1
|
Overgaard-Steensen C, Stødkilde-Jørgensen H, Larsson A, Tønnesen E, Frøkiaer J, Ring T. The frequently used intraperitoneal hyponatraemia model induces hypovolaemic hyponatraemia with possible model-dependent brain sodium loss. Exp Physiol 2016; 101:932-45. [PMID: 27197619 DOI: 10.1113/ep085751] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/17/2016] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the central question of this study? The brain response to acute hyponatraemia is usually studied in rodents by intraperitoneal instillation of hypotonic fluids (i.p. model). The i.p. model is described as 'dilutional' and 'syndrome of inappropriate ADH (SIADH)', but the mechanism has not been explored systematically and might affect the brain response. Therefore, in vivo brain and muscle response were studied in pigs. What is the main finding and its importance? The i.p. model induces hypovolaemic hyponatraemia attributable to sodium redistribution, not dilution. A large reduction in brain sodium is observed, probably because of the specific mechanism causing the hyponatraemia. This is not accounted for in current understanding of the brain response to acute hyponatraemia. Hyponatraemia is common clinically, and if it develops rapidly, brain oedema evolves, and severe morbidity and even death may occur. Experimentally, acute hyponatraemia is most frequently studied in small animal models, in which the hyponatraemia is produced by intraperitoneal instillation of hypotonic fluids (i.p. model). This hyponatraemia model is described as 'dilutional' or 'syndrome of inappropriate ADH (SIADH)', but seminal studies contradict this interpretation. To confront this issue, we developed an i.p. model in a large animal (the pig) and studied water and electrolyte responses in brain, muscle, plasma and urine. We hypothesized that hyponatraemia was induced by simple water dilution, with no change in organ sodium content. Moderate hypotonic hyponatraemia was induced by a single i.v. dose of desmopressin and intraperitoneal instillation of 2.5% glucose. All animals were anaesthetized and intensively monitored. In vivo brain and muscle water was determined by magnetic resonance imaging and related to the plasma sodium concentration. Muscle water content increased less than expected as a result of pure dilution, and muscle sodium content decreased significantly (by 28%). Sodium was redistributed to the peritoneal fluid, resulting in a significantly reduced plasma volume. This shows that the i.p. model induces hypovolaemic hyponatraemia and not dilutional/SIADH hyponatraemia. Brain oedema evolved, but brain sodium content decreased significantly (by 21%). To conclude, the i.p. model induces hypovolaemic hyponatraemia attributable to sodium redistribution and not water dilution. The large reduction in brain sodium is probably attributable to the specific mechanism that causes the hyponatraemia. This is not accounted for in the current understanding of the brain response to acute hyponatraemia.
Collapse
Affiliation(s)
- Christian Overgaard-Steensen
- Department of Anaesthesiology, Aarhus University Hospital NBG, Aarhus, Denmark.,Institute of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skejby, Denmark
| | | | - Anders Larsson
- Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Else Tønnesen
- Department of Anaesthesiology, Aarhus University Hospital NBG, Aarhus, Denmark.,Institute of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skejby, Denmark
| | - Jørgen Frøkiaer
- Institute of Clinical Medicine, Aarhus University, Aarhus University Hospital, Skejby, Denmark.,The Water and Salt Research Centre, Aarhus University, Aarhus, Denmark
| | - Troels Ring
- Department of Nephrology, Aalborg University Hospital, Aalborg, Denmark
| |
Collapse
|
2
|
Overgaard-Steensen C, Stødkilde-Jørgensen H, Larsson A, Broch-Lips M, Tønnesen E, Frøkiaer J, Ring T. Regional differences in osmotic behavior in brain during acute hyponatremia: an in vivo MRI-study of brain and skeletal muscle in pigs. Am J Physiol Regul Integr Comp Physiol 2010; 299:R521-32. [PMID: 20445159 DOI: 10.1152/ajpregu.00139.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Brain edema is suggested to be the principal mechanism underlying the symptoms in acute hyponatremia. Identification of the mechanisms responsible for global and regional cerebral water homeostasis during hyponatremia is, therefore, of utmost importance. To examine the osmotic behavior of different brain regions and muscles, in vivo-determined water content (WC) was related to plasma sodium concentration ([Na(+)]) and brain/muscle electrolyte content. Acute hyponatremia was induced with desmopressin acetate and infusion of a 2.5% glucose solution in anesthetized pigs. WC in different brain regions and skeletal muscle was estimated in vivo from T(1) maps determined by magnetic resonance imaging (MRI). WC, expressed in gram water per 100 g dry weight, increased significantly in slices of the whole brain [342(SD = 14) to 363(SD = 21)] (6%), thalamus [277(SD = 13) to 311(SD = 24)] (12%) and white matter [219(SD = 7) to 225(SD = 5)] (3%). However, the WC increase in the whole brain and white mater WC was less than expected from perfect osmotic behavior, whereas in the thalamus, the water increase was as expected. Brain sodium content was significantly reduced. Muscle WC changed passively with plasma [Na(+)]. WC determined with deuterium dilution and tissue lyophilzation correlated well with MRI-determined WC. In conclusion, acute hyponatremia induces brain and muscle edema. In the brain as a whole and in the thalamus, regulatory volume decrease (RVD) is unlikely to occur. However, RVD may, in part, explain the observed lower WC in white matter. This may play a potential role in osmotic demyelination.
