Using an orbit shield during volume perfusion CT: is it useful protection or an obstacle?

Hakim, Arsany; Vulcu, Sonja; Dobrocky, Tomas; Z'Graggen, Werner Josef; Wagner, Franca (2018). Using an orbit shield during volume perfusion CT: is it useful protection or an obstacle? Clinical radiology, 73(9), 834.e1-834.e8. Elsevier Science 10.1016/j.crad.2018.05.003

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To evaluate the image quality and artefacts resulting from in-plane orbit shielding during computed tomography (CT) perfusion and to assess the possibility of artefact reduction using the iterative metal artefact reduction (iMAR) algorithm.


Twenty-eight perfusion CT examinations obtained from 20 patients using orbit shields were included in this study. Source images and perfusion maps were analysed retrospectively to detect the type and extent of artefacts. Original images were compared with images processed using the iMAR algorithm. The extent of artefacts was categorised into three groups: orbital/frontal, middle fossa, and posterior fossa. Types of artefacts in source images were categorised as noise, streak, beam hardening, or a combination of those, and types of artefacts in perfusion maps were categorised as: noise, image distortion, areas with missing colour codes, or incorrect colour-coding.


All source images evaluated showed artefacts related to orbit shielding and 85.7% reached the posterior fossa. In 92.8% of scans, perfusion maps showed artefacts, mostly as incorrect colour codes. Of the perfusion maps with artefacts, 92.3% reached the posterior fossa. After application of the iMAR algorithm, an increase in the extent of artefacts was observed in 93% of perfusion maps, and no improvement of image quality was noted.


Orbit shields cause significant artefacts if used for in-plane shielding during whole-brain CT perfusion, and render areas at the level of the shield undiagnosable. Usage of an orbit shield during whole-brain CT perfusion is not recommended, so alternative methods for reducing the radiation dose are advisable.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic and Interventional Neuroradiology
04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurosurgery

UniBE Contributor:

Hakim, Arsany, Vulcu, Sonja, Dobrocky, Tomas, Z'Graggen, Werner Josef, Wagner, Franca


600 Technology > 610 Medicine & health




Elsevier Science




Martin Zbinden

Date Deposited:

06 Jun 2018 16:13

Last Modified:

05 Dec 2022 15:14

Publisher DOI:


PubMed ID:





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