Dual-energy CT: clinical applications in various pulmonary diseases.

The dual-energy computed tomographic (CT) technique allows the differentiation of materials with large atomic numbers such as iodine and xenon. The basic principle of dual-energy CT is material decomposition based on attenuation differences at different energy levels. By using dual-energy CT angiography for the evaluation of perfusion defects in cases of pulmonary embolism, and using xenon CT for the evaluation of ventilation defects, it may be possible to replace perfusion and ventilation scanning. An iodine map from dual-energy CT can demonstrate the distribution of pulmonary perfusion, whereas xenon ventilation CT can be used to generate a ventilation map. Furthermore, the virtual nonenhanced dual-energy CT technique can be used for the evaluation of pulmonary nodule characteristics without acquisition of true nonenhanced CT images. Knowledge of the applications of dual-energy CT and the typical images produced may lead to wider use of dual-energy CT for pulmonary applications and better interpretation of the results.