WSO December 2023 – Issue 3 - 1231

Pham et al.
1231
Figure 2. Relative hemispheric volume. Axial images demonstrating a right middle cerebral infarct with minimal midline shift but
ischemic mass effect with effacement of sulci (a-f) and compression of the lateral ventricles (b-f). Midbrain and cerebellum were
excluded in the segmentation (e and f). rHV is calculated to be 1.11, representing an 11% increase in volume of the ischemic
hemisphere compared to the non-ischemic normal hemispheric.
To identify factors associated with ∆NWU, variables with
p-values < 0.1 in univariable analysis (Mann-Whitney U
test; Kruskal-Wallis test and quantile regression as appropriate)
were included in a subsequent multivariable
median regression model. Post-hoc sensitivity analysis
with ΔadjustmentNWU analyzed as a dichotomized outcome
(high (⩾ median ΔadjustmentNWU) vs low (< median
Δadjustment)) was performed. To assess the impact of occult
retained contrast on the accuracy of NWU, we tested the
correlation (Spearman's rho) of NCCT-NWU and DECTNWU
with the established markers of cerebral edema,
MLS and rHV. Agreement between ΔadjustmentNWU measured
by syngo.via and Analyze v14.0 was tested in 10% of
the study cohort using Bland-Altman analysis (Supplementary
material). All statistical analysis was performed
using IBM SPSS Statistics Version 28.0.1.0.
Results
During the study period, 190 patients received thrombectomy
for acute large vessel occlusion. Analysis was performed
in 125 patients
after excluding patients with
posterior circulation stroke, obvious hyperdense lesion
from hemorrhagic transformation or contrast, contralateral
structural abnormalities or with no visible infarct lesion on
CT at 24 h (Supplementary material). The median age was
71 (IQR = 61-80) and baseline NIHSS was 16 ((IQR = 9.75-
21], Table 1). Sixty-six patients (52.8%) received bridging
thrombolytic pre-thrombectomy. Eight-five patients (68%)
had isolated intracranial middle cerebral artery occlusions.
Median time to EVT was 5.52 h (IQR = 3.7-8.72 hours),
with a median procedural time of 39 min (IQR = 22-68 min).
Angiographic reperfusion (eTICI 2b-3) was achieved in
113 patients (90.4%). Median time from reperfusion to follow-up
DECT was 22.95 h (IQR = 16.33-24.74 h).
First, we tested for the presence of occult contrast staining
by comparing NWU between DECT-derived iodineadjusted
VNC and conventional single spectra CT.
DECT-NWU was significantly higher than NCCT-NWU
overall (median 17.1% vs 10.8%, p < 0.001), and in subgroup
analysis by center (Center 1 21.0% vs 16.1%,
p < 0.001; Center 2 12.8% vs 10.7% p < 0.001). Illustrative
example of two patients is provided in Figure 3.
Second, we tested the associations between clinical and
imaging characteristics with the amount of contrast retention.
In univariable analysis, final infarct volume (p = 0.040),
study site (Center 2 vs Center 1; p = 0.042), procedural
time (p = 0.025), number of passes (p < 0.001) and eTICI
score (p = 0.043) were associated with ∆adjustmentNWU. In
multivariable median regression analysis, increased age
International Journal of Stroke, 18(10)
WSO December 2023 – Issue 3

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