MRI Research On The Mechanism Of Reverse Regurgitation Of Drainage Veins In Cerebellar Infarction Area

Part 1 Imaging analysis of the morphology and phase value of drainage veins in cerebellar infarction areaBackground:Cerebellar infarction is very common in clinical practice and its incidence is increasing with the deepening of Chinese aging society.There is a high incidence of complications and mortality in the patients with cerebellar infarction.The cerebellum and cerebral hemispheres have two independent blood supply systems that are inconsistent with each other,and there are few reports on the influence of the special anatomical characteristics of the cerebellum on the ischemic penumbra of cerebellar infarction.The research of cerebral infarction is always focusing on the indicators which involve arterial blood circulation,and perfusion status to evaluate the clinical outcome and curative effect.The research on the morphology and function of cerebral venous also gradually developed in recent years,some scholars found that patients with acute cerebral infarction whose cortical veins filled well and with quick speed will have a good prognosis.Obvious cortical vein sign on susceptibility-weighted imaging（SWI）suggested the presence of ischemic penumbra tissue can be salvaged.Digital subtraction angiography（DSA）in some patients with cerebral infarction shows signs of early venous filling in the ischemic core area.The cerebellar hemisphere is surrounded by a number of thick venous sinuses and drainage veins are often drained into adjacent venous sinuses directly or tortuously,There are relatively few reports on cerebellar venous drainage and its mechanism after cerebellar infarction.Objective:we applied magnetic resonance imaging（MRI）enhancement venous phase and SWI to observe and analyze the changes of venous morphology in cerebellar infarction area.SWI was used to analyze the venous distribution and confluence of bilateral cerebellar hemispheres in normal volunteers.Then we compared the phase changes of the corresponding regions in the bilateral cerebellar hemispheres,and measured the phase value of the drainage veins between the cerebellar infarction area and the healthy control group to clarify the change of veins’ morphology and phase value after cerebellar infarction.In a word,we aimed to investigate the possibility of reverse regurgitation of drainage veins in cerebellar infarction area.Methods:The cerebellar samples of cadavers were compared with MRI images to determine the regions of cerebellar hemispheres.Data were collected from 18 patients with an ischemic cerebellar infarction and 30 normal volunteers who underwent SIEMENS 3.0T MRI.Eleven patients underwent DCE-MRI.We selected cerebellar veins with diameter between 0.2mm to 2mm which are visible to naked eyes as defined by Chinese scholar Zhang Kai.Neural signal processing software（SPIN）was applyed to observe cerebellum vein from the foramen magnum to the tentorium,Then we recorded the number of all veins in the entire cerebellar hemisphere step by step and measured phase value at the same time.Each cerebellar hemisphere was divided into four regions which are corresponding to the contralateral cerebellar hemisphere,the mean amount and phase value of veins in the corresponding area of normal volunteers were compared and analyzed.Then we observed the venous sinuses which adjoined to the veins in each region.Meanwhile we observed and analyzed the morphological changes of the veins which involved in the infarct area of the cerebellar hemisphere and adjoined to the sinus,and the phase differences of drainage veins in infarct area and those in normal volunteers were compared and analyzed.Results:Bilateral cerebellar hemispheric veins were divided into left and right anterior superior cerebellar hemispheric veins（LASCV,RASCV）,left and right posterior superior cerebellar hemispheric veins（LPSCV,RPSCV）,left and right anterior inferior cerebellar hemispheric veins（LAICV,RAICV）,and left and right posterior inferior cerebellar hemispheric veins（LPICV,RPICV）.There was no statistically significant difference in the mean number of draining veins between the left and right sides of the corresponding cerebellar hemispheres in 30 normal volunteers.According to the statistics,a total of 425 ASCVs were obtained,of which 218 were injected into the tendric sinus and 121 into the suprasicular sinus and 81 into the suprasicular vein.577 PSCVs,about 480 were injected into the tendric sinus and 70 into the transverse sinus.Of the 437 AICVs,200 were injected into the inferior sinus,11 6 into the sigmoid sinus and 96 into the suprasicular sinus.Of the 683 PICVs,438 were injected into the transverse sinus,1 72 were injected into the tendric sinus,and 34 were injected into the sigmoid sinus.Chi-square test showed that the morphological score of the