Collapse
|
3
|
Driscoll I, Howard SR, Stone JC, Monfils MH, Tomanek B, Brooks WM, Sutherland RJ. The aging hippocampus: A multi-level analysis in the rat. Neuroscience 2006; 139:1173-85. [PMID: 16564634 DOI: 10.1016/j.neuroscience.2006.01.040] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 01/03/2006] [Accepted: 01/26/2006] [Indexed: 11/23/2022]
Abstract
In the current experiment we conducted a multi-level analysis of age-related characteristics in the hippocampus of young adult (3 months), middle-aged (12 months), and old (24 months) Fisher 344xBrown Norway hybrid (FBNF1) rats. We examined the relationships between aging, hippocampus, and memory using a combination of behavioral, non-invasive magnetic resonance imaging and spectroscopy, and postmortem neuroanatomical measures in the same rats. Aging was associated with functional deficits on hippocampus-dependent memory tasks, accompanied by structural alterations observed both in vivo (magnetic resonance imaging-hippocampal volume) and postmortem (dentate gyrus neuronal density and neurogenesis). Neuronal metabolic integrity, assessed by levels of N-acetylaspartate with magnetic resonance spectroscopy, was however, preserved. Further, our results suggest that neurogenesis (doublecortin) seems to be related to both performance deficits on hippocampus-dependent tasks and hippocampal volume reduction. The observed pattern of age-related alterations closely resembles that previously reported in humans and suggests FBNF1 rats to be a useful model of normal human aging.
Collapse
Affiliation(s)
- I Driscoll
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Alberta.
| | | | | | | | | | | | | |
Collapse
|
4
|
Abstract
Aging is associated with impairments in certain aspects of cognition, especially learning and memory. The hippocampus is a structure intimately involved with certain aspects of learning and memory, and is especially vulnerable to the course of aging. Recent findings, primarily from cognitive, magnetic resonance imaging, and magnetic resonance spectroscopy studies, but also briefly physiology and neurogenesis work, are reviewed. Evidence suggests that age-related impairment of hippocampus-dependent cognition is associated with changes on various levels of investigation in both humans and non-human animals. Also, the emphasis is placed on tasks and techniques that can be used to test both non-human and human animals in an attempt to bridge the gulf between the vast bodies of knowledge about the hippocampus in different species. To the extent that changes with normal aging are understood, they may aid in diagnosis, prevention, and/or treatment of age-related learning and memory deficits in both normal and pathological aging. In addition, studies of the aging hippocampus may have a side-effect in leading to a better understanding of the mechanisms that underlie learning and memory in general.
Collapse
Affiliation(s)
- Ira Driscoll
- Canadian Centre for Behavioural Neuroscience, Department of Psychology and Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada.
| | | |
Collapse
|
5
|
Venkatasubramanian PN, Tom B, Blei AT, Wyrwicz AM. Monitoring of brain water by chemical shift imaging during ammonia-induced brain swelling in rats after portacaval anastomosis. Artif Organs 2001; 25:551-7. [PMID: 11493276 DOI: 10.1046/j.1525-1594.2001.025007551.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Brain edema is a leading cause of death in acute liver failure (ALF). In experimental models of ALF, an increase in the content of brain water has been inferred indirectly by measuring intracranial pressure or determined directly via analysis of brain tissue postmortem. In this study, noninvasive proton two-dimensional chemical shift imaging (2-D CSI) was used to follow the time course of the development of brain edema in a well characterized model, namely ammonium acetate infusion into rats 48 to 72 h after portacaval anastomosis (PCA). Clear differences between control and experimental rat brains were observed, with an increase of brain water signal only in the parietal cortex of the PCA + ammonia group. Selective swelling of the cerebral cortex points to a cytotoxic mechanism in the evolution of brain edema in this model. CSI signal enhancement was much greater than the gravimetrically determined water content increase. The significantly greater signal change observed with 2-D CSI may reflect enhanced proton density that results from increased water content as well as edema-related alterations in water relaxation times.
