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

Association between CT Perfusion Parameters and Hemorrhagic Transformation after Endovascular Treatment in Acute Ischemic Stroke: Results from the ESCAPE-NA1 Trial

BACKGROUND AND PURPOSE

Hemorrhagic transformation can occur as a complication of endovascular treatment for acute ischemic stroke. This study aimed to determine whether ischemia depth as measured by admission CTP metrics can predict the development of hemorrhagic transformation at 24 hours.

MATERIALS AND METHODS

Patients with baseline CTP and 24-hour follow-up imaging from the ESCAPE-NA1 trial were included. RAPID software was used to generate CTP volume maps for relative CBF, CBV, and time-to-maximum at different thresholds. Hemorrhage on 24-hour imaging was classified according to the Heidelberg system, and volumes were calculated. Univariable and multivariable regression analyses assessed the association between CTP lesion volumes and hemorrhage/hemorrhage subtypes.

RESULTS

Among 408 patients with baseline CTP, 142 (35%) had hemorrhagic transformation at 24-hour follow-up, with 89 (63%) classified as hemorrhagic infarction (HI1/HI2), and 53 (37%), as parenchymal hematoma (PH1/PH2). Patients with HI or PH had larger volumes of low relative CBF and CBV at each threshold compared with those without hemorrhage. After we adjustied for baseline and treatment variables, only increased relative CBF <30% lesion volume was associated with any hemorrhage (adjusted OR, 1.14; 95% CI, 1.02-1.27 per 10 mL), as well as parenchymal hematoma (adjusted OR, 1.23; 95% CI, 1.06-1.43 per 10 mL). No significant associations were observed for hemorrhagic infarction.

CONCLUSIONS

Larger "core" volumes of relative CBF <30% were associated with an increased risk of PH following endovascular treatment. This particular metric, in conjunction with other clinical and imaging variables, may, therefore, help estimate the risk of post-endovascular treatment hemorrhagic complications.

The value of CT-based radiomics in predicting hemorrhagic transformation in acute ischemic stroke patients without recanalization therapy

Objective

The aim of this study is to investigate the clinical value of radiomics based on non-enhanced head CT in the prediction of hemorrhage transformation in acute ischemic stroke (AIS).

Materials and methods

A total of 140 patients diagnosed with AIS from January 2015 to August 2022 were enrolled. Radiomic features from infarcted areas on non-enhanced CT images were extracted using ITK-SNAP. The max-relevance and min-redundancy (mRMR) and the least absolute shrinkage and selection operator (LASSO) were used to select features. The radiomics signature was then constructed by multiple logistic regressions. The clinicoradiomics nomogram was constructed by combining radiomics signature and clinical characteristics. All predictive models were constructed in the training group, and these were verified in the validation group. All models were evaluated with the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA).

Results

Of the 140 patients, 59 experienced hemorrhagic transformation, while 81 remained stable. The radiomics signature was constructed by 10 radiomics features. The clinicoradiomics nomogram was constructed by combining radiomics signature and atrial fibrillation. The area under the ROC curve (AUCs) of the clinical model, radiomics signature, and clinicoradiomics nomogram for predicting hemorrhagic transformation in the training group were 0.64, 0.86, and 0.86, respectively. The AUCs of the clinical model, radiomics signature, and clinicoradiomics nomogram for predicting hemorrhagic transformation in the validation group were 0.63, 0.90, and 0.90, respectively. The DCA curves showed that the radiomics signature performed well as well as the clinicoradiomics nomogram. The DCA curve showed that the clinical application value of the radiomics signature is similar to that of the clinicoradiomics nomogram.

Conclusion

The radiomics signature, constructed without incorporating clinical characteristics, can independently and effectively predict hemorrhagic transformation in AIS patients.

Predictors for hemorrhagic transformation and cerebral edema in stroke patients with first-pass complete recanalization

BACKGROUND

Predictors of radiological complications attributable to reperfusion injury remain unknown when baseline setting is optimal for endovascular treatment and procedural setting is the best in stroke patients with large vessel occlusion (LVO).

