| Objective:To identify the imaging characteristics that can help differentiate hemorrhage from contrast extravasation on early non-contrast CT(NCCT)scan after mechanical thrombectomy(MT)and evaluate the clinical diagnosis value,after retrospectively analyzing the early NCCT manifestations of intraparenchymal hyperdense after MT for ischemic stroke patients.Material and methods:Data of acute ischemic stroke patients who received MT in our center from October 2016 to December 2019 were retrospectively analyzed.Patients were included with abnormal post-thrombectomy intraparenchymal hyperdense(PTIH)on early NCCT scan(within 24 hours after MT).Clinic data were collected,including age,sex,hypertension,diabetes,cardiogenic thrombus,IV thrombolysis,NIHSS score,time from onset to puncture,revascularization attempts,rate of rescue stenting and success rate of recanalization.The finding of washout or near-complete clearing of the hyperdense area in 24-48 hours at non-contrast CT was used as evidence that the area of hyperdense represented contrast extravasation.If the area of hyperdense persisted for more than 48 hours or increased significantly,it was classified as hemorrhage.Clinic data and adjunctive NCCT signs were compared between the parenchymal hemorrhage group and the contrast extravasation group.The adjunctive signs included the presence of subarachnoid hyperdense,intraventricular hyperdense or mass effect.Using the single PTIH as the research unit,the direct image characteristics of hyperdense on NCCT,including the PTIH’s position,the PTIH’s maximum CT value,the PTIH’s volume and the blending with hypodense sign,were analyzed to identify intraparenchymal hemorrhage from contrast extravasation.The blending with hypodense sign was defined as the sign of relatively hypodense area mixed in the newly developed hyperdense of parenchyma,and the difference of the average CT value between the relatively hypodense area and the adjacent hyperdense area was ≥18HU.The results of continuous variables were presented as mean±standard deviation or median(interquartile range),and t-test or Mann-Whitney rank sum test was used to analyze the data.The classification variables were presented with composition ratio,chi-square test or Fisher’s exact test was used to analyze the data.Multivariate logistic regression analysis was performed on the factors that might help to differentiate intraparenchymal hemorrhage from contrast extravasation.Drew the receiver operator characteristic curve(ROC),obtained the best cut-off point and evaluated the diagnostic efficiency of the single and combined image signs.Results:A retrospective analysis was performed on 136 patients with acute ischemic stroke who received MT in our center.There were 77 patients(38 male and 39 female,mean age 65.3±12.8y)with intraparenchymal hyperdense on the early NCCT scan,38 patients with intraparenchymal hemorrhage and 39 patients with intraparenchymal contrast extravasation.There were a total of 90 hyperdense lesions on early NCCT.Finally,43 of 90 hyperdense lesions were confirmed as intraparenchymal hemorrhage and 47 lesions as contrast extravasation on NCCT reexamination in 24-48h after the MT.There was no significant difference in age,gender,hypertension,diabetes,cardiogenic,intravenous thrombolysis,NIHSS score,time from onset to puncture,revascularization attempts,rate of rescue stenting and rate of recanalization between the patients in the hemorrhage group and in the contrast extravasation group.Subarachnoid hyperdense on early NCCT was found in 11 patients(28.9%,11/38)who were confirmed with intraparenchymal hemorrhage,and was found in 13 patients(33.33%,13/39)who were confirmed with contrast extravasation,with no statistically significant difference(χ2=0.173,P=0.678).Five patients with intraparenchymal hemorrhage(13.16%,5/38)had concomitant intraventricular hyperdense on early NCCT,and no patient with contrast extravasation(0/39)had concomitant intraventricular hyperdense on early NCCT within 24 hours,with statistically significant difference(Fisher exact text,P=0.025).The specificity and sensitivity of intraventricular hyperdense in identification of intraparenchymal hemorrhage were 100%and 13.16%respectively.The early NCCT scans showed mass effect in 28 patients(73.68%,28/38)of parenchymal hemorrhage group and in 9 patients(23.08%,9/39)of contrast extravasation group,with statistically significant difference(χ2=19.754,P=0.001).The specificity and sensitivity of mass effect in identification of intraparenchymal hemorrhage were 76.92%and73.68%,respectively.Then,the single hyperdense was analyzed as an individual research unit.Thirty-two of 43(74.42%)hemorrhage lesions located in the basal ganglia region and 11 of 43(25.58%)hemorrhage lesions located in the cortex,and 25 of 47(53.19%)contrast extravasation lesions located in basal ganglia region and 22 of 47(46.81%)contrast extravasation located in the cortex;The PTIH’s maximum CT value of cerebral hemorrhage group and of contrast extravasation group were 90 HU(72-108)and76 HU(67-86),respectively;The hyperdense volume of the intraparenchymal hemorrhage group and of the contrast extravasation group were 20.00 cm3(9.96-30.00)and 6.32 cm3(3.54-12.52),respectively;There were 36(83.72%,36/43)PTIH blending with hypodense sign in hemorrhage group,and10(21.28%,10/47)PTIH blending with hypodense sign in the contrast extravasation group;all those four characteristics show statistically difference between the two groups.Multivariate logistic regression analysis showed that only the PTIH’s volume and the blending with hypodense sign had statistically difference(P<0.05),and the odds ratio(OR)were 2.93(95%CI:1.27-6.74)and 9.24(95%CI:2.91-29.34),respectively.Drawing ROC curve of PTIH’s volume,blending with hypodense sign and the combined characteristics,the area under the curve(AUC)were 0.76(95%CI:0.66 0.87,P<0.001),0.81(95%CI:0.72 0.91,P<0.001)and 0.85(95%CI:0.77 0.94,P<0.001),respectively.Conclusion:The PTIH is more likely to be an intraparenchymal hemorrhage when the early NCCT showed the newly developed intraparenchymal hyperdense accompanied by mass effect or intraventricular hyperdense.The specificity of intraventricular hyperdense in the identification of intraparenchymal hemorrhage was 100%,but the sensitivity was low.The PTIH’s volume≥9.3cm3 and the blending with hypodense sign can be used as the independent diagnostic signs of intraparenchymal hemorrhage,and thecombined diagnostic tests can improve the diagnostic efficiency. |
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