RESUMEN
Objective To compare the virtual non-enhanced chest CT (VNCT)generated from spectral CT with conventional non-enhanced chest CT in patients with lung disease in terms of CT number accuracy and image quality.Methods A total of 30 patients with lung disease proved by pathology underwent the conventional non-enhanced thoracic CT and contrast enhanced CT with spectral imaging mode in arterial phase (AP)and venous phase (VP).The VNCT images were reconstructed based on the enhanced spectral CT imaging data.The mean CT number,signal to noise ratio (SNR)for the lesions and image quality score were obtained and compared between the true non-contrast CT (TNCT)and the VNCT (including AP and VP)with paired t test.Results The mean±standard deviation for CT number were (38.74±5.17)HU,(39.08±5.07)HU and (38.96± 5.18)HU for TNCT,VNCT at AP and VNCT at VP,respectively, with no statistical difference (P>0.05).All 3 sets of images demonstrated acceptable image quality,even though there were statistically significant differences in the SNR value and image quality score.The mean ± standard deviation values for SNR were 4.74±0.42 with TNCT, 3.79 ± 0.5 1 with VNCT at AP and 3.77 ± 0.39 with VNCT at VP (P <0.05),and the image quality scores were 5.00 ±0.00 with TNCT,4.17±0.65 with VNCT at AP and 4.17±0.53 with VNCT at VP (P<0.05).Conclusion In patients with lung disease,the vir-tual non-enhanced CT images generated from spectral CT provide accurate CT numbers for lesions and acceptable image quality com-pared with the true non-contrast CT.VNCT may be used to replace TNCT to improve work flow and reduce radiation dose.