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Wang FX, Xu CL, Su C, Li J, Lin JY. β-Hydroxybutyrate Attenuates Painful Diabetic Neuropathy via Restoration of the Aquaporin-4 Polarity in the Spinal Glymphatic System. Front Neurosci 2022; 16:926128. [PMID: 35898407 PMCID: PMC9309893 DOI: 10.3389/fnins.2022.926128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
Waste removal is essential for maintaining homeostasis and the normal function of the central nervous system (CNS). The glymphatic system based on aquaporin-4 (AQP4) water channels on the endfeet of astrocytes is recently discovered as the excretion pathway for metabolic waste products of CNS. In the CNS, α-syntrophin (SNTA1) directly or indirectly anchors AQP4 in astrocyte membranes facing blood vessels. Studies have indicated that β-hydroxybutyrate (BHB) can raise the expression of SNTA1 and thus restoring AQP4 polarity in mice models with Alzheimer’s disease. The study aims to evaluate the neuroprotective mechanism of BHB in rats with painful diabetic neuropathy (PDN). PDN rats were modeled under a high-fat and high-glucose diet with a low dose of streptozotocin. Magnetic resonance imaging (MRI) was applied to observe the clearance of contrast to indicate the functional variability of the spinal glymphatic system. Mechanical allodynia was assessed by paw withdrawal threshold. The expressions of SNTA1 and AQP4 were tested, and the polarity reversal of AQP4 protein was measured. As demonstrated, PDN rats were manifested with deceased contrast clearance of the spinal glymphatic system, enhanced mechanical allodynia, lower expression of SNTA1, higher expression of AQP4, and reversed polarity of AQP4 protein. An opposite change in the above characteristics was observed in rats being treated with BHB. This is the first study that demonstrated the neuroprotective mechanism of BHB to attenuate PDN via restoration of the AQP4 polarity in the spinal glymphatic system and provides a promising therapeutic strategy for PDN.
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Affiliation(s)
- Fei-xiang Wang
- Department of Anesthesiology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Chi-liang Xu
- Department of Anesthesiology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Can Su
- Department of Medical Imaging, The Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Jiang Li
- Department of Anesthesiology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Jing-yan Lin
- Department of Anesthesiology, The Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- *Correspondence: Jing-yan Lin,
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Polycarpou I, Soultanidis G, Tsoumpas C. Synergistic motion compensation strategies for positron emission tomography when acquired simultaneously with magnetic resonance imaging. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200207. [PMID: 34218675 PMCID: PMC8255946 DOI: 10.1098/rsta.2020.0207] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/15/2021] [Indexed: 05/04/2023]
Abstract
Subject motion in positron emission tomography (PET) is a key factor that degrades image resolution and quality, limiting its potential capabilities. Correcting for it is complicated due to the lack of sufficient measured PET data from each position. This poses a significant barrier in calculating the amount of motion occurring during a scan. Motion correction can be implemented at different stages of data processing either during or after image reconstruction, and once applied accurately can substantially improve image quality and information accuracy. With the development of integrated PET-MRI (magnetic resonance imaging) scanners, internal organ motion can be measured concurrently with both PET and MRI. In this review paper, we explore the synergistic use of PET and MRI data to correct for any motion that affects the PET images. Different types of motion that can occur during PET-MRI acquisitions are presented and the associated motion detection, estimation and correction methods are reviewed. Finally, some highlights from recent literature in selected human and animal imaging applications are presented and the importance of motion correction for accurate kinetic modelling in dynamic PET-MRI is emphasized. This article is part of the theme issue 'Synergistic tomographic image reconstruction: part 2'.
