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PubMed2001

Effects of abstinence on the brain: quantitative magnetic resonance imaging and magnetic resonance spectroscopic imaging in chronic alcohol abuse.

BACKGROUND: Structural brain damage, especially to white matter, is well documented in chronic alcohol abuse. There is also evidence for brain metabolic abnormalities in this condition. It is unknown, however, to what extent these structural and metabolic changes are present in treated alcohol abusers who achieve long-term abstinence versus treatment-naïve, heavily drinking individuals. METHODS: This study compared 12 recovering alcoholics with 8 actively heavily drinking subjects. Participants underwent magnetic resonance (MR) imaging and proton MR spectroscopic imaging of the brain. Semiautomated image segmentation techniques yielded volumes for gray matter, white matter, white matter lesions, and cerebral spinal fluid in multiple brain regions defined by Talairach stereotaxic coordinates. Automated spectral processing methods yielded gray and white matter concentrations of the metabolites N-acetylaspartate, creatine, and choline for the same regions. RESULTS: Recovering alcoholics had greater volumes of frontal white matter, but the opposite was true for white matter in a "remainder" region encompassing the basal frontal and temporal lobes, the cerebellum, and the brainstem. Recovering alcoholics also had smaller volumes of white matter lesions in whole brain, in occipital and mesial parietal regions, and in the remainder region. Recovering alcoholics had greater gray matter volumes in the orbital frontal pole and postcentral gyrus, but smaller gray matter volumes in the anterior cingulate. Whole-brain and regional metabolite concentrations did not differ significantly between the two groups. CONCLUSIONS: White and gray matter volumes in different regions of the brain were greater or smaller in recovering, treated alcoholics. The findings suggest region-specific structural recovery from chronic alcohol-induced brain injury, but also region-specific long-term structural damage in abstinent alcoholics. White matter lesions were widespread in active drinkers and may partly resolve during long-term abstinence. Proton MR spectroscopic measures, as applied in this cross-sectional study, were largely ineffective in revealing metabolic effects of abstinence on the alcohol-damaged brain.

Adult↗

PubMed1992

Magnetic resonance imaging and 31P magnetic resonance spectroscopy study of the effect of temperature on ischemic brain injury.

Transient forebrain ischemia was induced in rats whose brain temperature was 31, 33, 35, 38, or 40 degrees C. The development of regional injury was followed using magnetic resonance (MR) imaging, with the ultimate extent of neuronal injury quantified histopathologically. Animals in the hypothermic groups showed minimal changes in MR images over 4 days; normothermic animals showed intensity enhancement attributed to progressive edema developing in the striatum and, later, in the hippocampus. Ischemia at 40 degrees C resulted in widespread edema formation by 1 day post-ischemia; animals in this group did not survive beyond 30 hours. Histopathological analysis at 4 days (1 day for the hyperthermic group) post-ischemia showed that neuronal damage in the normothermic group was confined to the hippocampus and striatum. Minimal damage was found in the hypothermic groups; damage in the hyperthermic group was severe throughout the forebrain. There were no differences in the pre-ischemia 31P MR spectra for the different groups. During ischemia, the increase in intensity of the Pi peak and the fall in tissue pH increased with temperature in the order hypothermic less than normothermic less than hyperthermic group of animals. Post-ischemia energy recovery was similar in all groups, while pH recovered more rapidly in hypothermic animals.

Animals↗

PubMed2005

Manganese dipyridoxyl diphosphate (MnDPDP)-enhanced magnetic resonance imaging of acute reperfused myocardial injury in a cat model: part II: comparison with cine magnetic resonance imaging.

