Clinical applications of virtual, non-contrast head images derived from dual-source, dual-energy cerebrovascular computed tomography angiography

ABSTRACT

Background: This study set out to evaluate the utility of cerebrovascular virtual non-contrast [VNC] scans. Materials and Methods: Conventional non-contrast [CNC] and dual-energy computed tomography angiography [DE-CTA] head scans were conducted on 100 subjects, of which 46 were normal, 15 had parenchymal hematomas of the brain, 13 had ischemic infarction, 22 had tumors, and 4 had calcified lesions. VNC images were extracted from the DE-CTA head scans by post-processing. The true [or conventional] and VNC images were compared in terms of the mean CT attenuation value and signal-to-noise ratio [SNR] of the cerebral parenchyma, the image quality, the lesion detection sensitivity, and the radiation exposure level. Results: The image qualities of the CNC and VNC scans were [4.95 +/- 0.22] points and [3.94 +/- 0.24] points [t = 31.18, P < 0.05], the mean CT values for the CNC and VNC images were [34.6 +/- 2.44] and [28.6 +/- 5.40] HU [t = 10.126, P < 0.05], the SNRs were [9.45 +/- 1.26] and [6.87 +/- 1.77], and the HU for white matter was [t = 11.859, P<0.05], respectively. The effective radiation doses from the DE-CTA head scans and the conventional non-contrast scans were [8.55 +/- 0.57] mSv and [9.41 +/- 1.00] mSv, respectively. No significant difference in the lesion detection sensitivities was observed between the CNC and VNC scans, except for tiny calcified lesions, which could not be identified by a VNC scan. Conclusion: VNC and contrast-enhanced images could be obtained from DE-CTA head scans and could aid in the diagnosis of cerebral lesions. The radiation dose from the VNC scan was less than that from the CNC scan