CONVENTIONAL CHEST RADIOGRAPHY VS DUAL-ENERGY COMPUTED RADIOGRAPHY INTHE DETECTION AND CHARACTERIZATION OF PULMONARY NODULES

OBJECTIVE. We evaluated a single-exposure, phosphor-plate, dual-energy imaging device that produces, in addition to conventional chest radio graphs, both tissue- and bone-selective images. Our purpose was to det ermine whether dual-energy radiography was more accurate than routine chest radiography for detection and characterization of pulmonary nodu les. SUBJECTS AND METHODS. Two hundred patients undergoing chest CT we re asked to volunteer to have dual-energy and conventional chest radio graphs obtained immediately before or after their CT scan. Radiographs from a subset of 50 of these patients with 116 CT-detected nodules an d 10 patients with normal findings on CT scans of the chest were prese nted to the observers for the nodule detection study. Similarly, radio graphs from a subset of 29 patients with 20 calcified and 20 uncalcifi ed nodules were presented to five observers to determine nodule calcif ication. Dual-energy images were produced by filtering the X-ray tube output with a gadolinium sheet while using a multiple phosphor plate r eceptor. A dual-energy triad of images consisting of a conventional im age, a tissue-selective image, and a bone-selective image were produce d. The conventional chest radiographs and dual-energy image sets were presented to observers in random order. Data from a free response rece iver operating curve and a receiver operating curve were generated for nodule detection and characterization, respectively. RESULTS. By usin g the dual-energy images, all five observers improved their ability to diagnose pulmonary nodules (p = .0005) and to characterize nodules as calcified (p = .005). CONCLUSION. By eliminating rib shadows with tis sue-selective images and enhancing calcified structures with bone-sele ctive images, dual-energy chest radiography improved the ability of al l observers, regardless of expertise, to detect and characterize pulmo nary nodules.