Symptomatic M1 stenosis of middle cerebral artery: the correlation between stenosis ratio and CT perfusion / 中华神经科杂志

ABSTRACT

Objective To quantitatively analyze the correlation between stenosis ratio and cerebral perfusion in patients with solely symptomatic M1 stenosis of middle cerebral artery.Methods All the patients with solely symptomatic M1 stenosis of middle cerebral artery were selected to this study from consecutive 203 patients with elective stenting of symptomatic intracranial artery stenosis.Brain CT, CT perfusion (CTP) and DSA examinations were performed in all cases.The CTP parameters of mean transit time (MTT), cerebral blood flow (CBF) and cerebral blood volume (CBV) were measured in regions of interest (ROIs) including bilateral frontal lobe, anterior watershed, opercula of the insula (including parsopercluaris and part of insula), temporal lobe, posterior watershed and occipital lobe.Compared with the unaffected side as control, the change of CTP and their relative CTP parameters in these ROIs at affected side were analyzed.Based on DSA data, the ratio of M1 stenosis was measured manually and blindly, the source of collateral branch of compensative artery was estimated and the blood flow was graded.Correlation between the ratio of M1 stenosis and the CTP parameters including the absolute and the relative values was investigated.Results Twenty patients were selected into this study; their average M1 stenosis ration of the affected side was 70.5% ± 10.6% (53% to 91%).Compared with the unaffected side, MTT and CBF were no significant change but CBV increased in the affected frontal lobe; MTT prolonged, CBF was normal and CBV increased in the affected anterior watershed and opercula of the insula; MTT prolonged, CBF and CBV had no significant difference in the affected temporal lobe; MTT prolonged, CBF decreased and CBV had no significant difference in the affected posterior watershed; MTT, CBF and CBV were normal in occipital lobe.Tissue perfusion gradually decreased from the front to the backward in all the M1 stenosis affected cerebral regions and the posterior watershed area was the only region at hemodynamic failure stage.Leptomeningeal vessels of the anterior cerebral artery were the major sources of compensative arteries shown in the DSA in all cases.The ratio of M1 stenosis was positively correlated (r =0.66, P =0.002) with the rCBV in posterior watershed and there is no significant correlation between the ratio and any other CTP parameters in any regions.Conclusions Associated with distribution of collateral compensative artery,tissue perfusion showed obvious spatial distribution at different level in different cerebral region.M1 stenosis ratio is positively correlated with rCBV in hemodynamic failure regions, and there is no correlation with tissue perfusion in hemodynamic compromise regions.