Measurement of regional brain temperature using proton spectroscopic imaging: validation and application to acute ischemic stroke (original) (raw)
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Sensors, 2021
Acute ischemic stroke is characterized by dynamic changes in metabolism and hemodynamics, which can affect brain temperature. We used proton magnetic resonance (MR) spectroscopy under everyday clinical settings to measure brain temperature in seven patients with internal carotid artery occlusion to explore the relationship between lesion temperature and clinical course. Regions of interest were selected in the infarct area and the corresponding contralateral region. Single-voxel MR spectroscopy was performed using the following parameters: 2000-ms repetition time, 144-ms echo time, and 128 excitations. Brain temperature was calculated from the chemical shift between water and N-acetyl aspartate, choline-containing compounds, or creatine phosphate. Within 48 h of onset, compared with the contralateral region temperature, brain temperature in the ischemic lesion was lower in five patients and higher in two patients. Severe brain swelling occurred subsequently in three of the five pati...
Noninvasive Measurement of Brain Temperature after Stroke
BACKGROUND AND PURPOSE: Brain temperature may be an important factor governing the extent of neuronal injury associated with stroke. The goal of this study was to develop a noninvasive method for measuring brain temperature, both to characterize the extent to which temperature changes after stroke and to test protocols designed to reduce brain temperature. We used an animal model to test the ability of 1 H MR spectroscopy to measure temperature from infarcted brain tissue at 24 hours after insult.
Stroke, 2009
Background and Purpose-Brain temperature is determined by the balance between heat produced by cerebral energy turnover and heat removed by cerebral blood flow. The purpose of the present study was to investigate whether brain temperature measured noninvasively using proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with unilateral chronic internal carotid or middle cerebral artery occlusive disease when compared with positron emission tomography. Methods-Brain temperature, cerebral blood flow, and metabolism were measured using proton MR spectroscopy and 15 O-positron emission tomography, respectively, in 21 normal subjects and 37 patients. Positron emission tomography images were coregistered with MR images and resliced automatically using image analysis software. Regions of interest placed in both cerebral hemispheres on MR images were automatically superimposed in these resliced positron emission tomography images. Results-A significant correlation was observed between brain temperature difference (affected hemisphere-contralateral hemisphere) and both cerebral blood volume and oxygen extraction fraction ratio (affected hemisphere/contralateral hemisphere; rϭ0.607; Pϭ0.0004 and rϭ0.631; Pϭ0.0002). With abnormally elevated cerebral blood volume or oxygen extraction fraction ratio defined as higher than the mean ϩ2 SDs obtained from normal subjects, brain temperature difference provided 86% or 92% sensitivity and 87% or 84% specificity with 80% or 73% positive and 91% or 95% negative predictive values for detecting abnormally elevated cerebral blood volume or oxygen extraction fraction ratios, respectively. Conclusions-Brain temperature measured using proton MR spectroscopy can detect cerebral hemodynamic impairment in patients with unilateral chronic major cerebral artery steno-occlusive disease. (Stroke. 2009;40:3012-3016.
NMR in biomedicine, 2016
We examined and compared the temperatures of the intraventricular cerebrospinal fluid (Tv ) and the brain parenchyma (Tp ) using MRI, with reference to the tympanic membrane temperature (Tt ) in healthy subjects. We estimated Tv and Tp values from data gathered simultaneously by MR diffusion-weighted imaging (DWI) and MRS, respectively, in 35 healthy volunteers (17 males, 18 females; age 25-78 years). We also obtained Tt values just before each MR examination to evaluate the relationships among the three temperatures. There were significant positive correlations between Tv and Tp (R = 0.611, p < 0.001). The correlation was also significant after correction for Tt (R = 0.642, p < 0.001). There was no significant correlation between Tv and Tt or between Tp and Tt in the men or the women. Negative correlations were found between Tv and age and between Tp and age in the males but not females. DWI thermometry seems to reflect the intracranial environment as accurately as MRS thermo...
Effect of temperature in focal ischemia of rat brain studied by31P and1H spectroscopic imaging
Magnetic Resonance in Medicine, 1997
P, 'H and lactate spectroscopic imaging was used to evaluate the effects of hypothermia on focal cerebral ischemia produced by middle cerebral artery occlusion. The effects on high energy phosphate metabolism, pH, lactate and NAA were investigated in 24 spontaneously hypertensive rats subjected to either permanent or transient ischemia. Under either normothermic (375°C) or hypothermic (32°C) conditions, with permanent 6-h occlusion, there was little difference between groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfusion, the ischemic changes in lactate, pH, NAA, and high-energy phosphate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 2 26 and 40 2 14 mm3 in normothermic and hypothermic groups, respectively). Thus, hypothermia did not ameliorate the changes in lactate, pH, NAA, or high energy phosphate levels occurring during ischemia, however, during reperfusion there was an improvement in both the recovery of these metabolites and pathological outcome in hypothermic compared with normothermic animals.
Medical Devices: Evidence and Research, 2012
There is overwhelming evidence that hypothermia can improve the outcome of an ischemic stroke. However, the most widely used systemic cooling method could lead to multiple side effects, while the incompatibility with magnetic resonance imaging of the present selective cooling methods highly limit their application in preclinical studies. In this study, we developed a magnetic resonance compatible selective brain temperature manipulation system for small animals, which can regulate brain temperature quickly and accurately for a desired period of time, while maintaining the normal body physiological conditions. This device was utilized to examine the relationship between T1 relaxation, cerebral blood flow, and temperature in brain tissue during magnetic resonance imaging of ischemic stroke. The results showed that this device can be an efficient brain temperature manipulation tool for preclinical studies needing local hypothermic or hyperthermic conditions.
Temperature Changes in the Brain of Patients Undergoing MRI Examination
International Journal of Sciences: Basic and Applied Research, 2013
Magnetic Resonance Imaging scanners have become important tools in modern day health care. During the imaging process, total radiofrequency power is transferred from the RF coil to the brain tissues resulting in increase in temperature in the subject being imaged. Currently, reliable and validated means to predict RF heating are not unavailable.This research was conducted to determine temperature changes in the human brain during MRI examination.This study was carried out at two MRI Units in Ghana. One hundred and twenty-six patients were investigated. Data collected include preand post-scan tympanic temperatures and specific absorption rates values. The average preand post-scan tympanic temperatures measured for Centre A were 36.5±0.1 °C and 37.0±0.1 °C respectively with an average change in temperature of 0.5±0.1 °C for 30.68 minutes scan and an average SAR value of 1.25 W/kg. Centre B measured average preand post-scan tympanic temperatures of 36.4±0.1 °C and 36.8±0.1 °C respectiv...
In Vivo Temperature Measurements in Brain Tumors Using Proton MR Spectroscopy
The chemical shift difference between the water resonance and the methyl resonance of N-acetylaspartate was used to determine the temperature in vivo in forty three patients with histologically proven brain tumors. Temperatures were also estimated from the contralateral side in 15 of these patients. Statistically significant difference (p < 0.05) in temperature was observed between meningiomas and the other tumors viz. low grade astrocytomas, grade IV astrocytomas and oligoastrocytomas. Temperature was also significantly different between the contralateral side and the meningiomas (p < 0.05).
Noninvasive monitoring of brain temperature during mild hypothermia
Magnetic Resonance Imaging, 2009
The main purpose of this study was to verify the feasibility of brain temperature mapping with high-spatial-and reduced-spectralresolution 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°C and 4°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/°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/°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.