RATIONALE AND OBJECTIVES: To compare manganese dipyridoxyl diphosphate (MnDPDP)-enhanced magnetic resonance imaging (MRI) with cine MRI for distinguishing the dysfunctional myocardium from the normal myocardium. MATERIALS AND METHODS: Seventeen cats were prepared for acute myocardial infarction with 90 minutes of occlusion followed by 120 minutes of reperfusion. In vivo inversion-recovery gradient-recalled echo MRI and cine MRI were performed. Two radiologists independently analyzed the MR images and recorded the size of the unenhanced area on the MnDPDP-enhanced MR images as well as that of the dysfunctional area on the cine MR images. Agreement between these abnormal areas was evaluated using Bland-Altman analysis. Interobserver agreement was assessed using Bland-Altman analysis. RESULTS: The sizes of the unenhanced area on the MnDPDP-enhanced MR images and the dysfunctional area on the cine MR images showed good agreement on Bland-Altman analysis (the limits of agreement: observer 1= 1.8% +/- 11.6, observer 2 = 0.1% +/- 9.9). The abnormal segments on both types of MR imaging showed a good interobserver agreement (the limits of agreement: MnDPDP-enhanced MRI = 0.3% +/- 7.6, cine MRI = -1.4% +/- 10.9). CONCLUSION: The size of the dysfunctional area on the cine MR images was well correlated with that of the unenhanced area on the MnDPDP-enhanced MR images.

Acute Disease↗

PubMed2005

[Magnetic resonance of magnetically ordered nanoscale particles in brain tissue].

Nature of unusual resonance signals, which can be registered by spectrometers of electron paramagnetic resonance, are studied in different weakly mineralized biological tissues. The experiments are carried out in a three-centimeter range of waves on human and animal (rats) brain tissues and on the organic component of mollusk shells. In these materials the unusual resonance signals, which have unique dynamic characteristics, are registered. Analysis of the characteristics of the anomalous signals shows that the signals are produced by magnetically ordered particles, which have dimensions in nanoscale range. On the basis of experimental data the conclusions are made, that as a result of biomineralization processes in brain tissues both physiological and pathological mineral particles are formed. The supposition is made, that physiological particles play the important role in operation of a brain, and pathological can be a causes of brain diseases.

Animals↗

PubMed1993

[Nuclear spin tomography, magnetic resonance tomography (MRT), nuclear magnetic resonance imaging (NMR). Technical and methodical hypotheses for the use of nuclear spin tomography on the hip joint of the dog].

The theoretical principles of nuclear magnetic resonance imaging and its application in human medicine are described. The most important parameters to produce informative images are explained. The tomographic examination of the canine hip joints demands a precise choice of section planes and measuring parameters. The resulting images of the hip joints of eight beagle puppies are evaluated and discussed.

Animals↗

PubMed1996

[Three-dimensional reconstructed magnetic resonance imaging for diagnosing persistent left superior vena cava: comparison with magnetic resonance angiography and plain chest radiography].

The usefulness of low-cost, three-dimensional (3D) images reconstructed from magnetic resonance (MR) imaging for investigating persistent left superior vena cava was assessed and compared to the diagnostic accuracy of chest radiography. MR imaging by the spin-echo technique and MR angiography were performed in 10 patients with this anomaly diagnosed previously by contrast echocardiography and radionuclide angiocardiography. Four patients had complicating cardiac anomalies, one with postoperative atrial septal defect, one with postoperative ventricular septal defect, one with atrial septal defect and partial anomalous pulmonary venous return, and one with aortic coarctation and patent ductus arteriosus. Multisectional and multiphasic MR images were used for the 3D-reconstruction of the cardiovascular and mediastinal structures with a NeXT workstation and a 3D-kit. The 3D-reconstructed MR imaging clearly showed the persistent left superior vena cava and the anatomical relationship with the other cardiovascular and mediastinal structures in all 10 patients. Vascular shadows were observed outside the upper left border of the aortic arch on the chest radiographs in seven patients, and the 3D-reconstructed MR images revealed these shadows to be compatible with superior caval vein. The ratios of the diameter between the left and right superior venae cavae with and without the left innominate vein were 0.63 +/- 0.14 (mean +/- SD) and 0.94 +/- 0.08, respectively. Three-dimensional reconstructed MR imaging is a useful method for recognizing persistent left superior vena cava and precise examination of the chest radiographs often allowed detection of the vascular shadows caused by this anomaly.

