| Objective:To detemine the clinical role of dual-energy computed tomography (CT) in evaluating solitary pulmonary nodules(SPNs).Methods:Forty-seven patients with SPNs proved by pathology underwent DECT scans. The virtual non-enhanced CT images and iodine images were derived from the venous data using Liver VNC processing.Between the true non-contrast CT(TNCT) and the virtual non-contrast CT(VNCT), mean CT HU, noise, signal to noise(SNR), nodual diameter with paired t test. the image quality, detectability of calcification were compared with TNCT as the standard.The CT values of SPNs on enhanced weighted average image and iodine-enhanced image were compared in terms of their diagnostic accuracy for distinguishing malignant and benign nodules with a20HU threshold. The independent t test was used to analyze the CT number of SPNs on the degree of enhancement and iodine-enhanced image,and the radiation dose significant differences of the Single phase scanning between the TNCT and the VNCT images, and both the ratio of iodine-based value in the portal venous phase and the Spectral curve of monochromatic of the benign and malignant nodules respectively.Results:There were no statistical significant of the mean CT Number(t=1.556,P>0.05), noise (t=-0.357, P>0.05), SNR (t=0.767, P>0.05) on TNCT and VNCT, the CT Number were (29.90±12.43) vs (27.52±116.67)HU, the noise were (9.60±3.74) vs (9.88±2.90), SNR were (3.07±1.93) vs (2.76±2.36). The CT number of SPNs on the degree of enhancement with TNCT(A) and VNCT(B) for baseline were (18.63±8.03) HU and (20.45±9.13) HU, respectively. The CT number of iodine-enhanced image (C) was (23.82±9.20) HU, there was statistical significant of the A and C (t=-2.371, P<0.05).The quality scores of VNCT image was(2.71±0.42), slightly worse than TNCT image, but does not affect the diagnostic requirements. The detectability of calcification rate of VNCT was92.3%(72/78)On the basis of TNCT,but the size of SPN was little on VNCT images. The sensitivity and accuracy was the highest of the CT number on iodine-enhanced image, there were82.3%(28/34) and74.5%(35/47) respectively. The specificity was the the highest of CT number on the degree of enhancement with VNCT for baseline, it was76.9%(10/13). Between the benign and malignant nodules,the ratio of iodine-based value in the portal venous phase was(0.28±0.11)and(0.26±0.19) respectively,there was no statistical significant (t=-0.47, P>0.05),the Spectral curve slope was (0.67±0.38) and (1.03±0.63) respectively, there was no statistical significant (t=1.60, P>0.05).The radiation dose statistical significant of the Single phase scanning were (5.68±1.31) mSv on TNCT, and (4.89±1.27) mSv on VNCT, and there were no statistical statistical difference (t=1.93, P>0.05).Conclusion:1. With the consequent reduction dose, DECT by using virtual non-enhanced images can satisfy completely the requirements of diagnosis, The VNCT can replance TNCT as As a baseline in dynamic enhanced scan.2. Iodine-image by using virtual non-enhanced images of dual-energy CT is more helpful in diagnosis of benign and malignant SPN.3. There was no statistical significance between the energy attenuation curve slope of the benign and malignant SPN, But the large difference in the CT value when it in the lower energy between40-60kev, and CT value difference was statistically significant.4. Integration of the various parameters from dual-energy imaging has a certain value for qualitative diagnosis on SPN. |
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