Prediction of Hemorrhage after Successful Recanalization in Patients with Acute Ischemic Stroke: Improved Risk Stratification Using Dual-Energy CT Parenchymal Iodine Concentration Ratio Relative to the Superior Sagittal Sinus

Deep-Learning Generated Synthetic Material Decomposition Images Based on Single-Energy CT to Differentiate Intracranial Hemorrhage and Contrast Staining Within 24 Hours After Endovascular Thrombectomy

AIMS

To develop a transformer-based generative adversarial network (trans-GAN) that can generate synthetic material decomposition images from single-energy CT (SECT) for real-time detection of intracranial hemorrhage (ICH) after endovascular thrombectomy.

MATERIALS

We retrospectively collected data from two hospitals, consisting of 237 dual-energy CT (DECT) scans, including matched iodine overlay maps, virtual noncontrast, and simulated SECT images. These scans were randomly divided into a training set (n = 190) and an internal validation set (n = 47) in a 4:1 ratio based on the proportion of ICH. Additionally, 26 SECT scans were included as an external validation set. We compared our trans-GAN with state-of-the-art generation methods using several physical metrics of the generated images and evaluated the diagnostic efficacy of the generated images for differentiating ICH from contrast staining.

RESULTS

In comparison with other generation methods, the images generated by trans-GAN exhibited superior quantitative performance. Meanwhile, in terms of ICH detection, the use of generated images from both the internal and external validation sets resulted in a higher area under the receiver operating characteristic curve (0.88 vs. 0.68 and 0.69 vs. 0.54, respectively) and kappa values (0.83 vs. 0.56 and 0.51 vs. 0.31, respectively) compared with input SECT images.

CONCLUSION

Our proposed trans-GAN provides a new approach based on SECT for real-time differentiation of ICH and contrast staining in hospitals without DECT conditions.

Predictive Value of Clinical and Dual-Energy Computed Tomography Parameters for Hemorrhagic Transformation and Long-Term Outcomes Following Endovascular Thrombectomy

OBJECTIVE

This study's objective was to explore whether certain parameters measurable by dual-energy computed tomography (DECT) performed 24 h after endovascular thrombectomy (EVT) can predict subsequent hemorrhagic transformation.

MATERIAL AND METHODS

We retrospectively reviewed patients with acute ischemic stroke (AIS) managed with EVT who had follow-up DECT within 24 h post-EVT between January 2019 and December 2023. Clinical and image parameters were recorded for predictive factor analysis. The primary outcome was hemorrhagic transformation, which was determined by using follow-up computed tomography (CT) or magnetic resonance imaging (MRI). The secondary outcomes were in-hospital mortality and 3-month post-EVT favorable functional outcome, as defined by a modified ranking scale (mRS) score of ≤2.

RESULTS

A total of 152 patients were included in this study. Multivariable analysis showed that the VNC-ASPECT score (p = 0.002) and superior sagittal sinus density (p = 0.01) were significantly associated with hemorrhagic transformation. For in-hospital survival rate analysis, post-EVT NIHSS measured 24 h post-EVT was an effective predictor, with a cutoff value of 23 (≤23: 88% vs. >23: 52.1%; p < 0.001). For functional outcome analysis, age (p < 0.001), tPA prior to EVT (p = 0.017), NIHSS 24 h post-EVT (p = 0.001), and VNC-ASPECT score (p < 0.003) were associated with a favorable functional outcome 3 months after EVT.

CONCLUSIONS

The VNC-ASPECT score was associated with both hemorrhagic transformation and a 3-month post-EVT favorable functional outcome, and could therefore be an useful predictor for the development of hemorrhagic transformation.

Post-endovascular therapy contrast extravasation in the mesial temporal region on dual-energy CT is associated with outcome in acute ischemic stroke patients

PURPOSE

Pre- and post-endovascular treatment (EVT) imaging may aid in predicting functional outcomes in acute middle cerebral artery (MCA) ischemic stroke. Low post-EVT contrast extravasation (CE)-ASPECTS is associated with poor functional outcomes. Besides the MCA regions included in the ASPECTS score, CE may be seen in the mesial temporal (MT) region. In this study, we investigated the frequency and prognostic implication of MT-CE in acute ischemic stroke patients.