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Affiliation(s)
- Irene Polycarpou
- Department of Health Sciences, European University of Cyprus, Nicosia, Cyprus
| | - Georgios Soultanidis
- Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Charalampos Tsoumpas
- Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Biomedical Imaging Science Department, University of Leeds, West Yorkshire, UK
- Invicro, London, UK
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Dynamic Contrast-Enhanced MRI of the Liver in Mrp2-Deficient Rats Using the Hepatobiliary Contrast Agent Gd-EOB-DTPA. Invest Radiol 2013; 48:548-53. [DOI: 10.1097/rli.0b013e3182856a06] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Peters BS, Dornaika R, Hosten N, Hadlich S, Mullins JJ, Peters J, Rettig R. Regression of cardiac hypertrophy in cyp1a1ren-2 transgenic rats. J Magn Reson Imaging 2012; 36:373-8. [PMID: 22517449 DOI: 10.1002/jmri.23661] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 03/07/2012] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To evaluate the usefulness of the cyp1a1ren-2 transgenic rat model of inducible hypertension for studies of the development and regression of cardiac hypertrophy. MATERIALS AND METHODS Cyp1a1ren-2 rats received a diet containing 0% or 0.167% indole-3-carbinonl (I3C) for 4 weeks to induce hypertension. Cardiac magnetic resonance imaging (MRI) at 7 T was performed every second week for 10 weeks to measure left ventricular mass and the ejection fraction. Concomitantly, in six cyp1a1ren-2 rats blood pressure was recorded telemetrically. RESULTS Plasma prorenin concentrations rose from 138 ± 38 to 15,490 ± 3990 ng/angiotensin I/mL/h (P < 0.001) in I3C-treated transgenic rats and returned to basal levels after cessation of I3C. Mean blood pressure increased to a plateau of 169 ± 11 mmHg by the second week of induction. After cessation of I3C (day 28), arterial pressure dropped to values slightly below those prior to induction within 4 days (basal: 106 ± 7 mmHg, day 32: 103 ± 21 mmHg; NS). At day 28, left ventricular mass was increased by 39% vs. 4% in controls (P < 0.001) without changes of the ejection fraction. Cardiac hypertrophy was completely reversed at day 70, as evaluated by MRI. CONCLUSION The cyp1a1ren-2 transgenic rat is a useful model to study reversal and healing in the absence of surgical interventions.
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Affiliation(s)
- Barbara S Peters
- Department of Cardiovascular Medicine, Institute of Physiology, University of Greifswald, Karlsburg, Germany.
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Hutchison RM, Mirsattari SM, Jones CK, Gati JS, Leung LS. Functional networks in the anesthetized rat brain revealed by independent component analysis of resting-state FMRI. J Neurophysiol 2010; 103:3398-406. [PMID: 20410359 DOI: 10.1152/jn.00141.2010] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The rodent brain is organized into functional networks that can be studied through examination of synchronized low-frequency spontaneous fluctuations (LFFs) of the functional magnetic resonance imaging -blood-oxygen-level-dependent (BOLD) signal. In this study, resting networks of LFFs were estimated from the whole-brain BOLD signals using independent component analysis (ICA). ICA provides a hypothesis-free technique for determining the functional connectivity map that does not require a priori selection of a seed region. Twenty Long-Evans rats were anesthetized with isoflurane (1%, n = 10) or ketamine/xylazine (50/6 mg . kg(-1) . h(-1) ip, n = 10) and imaged for 5-10 min in a 9.4 T MR scanner without experimental stimulation or task requirement. Independent, synchronous LFFs of BOLD signals were found to exist in clustered, bilaterally symmetric regions of both cortical and subcortical structures, including primary and secondary somatosensory cortices, motor cortices, visual cortices, posterior and anterior cingulate cortices, hippocampi, caudate-putamen, and thalamic and hypothalamic nuclei. The somatosensory and motor cortices typically demonstrated both symmetric and asymmetric components with unique frequency profiles. Similar independent network components were found under isoflurane and ketamine/xylazine anesthesia. The report demonstrates, for the first time, 12 independent resting networks that are bilaterally synchronous in different cortical and subcortical areas of the rat brain.
