Abstract
Acute stroke is a serious cerebrovascular disease and has been the second leading cause of death worldwide. Conventional diagnostic modalities for stroke, such as CT and MRI, may not be available in emergency settings. Hence, it is imperative to develop a portable tool to diagnose stroke in a timely manner. Since there are differences in impedance spectra between normal, hemorrhagic and ischemic brain tissues, multi-frequency electrical impedance tomography (MFEIT) shows great promise in detecting stroke. Measuring the impedance spectra of healthy, hemorrhagic and ischemic brain in vivo is crucial to the success of MFEIT. To our knowledge, no research has established hemorrhagic and ischemic brain models in the same animal and comprehensively measured the in vivo impedance spectra of healthy, hemorrhagic and ischemic brain within 10 Hz–1 MHz. In this study, the intracerebral hemorrhage and ischemic models were established in rabbits, and then the impedance spectra of healthy, hemorrhagic and ischemic brain were measured in vivo and compared. The results demonstrated that the impedance spectra differed significantly between healthy and stroke-affected brain (i.e., hemorrhagic or ischemic brain). Moreover, the rate of change in brain impedance following hemorrhagic and ischemic stroke with regard to frequency was distinct. These findings further validate the feasibility of using MFEIT to detect stroke and differentiate stroke types, and provide data supporting for future research.
Highlights
Acute stroke, a serious and acute cerebrovascular disease, is classified into two clinical types:(1) hemorrhagic stroke, caused by blood bleeding into the brain tissue or the subarachnoid space through a ruptured intracranial vessel, which accounts for 13% of all stroke cases; and (2) ischemic stroke, caused by vascular occlusion in the brain due to a blood clot, which accounts for87% of all stroke cases [1]
The intracerebral hemorrhage and ischemic models were established in rabbits, and the impedance spectra of healthy, hemorrhagic and ischemic brain were measured in vivo from 10 Hz to 1 MHz
The difference imaginary part differed significantly between the hemorrhage group and its control (p < 0.05). These results indicated that brain impedance spectra changed significantly following hemorrhagic stroke
Summary
(1) hemorrhagic stroke, caused by blood bleeding into the brain tissue or the subarachnoid space through a ruptured intracranial vessel, which accounts for 13% of all stroke cases; and (2) ischemic stroke, caused by vascular occlusion in the brain due to a blood clot (thrombosis), which accounts for. 87% of all stroke cases [1]. Stroke is characterized by sudden onset and high mortality and has been the second leading cause of death worldwide [2]. Prompt intervention improves the prognosis of stroke patients. Distinct interventions are needed for each stroke subtype. Hemorrhagic stroke patients require prompt surgical intervention, while ischemic stroke patients need thrombolytic therapy with tissue plasminogen activator within 3–4.5 h after the onset of stroke [3]. Stroke should be Sensors 2017, 17, 791; doi:10.3390/s17040791 www.mdpi.com/journal/sensors
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