Non-invasive Brain Temperature Measurement in Acute Ischemic Stroke

Abstract

Selective therapeutic hypothermia in the setting of mechanical thrombectomy (MT) is promising to further improve the outcomes of large vessel occlusion stroke. A significant limitation in applying hypothermia in this setting is the lack of real-time non-invasive brain temperature monitoring mechanism. Non-invasive brain temperature monitoring would provide important information regarding the brain temperature changes during cooling, and the factors that might influence any fluctuations. This review aims to provide appraisal of brain temperature changes during stroke, and the currently available non-invasive modalities of brain temperature measurement that have been developed and tested over the past 20 years. We cover modalities including magnetic resonance spectroscopy imaging (MRSI), radiometric thermometry, and microwave radiometry, and the evidence for their accuracy from human and animal studies. We also evaluate the feasibility of using these modalities in the acute stroke setting and potential ways for incorporating brain temperature monitoring in the stroke workflow.

Keywords: acute stroke; hypothermia; magnetic resonance spectroscopy or MRS; non-invasive temperature measurement; non-invasive temperature monitoring.

Figure 1

Brain regions downstream from an acute arterial occlusion. Following a cerebral arterial occlusion, the downstream brain territory evolves into an area of irreversible infarction (core), an ischemic area that is potentially salvageable if timely recanalization is achieved, and areas of somewhat reduced blood flow that can withstand ischemia even if recanalization is not achieved (benign oligemia). (Reprinted from Goyal et al. (42). Copyright (2013) by Radiology. Reprinted with permission).

Figure 2

3M™ Bair Hugger™. Temperature sensors are applied to the patient's forehead.