title: Acute ischaemic stroke-multimodal imaging and stroke outcomes
Creators: name: Cheripelli, Bharath kumar
Publisher: name: University of Glasgow
Year: 2020
Subjects: subject: Ischaemic stroke, acute stroke, imaging, stroke outcomes.

description: Introduction: Acute stroke Imaging plays a crucial role in understanding the cerebral tissue states and multimodal imaging with perfusion, collaterals and vessel occlusion provides more information on tissue dynamics in individual patient which can be useful for tailored treatments and prognosis. Perfusion parameters and their validation are important in achieving clinical practicality. A novel tissue parameter, Capillary transit time heterogeneity has been suggested to identify micro vascular flow patterns. The clinical utility of this is not yet established. Stroke outcome is dependant not only on the imaging parameters but also on patient demographics, co morbidities and probably on complex socio-economic and other unidentified patient factors. Methods: Using a database of single centre multi modal imaging I derived perfusion metrics in commercial software (MIstar). I conducted a few different analyses on: penumbra relationship with time, collaterals; haemorrhage, oedema relationship with recanalisation; Safety in Stroke Thrombolysis (SITS) registry Stroke outcomes; Deriving a new perfusion parameter called ‘Capillary transit time heterogeneity (CTTH)’ and comparing the values in different tissue compartments. Results: In a cross-sectional sample imaged within 6h, neither the proportions of penumbral tissue nor “target mismatch” varied by time from onset. A trend for reducing penumbra proportion only among those with poor collaterals may have pathophysiological and therapeutic importance. Among patients treated with IV thrombolysis, 24h recanalisation was not independently associated with significant early (24h) vasogenic oedema or significant haemorrhage, although incidence of HI/HI2 ICH was higher. Large ischaemic core was associated with both significant brain oedema and poor outcome. There was no interaction of recanalisation and large core lesions for any imaging outcomes. Early major clinical improvement as a marker of probable early reperfusion was associated with lower incidence of both significant haemorrhage and oedema. In SITS registry study, poorer 90 day outcomes after IV thrombolysis occurred frequently at a hospital (Southern General Hospital) that accepted secondary transfer patients compared to a hospital in the same city (Western Infirmary Glasgow) that did not routinely take such patients. Capillary transit time heterogeneity (CTTH) voxel wise maps were derived successfully using “vascular model” in Brain Lab, Arhus, Denmark. The CTTH values are closely related with MTT. There is no significant difference of CTTH between Core, penumbra. Conclusion: Multimodal imaging can provide us with valuable information on understanding ischemic brain tissue, predict patient outcomes in stroke. Patient imaging and clinical outcomes depend on recanalisation, and patient factors. A novel perfusion parameter, CTTH has been successfully derived and its utility and validity is yet to be evaluated.