Multimodal CT Assessment Of The Impact Of Cerebral Collateral Circulation On Cerebral Perfusion State Of Ischemic Stroke

Objective: To explore the value of Multimodal CT examination on the formation of collateral circulation after cerebral ischemia, as well as the evaluative meaning of cerebral perfusion status and prognosis.Method: 39 patients with ischemic cerebrovascular diseases after 3-day admission were evaluated by multimodal CT examination. Multimodal CT included non-contrast CT, CT perfusion, CT angiography, and post-processing software of Siemens 64-slice spiral CT system was used to evaluate the subjects’ cerebral perfusion state and cranial vessels conditions. NCCT was used to exclude cerebral hemorrhage, brain tumors, etc. CT perfusion was recorded and analyzed hemodynamic parameters(CBF、CBV、MTT and TTP), and then cerebral perfusion status would be evaluated. CT angiography was used to confirm the region and degree of cerebrovascular stenosis, and access collateral circulation compensatory characteristics. All patients had been followed up for clinical prognosis either by phone or by clinic within three months.Result:Among 39 patients, 2 patients were examined as negative by multimodal CT examination, one patient was followed up by MRI-DWI and was clinically proven as transient ischemic attack, the other one was lacunar infarction. Another 37 patients were positive, diagnostic sensitivity was 94.87%, and specificity was 100%. After being examined by multimodal CT, no collateral vessels abnormity beside lesions was found in 13 cases, offending vessels occlusion or stenosis beside lesions was found in 24 cases, among these 24 cases, collateral circulation formation can be checked beside lesions in 11 cases. At the lesions side of these 11 patients, CBF was lowered, CBV was normal or slightly elevated, TTP perfusion was prolonged. In this groups,theparameters of CBF and TTP of lesion side compared with normal side p is less than 0.01, with a significant difference; the parameters of CBV of lesion side compared with normal side p is greater than 0.05, with no significant difference, final infarct was found to be smaller than perfusion disorders in cerebral perfusion parameters after reviewing head CT or head MRI. In another 13 cases, visible bifurcation vessel was no found in offending distal vessel at lesions side, and collateral circulation formation was detective. CBF and CBV obviously were reduced, TTP value was unable to be measured(became black), lesions side was significantly different from offside(P<0.01). Final infarct was found to be same as perfusion disorders in cerebral perfusion parameters after imaging follow-up. After 3-month follow-up, patients who forms collateral circulation got favorable prognosis.Conclusion: 1. Multimodal CT can clearly shows occlusion or stenosis artery and the formation of collateral circulation. 2. Multimodal CT can evaluate perfusion status, TTP can be the assessment criteria of collateral circulation. There are some clinical significances for Multimodal CT examination in evaluating cerebral perfusion status, understanding the establishment condition of cerebral collateral circulation, and determining clinical prognosis.