Pulmonary nodule follow-up: be careful with volumetry between contrast enhanced and unenhanced CT.

Incident pulmonary nodules are a frequent finding on chest computed tomography (CT) of the lungs requiring follow-up. This case illustrates the importance of taking differences in CT scanning techniques (contrast versus non-contrast enhanced) into account. Comparing nodule size on unenhanced follow-up CT's with initial contrast-enhanced CT may consequently underestimate growth and mask malignant growth rates as demonstrated by our case report.