How can I differentiate between benign and malignant lung nodules in imaging results?

To differentiate between benign and malignant lung nodules based on imaging, key features on CT and PET/CT scans are assessed. Malignant nodules often present with irregular or spiculated margins, larger size (typically >8 mm), and growth over time on serial imaging, whereas benign nodules tend to be smaller, have smooth, well-defined edges, and remain stable in size ¹. The Lung-RADS classification system, used in lung cancer screening, helps stratify nodules by malignancy risk based on size, morphology, and growth patterns, with higher categories indicating greater suspicion of malignancy [1, (Kastner et al., 2021)].

Fluorine 18-FDG PET/CT is valuable in further characterizing nodules; malignant nodules usually show increased metabolic activity (high FDG uptake), while benign nodules typically have low or absent uptake, although inflammatory lesions can cause false positives (Basso Dias et al., 2019). Diffusion-weighted MRI can also aid differentiation by assessing cellular density, with malignant lesions showing restricted diffusion compared to benign ones (Basso Dias et al., 2019). Computer-aided quantitative analysis of nodule features such as texture and shape on CT can improve characterization accuracy (Bartholmai et al., 2015).

In summary, integrating nodule size, morphology, growth, metabolic activity on PET/CT, and advanced imaging features provides the best approach to distinguish benign from malignant lung nodules, as recommended by UK guidelines and supported by recent imaging research [1, (Bartholmai et al., 2015); (Basso Dias et al., 2019); (Kastner et al., 2021)].