Using diffusion MRI for measuring the temperature of cerebrospinal fluid within the lateral ventricles

AIM: Hypothermia is often induced to reduce brain injury in newborns, following perinatal hypoxic–ischaemic events, and in adults following traumatic brain injury, stroke or cardiac arrest. We aimed to devise a method, based on diffusion-weighted MRI, to measure non-invasively the temperature of the cerebrospinal fluid in the lateral ventricles. METHODS: The well-known temperature dependence of the water diffusion constant was used for the estimation of temperature. We carried out diffusion MRI measurements on a 3T Philips Achieva Scanner involving phantoms (filled with water or artificial cerebrospinal fluid while slowly cooling from 41 to 32°C) and healthy adult volunteers. RESULTS: The estimated temperature of water phantoms followed that measured using a mercury thermometer, but the estimates for artificial cerebrospinal fluid were 1.04°C lower. After correcting for this systematic difference, the estimated temperature within the lateral ventricles of volunteers was 39.9°C. Using diffusion directions less sensitive to cerebrospinal fluid flow, it was 37.7°C, which was in agreement with the literature. CONCLUSION: Although further improvements are needed, measuring the temperature within the lateral ventricles using diffusion MRI is a viable method that may be useful for clinical applications. We introduced the method, identified sources of error and offered remedies for each.