Characterization of small pulmonary nodules by CT

Small pulmonary nodules with diameters ≤10 mm are very frequent findings at CT examinations. Despite the traditional opinion that every pulmonary nodule should be considered malignant until proven otherwise, the vast majority of small lesions are benign, and therefore biopsy may not be necessary in all cases. During the last few years, several CT-based methods have been developed to differentiate between benign and malignant lesions non-invasively. A negative quantitative contrast-enhanced CT is a strong predictor for benignity. Repeat nodule volume measurements at short-term follow-up CT examinations can detect growth suggesting malignancy. Limitations and potential pitfalls of these methods must be observed to avoid false negative test results leading to delayed diagnosis and treatment of malignant tumours. An algorithm for diagnostic workup of incidentally detected small pulmonary nodules in subjects without known malignancy is proposed in this article. (orig.)