• Matteo Bonatti, Fabio Lombardo, Giulia A Zamboni, Patrizia Pernter, Pozzi MucelliRobertoRDepartment of Radiology, University of Verona, 10 LA Scuro Place, 37134, Verona, Italy., and Giampietro Bonatti.
• Department of Radiology, Bolzano Central Hospital, 5 Boehler Street, 39100, Bolzano, Italy. matteobonatti@hotmail.com.
• Eur Radiol. 2017 Jul 1; 27 (7): 2690-2697.

ObjectiveTo evaluate the diagnostic performance of virtual non-contrast (VNC) images in detecting intracranial haemorrhages (ICHs).MethodsSixty-seven consecutive patients with and 67 without ICH who underwent unenhanced brain CT and DECT angiography were included. Two radiologists independently evaluated VNC and true non-contrast (TNC) images for ICH presence and type. Inter-observer agreement for VNC and TNC image evaluation was calculated. Sensitivity and specificity of VNC images for ICH detection were calculated using Fisher's exact test. VNC and TNC images were compared for ICH extent (qualitatively and quantitatively) and conspicuity assessment.ResultsOn TNC images 116 different haemorrhages were detected in 67 patients. Inter-observer agreement ranged from 0.98-1.00 for TNC images and from 0.86-1.00 for VNC images. VNC sensitivity ranged from 0.90-1, according to the different ICH types, and specificity from 0.97-1. Qualitatively, ICH extent was underestimated on VNC images in 11.9% of cases. Haemorrhage volume did not show statistically significant differences between VNC and TNC images. Mean haemorrhage conspicuity was significantly lower on VNC images than on TNC images for both readers (p < 0.001).ConclusionVNC images are accurate for ICH detection. Haemorrhages are less conspicuous on VNC images and their extent may be underestimated.Key Points• VNC images represent a reproducible tool for detecting ICH. • ICH can be identified on VNC images with high sensitivity and specificity. • Intracranial haemorrhages are less conspicuous on VNC images than on TNC images. • Intracranial haemorrhages extent may be underestimated on VNC images.

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