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Evolution of early perihemorrhagic changes--ischemia vs. edema: an MRI study in rats
Berk Orakcioglu1, Jochen B Fiebach, Thorsten Steiner
1Department of Neurology, University of Heidelberg, Germany; Department of Neurosurgery, University of Heidelberg, Germany.
Objectives:
Cerebral ischemia has been proposed as a contributing mechanism to secondary neuronal injury after intracranial hemorrhage (ICH). The search for surrogate parameters that allow treatment stratification for spontaneous ICH continues. We aimed to examine perihemorrhagic ischemic changes with an animal experimental MRI study.
Methods:
A high field MRI compatible setup for male Wistar rats was established using a double injection model. ICH was stereotactically placed into the right basal ganglia of 29 Wistar rats. Coronal T2-WI, T2*-WI and DWI were generated with a 2.35 T animal MRI scanner 15 min, 60 min and 210 min after ICH. Clot signal characteristics, clot volumes and normalized ADC values were analyzed in four hematoma regions (core, periphery, outer rim, healthy ipsilateral tissue) in all sequences.
Results:
T2*-WI and DWI reliably demonstrated ICH in 100% with only small deviation from the applied volume (-20% to +26%) whereas T2-WI failed to conspicuously show ICH. There were no perihemorrhagic ADC decreases consistent with ischemic cytotoxic edema but a mild vasogenic edema surrounding the ICH could be observed.
Conclusion:
T2*-WI and DWI are accurate for the diagnosis of hyperacute ICH. According to serial and crossectional ADC analysis, there is no hint towards the existence of a perihemorrhagic ischemic area that might be saved by early intervention. Future studies should focus on perfusion and metabolic/neurotoxic studies of this particular area and neurotoxic properties of the surrounding edema.
Insights
This study found no evidence of perihemorrhagic ischemia after intracranial hemorrhage (ICH) in rats, suggesting early intervention targeting ischemia may not be beneficial. Advanced MRI techniques accurately detected ICH.
Area of Science:
- Neuroscience
- Radiology
- Medical Imaging
Background:
- Secondary neuronal injury after intracranial hemorrhage (ICH) may involve cerebral ischemia.
- Identifying surrogate parameters for treatment stratification in spontaneous ICH is crucial.
- This study investigates perihemorrhagic ischemic changes using advanced MRI in an animal model.
Purpose of the Study:
- To examine perihemorrhagic ischemic changes following induced intracranial hemorrhage (ICH) in a rat model.
- To evaluate the utility of different MRI sequences (T2-WI, T2*-WI, DWI) in detecting ICH and associated ischemic changes.
- To assess apparent diffusion coefficient (ADC) values in the perihemorrhagic area to identify cytotoxic or vasogenic edema.
Main Methods:
- Male Wistar rats underwent stereotactic basal ganglia ICH induction.
- High-field MRI (2.35 T) was performed at 15, 60, and 210 minutes post-ICH.
- T2-WI, T2*-WI, and DWI sequences were used to analyze clot characteristics and ADC values in different hematoma regions.
Main Results:
- T2*-WI and DWI accurately detected ICH with minimal volume deviation.
- T2-WI sequences were less effective in visualizing the hemorrhage.
- No significant perihemorrhagic ADC decreases indicative of cytotoxic edema were observed; mild vasogenic edema was present.
Conclusions:
- T2*-WI and DWI are reliable for diagnosing hyperacute ICH.
- Serial ADC analysis did not reveal evidence of a salvageable perihemorrhagic ischemic area.
- Future research should explore perfusion and metabolic studies in this region and the neurotoxic effects of surrounding edema.