METHODS

Patients with an acute ischemic stroke due to anterior large vessel occlusion who received EVT and post-EVT DECT between 2010 and 2019 were included. Iodine overlay maps of DECT were assessed for the occurrence of CE, using the ASPECTS for occurrence in the MCA region and, calculating a CE-ASPECTS, for whether the MT region was involved. Multivariable linear and logistic regression were used to assess the relationship between involvement of MT-CE and 24-48h NIHSS, mRS, and mortality on a multiple imputed dataset. All models were adjusted significant variables in univariate analyses and for total CE-ASPECTS.

RESULTS

501/651 patients met the inclusion criteria. MT-CE occurred in 97 (19 %) patients, and was more often present in patients with internal carotid artery occlusions. MT-CE was associated with higher NIHSS scores at 24-hours (aβ 2.2, 95 % CI 0.09-4.31), with increased risk of higher mRS scores (acOR 1.88, 95 % CI 1.16-3.06), and with increased risk of mortality (aOR 2.12, 95 % CI 1.16-3.86).

CONCLUSION

MT-CE is a common finding on post-EVT DECT and is an independent predictor for worse functional outcomes.

Predictive value of intracranial high-density areas in neurological function

BACKGROUND

Intracranial high-density areas (HDAs) have attracted considerable attention for predicting clinical outcomes; however, whether HDAs predict worse neurological function and mental health remains controversial and unclear, which requires further investigation.

AIM

To investigate the predictive value of intracranial HDAs for neurological function and mental health after endovascular treatment.

METHODS

In this prospective study, 96 patients with acute ischemic stroke (AIS) who accepted endovascular mechanical thrombectomy (EMT) were included. The enrolled patients underwent cranial computed tomography (CT) examination within 24 hours after EMT. Clinical data in terms of National Institutes of Health Stroke Scale (NIHSS), the 3-month modified Rankin Scale (mRS), self-rating depression scale (SDS), and self-rating anxiety scale (SAS) scores were collected and compared between patients with HDAs and non-HDAs and between patients with good and poor clinical prognosis.

RESULTS

Compared to patients without HDAs, patients with HDAs presented severe neurological deficits (admission NIHSS score: 18 ± 3 vs 19 ± 4), were more likely to have post-stroke disabilities (mRS < 3: 35% vs 62%), and suffered more severe depression (SDS score: 58 ± 16 vs 64 ± 13) and anxiety disorder (SAS score: 52 ± 8 vs 59 ± 10). Compared to patients with a good prognosis, patients with a poor prognosis presented severe neurological deficits (admission NIHSS score: 17 ± 4 vs 20 ± 3), were more likely to have HDAs on CT images (64% vs 33%), and suffered more severe depression (SDS score: 55 ± 19 vs 65 ± 11) and anxiety (SAS score: 50 ± 8 vs 58 ± 12). Multivariate analysis revealed that HDAs were independent negative prognostic factors.

CONCLUSION

In conclusion, HDAs on CT images predicted poor prognosis and severe depressive and anxiety symptoms in patients with AIS who underwent EMT.

An integrated nomogram combining clinical and radiomic features of hyperattenuated imaging markers to predict malignant cerebral edema following endovascular thrombectomy

Background

Malignant cerebral edema (MCE), a potential complication following endovascular thrombectomy (EVT) in the treatment of acute ischemic stroke (AIS), can result in significant disability and mortality. This study aimed to develop a nomogram model based on the hyperattenuated imaging marker (HIM), characterized by hyperattenuation on head noncontrast computed tomography (CT) immediately after thrombectomy, to predict MCE in patients receiving EVT.