Adolescent↗

PubMed1997

[Magnetic resonance tomography and magnetic resonance phlebography in studies of the brain in patients with severe arterial hypertension].

MR tomography of the brain, MR angiography of extra- and intracranial arteries and veins, duplex scanning of the extracranial arteries and veins were performed according to the technique spin-echo, by the technique 2D, 3D time-to-flight (unit "Magnetom 63 SP", 1.5 T), Acuson 128 technique, respectively, in 21 patients with high and malignant blood hypertension (BH) and 11 healthy controls. In BH patients magnetic resonance has detected signs of hypertensive encephalopathy: dilation of the liquor-conduction system, small hyperintensive foci in the white substance, zones of periventricular hyperintensity. MR angiograms visualized flexures of the extracranial arteries. MR phlebograms were characterized: 1) reduction of or absence of the signal from the blood flow along the cross, sigmoid sinus and internal jugular vein of the hemisphere associated with enlargement of the contralateral structures; 2) lowering of the signal intensity from the blood flow along the upper sagittal sinus; 3) dilation of the emission veins and superficial cerebral veins. These abnormalities should be considered in the treatment of BH.

Acute Disease↗

PubMed2001

Magnetic resonance imaging and magnetic resonance sialography of parotid glands in primary Sjogren's syndrome.

OBJECTIVE: To look for structural parotid gland changes on magnetic resonance (MR) imaging and MR sialography of primary Sjögren's syndrome (SS) patients and healthy control subjects and to compare these methods with each other. METHODS: MR imaging and MR sialography of both parotid glands were performed on 26 patients and 7 healthy controls. Bilateral surface coils were used to obtain high spatial resolution. RESULTS: Twenty-two of the 26 patients had abnormalities on MR imaging. Twenty-one had a nodular or dendritic parenchymal pattern, 5 had cavities, and 6 had duct dilatations. On MR sialography, 25 of the 26 patients had abnormalities of the ducts, and 16 of them also had cavities. One patient and all 7 controls had normal results with both methods. The structural appearance of the parotid glands on MR images had marginal linear association with the duct system changes but no correlation with the cavitary changes seen on MR sialography. Furthermore, duct system abnormalities did not correlate with cavitary changes. Both parenchymal and sialographic abnormalities were associated with the presence of Ro/SSA antibodies but not with age of the patient, disease duration, salivary flow rate, or the presence of hypergammaglobulinemia or extraglandular manifestations. CONCLUSION: MR imaging and MR sialography are noninvasive methods that provide definitive information of morphologic changes in parotid glands and can be used as diagnostic indicators of primary SS. Because these methods give information on different aspects of glandular pathology, both should be performed when evaluating parotid glands of SS patients. MR sialography is more sensitive, but conventional MR imaging gives complementary information on the progressive pathologic changes of glandular parenchyma.

Adult↗

PubMed1992

Hemifacial spasm: evaluation by magnetic resonance imaging and magnetic resonance tomographic angiography.

We evaluated 37 patients with hemifacial spasm and 16 age-matched control patients with other neurological disorders using magnetic resonance (MR) imaging, MR angiography, and MR tomographic angiography. MR tomographic angiography is a new technique using computer reconstruction of MR angiographic images to create coronal angiotomes that display tissue and arterial structures on the same image. Twenty-four of 37 (64.9%) patients with hemifacial spasm had ipsilateral vascular compression of cranial nerve VII or the pons noted by this technique, whereas only 1 of 16 (6.3%) control patients had compression. MR imaging and MR angiography were less sensitive and less specific in evaluating for vascular compression. This study supports vascular compression of cranial nerve VII or the pons as a cause of hemifacial spasm, and demonstrates MR tomographic angiography's value as an excellent, noninvasive technique to demonstrate the compression.

