion on PET-CT.

Figure 14

Carcinoid.

Figure 15

Slowly growing malignancy from a ground glass nodule to a cavitary mass over 7 years: (A). 5 mm at baseline, (B) 10 mm 3 years later, (C) cavitary mass at diagnosis 4 years later – poorly differentiated sarcomatoid carcinoma.

Figure 16

Moderately differentiated lung carcinoma: (A) baseline, (B) 10 months later, (C) 6 months later.

Figure 17

Pattern of malignant enhancement: (A) plot of nodule enhancement over time, (B) attenuation of the nodule before contrast administration, and (C) post-contrast enhancement.

Figure 18

Computer-aided detection/diagnosis (CAD) system R2: (A) volume calculation of the nodule, (B) system detected spiculated mass in the right lung, (C) tiny nodule detected in the left lung.

Figure 19

Moderately-differentiated lung carcinoma with FDG-avid lesion on PET-CT.

Figure 20

Poorly-differentiated lung carcinoma with FDG-avid lesion on PET-CT.

Figure 21

FDG avid inflammatory lesion in the right lung and mediastinal and hilar adenopathy in pulmonary sarcoidosis.

Figure 22

Aspergilloma in the right lung with FDG avid lesion on PET-CT.

Figure 23

Peripheral pulmonary nodule due to rheumatoid arthritis. Note FDG avid inflammatory nodule on PET.

Figure 24

Bronchioalveolar carcinoma in the right lung. Note mild, heterogeneous FDG avidity on PET-CT.

Figure 25

Metastatic pulmonary nodule from a colorectal mucinous adenocarcinoma. Note minimal FDG avidity on PET-CT.

Figure 26

The Fleischner Society recommendations for a follow-up and management of a solitary pulmonary nodule detected incidentally during a non-screening CT [55].