venous in the infarct area was significantly higher than that on the opposite side of the infarct（mirror image side）（P<0.01）,that means the veins in the infarct area mostly showed thickened venous lumen and increased blood vessels.Eleven patients with cerebellar infarction underwent dynamic contrast-enhanced magnetic resonance examination,and the venous sinuses were obviously developed in the venous stage.Multiple cerebellar venous hyperemia and dilation were observed at the junction between the infarct area and the venous sinuses.At the same time,about 6 patients with larger infarct area could also be seen patchlike enhanced signal shadow in the ischemic infarct area,and the edge was blurred.All the 18 patients with cerebellar infarction underwent magnetic sensitivity weighted imaging.The drainage veins in the ischemic infarction area were thickened and expanded,and the bridging veins adjacent to the venous sinus were thickened and enlarged.Some patients also could be seen patchy low signal shadow in the ischemic infarction area.The relative SWI phase values of the bilateral cerebellar hemispheres of 30 healthy volunteers were measured respectively.Only the phase values of the right posterior superior vein were higher than those of the left,P=0.036,and the difference was statistically significant,while the phase values of the other groups were not significantly different,with no statistically significant difference（P>0.05）.There was no significant difference between normal volunteers and the opposite side of the cerebellar infarction area（P=0.13）.The phase values of drainage veins were compared between healthy side and infarcted area,and the difference was statistically significant（P<0.0001）.Conclusion:The cerebellar hemisphere is adjacent to the thick venous sinuses.After cerebellar infarction,multiple small veins and medullary vein hyperemia in the venous stage were enhanced by contrast enhance MRI.There is a possibility of reverse reflux in cerebellar vein.The SWI phase value of the draining vein in the area of cerebellar infarction increased,and it is possible for regurgitated venous blood to supply oxygen to the infarcted tissue cells of the cerebellar infarction.Regurgitated venous blood may play a certain role in delaying and hindering cerebellar infarction.Part 2 The study on the effect of drainage vein in cerebellar infarction area with MRIBackground:After the blood flows through the capillary bed around the brain tissue,part of the oxygen in the blood is absorbed by the brain tissue,and part of the oxygen passes through the capillary bed and enters the corresponding drainage vein,then it drains the venous blood into its adjacent venous sinus.When the cerebellar artery is occluded or narrowed,cerebral blood flow and perfusion in the capillaries around cerebellar tissue is reduced,and the automatic regulation of the cerebrovascular system fails to meet the oxygen needs of the brain tissue.In order to maintain oxygen metabolism and normal physiological function of cerebellar tissue,per unit volume oxygen uptake increasedly,so the OEF is increased,.The content of deoxyhemoglobin in the draining vein was significantly increased in the infarct area,then the venous phase value was significantly increased accordingly.When the oxygen uptake fraction reaches a certain value,the cerebral oxygen uptake rate（CMRO2）continues to decline with the continuous decline of cerebral blood flow,and the brain tissue is in a state of ischemia and hypoxia.In the first part of this paper,we speculated that drainage veins in the infarct area have the mechanism of reverse regurgitation and venous regurgitation.If the regurgitation venous blood continues to supply oxygen..the hypoxia state of the brain tissue will be relieved,thus delaying or hindering the development of cerebellar infarction process.As cerebral blood flow continues to decrease due to narrowing or occlusion of the offending arteries,the reverse regurgitation of oxygen supply continuous increase in the drainage veins.In theory,there may be a certain boundary between cerebral blood flow and venous phase value,which needs to be solved in order to maintain the survival of cerebellar cells.Objective:We applied magnetic resonance to measure the phase value of the drainage veins and cerebral blood flow value and apparent diffusion coefficient in the cerebellar infarction area and the opposite side to analyze the mutual relationship among these three parameter in cerebellar infarction area and the correlation between the three factors and the stroke scale score（NIHSS）.We aim to evaluate the characteristics of phase value of drainage veins in cerebellar infarction area.Furthermore,the feasibility of phase value measurement in the clinical diagnosis and treatment of acute cerebellar infarction was discussed.In this study,the boundary value of