Adult↗

PubMed2003

Computerized measurement of magnetic resonance imaging erosion volumes in patients with rheumatoid arthritis: a comparison with existing magnetic resonance imaging scoring systems and standard clinical outcome measures.

OBJECTIVE: One of the major aims of therapy in rheumatoid arthritis (RA) is to prevent erosive disease and subsequent disability. One of the important goals of therapy assessment must therefore be the accurate measurement of damage progression. We undertook this study to assess the feasibility, reliability, and validity of measuring magnetic resonance imaging (MRI) erosion volumes and synovial volumes in the wrists of RA patients with the use of a semiautomated computerized method. METHODS: Twelve subjects with seropositive RA were chosen to reflect a spectrum of RA severity as determined by the clinical Joint Alignment and Motion (JAM) Scale. MRI of the dominant wrist was performed at the same time of day at baseline and at 48 hours. Images were transferred to a workstation. Erosion volumes and synovial volumes were measured on the coronal images using OSIRIS imaging software. All images were reread in random order at 72 hours by 1 observer. The results were compared with erosion scores and global synovitis scores obtained by the same observer using the Outcome Measures in Rheumatology Clinical Trials MRI RA scoring system. Radiographs were performed at baseline and were read on 2 occasions by 1 observer using the Scott modification of the Larsen method. RESULTS: Total erosion volume per subject ranged from 0 cm(3) to 4.7 cm(3). The total synovial membrane volume per subject ranged from 0.1 mm(3) to 12.1 cm(3). Intraclass correlation coefficients for erosion volumes and synovial volumes demonstrated excellent intraobserver reliability and interoccasion reliability. There was a strong positive correlation between the total erosion volume and the total erosion score. The correlation between the synovial volumes and synovitis score was less favorable (r = 0.53-0.86). Positive correlations were demonstrated between the erosion volumes, the JAM score, and the modified Larsen scores. No significant correlation was demonstrated between the erythrocyte sedimentation rate, C-reactive protein level, swollen joint count, tender joint count, or the Disease Activity Score in 28 swollen and 28 tender joints and the synovial volumes or synovitis scores. CONCLUSION: This study is the first to demonstrate the feasibility, reliability, and validity of computerized MRI erosion volume measurements in the wrists of RA patients. The method will require further evaluation in terms of interobserver reliability, with examination of responsiveness in longitudinal studies, but the method demonstrates excellent interoccasion and intraobserver reliability and compares favorably with existing RA clinical outcome measures. Synovial volume measurements demonstrated good intraobserver reliability and appeared to be more responsive to synovial change over a 48-hour period in this group of patients.

Adult↗

PubMed2005

The smallest detectable difference and sensitivity to change of magnetic resonance imaging and radiographic scoring of structural joint damage in rheumatoid arthritis finger, wrist, and toe joints: a comparison of the OMERACT rheumatoid arthritis magnetic resonance imaging score applied to different joint combinations and the Sharp/van der Heijde radiographic score.