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Affiliation(s)
- R Matthew Hutchison
- Department of Physiology and Pharmacology, University of Western Ontario, Medical Sciences Bldg. Rm. 236, London, Ontario, N6A 5C1, Canada
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Pelled G, Bergstrom DA, Tierney PL, Conroy RS, Chuang KH, Yu D, Leopold DA, Walters JR, Koretsky AP. Ipsilateral cortical fMRI responses after peripheral nerve damage in rats reflect increased interneuron activity. Proc Natl Acad Sci U S A 2009; 106:14114-9. [PMID: 19666522 PMCID: PMC2720851 DOI: 10.1073/pnas.0903153106] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2009] [Indexed: 11/18/2022] Open
Abstract
In the weeks following unilateral peripheral nerve injury, the deprived primary somatosensory cortex (SI) responds to stimulation of the ipsilateral intact limb as demonstrated by functional magnetic resonance imaging (fMRI) responses. The neuronal basis of these responses was studied by using high-resolution fMRI, in vivo electrophysiological recordings, and juxtacellular neuronal labeling in rats that underwent an excision of the forepaw radial, median, and ulnar nerves. These nerves were exposed but not severed in control rats. Significant bilateral increases of fMRI responses in SI were observed in denervated rats. In the healthy SI of the denervated rats, increases in fMRI responses were concordant with increases in local field potential (LFP) amplitude and an increased incidence of single units responding compared with control rats. In contrast, in the deprived SI, increases in fMRI responses were associated with a minimal change in LFP amplitude but with increased incidence of single units responding. Based on action potential duration, juxtacellular labeling, and immunostaining results, neurons responding to intact forepaw stimulation in the deprived cortex were identified as interneurons. These results suggest that the increases in fMRI responses in the deprived cortex reflect increased interneuron activity.
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Affiliation(s)
- Galit Pelled
- Laboratory of Functional and Molecular Imaging and Neurophysiological Pharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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Yuan Y, Li F, Wang YM, Zhang RQ, Wei LP, Wang HC. Respiratory face mask: a novel and cost-effective device for use during the application of myocardial ischemia in rats. J Zhejiang Univ Sci B 2009; 10:391-4. [PMID: 19434766 DOI: 10.1631/jzus.b0820216] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To shorten operation time and improve survival rate of rats with myocardial ischemia or myocardial infarction, we use a novel device comprised of a face mask and a head/neck retainer in this study. We report the basic design of the novel respiratory face mask (RFM) and evaluate its performance in a rat model of myocardial ischemia. The device is cost-effective and easier to handle than other devices, such as tracheal intubation. Compared with conventional tracheal intubation, we found that RFM shortens operation time significantly while keeping blood indices normal; the mean operation time for rats in the mask group was (32+/-3) min, and that for the intubation group was (45+/-7) min (P<0.05). Moreover, the size and shape of the RFM can be changed according to the body weight of rats. In conclusion, RFM is an appropriate device for the establishment of myocardial infarction or ischemia-reperfusion in rats.
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Affiliation(s)
- Yuan Yuan
- Department of Cardiology, Xijing Hospital, the Fourth Military Medical University, Xi'an 710032, China
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Wegener S, Wong EC. Longitudinal MRI studies in the isoflurane-anesthetized rat: long-term effects of a short hypoxic episode on regulation of cerebral blood flow as assessed by pulsed arterial spin labelling. NMR IN BIOMEDICINE 2008; 21:696-703. [PMID: 18275045 DOI: 10.1002/nbm.1243] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
MRI is a powerful tool for measuring cerebral blood flow (CBF) longitudinally. However, most animal studies require anesthesia, potentially interfering with normal physiology. Isoflurane anesthesia was used here to study CBF regulation during repetitive scanning in rats. MR perfusion images were acquired using FAIR (flow-sensitive alternating inversion recovery) arterial spin labeling, and absolute CBF was calculated. CBF changes in response to a hypoxic (12% O2) and hypercapnic (5% CO2) gas stimulus were monitored. Hypercapnia led to a robust increase in CBF compared with baseline (195.5+/-21.5 vs 123.6+/-17.9 ml/100 g/min), and hypoxia caused a smaller non-significant increase in mean CBF values (145.4+/-13.4 ml/100 g/min). Strikingly, when measurements were repeated 5 days later, CBF was dramatically reduced in hypoxia (93.2+/-8.1 ml/100 g/min) compared with the first imaging session. Without application of the hypoxic and hypercapnic gases during the first MRI, baseline CBF and CBF changes in response to hypoxia at the second MRI were similar to naive rats. Blood gas analyses revealed a slight reduction in arterial oxygenation during the second period of anesthesia compared with the first. These findings indicate that, in isoflurane-anesthetized rats, even a short hypoxic episode can have long-lasting effects on cerebrovascular regulation.
