Quantification of calcium in solitary pulmonary nodules using single- and dual-energy CT

Separation of benign from malignant solitary pulmonary nodules by computed tomography (CT) is based on two assumptions: (a) those that are calcified are benign, and (b) high CT numbers reflect calcium deposits. The authors used dual-energy CT to quantify the minimum detectable calcium content in simulated nodules independent of absolute CT number and to separate high CT numbers due to calcium from those due to high-density organic material. A mineral concentration of 20 mg/cm3 was detectable with this method. Dual-energy CT may be a more accurate method of detecting calcium in solitary pulmonary nodules than single-energy CT