Methods

In this retrospective cohort study, we selected 151 patients with anterior circulation large-vessel occlusion who received endovascular treatment. The patients were randomly allocated into training (n=121) and test (n=30) cohorts. HIM was used to extract radiomics characteristics. Conventional clinical and radiological features associated with MCE were also extracted. A model based on extreme gradient boosting (XGBoost) machine learning using fivefold cross-validation was employed to acquire radiomics and clinical features. Based on HIM, clinical and radiological signatures were used to construct a prediction nomogram for MCE. Subsequently, the signatures were merged through logistic regression (LR) analysis in order to create a comprehensive clinical radiomics nomogram.

Results

A total of 28 patients out of 151 (18.54%) developed MCE. The analysis of the receiver operating characteristic curve indicated an area under the curve (AUC) of 0.999 for the prediction of MCE in the training group and an AUC of 0.938 in the test group. The clinical and radiomics nomogram together showed the highest accuracy in predicting outcomes in both the training and test groups.

Conclusions

The novel nomogram, which combines clinical manifestations and imaging findings based on postinterventional HIM, may serve as a predictor for MCE in patients experiencing AIS after EVT.

Procedural blood pressure and contrast extravasation on dual energy computed tomography after endovascular stroke treatment

BACKGROUND

Blood brain barrier disruption (BBBD) can be visualized by contrast extravasation (CE) after endovascular treatment (EVT) in patients with acute ischemic stroke. Elevated blood pressure is a risk factor for BBBD. However, the association between procedural blood pressure and CE post-EVT is unknown.

METHODS

In this single-center retrospective study, we analyzed 501 eligible patients who received a dual energy CT (DECT) immediately post-EVT for acute ischemic stroke. Procedural blood pressure values (SBPmean, SBPmax, SBPmax-min, and MAPmean) were collected. CE was quantified by measuring the maximum parenchymal iodine concentration on DECT iodine overlay map reconstructions. As a measure for the extent of BBBD, we created CE-ASPECTS by deducting one point per hyperdense ASPECTS region on iodine overlay maps. The association between blood pressure and CE was assessed using multivariable linear regression.

RESULTS

The procedural SBPmean, SBPmax, and MAPmean were 150 ± 26 mmHg, 173 ± 29 mmHg, and 101 ± 17 mmHg, respectively. The median maximum iodine concentration on post-EVT DECT was 1.2 mg/ml (IQR 0.7-2.0), and median CE-ASPECTS was 8 (IQR 5-11). The maximum iodine concentration was not associated with blood pressure. SBPmean, SBPmax, and MAPmean were significantly associated with CE-ASPECTS (per 10 mmHg, β = -0.2, 95 % CI -0.31 to -0.09, β = -0.15, 95 % CI -0.25 to -0.06, β = -0.33, 95 % CI -0.49 to -0.17, respectively).

CONCLUSION

In acute ischemic stroke patients undergoing EVT, particularly in patients achieving successful recanalization, SBPmean, SBPmax, and MAPmean are associated with the extent of BBBD on immediate post-EVT DECT, but not with maximum iodine concentration.

Dual-energy Computed Tomography (DECT) predicts the efficacy of contrast medium extravasation and secondary cerebral hemorrhage after stent thrombectomy in acute ischemic cerebral infarction

 To prospective research the efficacy of dual-energy computed tomography (DECT) in predicting contrast medium extravasation and secondary cerebral hemorrhage after stent thrombectomy in acute ischemic cerebral infarction. Ninety-two patients with acute ischemic stroke who underwent intra-arterial thrombolysis in our hospital from December 2019 to January 2022 have opted as the study subjects. DECT was performed immediately after stent thrombectomy. Images were generated through the image workstation and routine diagnosis was performed 24 hours after the operation. To analyze the diagnostic value of To analyze the diagnostic value of DECT, and to explore the diagnostic status of lesions with hemorrhagic transformation or increased hemorrhage and their correlation with iodine concentration. (1) 68 situations were confirmed, 56 positive and 12 negative with detection rates of 10.71% for hemorrhage, 75.00% for contrast agent extravasation, and 14.29% for extravasation combined with hemorrhage; (2) DECT diagnosed 8 cases of postoperative bleeding and 44 cases of extravasation of contrast media and 4 cases of extravasation of contrast media with hemorrhage ; The accuracy of DECT in diagnosing postoperative hemorrhage was 96.43%. The accuracy of diagnosis of extravasation was 96.43%. (3) The mean iodine concentration of lesions with increased hemorrhage or hemorrhagic transformation was higher compared to those without; (4) There was a correlation between hemorrhagic transformation or increased hemorrhage and iodine concentration. Dual-energy CT (DECT) can accurately distinguish the extravasation of contrast agent and secondary cerebral hemorrhage, and can predict the increased bleeding and bleeding transformation, with good diagnostic value and good predictive efficacy.

