Cerebral Blood Flow Thresholds for Tissue Infarction in Patients with Acute Ischemic Stroke Treated with Intra-Arterial Revascularization Therapy Depend on Timing of Reperfusion

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Fig 1.
Acute left MCA infarction. Ischemic tissue divided into 3 regions: 1) C (red) with DWI hyperintensity, CBF hypointensity, follow-up infarction; 2) PI (blue) with normal DWI, CBF hypointensity, follow-up infarction; 3) PNI (green) with CBF hypointensity, but normal DWI and follow-up images. Normal tissue in the contralateral hemisphere (pink) was outlined to provide normalization.
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Fig 2.
Relative CBF (mean, SEM) in ischemic penumbra grouped by final infarct outcome. Each voxel of ischemic tissue was scaled to the global contralateral mean CBF. Differences between early and late recanalizers and early recanalizers and nonrecanalizers in each region were statistically significant (P < .001). Total voxel volumes for C were 301.8, 116.3, and 437.2 cm³ for early recanalizers, late recanalizers, and nonrecanalizers, respectively. For PI, they were 87.4, 85.3, and 505.7 cm³ for early recanalizers, late recanalizers, and nonrecanalizers, respectively; and for PNI, they were 363.3, 344.3, and 545.3 cm³ for the early recanalizers, late recanalizers, and nonrecanalizers, respectively.
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Fig 3.
ROC curves for pooled-voxel rCBF data. The AUC corresponds to the discriminatory power of rCBF in predicting final infarct. The markers indicate optimal operating points, where the tangent line to the ROC curve has slope = 1.

Table 1:

Patient demographics^a

	Total Group	Recanalized		Not Recanalized	PValue^b
	Total Group	Early, T_onset ≤6 Hours	Late, T_onset >6 Hours	Not Recanalized	PValue^b
No. of Patients	26	6	12	8
Sex (female)	54% (14)	50% (3)	67% (8)	38% (3)	.47
Age (yr)	69.3 ± 17.4	73.7 ± 14.8	70.6 ± 14.5	64.1 ± 23.3	.58
Hemisphere (left)	58% (15)	50% (3)	58% (7)	63% (5)	1.00
NIHSS score	18 (15–21)	19 (14–23)	16.5 (14.5–18.5)	20.5 (18–21.5)	.12
Occlusion site					.85
ICA	50% (13)	50% (3)	50% (6)	50% (4)
M1	42% (11)	50% (3)	33% (4)	50% (4)
M2	8% (2)	0% (0)	17% (2)	0% (0)
IV tPA	38% (10)	83% (5)	8% (1)	50% (4)	.005
Onset to initial imaging (hr)	4.2 ± 2.5	2.1 ± 0.8	5.1 ± 2.9	4.4 ± 1.9	<.05
Onset to vessel recanalization or procedure end (hr)	7.5 ± 3.0	4.6 ± 0.8	9.0 ± 3.2	7.6 ± 2.0	.007
Onset to follow-up imaging (hr)	51.7 ± 49.8	46.5 ± 34.0	63.5 ± 64.4	37.9 ± 32.4	.53
Recanalization					<.001
Mori 0	23% (6)	0% (0)	0% (0)	75% (6)
Mori 1	8% (2)	0% (0)	0% (0)	25% (2)
Mori 2	38% (10)	33% (2)	67% (8)	0% (0)
Mori 3	23% (6)	33% (2)	33% (4)	0% (0)
Mori 4	8% (2)	33% (2)	0% (0)	0% (0)

Table 2:

ROC of relative CBF thresholds for acute ischemic tissue viability

	Halpern OOP	Sensitivity	Specificity	rCBF 90% Sensitivity	rCBF 90% Specificity	AUC	SE
Early recanalizers T_onset ≤6 hours	0.27	0.80	0.87	0.40	0.24	0.91	0.001
Late recanalizers T_onset >6 hours	0.44	0.77	0.75	0.63	0.28	0.83	0.002
Nonrecanalizers	0.41	0.78	0.77	0.60	0.28	0.85	0.001