Collapse
Affiliation(s)
- P N Venkatasubramanian
- Center for Magnetic Resonance Research, Evanston Northwestern Hospital Research Institute, Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, U.S.A
| | | | | | | |
Collapse
|
6
|
Mórocz IA, Zientara GP, Gudbjartsson H, Muza S, Lyons T, Rock PB, Kikinis R, Jólesz FA. Volumetric quantification of brain swelling after hypobaric hypoxia exposure. Exp Neurol 2001; 168:96-104. [PMID: 11170724 DOI: 10.1006/exnr.2000.7596] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We applied a novel MR imaging technique to investigate the effect of acute mountain sickness on cerebral tissue water. Nine volunteers were exposed to hypobaric hypoxia corresponding to 4572 m altitude for 32 h. Such an exposure may cause acute mountain sickness. We imaged the brains of the volunteers before and at 32 h of hypobaric exposure with two different MRI techniques with subsequent data processing. (1) Brain volumes were calculated from 3D MRI data sets by applying a computerized brain segmentation algorithm. For this specific purpose a novel adaptive 3D segmentation program was used with an automatic correction algorithm for RF field inhomogeneity. (2) T(2) decay rates were analyzed in the white matter. The results demonstrated that a significant brain swelling of 36.2 +/- 19.6 ml (2.77 +/- 1.47%, n = 9, P < 0.001) developed after the 32-h hypobaric hypoxia exposure with a maximal observed volume increase of 5.8% (71.3 ml). These volume changes were significant only for the gray matter structures in contrast to the unremarkable changes seen in the white matter. The same study repeated 3 weeks later in 6 of 9 original subjects demonstrated that the brains recovered and returned approximately to the initially determined sea-level brain volume while hypobaric hypoxia exposure once again led to a significant new brain swelling (24.1 +/- 12.1 ml, 1.92 +/- 0.96%, n = 6, P < 0.005). On the contrary, the T(2) mapping technique did not reveal any significant effect of hypobaria on white matter. We present here a technique which is able to detect reversible brain volume changes as they may occur in patients with diffuse brain edema or increased cerebral blood volume, and which may represent a useful noninvasive tool for future evaluations of antiedematous drugs.
Collapse
Affiliation(s)
- I A Mórocz
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Petropoulos H, Sibbitt WL, Brooks WM. Automated T2 quantitation in neuropsychiatric lupus erythematosus: a marker of active disease. J Magn Reson Imaging 1999; 9:39-43. [PMID: 10030648 DOI: 10.1002/(sici)1522-2586(199901)9:1<39::aid-jmri5>3.0.co;2-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Active neuropsychiatric systemic lupus erythematosus (NPSLE) is characterized by brain edema as measured by manual quantitative magnetic resonance (MR) relaxometry. An automated image processing method was developed to segment gray matter (GM), while minimizing the effects of confounding factors, specifically cerebral atrophy and volume averaging artifacts. Twenty patients with SLE (10 major, 10 minor), matched for atrophy, were studied. We compared T2 calculated for GM segmented by manual and automated methods. Both methods demonstrated a marked increase in GM T2 in patients with major NPSLE (P < 0.001), confirming the presence of cerebral edema. The results from each method were highly correlated, (r = 0.64, P = 0.002). The automated method effectively identifies GM, minimizes volume averaging artifacts, and produces results similar to the manual method. This method markedly decreases analysis time and will make quantitative relaxometry a valuable contribution to the clinical management of NPSLE.