Diagnostic accuracy of dual-energy computed tomography in the diagnosis of neurological complications after endovascular treatment of acute ischaemic stroke: a systematic review and meta-analysis

OBJECTIVES

To investigate dual-energy computed tomography's (DECT) diagnostic performance in detecting neurological complications following endovascular therapy (EVT) of acute ischaemic stroke (AIS).

METHODS

We performed the literature search using Web of Science, Scopus, PubMed, EBSCO, and Science Direct databases for published related studies. The selected studies estimated the validity of DECT in the detection of neurological complications after EVT for AIS. Study quality assessment was performed utilizing the Quality of Diagnostic Accuracy Studies-2 Tool. Our meta-analysis calculated the pooled sensitivity, negative likelihood ratio, specificity, and positive likelihood ratio for each detected complication. The summary receiver operating characteristics (sROC) curve was utilized to estimate the area under the curve (AUC).

RESULTS

Of 22 studies, 21 were included in the quantitative synthesis. In the detection of intracerebral haemorrhage (ICH), DECT pooled overall sensitivity and specificity were 69.9% (95% CI, 44.5%-86.8%) and 100% (95% CI, 92.1%-100%); whereas, in the detection of ischaemia, they were 85.9% (95% CI, 80.4%-90%) and 90.7% (95% CI, 87%-93.5%), respectively. On the sROC curve, AUC values of 0.954 and 0.952 were recorded for the detection of ICH and ischaemia, respectively.

CONCLUSIONS

DECT demonstrated high accuracy and specificity in the detection of neurological complications post-endovascular treatment of AIS. However, further prospective studies with a standardized reference test and a larger sample size are recommended to support these findings.

ADVANCES IN KNOWLEDGE

DECT is a rapid and valid imaging tool for the prediction of ICH and cerebral ischaemia after the EVT of AIS.

Absolute and relative iodine concentrations in the spot sign and haematoma for prediction of haematoma expansion in spontaneous intracerebral haemorrhage

AIM

To explore the predictive value of absolute and relative iodine concentrations in the spot sign (SS) and haematoma on gemstone spectral imaging (GSI) for haematoma expansion (HE).

MATERIALS AND METHODS

Patients with spontaneous intracerebral haemorrhage (ICH) who underwent computed tomography (CT) angiography using GSI were divided into an SS-positive group and an SS-negative group. In the SS-positive group, absolute and relative iodine concentrations in the SS (aICIS and rICIS, respectively) were measured. In the SS-negative group, absolute and relative iodine concentrations in haematoma (aICIH and rICIH, respectively) were measured. The area under the receiver operating characteristic curve (AUC-ROC) was used to investigate the HE predictive performance of aICIS, rICIS, and their combination in the SS-positive group, as well as the HE predictive performance of aICIH, rICIH, and their combination in the SS-negative group. The risk variables for HE in the two groups were investigated separately using logistic regression.

RESULTS

A total of 123 spontaneous ICH patients were enrolled. In the SS-positive group, the AUC of aICIS, rICIS, and their combination for predicting HE were 0.853, 0.893, and 0.922, respectively. rICIS was demonstrated to be a standalone predictor of HE via logistic regression. In the SS-negative group, aICIH, rICIH, and their combination had AUC-ROC values of 0.552, 0.783, and 0.851, respectively, to predict HE. According to multivariate analysis, rICIH was a reliable predictor of HE.