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Affiliation(s)
- Susanne Wegener
- Department of Radiology, University of California at San Diego, San Diego, CA 92103, USA.
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Abstract
Despite its excellent temporal resolution, electroencephalogram (EEG) has poor spatial resolution to study the participation of different brain areas in epileptic discharges, and the propagation of seizures to subcortical areas is not revealed. Furthermore, EEG provides no information about metabolic changes that occur in the brain before and during the epileptic discharges. Thus, monitoring variations in blood flow and oxygenation in response to epileptic discharges can provide additional complementary information. Functional magnetic resonance imaging (fMRI) technology can be used to study the hemodynamic changes associated with interictal epileptiform discharges or epileptic seizures (i.e., before, during or after them) in experimental animal models and may noninvasively monitor these changes over time. Blood oxygenation level-dependent fMRI has superior spatial resolution compared with other functional imaging modalities and utilizes changes in local magnetic field properties to measure the amount of deoxyhemoglobin in each brain areas as an indicator of brain activity. Simultaneous recording of EEG and fMRI is required to achieve this objective. This article describes methods of acquiring and monitoring EEG during fMRI studies in experimental animals. Particular attention will be paid to methods used to eliminate artifacts induced in the acquired magnetic resonance images by EEG equipment and MR-related artifacts in EEG recordings.
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Affiliation(s)
- Seyed M Mirsattari
- Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada.
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10
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Pelled G, Bergman H, Ben-Hur T, Goelman G. Manganese-enhanced MRI in a rat model of Parkinson's disease. J Magn Reson Imaging 2007; 26:863-70. [PMID: 17896372 DOI: 10.1002/jmri.21051] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To measure intra- and inter-hemispheric connectivity within the basal ganglia (BG) nuclei in healthy and in unilateral 6-hydroxydopamine (6-OHDA) Parkinson disease rat model in order to test the BG interhemispheric connectivity hypothesis. MATERIAL AND METHODS The manganese-enhanced MRI (MEMRI) method with direct injection of manganese chloride into the entopeduncular (EP), substantia nigra (SN), and the Habenula nuclei in unilateral 6-OHDA (N = 22) and sham-operated (N = 16) rat groups was used. MEMRI measurements were applied before, 3, 24, and 48 hours post-manganese injection. Signal enhancements in T1-weighted images were compared between groups. RESULTS Manganese injection into the EP nucleus resulted with bihemispheric signal enhancements in the habenular complex (Hab) at both groups with stronger enhancements in the 6-OHDA group. It also exhibited lower sensorimotor cortex signal enhancement in the 6-OHDA rat group. SN manganese injection caused enhanced anteroventral thalamic and habenular nuclei signals in the 6-OHDA rat group. Manganese habenula injection revealed enhanced interpeduncular (IP) and raphe nuclei signals of the 6-OHDA rat group. CONCLUSION Modulations in the effective intra- and interhemispheric BG connectivity in unilateral 6-OHDA Parkinson's disease (PD) rat model support the BG interhemispheric connectivity hypothesis and suggest a linkage between the dopaminergic and serotonergic systems in PD, in line with clinical symptoms.
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Affiliation(s)
- Galit Pelled
- MRI/MRS Laboratory, Human Biology Research Center, Department of Medical Biophysics and Nuclear Medicine, Hadassah Hebrew University Medical Center, Jerusalem, Israel
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11
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Mirsattari SM, Bihari F, Leung LS, Menon RS, Wang Z, Ives JR, Bartha R. Physiological monitoring of small animals during magnetic resonance imaging. J Neurosci Methods 2005; 144:207-13. [PMID: 15910980 DOI: 10.1016/j.jneumeth.2004.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 11/08/2004] [Accepted: 11/10/2004] [Indexed: 11/23/2022]
Abstract
Maintaining a stable physiologic state is essential when studying animal models of epilepsy with simultaneous electroencephalograph (EEG) and functional magnetic resonance imaging (fMRI) or EEG and magnetic resonance spectroscopy (MRS). To achieve and maintain such stability in rats in the MRI environment, a minimally invasive but comprehensive system was developed to monitor body temperature, heart rate, blood pressure, blood oxygen saturation and end-tidal CO2 (ETCO2) of expired gas. All physiologic parameters were successfully monitored in Sprague-Dawley rats without interfering with EEG recordings during simultaneous fMRI and MRS studies. Body temperature, heart rate, blood pressure, blood oxygen saturation, and ETCO2, were maintained between 36.5 and 37.5 degrees C, 250-450 beats/min, 136+/-17 mmHg, >90%, and 20-35 mmHg, respectively for 6-8 h under inhalational anesthesia. This set-up could be extended to study in vivo applications in other laboratory animals with only minor modifications.