CBF decrease and venous oxygen saturation under the survival state of ischemic penumbra cells in cerebellar infarction was investigated so as to provide quantitative imaging data for clinical control of the pathological status of patients with cerebellar infarction and formulation of treatment plan.Methods:Data were collected from 18 patients with an ischemic cerebellar infarction who underwent MRI at the Shandong Medical Imaging Research Institute from April 1 to December 31,201 7.Combined with previous partition of bilateral cerebellum,one side of the cerebellum has four partitions,there was only one area of cerebellar infarct in each of the ten patients.There were five patients take up two infarcted cerebellar areas,two patients take up three cerebellar infarct areas,one patient take up four cerebellar infarct areas.Totally,30 regions were taken into the research category.The phase value,CBF value and ADC value of the infarct area were compared with that of the corresponding area,the correlation among the phase value of drainage veins in the infarct area,the local cerebral blood flow（rCBF）and the local apparent diffusion coefficient（rADC）value were analyzed by Pearson correlation test.Similarly,the correlation among these three values involved in the difference between infacted area and the corresponding area,the correlation between the phase value,CBF,ADC and the stroke scale score（NIHSS）,and the correlation between the difference of the phase value,CBF,ADC from the infarcted area to healthy side and the stroke scale score（NIHSS）,were also analyzed by Pearson correlation test,the boundary value of the phase value and CBF in the ischemic penumbra of cerebellar infarction were measured by ROC.Results:The measured phase value of the drainage veins in the infarct area were significantly higher than that in the healthy side（t=6.329,P=0.03）,and the ADC value and CBF value in the infarct area were significantly lower than that in the contralateral side.The difference was statistically significant.The phase value of the venous drainage in the cerebellar hemisphere,the CBF value and the ADC value in the infarct area of 30 patients were measured.The infarction area drainage venous phase values were expressed as дФinfarction.The relative phase values were denoted as дФnormal,and the phase difference of bilateral cerebellar hemispheres was denoted as rrдФ,whererrдФ=дФinfarction-дФnormal.The difference of cerebral blood flow in the infarct region and contralateral was calculated as relative regional cerebral blood flow（rrCBF）,where rrCBF=rCBFnormal-rCBFinfarction,rrADC was the difference of apparent diffusion coefficient between the infarct region and contralateral,and rrADC=rADCnormal-rADC infarction.The phase value was negatively correlated with local cerebral blood flow in the infarct area（r=-0.433,P=0.027）and there was a negative correlation between rrдФ and rrCBF（r=-0.507,P=0.008）.Analysis of rCBF revealed a positive correlation with rADC（r=0.566,P=0.003）,and rrCBF had a positive correlation with rrADC（r=0.478,P=0.013）.However,the phase value was not correlated with the rADC valueof the infarct area（r=-0.293,P=0.146）,and rrдФ did not correlate with rrADC（r=0.381,P=0.055）.The phase value дФ and the rrдФ were positively correlated with the NIHSS score（r=0.567,P=0.001 and r=0.629,P<0.0001）,and the CBF and rrCBF are negatively correlated with the NIHSS score（r=0.402,P=0.028 and r=-0.427,P=0.018）,while ADC and rrADC had no correlation with NIHSS scores（r=-0.240,P=0.201 and r=0.241,P=0.199）.The phase valueдФ of the drainage veins in the ischemic penumbra area was used for the ROC curve analysis to distinguish the recoverable ischemic cerebellar tissue.The AUC under the curve was 0.773.The cutoff point was 301spin,and the sensitivity was 62.5%.The specificity was 66.7%,and the accuracy was 64.5%.The ROC curve analysis of cerebral blood flow CBF in the ischemic penumbra region for the differentiation of the rescued cerebellar ischemic tissue from infarction showed that the AUC was 0.908 and the cutoff point was 22.25 mL/（min·100g）.The sensitivity,specificity and accuracy were 93.8%,66.7%and 80.6%respectively.Conclusion:Infarcted cerebellar hemisphere may have reverse perfusion of drainage veins and venous congestion,which are closely related to the occurrence and development of infarction.We applied a combination of non-invasive imaging parameters including magnetic susceptibility-weighted imaging,cerebral perfusion and diffusionweighted imaging,.It can quantify and evaluate the role and value of cerebellar veins in the diagnosis and treatment of cerebellar infarction so as to provide help for the clinical control of cerebellar infarction and the choice of treatment means.Therefore,it is feasible to take the measurement of cerebellar veins in the diagnosis and treatment of cerebellar infarction.