WSO December 2023 – Issue 3 - 1204

1204
International Journal of Stroke 18(10)
Figure 2. Comparison of detailed and conventional DWIASPECTS.
The detailed ASPECTS and conventional DWIASPECTS
are 6 and 2, respectively. The white arrows show
the areas of hyperintensity, which were counted using the
detailed ASPECTS. Both white (M3, M6, insular cortex, and
lentiform) and red (M1, M2, M4, and M5) arrows show areas
of hyperintensity, which were counted using conventional
DWI-ASPECTS.
rate. Second, we compared conventional and detailed DWIASPECTS
and calculated the median score. Third, we calculated
the correlation coefficient between the ischemic
core volume and DWI-ASPECTS to determine the best
predictor of the infarct core volume. Fourth, we investigated
the association between the clinical outcomes at
90 days and the two DWI-ASPECTSs. Finally, we divided
patients with conventional DWI-ASPECTS ⩽6 into two
groups according to detailed DWI-ASPECTS ⩽6 or >6.
We then compared the clinical outcomes at 90 days and the
ischemic core volume between the two groups. Welch's and
two-tailed Fisher's tests were used to analyze differences in
continuous and categorical variables, respectively.
Statistical significance was set at a two-tailed P-value of
<0.05. All statistical analyses were performed using the
JMP version 11 software (SAS Institute, Cary, NC, USA).
Results
free open-source extensible software application, built with
support from the National Institutes of Health, for medical
image computing and visualization.16 DWI was obtained
using the following parameters: TR/TE, 6000/65 ms; b-values,
0 and 1000 s/mm2; field of view, 24 cm; acquisition
matrix, 128 × 128; and slice thickness, 4.5 mm with a
2.5 mm intersection gap. The patients' digital images were
imported, and a hyperintense lesion on DWI was semiautomatically
outlined on each slice using segmentation
tools within 3D Slicer. The hyperintense area (cm2) was
multiplied by the slice thickness plus the intersection gap,
resulting in a volume measurement (cm3).
Clinical outcomes
The patients were followed up for 90 days after symptom
onset. A favorable outcome was defined as an mRS score
⩽2 at the 90-day follow-up. The mRS score was assessed
by site personnel via physical examination or telephone
interviews with the patients or their relatives.
Imaging
To examine patients with suspected stroke, MRI was performed
immediately using a 1.5T scanner (ECHELON_
OVAL, Hitachi Medical Corporation, Tokyo, Japan),
including DWI, fluid-attenuated inversion recovery (FLAIR),
magnetic resonance angiography (MRA), and T2* imaging.
Statistical analysis
First, we assessed the patients' backgrounds, neurological
deficits, time from onset, radiological findings, and the IVT
International Journal of Stroke, 18(10)
Of the 448 consecutive patients with AIS who were treated
with EVT, 56 had posterior circulation, 51 had a pre-mRS
score >2, 22 did not undergo MRI before EVT, and 21 had
no infarct volume data owing to low-quality images. After
excluding these patients, 298 (median age, 75 (67-82)
years; 194 (65%) males; median NIHSS score, 15 (9-21))
were enrolled. The onset-to-door time was 150 (55-299)
min, and the door-to-imaging time was 22 (7-32) min. The
occluded vessel sites identified by MRA/CT angiography
were the internal carotid artery in 81 patients (27%), M1 in
128 (43%), M2/M3 in 93 (31%), and A1 in 4 (1%). The
median infarct volume was 11 (3-37) mL. A total of 108
(36%) patients were treated with IVT, and all patients were
treated with EVT (Table 1).
Conventional and detailed DWI-ASPECTS
The number of patients with conventional and detailed
DWI-ASPECTS ⩽6 was 134 (45%) and 73 (24%), respectively.
Therefore, 61 patients (20%) had conventional DWIASPECTS
⩽6 and detailed DWI-ASPECTS >6. The
detailed DWI-ASPECTS was significantly higher than the
conventional DWI-ASPECTS (8 (7-9) vs. 7 (5-9),
P < 0.01; Figure 3).
Next, we calculated the correlation coefficient (r)
between the ischemic core volume and both conventional
DWI-ASPECTS and detailed DWI-ASPECTS. The coefficient
was higher for detailed DWI-ASPECTS (r = 0.832,
P < 0.01) than for conventional DWI-ASPECTS (r = 0.773,
P < 0.01; Figure 4).
Clinical outcome according to
DWI-ASPECTS
Among 298 patients, 146 (49%) and 152 (51%) had favorable
and poor outcomes, respectively. Of the patients with
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