Spearman's rank and Pearson correlation coefficients between quantitative results of LPBV ([H.sub.LPBV], [V.sub.5], and %[V.sub.5]) and the various factors suggesting of the severity of the pulmonary embolic burden were analyzed, including the ejection fraction (EF; %) and estimated systolic PA pressure (ePAP; mmHg) using echocardiography, the short-axis RV diameters, RV/LV diameter ratio, PA diameter, PA/Ao diameter ratio and CTOI using the same statistical software program used to perform the calculations, SPSS for Windows, release 19.0 (SPSS, IBM Inc.).
The LPBV using DECT provides fine CTPA, high-resolution lung CT image and additional perfusion information at a single examination (16) and displays decreased attenuation area caused by PTE (17, 18).
Compared with the findings of a previous study using relative volumetric values of LPBV (AUC of %[V.sub.5]: 0.73) based on the presence of PTE (17), the AUCs for [H.sub.LPBV] and % [V.sub.5] were slightly higher in this study.
Second, the beam hardening artifact-related focal iodine defects without relation to PTE are detected in the upper lobe or medial segment of middle lobes on DECT (19) and may affect the histogram pattern of LPBV. In order to minimize contrast-related beam-hardening artifacts, caudocranial scans and a higher injection rate of iodine contrast-material may be employed to obtain the best image quality for both CTPA and perfusion map images of the lungs due to the high attenuation in the PAs (10).
* Dual-energy computed tomography (DECT) provides iodine perfusion map in lung parenchyma as lung perfused blood volume images (LPBV).
* The histogram pattern of LPBV have correlations with the factors suggesting right heart strain, including the right/left ventricular diameter ratio (r=0.36, P = 0.007) and CT obstruction index (r=0.63, P < 0.001).