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MR detection of hyperacute parenchymal hemorrhage of the brain
1Department of Radiology, Mount Sinai School of Medicine, New York, USA.
Background And Purpose:
The detection of hemorrhage in acutely ill patients is crucial to clinical management. The MR features that allow diagnosis of intracerebral hematomas of less than 24 hours' duration are described and the mechanistic basis of these features is investigated.
Methods:
The clinical MR features of seven confirmed hyperacute intracerebral hematomas were compared with those of experimentally induced hematomas in a rat model in which detailed analyses of iron metabolism and morphometry were performed.
Results:
In all patients and all animals, a hypointense rim on T2-weighted spin-echo images that was less marked on T1-weighted spin-echo images was seen surrounding a central isointense or heterogeneous region of hyperacute hematoma. Histologically, the clot showed interdigitation of intact erythrocytes and tissue at the hematoma-tissue interface without significant hemosiderin, ferritin, or phagocytic activity. Biochemically, the iron from the extravasated blood was present only as heme proteins within the first 24 hours.
Conclusion:
The hypointense rim on T2-weighted images, and to a lesser extent on T1-weighted images, is a distinctive feature of hyperacute hematoma. This pattern is consistent with magnetic susceptibility variations of paramagnetic deoxygenated hemoglobin within intact erythrocytes at a microscopically irregular tissue-clot interface. The detection of hemorrhage is important in the management of patients with acute stroke.
Insights
Detecting early intracerebral hemorrhage (ICH) is vital. A hypointense rim on MRI scans, particularly T2-weighted images, effectively identifies hyperacute hematomas within 24 hours.
Area of Science:
- Neuroradiology
- Biomedical Imaging
- Hematology
Background:
- Early detection of hemorrhage in acutely ill patients is critical for effective clinical management.
- Intracerebral hematomas require prompt diagnosis for appropriate treatment strategies.
Purpose of the Study:
- To describe the Magnetic Resonance (MR) features for diagnosing intracerebral hematomas under 24 hours.
- To investigate the underlying mechanistic basis of these observed MR features.
Main Methods:
- Comparison of clinical MR features from seven hyperacute intracerebral hematomas with experimentally induced hematomas in a rat model.
- Detailed analysis of iron metabolism and morphometry in the rat model.
Main Results:
- A hypointense rim surrounding an isointense or heterogeneous central region was consistently observed on T2-weighted and T1-weighted spin-echo images in both patients and animals.
- Histological examination revealed intact erythrocytes and tissue at the hematoma interface without significant hemosiderin or ferritin.
- Biochemical analysis showed iron present only as heme proteins within the first 24 hours.
Conclusions:
- The hypointense rim on T2-weighted and T1-weighted MR images is a distinctive indicator of hyperacute hematoma.
- This imaging pattern correlates with magnetic susceptibility variations from deoxygenated hemoglobin at the microscopic tissue-clot interface.
- Accurate detection of hemorrhage is crucial for managing patients presenting with acute stroke.