Ipsilateral Thalamic Diaschisis After Middle Cerebral Artery Infarction:A Combined DKI And ASL Study

Objective Our aim is to evaluate diaschisis related thalamic perfusion and microstructural tissue alterations and their inter-relationships after unilateral middle cerebral artery（MCA）infarction.Material and methods 87 MRI scans from 85 patients with MCA infarction,consisting of 23 subjects of acute phase（>6h～3d）,34 subjects of subacute phase（3d～7d）and 30subjects of chronic phase（>7d～30d）were included.Qualitative analysis of ITD was defined as ipsilateral thalamic hypoperfusion present on≥2 ASL-CBF maps.Quantitative analysis was performed to measure bilateral thalamic CBF and MK,MD,FA and calculate the asymmetric index（AI）,AI_parameter={(parameter_contra-parameter_ipsi)/parameter_contra}×100%.The infarction volume and the supratentorial perfusion lesion volume were measured.The patients’demographic and clinical features and outcomes were recorded.Results ITD was present in 56（65.9%）patients.In the ITD+group,larger perfusion lesion volume（P=0.003）,higher perfusion-infarct mismatch（P=0.022）and lower rates of focal hyperperfusion（P=0.013）,as well as higher admission and discharge NIHSS and mRS scores（each with P<0.05）were observed.Supratentorial lesions affecting the corona radiata（P=0.001）and basal ganglia（P=0.008）were significantly associated with the occurrence of ITD.Compared with the contralateral side,MK remained elevated within ipsilateral thalamus,in the subacute to chronic phase in ITD+group（P=0.004,P=0.034,respectively）.FA transiently increased and then significantly decreased in ipsilateral thalamus from subacute to chronic phase in all included patients（each with P<0.05）,The MD of the ipsilateral thalamus was significantly increased in chronic phase in all patients（ITD+:P<0.001,ITD-:P=0.050）.There were no significant association between ITD and thalamic diffusion alterations in all phases（P>0.05）.However,in ITD+group,the thalamic AI_CBFwas negatively correlated with AI_MK、AI_FAin subacute phase（MK:R=-0.528,P=0.008;FA:R=-0.442,P=0.040）and AI_MDin chronic phase（R=-0.603,P=0.006）.Additionally,the thalamic AI_CBFsignificantly correlated with admission and discharge neurological status even after partial correction for stroke volume in all patients.Conclusion The combination of ASL and DKI can reveal different,time-specific thalamic perfusion and microstructural changes after MCA infarction.In ipsilateral thalamic diaschisis,the degree of thalamic perfusion reduction significantly correlated with thalamic microstructural changes and neurological status at admission and discharge.