Résumé
Purpose To assess the feasibility of dual-energy dual-source virtual noncontrast (VNC) CT in the diagnosis of laryngeal carcinoma,in order to reduce radiation hazard.Materials and Methods Forty-nine patients with clinically identified laryngeal carcinoma underwent conventional non-contrast (CNC) scan as well as arterial and venous dual-phase and dual-energy VNC scan.The VCN images of arterial and venous phase were obtained by using the dual-energy software.The mean CT value,signal-to-noise ratio (SNR),contrast noise ratio (CNR),lesion morphology,image quality and radiation dose were compared between the VNC and CNC images.Results The mean CT value,SNR,CNR and image quality scores of CNC were higher than those of VNC images of arterial and venous phase (P＜0.05).There was no significant difference in the image quality scores of VNC between the arterial and venous phase (P＞0.05).The image quality scores of VNC were all above 3,which could meet the diagnostic requirements.There was no significant difference in the shape,size,boundary and cystic necrosis of the lesions,invasion of the surrounding space,osteolytic destruction and size of the surrounding lymph node between the CNC and VNC image.The radiation dose of dual-phase dual-energy scan was 0.42 mSv,which was 18.3％ lower than that of the conventional three-phase scan.Conclusion For laryngeal carcinoma,the VNC images from the dual-energy CT scan can be used to reduce the radiation dose without affecting image quality and diagnosis accuracy,which has good clinical value.
Résumé
Purpose To investigate the diagnostic value of dual energy CT spectrum curve combined with CT morphology in central lymph node metastasis of papillary thyroid carcinoma (PTC).Materials and Methods Thirty-one PTC patients who accepted dual energy CT double-phase enhanced scan before surgery were analyzed.Central lymph nodes with short diameter ＞ 5 mm were labelled using axial plus 3D positioning.Preoperative labelled lymph nodes were collected and marked during operation.The CT morphology of metastatic lymph nodes was analyzed.The spectrum curve slope (K) difference between metastatic and non-metastatic lymph nodes of arterial-phase and venous-phase primary lesion was compared.The critical K value and the diagnostic efficacy of K value combined with morphology were obtained according to receiver operating characteristic (ROC) curve.Results A total of 73 central lymph nodes were obtained from 31 patients,among which 51 were metastatic and 22 were non-metastatic.There was no significant difference in K value between metastatic and non-metastatic lymph nodes of arterial phase group (P＞0.05).While,there was a significant difference in K value between metastatic and non-metastatic lymph nodes of venous phase group (P＜0.05).For venous phase,the sensitivity and specificity of the K value in diagnosing central lymph node metastasis were 62.7％ and 59.1％,respectively,and combined with morphology,the sensitivity and specificity reached 76.5％ and 81.8％,respectively.Conclusion The K value of CT spectrum curve is of certain significance in predicting PTC central lymph node metastasis,and the K value combined with CT morphology can improve the accuracy of diagnosis.
Résumé
Objective To investigate the value of low-dose coronary artery imaging with flash dual-energy CT.Methods In total of 240 patients suspected with coronary heart disease were performed dual-energy CCTA(DE-CCTA)and were divided into four groups according to the A tube electric current and the methods of reconstruction,including group A(conventional group:180 mAs+FBP)and low-dose groups(including group B,C,D:1 50 mAs,120 mAs,90 mAs +SAFIRE,respectively).The mean of CT value, image noise,SNR,CNR,image quality and radiation dosage were compared among the four groups.Among the patients,52 cases with coronary artery stenosis which were diagnosised by DE-CCTA were also confirmed by CAG,and the consistency of these two methods in the diagnosis of coronary artery stenosis were compared.Results The scores of all image quality were more than 3 points and were statistically significant among the four groups(P 0.05), while the image noise,SNR,CNR and the radiation dosage were statistically significant (P <0.05)among the four groups.The ED of group D was lower 55.62% than group A.DE-CCTA and CAG in the diagnosis of coronary artery stenosis had satisfactory consistency (Kappa=0.84,P<0.05).Conclusion Low-dose coronary artery DE-CCTA not only have none affect of image quality and diagnostic accuracy, but also can significantly reduce the radiation dosage.