AIMS

To identify clinical and radiological/procedural predictors for hemorrhagic transformation (HT) and cerebral edema (CED) at 24 hr in patients obtaining complete recanalization in one pass of thrombectomy for ischemic stroke ⩽ 6 h from symptom onset with intra-cranial anterior circulation LVO and ASPECTS ⩾ 6.

METHODS

We conducted a cohort study on prospectively collected data from 1400 patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke.

RESULTS

HT was reported in 248 (18%) patients and early CED was reported in 260 (19.2%) patients. In the logistic regression model including predictors from a first model with clinical variables and from a second model with radiological/procedural variables, diabetes mellitus (odds ratio (OR) = 1.832, 95% confidence interval (CI) = 1.201-2.795), higher National Institutes of Health Stroke Scale (NIHSS) (OR = 1.076, 95% CI = 1.044-1.110), lower Alberta Stroke Program Early CT (ASPECTS) (OR = 0.815, 95% CI = 0.694-0.957), and longer onset-to-groin time (OR = 1.005, 95% CI = 1.002-1.007) were predictors of HT, whereas general anesthesia was inversely associated with HT (OR = 0.540, 95% CI = 0.355-0.820). Higher NIHSS (OR = 1.049, 95% CI = 1.021-1.077), lower ASPECTS (OR = 0.700, 95% CI = 0.613-0.801), intravenous thrombolysis (OR = 1.464, 95% CI = 1.061-2.020), longer onset-to-groin time (OR = 1.002, 95% CI = 1.001-1.005), and longer procedure time (OR = 1.009, 95% CI = 1.004-1.015) were predictors of early CED. After repeating a fourth logistic regression model including also good collaterals, the same variables remained predictors for HT and/or early CED, except diabetes mellitus and thrombolysis, while good collaterals were inversely associated with early CED (OR = 0.385, 95% CI = 0.248-0.599).

CONCLUSIONS

Higher NIHSS, lower ASPECTS, and longer onset-to-groin time were predictors for both HT and early CED. General anesthesia and good collaterals were inversely associated with HT and early CED, respectively. Longer procedure time was predictor of early CED.

Red blood cell distribution width in different time-points of peripheral thrombolysis period in acute ischemic stroke is associated with prognosis

The relationship between red blood cell distribution width (RDW) in peripheral thrombolysis period and prognosis is not fully clarified in those who underwent intravenous thrombolysis (IVT) for acute ischemic stroke (AIS). Our study aimed to clarify this issue. A retrospective analysis of about 510 consecutive thrombolysis cases for AIS from January 2015 to March 2019 in a single-center database was done and followed-up for 3 months. We used univariate and multivariable models to evaluate the relationship between RDW levels at various time-points after IVT and the occurrence risk of hemorrhagic transformation (HT) and recurrent stroke, and used COX regression to assess the hazard ratios of outcomes with RDW levels. Elevated risk of HT was found in higher tertiles of RDW (OR = 10.282, 95% confidence interval (CI) 2.841–39.209, P < 0.001 in Tp tertile G3; OR = 5.650, 95% CI 1.992–16.025, P = 0.001 in T24 tertile G3; OR = 4.308, 95% CI 1.480–12.542, P = 0.007 in T48 tertile G3 and OR = 6.384, 95% CI 2.201–18.515, P = 0.001 in T72 tertile G3, respectively). Occurrence of recurrent stroke was highest in the RDW tertile G3 (HR = 4.580, 95% CI 2.123–9.883, P < 0.001 in Tp tertile G3; HR = 5.731, 95% CI 2.498–13.151, P = 0.001 in T24 tertile G3; HR = 3.019, 95% CI 1.969–4.059, P = 0.031 in T48 tertile G3; HR = 3.318, 95% CI 1.598–6.890, P = 0.001 in T72 tertile G3, respectively). Mean RDW levels ≥13.60 among AIS patients undergoing thrombolysis was associated with higher risk of HT and recurrent stroke.