Analysis of changes of cerebral perfusion in surrounding brain parenchyma after aneurismal subarachnoid hemorrhage

Abstract

Objective To study cerebral perfusion in surroundin gbrain parenchyma within 24 hours and 6-8 days after aneurysmal subarachnoid hemorrhage (aSAH) by CT perfusion imaging,to explore the applied value of CT perfusion imaging in predicting delayed cerebral ischemia (DCI).Methods Imaging data of 32 consecutive aSAH patients of our hospital during December 2011 to December 2012 were retrospectively reviewed.All patients underwent non-contrast CT,CT angiography (CTA) and CT perfusion (CTP) imaging within 24 hours of onset.6-8 days after SAH,only non-contrast CT and CTP could be performed.The perfusion parameters values in hypoperfusion area or surrounding brain parenchyma of SAH and the mirror parenchyma were measured for the first and follow-up CTP,including cerebral blood flow (CBF),cerebral blood volume (CBV),mean transit time (MTT).To calculate the ratio of the two parts to get the relative cerebral blood flow(rCBF),relative cerebral blood volume (rCBV) and relative mean transit time (rMTT).According to presence of DCI,32 patients were divided into DCI group (8 patients) and no-DCI group(24 patients).The differences of rCBF、rCBV and rMTT of the two examination between the two group were compared with independent-sample t test.Results For the DCI group,rCBF was 1.0 ± 0.3、rCBV was 1.1 ±0.5 and rMTT was 1.1 ±0.2 in the first CTP,rCBF was 0.7 ±0.2、rCBV was 0.9 ±0.2 and rMTT was 1.5 ±0.3 in the follow-up CTP.For the no-DCI group,rCBF was0.9 ±0.3 、rCBV was 1.0 ±0.2 and rMTT was1.1 ±0.2 in the first CTP,rCBF was 0.9 ±0.2、rCBV was 0.9 ±0.2 and rMTT was 1.1 ± 0.2 in the follow-up CTP.Compared with the first CTP,there was lower rCBF、stable rCBV and higher rMTT in the follow-up CTP for the DCI group.Although perfusion was improved in some patients,but there were no significant changes overall for the rCBF、rCBV and rMTT for the twice CTP.There was significant statistical difference in the differences of rCBF and rMTT of the two examination between the two group (t rCBF =2.659,P rCBF =0.012 ; t rMTT =--3.747,P rCBF =0.001).But there were no significant statistical difference in rCBV of the two examination between the two group (t rCBv =1.031,P rCBF =0.311).Conclusion The CTP parameters of rCBF and rMTT has higher sensitivity and is important to predict the occurrnce of the DCI. Key words: Subarachnoid hemorrhage ; Tomography,X-ray compated ; Perfusion ; Delayed cerebral ischemia