For a patient with new lung nodules requiring follow-up, should I order a computed tomography (CT) chest scan with or without contrast?

CT Chest Without Contrast for Lung Nodule Follow-Up

For new lung nodules requiring 6-month follow-up, order a CT chest WITHOUT IV contrast. 1

Rationale for Non-Contrast CT

Noncontrast chest CT is adequate for identifying new lung nodules, assessing their growth, and determining stability. 1 The American College of Radiology explicitly states that IV contrast is not required to identify, characterize, or determine stability of pulmonary nodules in clinical practice. 1

Technical Specifications

• Use thin-section CT with 1.5 mm slices and multiplanar reconstructions for optimal nodule characterization and accurate size measurements. 1, 2
• Low-dose technique is recommended for follow-up CT scans to minimize radiation exposure (approximately 2 mSv), particularly since serial imaging may be needed. 1, 2
• Standardized acquisition protocols reduce measurement errors and improve comparison accuracy between studies. 1

When Contrast Is NOT Needed

IV contrast adds no value for:

• Detecting new lung nodules 1
• Assessing nodule growth or stability over time 1
• Characterizing nodule morphology, margins, or calcification patterns 1
• Following nodules of any size in routine surveillance 1

When Contrast MIGHT Be Considered

Contrast-enhanced CT is recommended over noncontrast only when you need to:

• Identify mediastinal or hilar lymphadenopathy suggesting disease progression 1
• Evaluate for abdominal disease progression (adrenal metastases) 1
• Differentiate post-surgical changes from recurrence in patients with prior lung cancer surgery 1

However, these indications fall outside the scope of simple nodule follow-up. 1

Important Caveats

• Adrenal nodules cannot be definitively characterized even with contrast in approximately one-third of cases (when intracytoplasmic lipid content is low), and may require PET/CT, MRI, or adrenal washout CT instead. 1
• There is no relevant literature supporting the use of CT chest with contrast specifically for pulmonary nodule surveillance. 1
• FDG-PET/CT has limited spatial resolution for nodules <8 mm and should not be used for small nodule evaluation. 1, 2

Follow-Up Timing Based on Size

For context on your 6-month follow-up recommendation:

• Nodules ≤5 mm: Follow-up at 6 months; if no growth, stop workup. 2
• Nodules 5-9 mm: Follow-up at 3 months, then 6 months if persistent but stable. 2
• Nodules <6 mm with no suspicious features: May not require routine follow-up (malignancy risk <1%). 1, 2