| BackgroundStroke is the most important cause of the death and disability among adults in China,and ischemic stroke accounts for about 80%of all strokes.The use of alteplase within 4.5 hours before the onset of symptoms is a reperfusion therapy recommended by the guidelines,but it has the deficiency of narrow time window.《The report on Prevention and treatment of Stroke in China》points out that the prevalence rate of AIS in China is still on the rise,and the prevalence of Wake-up Stroke is also increasing.Because the time of onset is not clear,the choice of early reperfusion treatment for patients with wake-up stroke is limited when there is no cranial magnetic resonance or multi-mode CT to evaluate the tissue window.Preclinical experimental data show that the progressive decrease of CT value in non-contrast CT represents the continuous deterioration of edema,which is a quantitative index.Some studies have found that it is feasible to use CT attenuation index in cerebral ischemic area to evaluate the onset time of stroke,especially in the case of limited imaging resources,but the specific relationship between them is not clear,and there is still a lack of related research.Objective1.To explore the correlation between the CT attenuation ratio of NCCT and the time of onset,and quantify the specific relationship between them.In addition,the feasibility and accuracy of using only CT attenuation ratio to distinguish the onset time of patients with AIS was explored.2.To explore the correlation between CT attenuation ratio and onset time in AIS patients with different onset time periods,TOAST types,infarction sites and stroke severity.MethodsThe imaging data of 24885 patients with AIS who underwent cranial CT examination in the third affiliated Hospital of Guangzhou Medical University from January 2017 to January 2022 were retrospectively selected.All patients had a definite time of onset and completed cranial CT scanning within 24 hours.The general clinical and imaging data of the patients were collected,and the time from the onset of the first symptom to cranial CT examination was recorded.According to the follow-up imaging data,the focus area(Region of Interest,ROI)was determined,and the ratio of CT value between the affected side and the healthy side was calculated(CT attenuation ratio).The relationship between onset time and attenuation ratio was analyzed by Pearson correlation analysis and ROC curve,the best fitting curve was obtained,and the relationship between CT value attenuation ratio and onset time was quantified.The correlation between onset time and attenuation ratio in different time periods,TOAST types,infarction sites and stroke severity were further analyzed.Results1.A total of 243 patients with acute ischemic stroke were included,including 137 males(56.37%),with a median age of 69(61-80)years.The onset time of most patients was less than 4.5 hours,with a total of 174 cases(71.60%).The median time of onset was 2.20(1.30-5.43)hours.Spearman analysis showed that the CT attenuation ratio in AIS within 24 hours was negatively correlated with the time of onset(r=0.425,p<0.001).The best fitting quadratic regression equation was Y= 0.9390.013+0.000032(R2=0.245,p<0.001).The results of rank sum test showed that the attenuation ratio of patients with different onset time periods was different(p<0.001).It was shown that the CT attenuation ratio could distinguish patients within 0-4.5 hours of onset from other four groups(p<0.05).ROC analysis showed that within 12 hours of onset,the area under the curve predicted by attenuation ratio was the largest,which was 0.833,the sensitivity and specificity were 64.9%and 85.7%.2.The feasibility of CT attenuation ratio in predicting the time of onset in different subgroups2.1 All patients are divided according to the time of onset,there were 174 cases in 0-4.5 hours,19 cases in 4.5-6 hours,17 cases in 6-9 hours,12cases in 9-12 hours and 21cases in 12-24 hours.The age,onset time and attenuation ratio of the four groups was statistically significant(p<0.001),but there was no significant difference in sex and NHISS scores.Spearman analysis showed that there was a significant negative between onset time and attenuation ratio in 12-24 group(p<0.05),but there was no correlation between onset time and attenuation ratio in 0-4.5h,4.5-6h,6-9h and 9-12h group(p>0.05).The curve regression coefficient between onset time and attenuation ratio was the highest in 12-24h group.2.2 According to TOAST classification,all patients were divided into LAA type(n=100,41%),CE type(n=86,35%),small artery occlusion type(n=3,14%),unknown cause type(n=15),and other determined cause type(n=9).The onset time of CE type was the shortest,with a median of 1.59 hours.There were significant differences in age,sex,NHISS score and onset time among different groups,but there was no significant difference in CT attenuation ratio among different groups.Spearman analysis showed that there was a significant negative correlation between onset time and CT attenuation ratio in LAA type,CE type and small artery occlusion type(p<0.001),and the correlation between them was the strongest in small artery occlusion type.Curvilinear regression analysis showed that the R2 value of arteriole occlusion group was the highest.2.3 According to the location of infarction,all patients were divided into two groups:anterior circulation infarction(n=191,78.60%)and posterior circulation infarction(n=43,17.70%).There were significant differences in NHISS score,onset time and CT attenuation ratio between the two groups,but there was no significant difference in age and sex.Spearman analysis showed that there was a significant negative correlation between the time of onset and the decay rate of CT in both groups(p<0.000),and the correlation between them was the strongest in the posterior circulation(R=0.702).Curvilinear regression analysis showed that the R2 value of posterior circulation infarction group was the highest.2.4 According to NHISS score,all patients were divided into four groups(mild,moderate,moderate-severe,severe),accounting for 29%,63%,39%,14%and 8%,respectively.Patients with moderate or above accounted for 61.23%.There were significant differences in sex,NHISS score,onset time and CT decay rate among different groups,but there was no significant difference in age.Spearman analysis showed that there was a negative correlation between onset time and CT decay rate in patients with different severity of stroke(p<0.05),and the correlation between them was the strongest in severe stroke group(R=-0.51).Curvilinear regression analysis showed that the R2 value was the highest in the moderate-severe stroke group.Conclusion1.The results show that within 24 hours of the onset of AIS,the attenuation ratio of NCCT is significantly negatively correlated with the onset time,but the correlation degree is weak.The attenuation ratio can be used to distinguish different time periods,which has high predictive value.2.Subgroup analysis suggested that the correlation between the attenuation ratio and the onset time,the correlation intensity is different,and the best fitting curve is also different.The CT attenuation ratio within 12-24 hours of onset,small artery occlusion,posterior circulation infarction and moderate to severe stroke groups is of great value in predicting the time of onset. |
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