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Noninvasive monitoring of brain temperature during mild hypothermia
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Radiology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
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2009 (English)In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 27, no 7, 923-932 p.Article in journal (Refereed) Published
Abstract [en]

The main purpose of this study was to verify the feasibility of brain temperature mapping with high-spatial- and reduced-spectral-resolution magnetic resonance spectroscopic imaging (MRSI). A secondary goal was to determine the temperature coefficient of water chemical shift in the brain with and without internal spectral reference. The accuracy of the proposed MRSI method was verified using a water and vegetable oil phantom. Selective decrease of the brain temperature of pigs was induced by intranasal cooling. Temperature reductions between 2 degrees C and 4 degrees C were achieved within 20 min. The relative changes in temperature during the cooling process were monitored using MRSI. The reference temperature was measured with MR-compatible fiber-optic probes. Single-voxel (1)H MRS was used for measurement of absolute brain temperature at baseline and at the end of cooling. The temperature coefficient of the water chemical shift of brain tissue measured by MRSI without internal reference was -0.0192+/-0.0019 ppm/degrees C. The temperature coefficients of the water chemical shift relative to N-acetylaspartate, choline-containing compounds and creatine were -0.0096+/-0.0009, -0.0083+/-0.0007 and -0.0091+/-0.0011 ppm/degrees C, respectively. The results of this study indicate that MRSI with high spatial and reduced spectral resolutions is a reliable tool for monitoring long-term temperature changes in the brain.

Place, publisher, year, edition, pages
2009. Vol. 27, no 7, 923-932 p.
Keyword [en]
Selective brain cooling, Hypothermia, Temperature mapping, Spectroscopy, Spectroscopic imaging
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-113253DOI: 10.1016/j.mri.2009.01.011ISI: 000269613000005PubMedID: 19282122OAI: oai:DiVA.org:uu-113253DiVA: diva2:290272
Available from: 2010-01-26 Created: 2010-01-26 Last updated: 2015-06-08Bibliographically approved
In thesis
1. Intranasal Cooling for Cerebral Hypothermia Treatment
Open this publication in new window or tab >>Intranasal Cooling for Cerebral Hypothermia Treatment
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The controlled lowering of core body temperature to 32°C to 34°C is defined as therapeutic hypothermia (TH). Therapeutic hypothermia has been shown to improve neurological outcome and survival in unconscious patients successfully resuscitated after cardiac arrest. Brain temperature is important for cerebral protection therefore methods for primarily cooling the brain have also been explored.

This thesis focuses on the likelihood that intranasal cooling can induce, maintain and control cerebral hypothermia. The method uses bilaterally introduced intranasal balloons circulated with cold saline.

Selective brain cooling induced with this method was effectively accomplished in pigs with normal circulation while no major disturbances in systemic circulation or physiological variables were recorded. The temperature gradients between brain and body could be maintained for at least six hours.

Intranasal balloon catheters were used for therapeutic hypothermia initiation and maintenance during and after successful resuscitation in pigs. Temperature reduction was also obtained by combined intranasal cooling and intravenous ice-cold fluids with possible additional benefits in terms of physiologic stability after cardiac arrest. Rewarming was possible via the intranasal balloons.

In these studies brain temperature was recorded invasively by temperature probes inserted in the brain. The fast changes in pig’s brain temperature could also be tracked by a non-invasive method. High-spatial resolution magnetic resonance spectroscopic imaging (MRSI) without internal reference showed a good association with direct invasive temperature monitoring. In addition the mapping of temperature changes during brain cooling was also possible.

In awake and unsedated volunteers subjected to intranasal cooling brain temperature changes were followed by two MR techniques. Brain cooling was shown by the previously calibrated high-spatial resolution MRSI and by the phase-mapping method. Intranasal cooling reduced body temperature slightly. The volunteers remained alert during cooling, the physiological parameters stable, and no shivering was reported.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Uppsaliensis, 2010. 58 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 627
Selective brain cooling, cerebral hypothermia, therapeutic hypothermia, cardiac arrest, stroke, traumatic brain injury, brain temperature, magnetic resonance spectroscopy, trigeminal reflex
National Category
Anesthesiology and Intensive Care Radiology, Nuclear Medicine and Medical Imaging
Research subject
Anaesthesiology and Intensive Care
urn:nbn:se:uu:diva-134278 (URN)978-91-554-7959-6 (ISBN)
Public defence
2011-01-14, Rosénsalen, Akademiska Sjukhuset, Uppsala, 13:00 (English)
Available from: 2010-12-21 Created: 2010-11-23 Last updated: 2011-01-13Bibliographically approved

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