Feasibility of Internally Referenced Brain Temperature Imaging with a Metabolite Signal

BACKGROUND AND PURPOSE:Therapeutic hypothermia is the current treatment for neonates with hypoxic-ischemic encephalopathy. It is believed to work by decreasing the brain temperature and reducing the baseline metabolism and energy demand of the brain. This study aimed to noninvasively assess brain temperature during the first month of life in neonates with hypoxic-ischemic encephalopathy treated with hypothermia.

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“…Then, for each scan, brain temperature was estimated with a previously described calibration equation. 30 …”

Section: Temperature Measurements In Neonatesmentioning

confidence: 99%

Brain Temperature Is Increased During the First Days of Life in Asphyxiated Newborns: Developing Brain Injury Despite Hypothermia Treatment

Owji

Gilbert

Saint‐Martin

et al. 2017

AJNR Am J Neuroradiol

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“…The technique was applied to breast imaging using the lipid signal as a reference 75 and to brain imaging using the NAA signal as a reference. 55 In experiments at 3.0 T, temperature distributions in a rabbit brain following laser heating were monitored. 55 The signal acquisition time per 32 voxel column in the brain experiment was 66 s with a 2 s sequence repetition period (TR), for a pair of nonsuppressed and water-suppressed scans.…”

Section: Comparison Of the Acquisition Techniquesmentioning

confidence: 99%

“…55 In experiments at 3.0 T, temperature distributions in a rabbit brain following laser heating were monitored. 55 The signal acquisition time per 32 voxel column in the brain experiment was 66 s with a 2 s sequence repetition period (TR), for a pair of nonsuppressed and water-suppressed scans. The EPSI Figure 2.…”

Section: Comparison Of the Acquisition Techniquesmentioning

confidence: 99%

Temperature Monitoring Using Chemical Shift

Kuroda

2016

eMagRes

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Methodologies in MRS provide noninvasive thermometry with a number of temperature-dependent MR parameters. Among these, the most representative is the proton chemical shift of the hydroxyl group. The electronic shielding effect of protons in this group changes linearly with temperature owing to intermolecular hydrogen bonding. Internally referenced measurements of the chemical shift difference between water and the protons in methyl or ethyl groups, whose frequencies are temperature insensitive, can provide precise measures of temperature. The proton chemical shift differences between water and N-acetylaspartate, creatine, choline, and the methylene chain in fat, or the relative change of the water proton chemical shift, may be used to monitor temperature in biological tissues. However, factors such as bulk susceptibility, electrolytes, pH, and macromolecules also affect chemical shifts in tissues. Although the internal reference technique can reduce the susceptibility effect, the bond-breaking effect of electrolytes can alter the absolute value, as well as the temperature coefficient of the chemical shift. Thus, absolute temperature monitoring in vivo has not been achieved to date. Nevertheless, monitoring relative temperature differences is useful. Alternative methodologies for MRS temperature monitoring include the use of proton chemical shifts in lanthanide complexes, chemical exchange saturation transfer agents, nonproton nuclei, spectroscopic T 1 measurements, and quantum coherence.

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“…In our experiments using fat proton as the internal reference for skeletal muscle extracted from mice, the coefficient was À0.00853 ppm/ C [50]. For rabbit brain in vivo with NAA as the internal reference, temperature coefficient was À0.0097 [51].…”

Section: Temperature Dependence In Biological Tissuesmentioning

confidence: 99%

“…They applied the technique to breast imaging with the lipid signal as a reference [83] and brain imaging with the NAA signal as a reference [51]. In experiments using a 3.0 T scanner, temperature distributions in a rabbit brain under laser heating was visualized [51].…”

Section: Spectroscopy and Spectroscopic Imagingmentioning

confidence: 99%

Noninvasive Temperature Monitoring

Kuroda

2016

Hyperthermic Oncology From Bench to Bedside

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Noninvasive thermometry of target tissue is one of the key issues for successful and safe thermal therapy. Although various techniques using X-ray, infrared, photoacoustics, radiometry, impedance, ultrasound, and magnetic resonance imaging (MRI) have been investigated, to date, infrared imaging for skin surface or MRI for cross-sectional temperature distribution is accepted as a tool for clinical use. Since cross-sectional temperature distribution deep inside a human body is important in thermal therapy in general, practically, MRI is the only practical modality applicable for the therapies. Among several intrinsic MR parameters including proton density, spin-lattice relaxation time, spin-spin relaxation time, diffusion coefficient and chemical shift, the chemical shift is known to be the most reliable for temperature imaging in aqueous tissues. Because this parameter can be measured only from the resonance frequency of water protons and hence independent from the other parameters, which are measured based on the intensity of the MR signals. Phase mapping or spectroscopic technique are applicable for measuring and/or imaging distribution of temperature change. For adipose tissue spin-lattice relaxation time of fat may be used.

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Feasibility of Internally Referenced Brain Temperature Imaging with a Metabolite Signal

Cited by 43 publications

References 21 publications

Brain Temperature Is Increased During the First Days of Life in Asphyxiated Newborns: Developing Brain Injury Despite Hypothermia Treatment

Brain Temperature Is Increased During the First Days of Life in Asphyxiated Newborns: Developing Brain Injury Despite Hypothermia Treatment

Temperature Monitoring Using Chemical Shift

Noninvasive Temperature Monitoring

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