Perihematomal Cerebral Tissue Iron Quantification on MRI Following Intracerebral Hemorrhage in Two Human Subjects: Proof of Principle.

Abstract

Spontaneous intracranial hemorrhage (ICH) is a common hemorrhagic stroke subtype with significant neurological sequelae. The management of ICH is usually supportive treatment in the neuro-intensive care setting, while the body humors deal with the hematoma. Treatment of the hematoma is usually expectant management unless there is neurological deterioration caused by mass effect from the hemorrhage. Some minimally invasive techniques have been explored for lysing and evacuating the hematoma, but none of them have gained a stronghold in the routine clinical management of this condition. Studies mainly in animal (rodent and porcine) ICH models have shown the role of bound and unbound iron in causing neurotoxicity following an ICH. There is currently no noninvasive method for assessing iron levels in the cerebral tissue following ICH. Our study intends to explore the role of magnetic resonance imaging (MRI) in establishing iron levels in cerebral tissue at the periphery of the hematoma following an ICH. Initially, an MRI phantom was constructed with varying concentrations of liquid iron preparation in a water bath container. Susceptibility weighted sequences were utilized to scan this phantom to generate T2* signal magnitude measurements corresponding to the iron concentration in the phantom. Encouraged by the reliability of the measurements on the phantom, patients with ICH were then recruited into this experimental study once the inclusion criteria were met. One control and two human subjects had their brains scanned in a 3 T MRI scanner utilizing the same susceptibility weighted sequence. We found that ICH perihematomal brain tissue iron susceptibility signal measurements were 4 times higher than those of the baseline control and normal contralateral brain tissue. Three different baseline measurements (one control and two contralateral normal brain) revealed a level of 0.1 mg/ml of iron concentration in the contralateral brain tissue in the identical anatomical location as the hematoma, typically in the basal ganglia region. T2 * signal measurements in the brain tissue at the periphery of the basal ganglia hematoma at day 7 following hemorrhage revealed iron concentration of 0.4 mg/ml (approximately 4 times the baseline/control) in two human subjects included in the study. These measurements mimic those obtained in published animal ICH model studies.