AJR 2009;193:144-149
Sven F. Thieme, Thorsten R. C. Johnson, Christopher Lee, Justin McWilliams, Christoph R. Becker, Maximilian F. Reiser1 Konstantin Nikolaou
OBJECTIVE. The purpose of this study was to assess the feasibility and diagnostic value of dual-energy CT iodine mapping at pulmonary CT angiography.
SUBJECTS AND METHODS. Ninety-three patients underwent CT angiography with the dual-energy technique on a dual-source CT scanner. Postprocessing was used to map io¬dine in the lung parenchyma on the basis of its spectral behavior, and image quality was as¬sessed by two readers. Iodine distribution patterns were rated as homogeneous, patchy, or cir¬cumscribed defects. Conventional CT angiographic images reconstructed from the same data sets were reviewed for the presence and localization of pulmonary embolism, whether embo¬lic occlusion was partial or complete, and the presence of changes in the lung parenchyma. Dual-energy perfusion findings were correlated with the CT angiographic and lung-window CT findings in per-patient and per-segment analyses.
RESULTS. Iodine distribution was homogeneous in 49 patients, of whom CT angiogra¬phy showed no pulmonary embolism in 46 patients and nonocclusive pulmonary emboli in three patients. Images of 29 patients showed a patchy pattern; 24 of these patients had no pul¬monary embolism, and five had nonocclusive pulmonary emboli with solely nonocclusive in¬travascular clots. Images of 15 patients showed segmental or subsegmental defects; four of these patients had evidence of pulmonary embolism, and 11 had occlusive pulmonary emboli with at least one occlusive clot in the pulmonary vasculature.
CONCLUSION. Dual-energy CT is reliable in the detection of defects in pulmonary pa¬renchymal iodine distribution that correspond to embolic vessel occlusion.