ABSTRACT
Objective To investigate the clinical utility of dual-energy virtual non-contrast CT(VNCT)of dual source CT in the di-agnosis and differential diagnosis of solitary pulmonary nodule(SPN).Methods Thirty-six patients with suspected SPN underwent chest plain single energy CT and dual-phase contrast enhanced CT (DECT)(25 and 90 s).The images of dual energy were sent to a commercial workstation for VNC image generation.CT values of SPN on VNC and true non-contrast(TNC),as well as signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)were compared.The accuracy of calcification detection was compared according to the diameter and density of the calcification.The TNC images were used as the reference.Results CT values,SNR and CNR of VNC had no statistical difference among TNC and VNC at 25 s and 90 s(P >0.05).DECT VNC(5mm slice)could accurate detected calci-fication(diameter>2 mm,CT value>1 50 HU)in SPN.The 2 mm slice performed significantly better than 5 mm slice VNC images. Conclusion The VNC could provide consistent diagnostic information with TNC.The thin slice DECT VNC images can be used in clinical practice to replace TNC without losing small calcification in SPN,which has potential to reduce the patient radiation dose.
ABSTRACT
Objective To evaluate the capability of virtual non-contrast (VNC)of the second-generation dual-source CT (DSCT), and to display the adipose tissue of gastric serosa.Methods 48 patients with gastric cancer undergoing preoperative DSCT and sur-gery were enrolled.The true non-contrast (TNC)values and VNC values of perigastric adipose tissue were measured and compared with conventional non-contrast scanning and VNC of arterial phase and venous phase.The VNC values of perigastric adipose tissue were compared between serosal involvement group and non-serosal involvement group.Results There was statistical difference be-tween TNC values and VNC values of perigastric adipose tissue (P <0.05),the absolute differences were under 13 HU.The differ-ence of VNC values between serosal involvement group and non-serosal involvement group was significant (P <0.05).Conclusion VNC of the second-generation DSCT can clearly display the adipose tissue of gastric serosa.It has certain capability in judging sero-sal involvement.VNC has the proficiency to replace conventional non-contrast scanning.
ABSTRACT
Objective To investigate the intra- and interobserver repeatability of coronary artery disease (CAD) diagnosis based on invasive coronary angiography (ICA) and CT coronary angiography (CTCA).Methods Two readers with comparable experience ( over 10 years) independently evaluated ICA results of 42 consecutive patients with a blind method. After 30 days,one of them reviewed the same patients again.Another two comparable-experience (over 10 years) readers evaluated the results of CTCA (prospectively ECG-triggering) from the same 42 patients in the same way.The inter-reader and intra-reader repeatability of ICA and CTCA were analyzed by performing Kappa test and calculating the percentage of the segments with agreement on stenotic degree.Using ICA as reference,the accuracy of CTCA in diagnosing CAD was studied by comparing the area under ROC. Results The Kappa between readers for ICA and CTCA were 0.91 and 0.81.Intra-reader Kappa were 0.92 and 0.83 respectively (x2 =509.4 and 432.5,all P ＜0.01 ).The percentage of the segments with agreement between readers on the degree of stenosis were 80.8％ (494/611) in ICA and 75.2％ (469/624) in CTCA ( x2 =2.75,P =0.10),and within the same reader,86.9％ (531/611)in ICA and 81.9％ (511/624) in CTCA(x2 =3.76,P =0.053).With≥ 50％narrowing as a CAD diagnosis criterion,the agreement rates for two readers were 96.6％ (590/611 ) in ICA and 94.4％ (589/624) in CTCA( x2 =3.36,P =0.07),and for the same reader,97.4％ (595/611) in ICA,95.4％ (595/624) in CTCA ( x2 =3.62,P =0.06).Using ICA as reference,two readers of CTCA results achieved a sensitivity and specificity of 84.9％ (530/624)and 98.1％ (612/624).The area under ROC was 0.94 (95％ CI 0.91-0.97).Conclusions Both ICA and CTCA demonstrate good repeatability in diagnosing CAD.The repeatability of ICA is superior to that of CTCA.A certain discrepancy exists in two readings from the same reader or two readers.