Real-time Mr Imaging-guided Interventional Treatment Of Cerebrovascular Disease Animal Studies

Background:For interventional neurovascular procedures,real-time magneticresonance imaging(rtMRI)guidance has many advantages overconventional x-ray angiography guidance.In the past few years,the rapidadvances of MR imaging techniques have offered a possibility whichinterventional neurovascular procedures can be done under the real-timeMR imaging guidance.Thus,we carried out preliminary animal studies toinvestigate the feasibility of performing interventional neurovascularprocedures with real-time MR imaging guidance.PartⅠ:Catheterization of Cerebral arteries and Intra-arterial Thrombolysiswith Real-time MR Imaging Guidance in PigsPurpose:To investigate the feasibility of catheterization of cerebral arteries andintra-arterial thrombolysis with real-time MR imaging guidance in pigs.Material and methods:There were 10 U.S.A domestic female pigs studied.After obtainingaccess to femoral arteries using percutaneous technique,real-time MRI guided transfemoral catheterization of the carotid arteries was performed.Bilateral ascending pharyngeal arteries were catheterised with 3F activeMR-tracking microcatheter.Aged thrombi were injected to occlude these vessels.Following aperiod of 30-60 minutes,500,000-750,000 units of urokinase was infusedeither into one of the occluded ascending pharyngeal arteries forthrombolysis.IA contrast enhanced MRA and T1 fat suppressed coronalimages were obtained to assess vessel occlusion and thrombolysis.Gross pathologic examination was performed in aortic arches,brachio-cephalic arteries,carotid arteries and ascending pharyngealarteries to look for perforation and dissection.Results:MR angiography depicted that the ascending pharyngeal arteries forman arteriolar network,the rete mirabile,which provides the major cerebralblood supply in pigs.Catheterization of ascending pharyngeal arteries from the femoralartery access point was successfully performed in 10 pigs with real-timeMR imaging guidance.It took 4-12mins to accomplish eachcatheterization.All the ascending pharyngeal arteries were totally occluded afterinjection of aged thromboli.After urokinase infusion into the ascendingpharyngeal arteries,the blood clots were resolved with re-established blood flow.There was no evidence of vascular injury on gross examination ofnecropsy specimens.Conclusions:It is feasible to perform catheterization of cerebral arteries andintra-arterial thrombolyis in a swine model under real-time guidance.PartⅡ:Acute global cerebral ischemia and reperfusion injury and treatedwith conditioned blood reperfusion in pigsPurpose:To study the feasibility of making a pig model on acutenormothermic global cerebral ischemia and reperfusion injury underreal-time MR imaging guidance,and to assess the feasibility and theefficiency of controlled reperfusion using leukodepleted arterial blood intreatment of cerebral ischemia and reperfusion injury.Material and methods:There were 24 U.S.A domestic pigs studied.After catheterization ofthese vessels from the femoral and axillary artery access point under real-time MR imaging guidance,the bilateral common carotid arteriesand left subclavian artery occlusion were performed with ballooncatheters,allowing 30 mins of temporary occlusion.The cerebral bloodflow(CBF)was measured using MR perfusion weighted imaging(PWI).The COBRA filter conditioned the arterial blood by removingleukocytes,platelets and complement.At the start of reperfusion,12 pigswere given 10 mins of conditioned blood reperfusion with this controlledarterial blood.The other 12 pigs underwent normal reperfusion withdirect restoration of blood circulation.Biochemical analysis was done with jugular venous samples.Neurologic deficit scoring was conducted for neurologic assessment.Results:Compared with the CBF during reperfusion,the CBF after cerebralischemia was significantly decreased in both groups(P＜0.05).After cerebral ischemia,the conjugated dienes,Creatinine kinase andendothelin-1 release were increased in both groups.Compared with thisof controlled group,the level of biochemicals was significantly lower intherapy group after reperfusion.Aft 24 hrs of reperfusion,animals with normal blood reperfusion weresignificantly neurologically impaired(neurologic score 152.25±30.88),while pigs in therapy group had only minor neurologicdeficits(neurologic score39.25±-14.35).There was a statistical difference in neuorlogic score between both groups(P＜0.05).Conclusions:Under real-time MR imaging guidance,the occlusion of bilateralcommon carotid arteries and left sublavian artery using balloon catheterscan successfully create a model of acute global cerebral ischemia andreperfusion injury in pigs.The neurological damage can be significantlylimited by conditioned blood reperfusion therapy using controlled blooddevoid of leukocytes,platelets and complement during the initial periodof reperfusion.