Adapting the Computed Tomography Criteria of Hemorrhagic Transformation to Stroke Magnetic Resonance Imaging

Abstract

Background: The main safety aspect in the use of stroke thrombolysis and in clinical trials of new pharmaceutical or interventional stroke therapies is the incidence of hemorrhagic transformation (HT) after treatment. The computed tomography (CT)-based classification of the European Cooperative Acute Stroke Study (ECASS) distinguishes four categories of HTs. An HT can range from a harmless spot of blood accumulation to a symptomatic space-occupying parenchymal bleeding associated with a massive deterioration of symptoms and clinical prognosis. In magnetic resonance imaging (MRI) HTs are often categorized using the ECASS criteria although this classification has not been validated in MRI. We developed MRI-specific criteria for the categorization of HT and sought to assess its diagnostic reliability in a retrospective study. Methods: Consecutive acute ischemic stroke patients, who had received a 3-tesla MRI before and 12-36 h after thrombolysis, were screened retrospectively for an HT of any kind in post-treatment MRI. Intravenous tissue plasminogen activator was given to all patients within 4.5 h. HT categorization was based on a simultaneous read of 3 different MRI sequences (fluid-attenuated inversion recovery, diffusion-weighted imaging and T2* gradient-recalled echo). Categorization of HT in MRI accounted for the various aspects of the imaging pattern as the shape of the bleeding area and signal intensity on each sequence. All data sets were independently categorized in a blinded fashion by 3 expert and 3 resident observers. Interobserver reliability of this classification was determined for all observers together and for each group separately by calculating Kendall's coefficient of concordance (W). Results: Of the 186 patients screened, 39 patients (21%) had an HT in post-treatment MRI and were included for the categorization of HT by experts and residents. The overall agreement of HT categorization according to the modified classification was substantial for all observers (W = 0.79). The degrees of agreement between experts (W = 0.81) and between residents (W = 0.87) were almost perfect. For the distinction between parenchymal hematoma and hemorrhagic infarction, the interobserver agreement was almost perfect for all observers taken together (W = 0.82) as well as when experts (W = 0.82) and residents (W = 0.91) were analyzed separately. Conclusion: The ECASS CT classification of HT was successfully adapted for usage in MRI. It leads to a substantial to almost perfect interobserver agreement and can be used for safety assessment in clinical trials.

Prevalence and Evolution of Susceptibility‐Weighted Imaging Lesions in Patients With Artificial Heart Valves

“…15 Embolic and hemodynamic ischemic brain infarcts are a well-known complication of valve surgery, 27 and secondary hemorrhagic transformation may thus explain occurrence of SWI lesions after valve implantation procedures. 28 However, the SWI lesions observed in our study were not associated with diffusion-weighted imaging lesions when brain MRI was performed shortly after the intervention. Furthermore, the frequency of SWI lesions in our study was higher than the known rates for diffusion-weighted imaging lesions after valve surgery and the rate of hemorrhagic transformation of ischemic stroke is usually only at %20% to 30%.…”

Hemorrhagic Transformation after Tissue Plasminogen Activator Reperfusion Therapy for Ischemic Stroke: Mechanisms, Models, and Biomarkers

“…Using dynamic perfusion CT, Lin et al [87] reported that in 88% of the patients with ischemic stroke, microvascular permeability increased within the first 3 h after stroke onset. Neeb et al [88] successfully adapted the European Cooperative Acute Stroke Study (ECASS) CT classification of HT for usage in magnetic resonance imaging (MRI). In their study, classification of HT had nearly perfect inter-observer agreement.…”

Dabigatran Therapy in Acute Ischemic Stroke Patients Without Atrial Fibrillation

“…In 23 (43%) patients, the symptoms were transient (2 [0. [4][5][6] hours). The median baseline DWI lesion was 0.8 (range, 0.1-43.2) mL ( Figure 1).…”

“…MRI sequences included DWI, fluid-attenuated inverse recovery, and a susceptibility weighted imaging (to assess HT) sequence. 6 DWI sequences were assessed for the presence, number, and total volume of regions with diffusion restriction (ANALYZE 11.0, Biomedical Imaging Resource, Rochester, Figure 1). 7 …”