What characterizes malignant pulmonary nodules on CT imaging?

Malignant pulmonary nodules on CT imaging are often characterized by mixed attenuation. This is due to the heterogeneous nature of malignant tissues, which can exhibit various densities depending on factors such as the presence of necrosis, calcification, or associated edema. This variability in attenuation can help radiologists differentiate between benign and malignant nodules.

In contrast, well-defined borders typically suggest a benign process, as malignancies tend to have irregular or spiculated margins due to their infiltrative nature. High attenuation might imply the presence of dense materials, such as calcified tumors or associated structures, rather than indicating malignancy. A hypodense appearance could correlate with certain benign lesions or fluid-filled cysts, which is generally not a characteristic of malignant nodules. The presence of mixed attenuation, therefore, serves as a vital indicator and contributes to the assessment of the nodules’ potential malignancy.