CONCLUSION

Absolute and relative iodine concentrations in the SS and haematoma can predict HE.

Prognostic value of contrast staining on dual-energy CT after endovascular therapy in acute ischemic stroke: a meta-analysis

BACKGROUND

Contrast staining (CS) on dual-energy CT (DECT) is common after endovascular therapy (EVT) in acute ischemic stroke (AIS). We performed a meta-analysis to investigate the prognostic significance of CS detected by DECT after EVT in AIS.

METHOD

MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Web of Science and Scopus databases were searched from inception to July 2023 for publications on the prognostic significance of CS on DECT after EVT in patients with AIS. Prognostic outcomes were hemorrhage transformation (HT) and poor functional outcome (modified Rankin Scale [mRS] Score of 3-6 at the 90-day follow-up). Data are presented as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Eleven studies including 1123 cases of AIS were included. Pooled results indicated a higher risk of HT in patients with CS than in those without CS (OR = 2.22; 95% CI 1.41-3.51, P = 0.001; I2 = 45.4%). No association between CS and symptomatic HT was observed (OR = 2.10; 95% CI 0.64-6.95, P = 0.223; I2 = 67.3%). Moreover, there was also higher odds of poor functional outcome in patients with CS than in those without CS (OR = 2.76; 95% CI 1.53-4.97, P = 0.001; I2 = 44.9%).

CONCLUSIONS

The presence of contrast staining on DECT after EVT is associated with a higher risk of hemorrhage transformation and poor functional outcome. However, further high-quality studies with standardized processes are required to confirm these results.

Hemorrhagic Transformation Assessment Based on Dual Energy CT of Immediately and Twenty-Four Hours after Endovascular Thrombectomy for Acute Ischemic Stroke

BACKGROUND

Dual-energy CT (DECT) shows good performance in differentiating hemorrhage from contrast staining (CS). However, no guidelines have standardized the post-endovascular thrombectomy (EVT) examination time. We evaluated the value of performing DECT immediately and 24 h post-EVT in the diagnosis and prediction of hemorrhagic transformation (HT).

METHODS

Two readers evaluated simulated conventional CT (sCCT) images compared with a second reading with DECT, establishing the diagnosis of HT immediately and 24 h post-EVT. Another reader's diagnosis 2-7 days post-EVT using non-contrast CT was identified as the final diagnostic criteria.

RESULTS

DECT performed immediately and 24 h post-EVT changed 22.4% (52/232) and 12.5% (29/232) of sCCT-based HT diagnoses, respectively (χ2 = 10.7, p < 0.05). The sensitivity, negative predictive value (NPV), and accuracy of DECT performed immediately post-EVT for predicting the final diagnosis of HT were 33.6%, 58.9%, and 65.9%, respectively, whereas those for DECT performed 24 h post-EVT were 82.4%, 84.3%, and 90.9%, respectively (χ2 = 58.0, χ2 = 42.9, χ2 = 13.6; p < 0.05). The specificity and positive predictive value were both 100.0%. Delayed HT occurred in 50.0% (78/156) and 42.2% (19/45) of patients with CS diagnosed immediately and 24 h post-EVT, respectively.

CONCLUSIONS

DECT performed immediately post-EVT changed a greater proportion of real-time HT diagnoses, whereas that performed 24 h post-EVT had higher sensitivity, NPV, and accuracy in predicting the final diagnosis of HT. A substantial proportion of patients with CS diagnosed at these two post-EVT timepoints subsequently developed delayed HT.

Early post-endovascular treatment contrast extravasation on dual-energy CT is associated with clinical and radiological stroke outcomes: A 10-year single-centre experience

OBJECTIVE

To determine the association between early post-endovascular treatment (EVT) contrast extravasation (CE) on dual-energy CT (DECT) and stroke outcomes.

