Preliminary experience with thoracic dual-energy CT: true versus virtual non-enhanced images of solitary pulmonary nodules / 中华放射学杂志

ABSTRACT

Objective To compare the conventional non-enhanced and virtual non-enhanced images of dual-energy computed tomography (CT) in evaluating solitary pulmonary nodules (SPNs).Methods Forty-seven patients with SPNs proved by pathology underwent conventional and enhanced thoracic DECT.The virtual non-enhanced CT images and iodine images were reconstructed based on the enhanced imaging data.The mean CT number,noise,signal to noise (SNR),nodual diameter of SPNs were compared between the true non-contrast CT(TNCT) and the virtual non-contrast CT (VNCT),with paired t test.The image quality and detectability of calcification were also compared.The diagnostic accuracy for malignant nodulesbased on the increased CT values and iodine-enhanced image were compared.The independent t test was used to compare the increased CT number of SPNs and iodine images.The single-phase radioation dose of the single energy,was compared with dual energy scan.Results No significant difference in 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 mean CT Number,the noise,and SNR were (29.90 ± 12.43)vs (27.52 ± 16.67) HU,(9.60 ±3.74) vs (9.88 ± 2.90),and (3.07 ± 1.93) vs (2.76 ± 2.36),respectively.The increased CT number ofSPNs with TNCT and VNCT from baseline were(18.63 ± 8.03) and(20.45 ± 9.13) HU.The CT number of iodine image was(23.82 ± 9.20)HU.A significant difference was observed between the TNCT and iodineed image (t =-2.371,P ＜ 0.05).The quality scores of VNCT image wasslightly worse than TNCT image.The detectability rate of calcification on VNCT was 92.3％ (72/78).The iodine image carried the highest diagnostic sensitivity rate and accuracy rate,82.3％ (28/34)and 74.5％ (35/47),respectively.The highest specificity rate was 76.9％ (10/13) from the increased CT number with VNCT.No significant difference in single-phase radiation dose was observed between TNCT and VNCT,(5.68 ± 1.31) vs.(4.89 ± 1.27)mSv.Conclusions VNCT could be obtained with similar image quality as TNCT.This methods might favor a reduction in radiation exposure.