What are the findings of a Computed Tomography (CT) scan for lung nodules?

From the Guidelines

Lung nodules detected on CT scans should be characterized using thin-section CT with contiguous 1.5 mm sections and reconstructed multiplanar images to ensure adequate characterization, particularly for nodules with a ground-glass attenuation component, as recommended by the American College of Radiology 1. When a lung nodule is found on a CT scan, it is essential to consider the nodule's size, appearance, and the patient's risk factors to determine the best course of action.

• Nodules less than 6 mm with low risk factors may not require follow-up, while nodules 6-8 mm typically require follow-up CT scans at 6-12 months and possibly again at 18-24 months.
• Larger nodules (>8 mm) may need more frequent imaging or additional testing like PET scans or biopsies, as they are more likely to be malignant. The use of intravenous (IV) contrast is not required to identify or initially characterize pulmonary nodules in clinical practice, as stated in the American College of Radiology guidelines 1. Key factors associated with increased sensitivity for nodule detection and characterization on CT include thinner CT sections, nodule location and larger size, and nodule attenuation, with reported detection sensitivities ranging from 30% to 97% 1. It is crucial to note that most lung nodules (about 95%) are benign, resulting from previous infections, inflammation, or non-cancerous growths, and that risk factors such as older age, smoking history, larger nodule size, irregular borders, and growth over time increase concern for malignancy.
• Patients with lung nodules should avoid smoking and report any new symptoms like persistent cough, chest pain, or shortness of breath to their doctor immediately. Regular follow-up is essential to monitor for any changes that might indicate a need for more aggressive evaluation, and CT scans are widely recognized as the modality of choice to evaluate pulmonary nodules, being 10 to 20 times more sensitive than standard radiography 1.

From the Research

Lung Nodules Detection and Management

• Lung nodules are identified in approximately 1.6 million patients per year in the US and are detected on approximately 30% of computed tomographic (CT) images of the chest 2.
• The probability of malignancy is less than 1% for all nodules smaller than 6 mm and 1% to 2% for nodules 6 mm to 8 mm 2.
• Nodules that are 6 mm to 8 mm can be followed with a repeat chest CT in 6 to 12 months, depending on the presence of patient risk factors and imaging characteristics associated with lung malignancy, clinical judgment about the probability of malignancy, and patient preferences 2.

CT Scan and Diagnosis

• CT-guided lung nodule biopsy has a high diagnostic yield, but the risk of pneumothorax is often a concern 3.
• Bronchoscopy has a better safety profile, but diagnostic ability falls short of CT-guided biopsy 3.
• Emerging technologies such as cone-beam CT scan and robotic bronchoscopy have addressed some of these issues and initial experience has demonstrated better diagnostic yield 3.

Management and Treatment

• The treatment of an individual with a solid pulmonary nodule 8 mm or larger is based on the estimated probability of malignancy; the presence of patient comorbidities, such as chronic obstructive pulmonary disease and coronary artery disease; and patient preferences 2.
• Management options include surveillance imaging, defined as monitoring for nodule growth with chest CT imaging, positron emission tomography-CT imaging, nonsurgical biopsy with bronchoscopy or transthoracic needle biopsy, and surgical resection 2.
• Part-solid pulmonary nodules are managed according to the size of the solid component, with larger solid components associated with a higher risk of malignancy 2.

Follow-up and Adherence

• High adherence to appropriate follow-up of positive results, including imaging or interventional approaches, is an important aspect of pulmonary nodule management 4.
• Despite the radiologist's recommendation for follow-up within a certain time interval, only 36% had repeat imaging in a timely manner, suggesting a need for improvement in adherence to follow-up 4.