The impact of phantom CT scanning on surgery for the solitary pulmonary nodule

A reliable preoperative method to distinguish benign from malignant peripheral solitary pulmonary nodules (SPNs) would be clinically valuable. New techniques using epoxy resin plastic models of the thorax combined with calcium carbonate (phantom) nodules to determine the density of SPN have been proposed as a partial solution to this problem. During the first 3 years that phantom computed tomography (CT) has been available, 50 consecutive patients in whom SPN was discovered on screening chest x-ray film and who were considered to be candidates for surgery were evaluated by this technique. Twenty patients (40%) clearly met the phantom CT criteria for benign nodules (more dense than the phantom nodule, at least 10% of the surface area uniformly calcified, round or oval lesions without spicules, and lesions less than 3.0 cm in diameter) and have been followed up without surgery (no change on periodic screening chest x-ray film or CT for as many as 36 months). Only one of these 20 patients would have met standard x-ray criteria for benign nodules. Thirty patients who had lesions with densities less than the phantom nodule underwent thoracotomy, and in 17 (57%) of these, the lesions were malignant. No patient in this study who had a benign reading on the phantom CT scan had a malignancy at surgery or during follow-up. We conclude that phantom CT scanning is a useful adjunct to standard technique (review of prior screening chest x-ray film) and may prevent unnecessary thoracotomy in a significant percentage of patients with SPN.