OBJECTIVE: To compare 2 magnetic resonance imaging (MRI) approaches and radiographic evaluation according to the Sharp/van der Heijde method with respect to sensitivity to change in joint destruction in patients with rheumatoid arthritis (RA). METHODS: Thirty-five RA patients and 9 healthy controls underwent MRI and radiography on 2 occasions 1 year apart. Conventional radiographs of the hands, wrists, and forefeet were evaluated according to the Sharp/van der Heijde method. MRIs of unilateral wrist and second through fifth metacarpophalangeal (MCP) joints ("few-joints approach") and of bilateral wrist and MCP joints plus unilateral metatarsophalangeal (MTP) joints ("many-joints approach") were assessed for bone erosions according to the scoring system recommended by the OMERACT (Outcome Measures in Rheumatology Clinical Trials) group. The smallest detectable differences (SDDs) of the radiography and MRI scores were computed based on reevaluation of one-third of the study population. RESULTS: Progressive joint destruction, i.e., an increase in score after the followup period, was observed more frequently with the MRI "many-joints approach" (30 subjects) and "few-joints approach" (25 subjects) than with the Sharp/van der Heijde radiographic method (9 subjects) (P < 0.001 by chi-square analysis). No significant difference between the MRI approaches was observed. When only subjects with a change greater than the SDD were considered, progression was revealed with the MRI "many-joints approach," the MRI "few-joints approach," and radiography in 15, 13, and 5 RA subjects, respectively. With both MRI approaches, significantly more subjects with progression were detected than were detected by radiography (P < 0.05). CONCLUSION: MRI, regardless of whether it covers unilateral wrist and MCP joints or bilateral wrist and MCP joints plus unilateral MTP joints, is significantly superior to radiography of the hands, wrists, and forefeet with respect to detection of progressive joint destruction in RA.

Adult↗

PubMed2006

Noise magnetic fields abolish the gap junction intercellular communication suppression induced by 50 hz magnetic fields.

Previously, we have reported that exposure to 50 Hz coherent sinusoidal magnetic fields (MF) for 24 h inhibits gap junction intercellular communication (GJIC) in mammalian cells at an intensity of 0.4 mT and enhances the inhibition effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) at 0.2 mT. In the present study, we further explored the effects of incoherent noise MF on MF-induced GJIC inhibition. GJIC was determined by fluorescence recovery after photobleaching (FRAP) with a laser-scanning confocal microscope. The rate of fluorescence recovery (R) at 10 min after photobleaching was adopted as the functional index of GJIC. The R-value of NIH3T3 cells exposed to 50 Hz sinusoidal MF at 0.4 mT for 24 h was 30.85 +/- 14.70%, while the cells in sham exposure group had an R-value of 46.36 +/- 20.68%, demonstrating that the GJIC of NIH3T3 cells was significantly inhibited by MF exposure (P < .05). However, there were no significant differences in the R-values of the sham exposure, MF-plus-noise MF exposure (R: 49.58 +/- 19.38%), and noise MF exposure groups (R: 46.74 +/- 21.14%) (P > .05), indicating that the superposition of a noise MF alleviated the suppression of GJIC induced by the 50 Hz MF. In addition, although MF at an intensity of 0.2 mT synergistically enhanced TPA-induced GJIC inhibition (R: 24.90 +/- 13.50% vs. 35.82 +/- 17.18%, P < .05), further imposition of a noise MF abolished the synergistic effect of coherent MF (R: 32.51 +/- 18.37%). Overall, the present data clearly showed that although noise MF itself had no effect on GJIC of NIH3T3 cells, its superposition onto a coherent sinusoidal MF at the same intensity abolished MF-induced GJIC suppression. This is the first report showing that noise MF neutralizes 50 Hz MF-induced biological effect by using a signaling component as the test endpoint.

Animals↗

PubMed2003

Functional magnetic resonance cholangiography (fMRC) of the gallbladder and biliary tree with contrast-enhanced magnetic resonance cholangiography.