Collapse
Affiliation(s)
- H Petropoulos
- Center for Non-Invasive Diagnosis, University of New Mexico Health Sciences Center, Albuquerque 87131, USA
| | | | | |
Collapse
|
8
|
Bacher A, Wei J, Grafe MR, Quast MJ, Zornow MH. Serial determinations of cerebral water content by magnetic resonance imaging after an infusion of hypertonic saline. Crit Care Med 1998; 26:108-14. [PMID: 9428551 DOI: 10.1097/00003246-199801000-00024] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To determine regional cerebral water content in vivo by magnetic resonance imaging (MRI) after the administration of 7.5% saline in brain-lesioned rabbits. DESIGN Randomized, controlled, intervention trial. SETTING University animal laboratory. SUBJECTS Eighteen male New Zealand white rabbits, randomly assigned to one of three groups. INTERVENTIONS The animals were anesthetized (1% halothane), intubated, and mechanically ventilated to maintain end-tidal CO2 tension between 30 and 35 mm Hg (4 and 4.7 kPa). Arterial and central venous catheters were inserted and arterial blood samples were serially obtained during the experiment. Serum osmolality was measured. A cryogenic cerebral lesion was produced by pouring liquid nitrogen for 1 min into a funnel placed on the intact skull over the right hemisphere. One group of animals received 20 mL of 7.5% saline intravenously 150 mins after the cerebral lesion was generated (7.5% saline group, n = 7). A second group of animals received the same volume of 0.9% saline intravenously (0.9% saline group, n = 7). In a third group of animals (control group, n = 4) no lesion was created and no fluid administered. MEASUREMENTS AND MAIN RESULTS Five spin-echo T2-weighted MRIs of the brain were acquired at 90 mins (Baseline 1), 120 mins (Baseline 2), 150 mins (Infusion), 180 mins (Infusion + 30 mins), and 210 mins (Infusion + 60 mins) after the generation of the cerebral lesion. In the control group, two scans separated by a time interval of 120 mins were performed. The percent changes in signal intensity between the first and the four following scans of a coronal slice of the central region were determined. Analysis of variance and the Mann-Whitney U test were used for statistical analysis. Data are presented as mean +/- SD; p < .05 was considered significant. Serum osmolality increased significantly from 308 +/- 13 mosm/L to 349 +/- 19 mosm/L after the infusion of 20 mL of 7.5% saline, but did not change after the administration of 0.9% saline. Signal intensity in the area between the caudal edge of the core of the lesion and the basal ganglia was 9 +/- 8% higher on the injured side than in the corresponding area on the contralateral side (p < .05). Compared with Baseline 1, signal intensity at Infusion + 60 mins decreased by 26.3 +/- 13.7% in the 7.5% saline group, whereas it decreased by 10.4 +/- 8.6% in the 0.9% saline group (p < .05 between groups). Signal intensity decreased only slightly and nonsignificantly by 0.6 +/- 4.4% between the two scans in the control group. CONCLUSIONS The administration of a 7.5% saline solution causes a prompt and substantial decrease in cerebral water content as assessed by spin-echo T2-weighted MRI. Magnetic resonance imaging offers the opportunity for repeated, noninvasive in vivo determinations of cerebral water content.
Collapse
Affiliation(s)
- A Bacher
- Department of Anesthesiology and General Intensive Care, University of Vienna, Austria
| | | | | | | | | |
Collapse
|
9
|
Olson JE, Banks M, Dimlich RV, Evers J. Blood-brain barrier water permeability and brain osmolyte content during edema development. Acad Emerg Med 1997; 4:662-73. [PMID: 9223688 DOI: 10.1111/j.1553-2712.1997.tb03757.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE To determine mechanisms that limit changes in brain water content during acute edema development. METHODS A controlled, laboratory investigation of the physiologic and biochemical correlates of osmotic edema was performed in rats. Hypoosmotic hyponatremia was induced by intraperitoneal injection of distilled water. Serum osmolality and electrolytes and regional blood-brain barrier water permeability. Surface area (P.S) product, osmolyte contents, and capillary size were determined during 120 minutes of hypoosmotic brain edema development. Cerebral water content predicted from these data using a mathematical model of brain water movements was compared with measured changes in brain water content. RESULTS Fifteen minutes after distilled water injection, mean +/- SEM blood serum osmolality and sodium concentration decreased from 291 +/- 3 mOsm and 131 +/- 13 mmol/L to 267 +/- 3 mOsm and 102 +/- 9 mmol/L, respectively. Specific gravity of cerebral gray matter, cerebral white matter, and basal ganglia decreased throughout the hypoosmotic exposure period and, for gray and white matter, correlated with blood serum osmolality and sodium plus potassium content. Glutamate, but not glutamine, glycine, or taurine, decreased 120 minutes after water injection. The regional water P.S product decreased by 40% to 60% within 60 minutes of the water injection, while capillary diameters in gray and white matter were unchanged. Brain water movements calculated from the mathematical model correctly predicted actual brain water content only if the hydraulic conductivity of the blood-brain barrier was allowed to vary in proportion to the measured P.S product and the measured loss of brain osmolytes was incorporated into the formulation. CONCLUSIONS During the first hours of hypoosmotic hyponatremia, changes in brain volume are limited by increased resistance to osmotic flux of water into the brain and reduction in the brain content of inorganic and, to a smaller degree, organic osmolytes.