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Affiliation(s)
- Seyed M Mirsattari
- Department of Clinical Neurological Sciences, University of Western Ontario, 10-OP3, 339 Windermere Rd, London, Ont., Canada, N6A 5A5.
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Mirsattari SM, Ives JR, Bihari F, Leung LS, Menon RS, Bartha R. Real-time display of artifact-free electroencephalography during functional magnetic resonance imaging and magnetic resonance spectroscopy in an animal model of epilepsy. Magn Reson Med 2005; 53:456-64. [PMID: 15678533 DOI: 10.1002/mrm.20357] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Simultaneous recording of electroencephalogram (EEG) and functional MRI (fMRI) or MR spectroscopy (MRS) can provide further insight into our understanding of the underlying mechanisms of neurologic disorders. Current technology for simultaneous EEG and MRI recording is limited by extensive postacquisition processing of the data. Real-time display of artifact-free EEG recording during fMRI/MRS studies is essential in studies that involve epilepsy to ensure that they address specific EEG features such as epileptic spikes or seizures. By optimizing the EEG recording equipment to maximize the common mode rejection ratio of its amplifiers, a unique EEG system was designed and tested that allowed real-time display of the artifact-free EEG during fMRI/MRS in an animal model of epilepsy. Spike recordings were optimized by suppression of the background EEG activity using fast-acting and easily controlled inhalational anesthesia. Artifact suppression efficiency of 70-100% was achieved following direct subtraction of referentially recorded filtered EEG tracings from active electrodes, which were located in close proximity to each other (over homologous occipital cortices) and a reference electrode. Two independent postacquisition processing tools, independent component analysis and direct subtraction of unfiltered digital EEG data in MATLAB, were used to verify the accuracy of real-time EEG display.
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Affiliation(s)
- Seyed M Mirsattari
- Neuroscience Graduate Program, University of Western Ontario, London, Ontario, Canada.
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Vallée JP, Ivancevic MK, Nguyen D, Morel DR, Jaconi M. Current status of cardiac MRI in small animals. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2004; 17:149-56. [PMID: 15605278 DOI: 10.1007/s10334-004-0066-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 08/27/2004] [Accepted: 09/15/2004] [Indexed: 10/26/2022]
Abstract
Cardiac magnetic resonance imaging (MRI) on small animals is possible but remains challenging and not well standardized. This publication aims to provide an overview of the current techniques, applications and challenges of cardiac MRI in small animals for researchers interested in moving into this field. Solutions have been developed to obtain a reliable cardiac trigger in both the rat and the mouse. Techniques to measure ventricular function and mass have been well validated and are used by several research groups. More advanced techniques like perfusion imaging, delayed enhancement or tag imaging are emerging. Regarding cardiac applications, not only coronary ischemic disease but several other pathologies or conditions including cardiopathies in transgenic animals have already benefited from these new developments. Therefore, cardiac MRI has a bright future for research in small animals.
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Affiliation(s)
- J-P Vallée
- Digital Imaging Unit, Radiology and Medical Informatics Department, Geneva University Hospitals, CH-1211, Geneva 14, Switzerland.