PURPOSE: To determine the diagnostic performance of functional magnetic resonance cholangiography (fMRC) for the evaluation of anatomic and functional biliary disorders. MATERIALS AND METHODS: At 1.5 T, 39 MR examinations with conventional MRC and mangafodipir trisodium-enhanced fMRC were retrospectively reviewed by three observers who recorded anatomic (duct dilation, stricture, filling defects) and functional (cholecystitis, obstruction) abnormalities in three modes: MRC alone, fMRC alone, and MRC and fMRC images together (combined-MRC). Performance was determined by comparing findings with each mode to findings of invasive cholangiography (IC) and surgery. RESULTS: Among 75 biliary segments (correlated with IC), the sensitivity/specificity for diagnosing dilation (N = 41) with MRC was 95%/97%; with fMRC, 90%/100%; with combined-MRC, 100%/97%. For stricture (N = 7), the sensitivity/specificity of MRC was 86%/98%; of fMRC, 43%/100%; of combined-MRC, 86%/100%. For filling defects (N = 9), the sensitivity/specificity of MRC was 91%/98%; of fMRC, 82%/100%; of combined-MRC, 91%/100%. For diagnosing obstruction (N = 9), the sensitivity/specificity of MRC, fMRC, and combined-MRC were 89%/100%, 100%/100%, and 100%/100%, respectively. For surgically proven cholecystitis (N = 13), positive predictive values for diagnosing acute/chronic cholecystitis for MRC were 33%/40%; for fMRC, 100%/50%; for combined-MRC, 100%/50%. CONCLUSION: Although single-shot fast spin echo (SSFSE)-MRC is valuable, the addition of fMRC increased diagnostic performance for functional biliary disorders.

Biliary Tract↗

PubMedDate not supplied

Evaluation of the iliac arteries: comparison of two-dimensional time of flight magnetic resonance angiography with cardiac compensated fast gradient recalled echo and contrast-enhanced three-dimensional time of flight magnetic resonance angiography.

We compared dynamic contrast-enhanced three-dimensional time of flight (3DTOF) magnetic resonance angiography (MRA) with two-dimensional time of flight (2DTOF) MRA with cardiac compensated fast gradient recalled echo (C-MON) and conventional angiography (CA) when it was available. C-MON re-orders the normal data acquisition to minimize ghosting artifacts generated by pulsatile flow. The initial phase of the study involved optimization of parameters and comparison C-MON with no C = MON in eight patients and volunteers. The final phase of the study involved 53 patients who were imaged with contrast-enhanced 3DTOF MRA and 2DTOF MRA with C-MON. Thirty of these patients also had CA. In the initial phase, 2DTOF MRA with C-MON was found to be equal (n = 3) or superior (n = 5) to 2DTOF without C-MON. In the final phase, the agreement among all imaging modalities varied from substantial to almost perfect (Cohen's kappa = .6-.83). The lowest agreement was using 2DTOF to evaluate the external iliac segments. The among suggested treatments varied from substantial to almost perfect for all imaging modalities (Cohen's kappa = .73-93). The diagnostic efficacies of 2DTOF with C-MON and contrast-enhanced 3DTOF were high overall, with the lowest value being a specificity of 63% for one reader in the evaluation of an external iliac segment using 2DTOF. In summary, 2DTOF with C-MON helped to eliminate artifacts due to pulsatility in the iliac arterial segments. In our experience, both dynamic contrast-enhanced 3DTOF MRA and 2DTOF MRA with C-MON performed well in the evaluation of the iliac arteries. Both studies have high interobeserver agreement and high diagnostic efficacy. Contrast-enhanced 3DTOF MRA should be reserved for situations in which the iliac vessels are extremely tortuous or occluded or the external iliac segments are poorly seen.

Adult↗

PubMed2005

High-resolution anatomic, diffusion tensor, and magnetization transfer magnetic resonance imaging of the optic chiasm at 3T.

PURPOSE: To evaluate techniques for anatomical and physiological imaging of the intracranial optic nerve (ON), optic chiasm (OC), and optic tract (OT) at 3T with the aim of visualizing axonal damage in multiple sclerosis (MS). MATERIALS AND METHODS: Imaging was performed on a 3T scanner employing a custom-designed head coil that consisted of a coil array with four coils (30 x 30 cm(2)). Oblique fast spin echo (FSE) images, magnetization transfer (MT)-enhanced 3D gradient-echo (GRE) time-of-flight (TOF) images, and line scan diffusion images (LSDI) were obtained. Full diffusion tensor (DT) analysis was performed, and apparent diffusion coefficient (ADC), fractional anisotropy (FA), and fiber direction maps were obtained. RESULTS: FSE anatomic images were obtained with an in-plane resolution of 0.39 x 0.52 mm(2). The in-plane resolution of the MT and LSDI images was 0.78 x 0.78 mm(2). The OC, intracranial ON, and OT can be seen on these images. The dominant fiber orientations in the OC, ON, and OT, as derived from the DT images, are displayed. CONCLUSION: This study shows that by using 3T and a custom-designed, four-channel head coil, it is possible to acquire high-resolution anatomical and physiological images of the OC, ON, and OT. The pilot results presented here pave the way for imaging the anterior visual pathway in patients with MS.