Collapse
Affiliation(s)
- J E Olson
- Wright State University, School of Medicine, Department of Emergency Medicine, Cox Institute, Kettering, OH 45429, USA.
| | | | | | | |
Collapse
|
10
|
Kleine LJ, Mulkern RV, Guttmann CR, Colucci VM, Jolesz FA. In vivo characterization of cytotoxic intracellular edema by multicomponent analysis of transverse magnetization decay curves. Acad Radiol 1995; 2:365-72. [PMID: 9419577 DOI: 10.1016/s1076-6332(05)80335-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
RATIONALE AND OBJECTIVES We investigated the multicompartmental nature of T2 decay in a specific white matter edema model. METHODS Triethyltin (TET) intoxication was produced in six male New Zealand White rabbits. Images were obtained over the 23-day study duration using a 64-echo Carr-Purcell-Meiboom-Gill (CPMG) sequence (repetition time = 3000 msec, echo time = 20 msec). T2 decay curves were extracted from 0.7 x 0.7 x 3.0 mm3 voxels in the corpus callosum and contiguous white matter tracts, cortex, thalamic nuclei, hypothalamic nuclei, and the masseter muscles. The curves were fit with biexponential functions. RESULTS Increased signal intensity in the corpus callosum was evident 2-3 days after the first TET injection. At this time, a substantial slowly relaxing component appeared in the decay curves of the corpus callosum and, to a lesser extent, in the thalamus and hypothalamus. Changes in the rabbits' body weight, general physical condition, and neurologic state paralleled the growth and regression of the second, slowly relaxing component. CONCLUSION The appearance and regression of a slowly decaying second component in the T2 decay curve is consistent with the formation and shrink-age of intracellular vesicles in the intramyelin sheaths of central white matter.
Collapse
Affiliation(s)
- L J Kleine
- Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA
| | | | | | | | | |
Collapse
|
11
|
Kamada K, Houkin K, Iwasaki Y, Abe H. A high-field magnetic resonance imaging study of experimental vasogenic brain edema and its response to AVS: 1,2-bis (nicotinamido)-propane. ACTA NEUROCHIRURGICA. SUPPLEMENTUM 1994; 60:491-3. [PMID: 7976628 DOI: 10.1007/978-3-7091-9334-1_134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We clearly represented brain structures of rats and permitted a rapid assessment of water gradient of the brain edema by cortical freezing utilizing a high-field (7T) proton magnetic resonance imaging (MRI). The typical time course of vasogenic edema and the efficacy of AVS; 1,2-bis (nicotinamide)-propane upon the edema were presented. Twelve rats with edema induced by cortical freezing were divided into two groups; one group of animals received 0.5 ml of physiological saline with 100 mg (/kg) AVS every eight hours intraperitoneally. The other group of untreated animals received only saline. One three, six, 12, and 24 hours after lesion production, the profiles of edema fluid spreading and the maximum signal intensity (MI) of some regions of interest (ROI) were assessed by T2 weighted images (TE = 70 ms, TR = 3500 ms). One hour after lesion production in the untreated group, a low heterogeneous intensity area was seen mainly in the primarily injured cortex. Two hours later, the margin of the lesion gradually increased in intensity and MI of ROIs around the lesion also gradually increased. Twenty-four h after lesion production edema extended contralaterally via corpus callosum. AVS reduced edema fluid spreading beginning from about six hours after lesion production. The MIs of the AVS treated group were significantly lower than in the untreated group (p < 0.01). We conclude that sequential observation of edema using MRI is a quite practical technique for evaluation of the efficacy of any therapeutic agent.
Collapse
Affiliation(s)
- K Kamada
- Department of Neurosurgery, Hokkaido University School of Medicine, Japan
| | | | | | | |
Collapse
|
12
|
Jolesz FA. Compartmental analysis of brain edema using magnetic resonance imaging. ACTA NEUROCHIRURGICA. SUPPLEMENTUM 1994; 60:179-83. [PMID: 7976539 DOI: 10.1007/978-3-7091-9334-1_48] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The potential exists for increasing the sensitivity of magnetic resonance imaging (MRI) to white matter (WM) pathologies by identifying compartments of tissue water. We have found the physical equivalents of myelin-associated biological water compartments in normal and pathologic states by using multiexponential analysis of T2 relaxation. In addition, we have applied this multi-parametric technique for the definition of various types of white matter edemas. We were able to identify some changes in physical compartments visible by MRI with simultaneous changes in biological compartments. We conclude that MRI is a very sensitive method to quantify abnormal accumulation of intracerebral water; however, it is a somewhat limited probe for identifying the biologic compartmentation of edema among the various biological compartments of the brain.
Collapse
Affiliation(s)
- F A Jolesz
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| |
Collapse
|