METHODS

EVT records in 2010-2019 were screened. Exclusion criteria included the occurrence of immediate post-procedural intracranial haemorrhage (ICH). Hyperdense areas on iodine overlay maps were scored according to the Alberta Stroke Programme Early CT Score (ASPECTS), thus forming a CE-ASPECTS. Maximum parenchymal iodine concentration and maximum iodine concentration relative to the torcula were recorded. Follow-up imaging was reviewed for ICH. The primary outcome measure was the modified Rankin Scale (mRS) at 90 days.

RESULTS

Out of 651 records, 402 patients were included. CE was found in 318 patients (79%). Thirty-five patients developed ICH on follow-up imaging. Fourteen ICHs were symptomatic. Stroke progression occurred in 59 patients. Multivariable regression showed a significant association between decreasing CE-ASPECTS and the mRS at 90 days (adjusted (a)cOR: 1.10, 95% CI: 1.03-1.18), NIHSS at 24-48 h (aβ: 0.57, 95% CI: 0.29-0.84), stroke progression (aOR: 1.14, 95% CI: 1.03-1.26) and ICH (aOR: 1.21, 95% CI: 1.06-1.39), but not symptomatic ICH (aOR 1.19, 95% CI: 0.95-1.38). Iodine concentration was significantly associated with the mRS (acOR: 1.18, 95% CI: 1.06-1.32), NIHSS (aβ: 0.68, 95% CI: 0.30-1.06), ICH (aOR: 1.37, 95% CI: 1.04-1.81) and symptomatic ICH (aOR: 1.19, 95% CI: 1.02-1.38), but not stroke progression (aOR: 0.99, 95% CI: 0.86-1.15). Results of the analyses with relative iodine concentration were similar and did not improve prediction.

CONCLUSIONS

CE-ASPECTS and iodine concentration are both associated with short- and long-term stroke outcomes. CE-ASPECTS is likely a better predictor for stroke progression.

A Novel Dual-Energy CT Method for Detection and Differentiation of Intracerebral Hemorrhage From Contrast Extravasation in Stroke Patients After Endovascular Thrombectomy : Feasibility and First Results

PURPOSE

Dual-energy computed tomography (DECT) has been shown to be able to differentiate between intracranial hemorrhage (ICH) and extravasation of iodinated contrast media (contrast staining [CS]). TwinSpiral DECT is a recently introduced technique, which allows image acquisition at two different energy levels in two consecutive spiral scans. The aim of this study was to evaluate the feasibility and accuracy of TwinSpiral DECT to distinguish between ICH and CS after endovascular thrombectomy (EVT) in patients with acute ischemic stroke.

METHODS

This retrospective single-center study conducted between November 2019 and July 2020 included non-contrast TwinSpiral DECT scans (tube voltages 80 and 150Sn kVp) of 39 ischemic stroke patients (18 females, 21 males, mean age 69 ± 11 years) within 48-72 h after endovascular thrombectomy. Parenchymal hyperdensity was assessed for the presence of ICH or/and CS by two board certified and fellowship-trained, blinded and independent neuroradiologists using standard mixed images and virtual non-contrast (VNC) images with corresponding iodine maps from TwinSpiral DECT. Follow-up examinations (FU; CT or MRI) were used as a standard of reference. Sensitivity, specificity, and accuracy for the detection of ICH as well as the inter-reader agreement were calculated.

RESULTS

Parenchymal hyperdensities were detected in 17/39 (44%) patients. Using DECT, they were classified by both readers as ICH in 9 (53%), CS in 8 (47%), and mixture of both in 6 (35%) cases with excellent agreement (κ = 0.81, P < 0.0001). The sensitivity, specificity, and accuracy for the detection of ICH in DECT was 90% (95% confidence interval [CI]: 84-96%), 100% (95% CI 94-100%) and 95% (95% CI 89-100%), and in mixed images 90% (95% CI 84-96%), 86% (95% CI 80-92%) and 88% (95% CI 82-94%), respectively. Inter-reader agreement for detecting ICH on DECT compared to the mixed images was κ = 1.00 (P < 0.0001) vs. κ = 0.51 (P = 0.034).

