WSO December 2023 – Issue 3 - 1228

1182018
WSO
International Journal of StrokePham et al.
Research
Occult contrast retention postthrombectomy
on 24-h follow-up
dual-energy CT: Associations and
impact on imaging analysis
Jenny Pham1 , Calvin Gan2, Jasmin Dabboucy3
,
Damien L Stella2, Richard Dowling2, Bernard Yan2,4, Steven Bush2,
Cameron Williams2, Peter J Mitchell2, Patricia Desmond2,5,
Vincent Thijs3,6, Hamed Asadi4, Mark Brooks4, Julian Maingard4,
Ash Jhamb4, Davor Pavlin-Premrl4,7, Bruce CV Campbell1,7
and Felix C Ng1,3,7
International Journal of Stroke
2023, Vol. 18(10) 1228 -1237
© 2023 World Stroke Organization
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/17474930231182018
journals.sagepub.com/home/wso
https://doi.org/10.1177/17474930231182018
Abstract
Background: Following reperfusion treatment in ischemic stroke, computed tomography (CT) imaging at 24 h is widely
used to assess radiological outcomes. Even without visible hyperattenuation, occult angiographic contrast may persist in
the brain and confound Hounsfield unit-based imaging metrics, such as net water uptake (NWU).
Aims: We aimed to assess the presence and factors associated with retained contrast post-thrombectomy on 24-h
imaging using dual-energy CT (DECT), and its impact on the accuracy of NWU as a measure of cerebral edema.
Methods: Consecutive patients with anterior circulation large vessel occlusion who had post-thrombectomy DECT
performed 24-h post-treatment from two thrombectomy stroke centers were retrospectively studied. NWU was calculated
by interside comparison of HUs of the infarct lesion and its mirror homolog. Retained contrast was quantified by
the difference in NWU values with and without adjustment for iodine. Patients with visible hyperdensities from hemorrhagic
transformation or visible contrast retention and bilateral infarcts were excluded. Cerebral edema was measured
by relative hemispheric volume (rHV) and midline shift (MLS).
Results: Of 125 patients analyzed (median age 71 (IQR = 61-80), baseline National Institutes of Health Stroke Scale
(NIHSS) 16 (IQR = 9.75-21)), reperfusion (defined as extended-Thrombolysis-In-Cerebral-Infarction 2b-3) was achieved
in 113 patients (90.4%). Iodine-subtracted NWU was significantly higher than unadjusted NWU (17.1% vs 10.8%,
p < 0.001). In multivariable median regression analysis, increased age (p = 0.024), number of passes (p = 0.006), final
infarct volume (p = 0.023), and study site (p = 0.021) were independently associated with amount of retained contrast.
Iodine-subtracted NWU correlated with rHV (rho = 0.154, p = 0.043) and MLS (rho = 0.165, p = 0.033) but unadjusted
NWU did not (rHV rho = -0.035, p = 0.35; MLS rho = 0.035, p = 0.347).
Conclusions: Angiographic iodine contrast is retained in brain parenchyma 24-h post-thrombectomy, even without
visually obvious hyperdensities on CT, and significantly affects NWU measurements. Adjustment for retained iodine
1Department of Neurology, The Royal Melbourne Hospital, Parkville, VIC, Australia
2Department of Radiology, The Royal Melbourne Hospital, Parkville, VIC, Australia
3Department of Neurology, Austin Health, Heidelberg, VIC, Australia
4Department of Radiology, Austin Health, Heidelberg, VIC, Australia
5The University of Melbourne, Parkville, VIC, Australia
6Division of Stroke, Florey Institute of Neuroscience and Mental Health, Heidelberg, VIC, Australia
7Melbourne Brain Centre, Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
Corresponding author:
Felix C Ng, Melbourne Brain Centre, Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC 3050, Australia.
Email: felix.c.ng@mh.org.au
International Journal of Stroke, 18(10)
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WSO December 2023 – Issue 3

Table of Contents for the Digital Edition of WSO December 2023 – Issue 3
