Secondary injury in rats with intra-cerebral hematoma: a 7 Tesla high-field strength MRI study / 中华神经医学杂志

ABSTRACT

Objective To dynamically analyze the evolutionary process of cerebral edema absorption and the level of local iron in rats with intra-cerebral hematoma by high-field strength 7 Tesla MRI and explore the characteristics and mechanism of secondary injury after intra-cerebral hematoma.Methods Sixteen adult SD rats (about 150 g) were randomly divided into experimental group (n=10) and control group (n=6).Rat models in the experimental group were established by performing injection of 50 μL their own venous blood into their right caudate nucleus accurately. Rats in the control group were used normal saline,instead.After that,head MRI (T2 and T2-star scans) was performed 1,2,3,7 and 14 d after the injection; their imaging features were compared. Results Nine rats in the experimental group survived and 1 died after the operation; in the early days (within 3 d), the T2 weighing imaging showed that the time of relaxation surrounding the hematoma was longer than that in control group,suggesting that the zone of the edema surrounding the hematoma became more clearly.In the early days (within 3 d),T2-weighted imaging was clear,and the time of relaxation surrounding the hematoma increased rapidly,steadily improved 3 d after the operation and reached its peak level 7 dafter the operation; the damage area absorption decreased steadily but turned widening 3 d later and reached the peak 7 d later.T2-star value reached the peak rapidly 3 d after the operation,and then,moderated the downturn.The rats in the control group showed no obvious signal changes under MRI,except those with needle tract injury. Conclusion Secondary injury after intra-cerebral hemorrhage shows a rapidly injury progress in the short terrn at first,and then,has intensify again after a stable period; the local iron diffusion trend is synchronized to the secondary injury,suggesting that iron may play a key role in the mechanism of secondary brain edema.