CONCLUSION

TwinSpiral DECT demonstrates high accuracy and excellent specificity for differentiating ICH from CS in patients after mechanical thrombectomy due to acute ischemic stroke, and improves inter-reader agreement for detecting ICH compared to the standard mixed images.

Quantitative Intracerebral Iodine Extravasation in Risk Stratification for Intracranial Hemorrhage in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Intracerebral hemorrhage poses a severe threat to the outcomes in patients with postthrombectomy acute stroke. We aimed to compare the absolute intracerebral iodine concentration and normalized iodine concentration ratio in predicting intracerebral hemorrhage in patients postthrombectomy.

MATERIALS AND METHODS

Patients with acute anterior circulation large-vessel occlusion who underwent mechanical thrombectomy and had successful recanalization were retrospectively included in the study. Dual-energy CT was performed within 1 hour after mechanical thrombectomy. Postprocessing was performed to measure the absolute intracerebral iodine concentration and the normalized iodine concentration ratio. The correlation between the absolute intracerebral iodine concentration and the normalized iodine concentration ratio was analyzed using the Spearman rank correlation coefficient. We compared the area under the receiver operating characteristic curve of the absolute intracerebral iodine concentration and the normalized iodine concentration ratio using the DeLong test.

RESULTS

We included 138 patients with successful recanalization. Of 43 patients who did not have parenchymal contrast staining on postthrombectomy dual-energy CT, 5 (11.6%) developed intracerebral hemorrhage. Among patients (95/138, 68.8%) with parenchymal contrast staining, 37 (38.9%, 37/95) developed intracerebral hemorrhage. The absolute intracerebral iodine concentration was significantly correlated with the normalized iodine concentration ratio (ρ = 0.807; 95% CI, 0.718-0.867; P < .001). The cutoffs of the normalized iodine concentration ratio and absolute intracerebral iodine concentration for identifying patients with intracerebral hemorrhage development were 222.8%, with a sensitivity of 67.6% and specificity of 76.4%, and 2.7 mg I/mL, with a sensitivity of 75.7% and specificity of 65.5%, respectively. No significant difference was found between the areas under the receiver operating characteristic curve for the absolute intracerebral iodine concentration and the normalized iodine concentration ratio (0.753 versus 0.738) (P = .694).

CONCLUSIONS

The hemorrhagic transformation predictive power of the normalized iodine concentration ratio is similar to that of the absolute intracerebral iodine concentration in patients with successful recanalization.

Diagnostic accuracy of dual-energy computed tomography to differentiate intracerebral hemorrhage from contrast extravasation after endovascular thrombectomy for acute ischemic stroke: systematic review and meta-analysis

OBJECTIVES

To assess whether dual-energy computed tomography (DECT), using conventional computed tomography or magnetic resonance imaging as a reference standard, is sufficiently accurate to differentiate intracerebral hemorrhage from contrast extravasation after endovascular thrombectomy for acute ischemic stroke.

METHODS

On January 20, 2021, we searched the PubMed Medline, Embase, Web of Science, and Cochrane Library databases. QUADAS-2 was used to assess the risk of bias and applicability. Meta-analyses were performed using a bivariate random-effects model. To explore sources of heterogeneity, meta-regression analyses were performed. Deeks' funnel plot asymmetry test was used to assess publication bias.

RESULTS

A total of 7 studies (269 patients, 269 focal areas) were included. The pooled mean sensitivity, specificity, and accuracy of DECT in identifying intracerebral hemorrhage from contrast extravasation after mechanical thrombectomy for acute ischemic stroke were 0.77 (95% confidence interval (CI) 0.29 to 0.96), 1 (95% CI 0.86 to 1), and 0.99 (95% CI 0.98 to 1), respectively. This evidence was of moderate certainty due to the risk of bias. Higgin's I-squared for study heterogeneity was observed for the pooled sensitivity (I² = 78.88%) and pooled specificity (I² = 82.12%). Moreover, Deeks' funnel plot asymmetry test revealed no publication bias (p = 0.38).