Adult↗

PubMed2003

Magnetic resonance measurement of tetramethylammonium diffusion in rat brain: Comparison of magnetic resonance and ionophoresis in vivo diffusion measurements.

Magnetic resonance (MR) and ionophoresis are two experimental methods that provide measurements of molecular diffusion in living tissue. Typical experimental settings yield MR studies that are sensitive to mean molecular displacements of approximately 5 microm, and ionophoresis experiments to displacements of > or =100 microm. An assessment of the correspondence between the methods is hampered by the fact that no common probe molecule has been used. One of the most frequently utilized probe molecules in ionophoresis measurements is the tetramethylammonium (TMA) ion. In the current work the diffusion properties of TMA were studied in rat brain in vivo with localized (1)H MR spectroscopy (MRS). Standard treatment of the MR data yielded a 3.6-fold lower apparent diffusion coefficient (ADC) compared to ionophoresis. To explore the source of this discrepancy, a separate data processing scheme was applied to the MR data to monitor individual elapsed displacement-distance subpopulations of TMA molecules. This analysis revealed a dependence of the ADC estimation on a given subpopulation's elapsed displacement distance. The MR-derived ADC approached the ionophoresis-derived value as the elapsed displacement distance increased to 15 microm. These observations demonstrate that MR and ionophoresis studies provide complementary information, and that ADC estimates obtained from the two techniques are sensitive to different biophysical determinants.

Animals↗

PubMed1992

Magnetization transfer time-of-flight magnetic resonance angiography.

Time-of-flight (TOF) angiography based on inflow enhancement is limited by the steady-state signal differences between blood and the surrounding stationary tissues. We present a new TOF sequence in which magnetization transfer contrast is used to supplement wash-in effects. Angiograms demonstrating the superior performance of this technique are presented.

Blood Vessels↗

PubMed1997

Effect of brain, body, and magnet bore temperatures on energy metabolism during global cerebral ischemia and reperfusion monitored by magnetic resonance spectroscopy in rats.

To record brain temperature for comparison with rectal and temporalis muscle temperatures in preliminary studies before MR spectroscopy experiments, a thermistor was inserted into the basal ganglia in eight anesthetized, ventilated, and physiologically monitored rats. The rats were placed in an MR spectrometer and subjected to 60 min of global cerebral ischemia and 2 h of reperfusion without radiofrequency (RF) pulsing. Body temperature was maintained at 37.5-38.0 degrees C (normothermia) or 36.5-37.0 degrees C (mild hypothermia). Brain temperature during ischemia, which dropped to 31.9 +/- 0.3 (hypothermia) and 33.6 +/- 0.5 degrees C (normothermia), correlated with temporalis muscle temperature (r2 = 0.92) but not with body or magnet bore temperature measurements. Ischemia reduced brain temperature approximately 1.7 degrees C in rats subjected to mild hypothermia (1 degree reduction of body temperature). Parallel MR spectroscopy experiments showed no significant difference in energy metabolites between normothermic and hypothermic rats during ischemia. However, the metabolic recovery was more extensive 20-60 min after the onset of reperfusion in hypothermic rats, although not thereafter (P < 0.05). Mild hypothermia speeds metabolic recovery temporarily during reperfusion but does not retard energy failure during global ischemia in rats.

Adenosine Triphosphate↗