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Giannesini B, Cozzone PJ, Bendahan D. In vivo MR investigation of skeletal muscle function in small animals. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2004; 17:210-8. [PMID: 15592946 DOI: 10.1007/s10334-004-0080-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 10/26/2004] [Accepted: 10/26/2004] [Indexed: 11/30/2022]
Abstract
In vivo 31P-MRS investigations have been widely used in small animals to study skeletal muscle function under normal and pathological conditions. Paradoxically in these studies, the benefit provided by 31P-MRS in terms of non-invasiveness is lost because of the utilization of experimental setups that integrate invasive devices for inducing muscle contractions and for measuring mechanical performance. These traditional methodologies, which require surgical preparations, have obvious limitations regarding repeatability in the same animal. The purpose of this review is to highlight the technical aspects of the in vivo MR investigations of skeletal muscle function in small animal models. We will more particularly address the issue related to the invasiveness of different procedures used so far in order to show finally that a further step into non-invasiveness can be achieved, in particular with the support of muscle functional 1H-MRI.
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Affiliation(s)
- B Giannesini
- Centre de Résonance Magnétique Biologique et Médicale (CRMBM), UMR CNRS 6612, Faculté de Médecine de Marseille, 27 Boulevard Jean Moulin, 13005, Marseille, France
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15
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Pickup S, Wood AKW, Kundel HL. GadodiamideT1 relaxivity in brain tissue in vivo is lower than in saline. Magn Reson Med 2004; 53:35-40. [PMID: 15690500 DOI: 10.1002/mrm.20336] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In vivo measurements of gadodiamide (Gd-DTPA-BMA) T(1) relaxivity were performed at 4.7 T in injured and normal rat brains. Cerebral lesions were induced in nine rats by a localized freezing method. T(1) maps of the lesions were generated before and after injection of Gd-DTPA-BMA (0.1-0.6 mmol/kg). Samples of normal and necrotic brain were collected postmortem; the wet and dry weights were determined, and Gd content was measured by inductively coupled plasma mass spectroscopy. The in vivo relaxivity was determined by a linear fit of a plot of the change in relaxation rate following injection of the contrast agent as a function of Gd content. This analysis yielded a relaxivity in the injured brain of 2.8 sec(-1) mmol(-1) kg tissue water at 36 degrees C. The water weight fraction was 0.90 +/- SD 0.02 wt/wt in injured brain and 0.79 +/- 0.02 in normal brain. Relaxivity measurements were also performed on solutions of Gd-DTPA-BMA (0.0-0.6 mmol) and albumin (0-30% wt/wt) in normal saline at room and physiologic temperatures. The relaxivity in the albumin/saline increased with increasing solids content with values of 4.0-4.9 sec(-1) mmol(-1)kg at 21 degrees C and 3.4-4.5 sec(-1) mmol(-1) kg at 37 degrees C. The relaxivity of the tissues differed significantly from that of the saline solutions of comparable solids content, suggesting that the solids content of a tissue is not the only factor that determines in vivo relaxivity.
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Affiliation(s)
- Stephen Pickup
- Department of Radiology, University of Pennsylvania Medical Center, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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Benveniste H, Blackband S. MR microscopy and high resolution small animal MRI: applications in neuroscience research. Prog Neurobiol 2002; 67:393-420. [PMID: 12234501 DOI: 10.1016/s0301-0082(02)00020-5] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The application of magnetic resonance (MR) imaging in the study of human disease using small animals has steadily evolved over the past two decades and strongly established the fields of "small animal MR imaging" and "MR microscopy." An increasing number of neuroscience related investigations now implement MR microscopy in their experiments. Research areas of growth pertaining to MR microscopy studies are focused on (1). phenotyping of genetically engineered mice models of human neurological diseases and (2). rodent brain atlases. MR microscopy can be performed in vitro on tissue specimens, ex vivo on brain slice preparations and in vivo (typically on rodents). Like most new imaging technologies, MR microscopy is technologically demanding and requires broad expertise. Uniform guidelines or "standards" of a given MR microscopy experiment are non-existent. The main focus therefore of this review will be on biological applications of MR microscopy and the experimental requirements. We also take a critical look at the biological information that small animal (rodent) MR imaging has provided in neuroscience research.
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Affiliation(s)
- Helene Benveniste
- Medical Department, Brookhaven National Laboratory, Building 490, 30 Bell Avenue, Upton, NY 11793, USA.
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