European Radiology: How imaging can be used to predict poor reperfusion and poor clinical outcomes in ischemic stroke patients

Reperfusion therapy, including intravenous thrombolysis and intra-arterial mechanical thrombectomy (MT), is known to be beneficial in resuscitating brain tissue and preventing the progression
of cerebral edema in patients with acute ischemic stroke (AIS).
While previous evidence supports the benefits of recanalization, there is growing recognition that recanalization does not necessarily lead to reperfusion
.
One of the reasons may be the phenomenon of "no return" in the local capillary bed caused by microvascular damage or thrombosis
.
Not only vascular imaging, but also specific imaging data, including early assessment of post-treatment reperfusion, can assist in early clinical identification of ineffective reperfusion and better predict the prognosis of
long-term stroke.

Cerebral edema caused by obstruction of cerebral microvascular circulation is an important pathophysiology feature of ischemic cerebral infarction.

Recent studies have shown that successful reperfusion can reduce cerebral edema
after ischemic stroke.
Conversely, persistent capillary dysfunction is associated with
the degree of ischemic cerebral edema.

Recently, a new quantitative imaging biomarker, clean water intake (NWU), has been confirmed as an important biomarker for edema and an individual indicator
of the "tissue clock" of AIS patients.
Early elevation of NWU in ischemic lesions is associated with malignant edema and malignant infarction, and the clinical prognosis is poor
.

Recently, a study published in the journal European Radiology explored the correlation between ischemic lesion NWU using automated analysis of Alberta Stroke Program Early CT Scores (ASPECTS) and tissue-level reperfusion status imaged using arterial spin markers (ASL), as well as baseline and subsequent NWU as imaging markers to predict the 90-day functional prognosis of AIS patients after reperfusion therapy.
It provides an imaging reference for
early clinical prediction of patients' condition and treatment prognosis.

A total of 112 patients with AIS who received reperfusion therapy were included in the study
.
ASPECTS-NWU was calculated based on admission CT (NWU _admission) and follow-up CT (NWU_FCT), and its difference (ΔNWU)
was calculated.
Tissue level reperfusion status was assessed by subsequent arterial spin labeling imaging, and the relationship between
ASPECTS-NWU and tissue-level reperfusion was evaluated.
Multivariate logistic regression analysis and receiver operational characteristics (ROC) curves were used to assess predictors of 90-day adverse prognosis (improved Rankin score>2).


Poor reperfusion was observed in 40 patients (35.
7%) after treatment
.
Compared with patients with good reperfusion, these patients had significantly elevated NWU_FCT (median, 14.
15% vs.
8.
08%, P = 0.
018) and higher ΔNWU (median, 4.
12% vs.
-2.
03%, P < 0.
001).

High ΔNWU is an important sign of poor reperfusion, despite successful
reperfusion.
NIH stroke scale scores (odds [OR], 1.
11; 95% confidence interval [CI] 1.
03 to 1.
20, p = 0.
007) and ΔNWU (OR, 1.
07; 95% CI 1.
02 to 1.
13, p = 0.
008) were independently associated with
adverse outcomes on admission.
The resulting prediction model that includes these two parameters yields an area under the curve of 0.
762 (sensitivity 70.
3%, specificity 84.
2%)
.

Figure ΔNWU in predicting adverse prognosis in patients with AIS within 90 days.

The AUC of ΔNWU was 0.
682 (95% CI, 0.
546-0.
817; sensitivity, 71.
1%; specificity, 74.
0%)
.
Combining NIHSS score and ΔNWU on admission, AUC increased to 0.
762 (95% CI, 0.
672-0.
837; sensitivity, 70.
3%; specificity, 84.
2%), significantly higher than ΔNWU alone (P < 0.
05).

This study shows that the progression of edema in ischemic foci quantified by NWU_FCT and ΔNWU is strongly associated
with poorly reperfusion at the tissue level.
Despite successful recanalization in patients with AIS, higher ΔNWU is an important predictor
of poor reperfusion and adverse prognosis after 90 days.
Simplified measurements of ASPECTS-NWU provide additional pathophysiological information about tissue-level reperfusion status beyond angigraphy, providing significant prognostic and therapeutic value
for AIS patients after reperfusion therapy.

Original source:

Shan-Shan Lu,Rong-Rong Wu,Yue-Zhou Cao,et al.
ASPECTS-based net water uptake predicts poor reperfusion and poor clinical outcomes in patients with ischemic stroke.
DOI:10.
1007/s00330-022-09077-8