Related Research and Recent Progress of Ischemic Penumbra.

We reviewed recent studies on ischemic penumbra, including the evolution of the definitions of ischemic penumbra and observations on the characteristics of blood flow and the molecular evolutionary mechanism of ischemic tissues; at the same time, a brief summary of current clinical treatment methods were included. From the perspective of neuroimaging and clinical treatment, the characteristics of cerebral blood flow, oxygen consumption, cell water content, and metabolites were analyzed, to evaluate the diagnosis and evolution of ischemic penumbra. The analysis of the evolutionary characteristics of multiple gene molecules and metabolites may provide ideas for clinical imaging diagnosis and clinical treatment, also allow the combination of multiparameter imaging indexes to be more accurate and effective for the assessment of ischemic penumbra. The research hotspot of imaging on the ischemic penumbra region in the future may be more focused on reflecting the evolutionary characteristics of local metabolites in the ischemic area. Using multimodality imaging to evaluate IP zones and guide the formulation of clinical treatment protocols.

Expression of RGMb in brain tissue of MCAO rats and its relationship with axonal regeneration.

OBJECTIVE: To investigate the changes in the expression of repulsive guidance molecule b (RGMb) in brain tissue of rats with ischemic cerebral infarction and determine its relationship with axonal regeneration, synapse remodeling and magnetic resonance imaging (MRI) parameters with magnetic resonance diffusion tensor imaging as the dynamic continuous monitoring method in vivo, so as to explore the pathophysiological mechanism of the occurrence, development and prognosis of cerebral infarction. METHODS: Ninety Sprague-Dawley (SD) rats were randomly divided into six groups, namely control group, middle cerebral artery occlusion (MCAO) 12-h group, MCAO 24-h group, MCAO 48-h group, MCAO 7-day group and MCAO 10-day group, each of 15 animals. Rats were examined by head MRI at corresponding time points, followed by measurement of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values. Subsequently, brain tissues were taken to detect the expression of RGMb, axonal regeneration and synapse remodeling. RESULTS: After infarction, ADC and FA values of the infarcted core area were lower in rats of each group compared to those in rats of normal group (P<0.05), which was lowest at 12h. The positive expressions of RGMb and synaptophysin were continuously increased from the 12th hour after operation, which reached a peak at 48h; while axonas was gradually reduced after operation in each group, which revealed the most obvious damage in the MCAO 24-h group. The protein expression of RGMb was negatively correlated with MRI parameters and axon growth. CONCLUSION: After supratentorial cerebral infarction, the expressions of RGMb and synaptophysin were up-regulated in rats, neurofilament protein (NF-200) expression was decreased, and MRI parameters (ADC and FA values) were reduced, indicating that RGMb protein may be involved in the regeneration and remodeling of axons and synapses, and exert an important role in pathophysiological processes such as nerve regeneration disturbance and neuron apoptosis after cerebral ischemia injury. In vivo MRI can be a noninvasive technique to monitor the areas of cerebral infarction and the recovery of neurological function.

Perfusion-weighted magnetic resonance imaging in the assessment of haemodynamics following stent angioplasty in patients with symptomatic middle cerebral artery plaque stenosis at the M1 segment.

The most effective strategy to assess changes in the brain haemodynamics of stent angioplasty in patients with symptomatic ischemia of the M1 segment of the middle cerebral artery (MCA) remains unknown. The purpose of the present study was to use perfusion-weighted magnetic resonance imaging (PWI) to evaluate the effect of stent angioplasty in treating patients with symptomatic MCA plaque stenosis. Stent angioplasty was performed on 23 patients with reduplicative transient ischaemic attack who were refractory to medical therapy. All patients had MCA plaque stenosis at the M1 segment. Brain PWI was obtained from four major regions of interest (ROIs) at the frontal parietal, temporal, lateral ventricle and basal ganglia lobes prior to and following stent implantation. In addition, cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT) and time to peak (TTP) parameters derived from PWI were calculated. All patients underwent digital subtraction angiography following surgery to confirm the patency. Computed tomography angiography or PWI was performed 1 week and 3 months post-surgery. According to pre-operative PWI, there was significant hypoperfusion in the symptomatic frontal parietal, temporal, lateral ventricle and basal ganglia lobes. By contrast, the regional CBF and CBF increased in the ROIs of the affected cerebral hemisphere 3 months after stent implantation (P<0.05 vs. pre-operative data). Additionally, post-operative MTT and TTP in the ROIs on the operative side were significantly shorter than pre-operative MTT and TTP (P<0.05). During the follow-up period, the frequency of transient ischaemic attack was reduced or disappeared in all patients during the follow-up. In conclusion, PWI enables an effective and objective assessment of haemodynamics prior to and following stent angioplasty in patients with plaque stenosis of MCA at the M1 segment.