CONCLUSION

DECT shows excellent accuracy and specificity in differentiating intracerebral hemorrhage from contrast extravasation after endovascular thrombectomy for acute ischemic stroke. Nevertheless, there was substantial and moderate heterogeneity among the studies. Future large-scale, prospective cohort studies are warranted to validate our findings.

KEY POINTS

• Dual-energy computed tomography shows excellent accuracy and specificity in differentiating intracerebral hemorrhage from contrast extravasation after endovascular thrombectomy for acute ischemic stroke. • Via meta-regression analysis, we found various possible covariates, including the publication date, image analysis, index test time, time of follow-up imaging, and reference standard judgment, that had an important effect on the heterogeneity. • There were no concerns regarding applicability in any of the included studies.

Imaging for Predicting Hemorrhagic Transformation of Acute Ischemic Stroke-A Narrative Review

Hemorrhagic transformation is caused by extravasation of blood products from vessels after acute ischemic stroke. It is an undesirable and potentially devastating complication, which occurs in 10%-40% of clinical cases. Hemorrhagic transformation is classified into four subtypes based on European cooperative acute stroke study II. Predicting hemorrhagic complications at presentation can be useful life saving/altering decisions for the patient. Also, understanding the mechanisms of hemorrhagic transformation can lead to new treatments and intervention measures. We highlighted various imaging techniques that have been used to predict hemorrhagic transformation. Specifically, we looked at the usefulness of perfusion and permeability imaging for hemorrhagic transformation. Use of imaging to predict hemorrhagic transformation could change patient management that may lead to the prevention of hemorrhagic transformation before it occurs. We concluded that the current evidence is not strong enough to rely on these imaging parameters for predicting hemorrhagic transformation and more studies are required.

Early diagnosis and prediction of intracranial hemorrhage using dual-energy computed tomography after mechanical thrombectomy in patients with acute ischemic stroke

PURPOSE

This study assesses the clinical value of dual-energy computed tomography (DECT) in the early diagnosis of intracranial hemorrhage and evaluates the risk of hemorrhagic transformation in patients with acute ischemic stroke (AIS) after mechanical thrombectomy.

METHODS

Patients with AIS who have undergone thrombectomy with Solitaire stent and DECT within one hour after surgery were prospectively enrolled. Linear mixed energy images, virtual non-contrast (VNC) image, and iodine overlay map (IOM) were obtained. Routine CT scan was performed 24 h postoperatively. The sensitivity, specificity, positive and negative predictive values, and accuracy of DECT in the early diagnosis of intracranial hemorrhage was evaluated. The iodine concentration of intracranial lesions was measured by IOM with the follow-up results taken as reference. Receiver operating characteristic (ROC) analysis was performed to obtain the threshold of hemorrhagic transformation and increased bleeding.

RESULTS

Among the 44 patients enrolled in this study, 25 (56.8 %) were diagnosed with simple extravasation of iodinated contrast agent, and 19 (43.2 %) showed intracranial hemorrhage in DECT. Compared with the follow-up CT 24 h after surgery, early diagnosis of postoperative intracranial hemorrhage using DECT demonstrated a sensitivity of 90.5 %, specificity of 100 %, positive predictive rate of 100 %, negative predictive rate of 92.0 %, and accuracy of 95.5 %. Among the 86 intracranial lesions that underwent iodine concentration measurement, 19 were diagnosed with hemorrhagic transformation or increased bleeding, and 67 were diagnosed without the aforementioned conditions. The sensitivity and specificity for differentiating the two groups were 73.7 % and 92.5 %, respectively, with a cut-off value of 2.7 mg/mL.

CONCLUSION

DECT is clinically valuable in early diagnosis and prediction of intracranial hemorrhage after mechanical thrombectomy in AIS patients.