[Application of virtual non-enhanced images in evaluating subarachnoid hemorrhage by dual-energy computed tomography angiography].

Objective To investigate the feasibility of virtual non-enhanced images in evaluating the spontaneous subarachnoid hemorrhage (SAH) by dual-energy computed tomography angiography.Methods Dual-energy computed tomography angiography was performed in 43 SAH patients.Virtual non-enhanced images were obtained by using Liver VNC software.Paired t-test was performed to compare the signal to noise ratio between the conventional plain scan and virtual non-enhanced images.Diagnostic accuracy for SAH by virtual non-enhanced imags was calculated by using the conventional plain scan images as a gold standard.Quality score was calculated to evaluate whether virtual non-enhanced images can meet the imaging requirements of SAH.Results The signal to noise ratio was 8.63±0.53 among plain scan images and 3.96±0.52 among virtual non-enhanced images ( t=43.18,P=0.000).The sensitivity,specificity,and accuracy of virtual non-enhanced imaging in diagnosing the SAH were 97.05%,100%,and 97.67% in per-patient analysis,and were 94.64%,100%,and 98.97% in per-lesion analysis.The quality scores were 3 in six patients,2 in 27 patients,and 1 in two patients.Conclusions Virtual non-enhanced images can meet the clinical requirements of diagnosis,althought it has more intensive noise than conventional plain scan images.Furthermore,it has higher accuracy in evaluating SAH.