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Vivo MRI (vivo + mri)
Selected AbstractsThe human hippocampus at 7 T,In vivo MRIHIPPOCAMPUS, Issue 1 2009Jens M. Theysohn Abstract The human hippocampus plays a central role in various neuropsychiatric disorders, such as temporal lobe epilepsy (TLE), Alzheimer's dementia, mild cognitive impairment, and schizophrenia. Its volume, morphology, inner structure, and function are of scientific and clinical interest. Magnetic resonance (MR) imaging is a widely employed tool in neuroradiological workup regarding changes in brain anatomy, (sub-) volumes, and cerebral function including the hippocampus. Gain in intrinsic MR signal provided by higher field strength scanners and concomitant improvements in spatial resolution seem highly valuable. An examination protocol permitting complete, high-resolution imaging of the human hippocampus at 7 T was implemented. Coronal proton density, T2, T2*, and fluid-attenuated inversion recovery contrasts were acquired as well as an isotropic 3D magnetization-prepared rapid acquisition gradient-echo (500 ,m isotropic voxel dimension, noninterpolated). Observance of energy deposition restrictions within acceptable scan times remained challenging in the acquisition of thin, spin-echo-based sections. At the higher resolution enabled by 7 T, demarcation of the hippocampus and some internal features including gray/white matter differentiation and depiction of the hippocampal mantle becomes much more viable when compared with 1.5 T; thus, in the future, this imaging technology might help in the diagnosis of subtle hippocampal changes. © 2008 Wiley-Liss, Inc. [source] Imaging biomarkers of cardiovascular diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Jinnan Wang PhD Abstract Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Current clinical techniques that rely on stenosis measurement alone appear to be insufficient for risk prediction in atherosclerosis patients. Many novel imaging methods have been developed to study atherosclerosis progression and to identify new features that can predict future clinical risk. MRI of atherosclerotic vessel walls is one such method. It has the ability to noninvasively evaluate multiple biomarkers of the disease such as luminal stenosis, plaque burden, tissue composition and plaque activity. In addition, the accuracy of in vivo MRI has been validated against histology with high reproducibility, thus paving the way for application to epidemiological studies of disease pathogenesis and, by serial MRI, in monitoring the efficacy of therapeutic intervention. In this review, we describe the various MR techniques used to evaluate aspects of plaque progression, discuss imaging-based measurements (imaging biomarkers), and also detail their validation. The application of plaque MRI in clinical trials as well as emerging imaging techniques used to evaluate plaque compositional features and biological activities are also discussed. J. Magn. Reson. Imaging 2010;32:502,515. © 2010 Wiley-Liss, Inc. [source] In vivo magnetic resonance imaging of iron oxide,labeled, arterially-injected mesenchymal stem cells in kidneys of rats with acute ischemic kidney injury: Detection and monitoring at 3TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007Harald Ittrich MD Abstract Purpose To evaluate MRI for a qualitative and quantitative in vivo tracking of intraaortal injected iron oxide,labeled mesenchymal stem cells (MSC) into rats with acute kidney injury (AKI). Materials and Methods In vitro MRI and R2* measurement of nonlabeled and superparamagnetic iron oxide (SPIO)-labeled MSC (MSCSPIO) was performed in correlation to cellular iron content and cytological examination (Prussian blue, electron microscopy). In vivo MRI and R2* evaluation were performed before and after ischemic/reperfusion AKI (N = 14) and intraaortal injection of 1.5 × 106 MSCSPIO (N = 7), fetal calf serum (FCS) (medium, N = 6), and SPIO alone (N = 1) up to 14 days using a clinical 3T scanner. Signal to noise ratios (SNR), R2* of kidneys, liver, spleen, and bone marrow, renal function (creatinine [CREA], blood urea nitrogen [BUN]), and kidney volume were measured and tested for statistical significance (Student's t -test, P < 0.05) in comparison histology (hematoxylin and eosin [H&E], Prussian blue, periodic acid-Schiff [PAS], CD68). Results In vitro, MSCSPIO showed a reduction of SNR and T2* with R2* , number of MSCSPIO (R2 = 0.98). In vivo MSCSPIO administration resulted in a SNR decrease (35 ± 15%) and R2* increase (101 ± 18.3%) in renal cortex caused by MSCSPIO accumulation in contrast to control animals (P < 0.01). Liver, spleen, and bone marrow (MSCSPIO) showed a delayed SNR decline/R2* increase (P < 0.05) resulting from MSCSPIO migration. The increase of kidney volume and the decrease in renal function (P < 0.05) was reduced in MSC-treated animals. Conclusion Qualitative and quantitative in vivo cell-tracking and monitoring of organ distribution of intraaortal injected MSCSPIO in AKI is feasible in MRI at 3T. J. Magn. Reson. Imaging 2007;25:1179,1191. © 2007 Wiley-Liss, Inc. [source] Highly efficient square wave distant dipolar field and its application for in vivo MRIMAGNETIC RESONANCE IN MEDICINE, Issue 4 2010Congbo Cai Abstract Intermolecular multiple quantum coherences generated by distant dipolar field (DDF) have some attractive properties, but the intrinsic weak signal intensity prevents their widespread applications. Recently, Branca et al. (J Chem Phys 2008;129:054502) suggested that square wave DDF was more efficient than conventional sinusoidal DDF because it could simultaneously produce intermolecular multiple quantum coherences signal with various major orders. In this article, instead of a series of adiabatic inversion pulses proposed previously, a more efficient composite adiabatic inversion pulse was applied to create square wave DDF. The square wave DDF was applied to in vivo MRI for the first time, and the corresponding simulations were performed. Both experimental and simulated results show that square wave DDF with composite adiabatic inversion pulse improves over the original Z-modulation enhanced to binary for self-refocused acquisition implementation and can enhance the signal intensity to about 2-fold of that from conventional correlation spectroscopy (COSY) revamped with asymmetric Z-gradient echo detection sequence for in vivo MRI, close to the theoretical prediction. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] Magnetosonoporation: Instant magnetic labeling of stem cellsMAGNETIC RESONANCE IN MEDICINE, Issue 6 2010Bensheng Qiu Abstract The purpose of this study was to develop an instant MR cell labeling technique, called magnetosonoporation. First, a magnetosonoporation apparatus was successfully established for MR labeling of stem cells. Then, the safety of this new cell labeling approach was confirmed by evaluation of cell viability, proliferation, and differentiation of magnetosonoporation-labeled and unlabeled C17.2 neural stem cells. Subsequently, the feasibility of using in vivo MRI to detect magnetosonoporation/Feridex-labeled stem cells was validated in living animals and confirmed by histologic correlation. The magnetosonoporation technique is expected to be convenient, efficient, and safe for future clinical application of MRI-guided cell therapies. Magn Reson Med 63:1437,1441, 2010. © 2010 Wiley-Liss, Inc. [source] In vivo MRI using real-time production of hyperpolarized 129XeMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Bastiaan Driehuys Abstract MR imaging of hyperpolarized (HP) nuclei is challenging because they are typically delivered in a single dose of nonrenewable magnetization, from which the entire image must be derived. This problem can be overcome with HP 129Xe, which can be produced sufficiently rapidly to deliver in dilute form (1%) continuously and on-demand. We demonstrate a real-time in vivo delivery of HP 129Xe mixture to rats, a capability we now routinely use for setting frequency, transmitter gain, shimming, testing pulse sequences, scout imaging, and spectroscopy. Compared to images acquired using conventional fully concentrated 129Xe, real-time 129Xe images have 26-fold less signal, but clearly depict ventilation abnormalities. Real-time 129Xe MRI could be useful for time-course studies involving acute injury or response to treatment. Ultimately, real-time 129Xe MRI could be done with more highly concentrated 129Xe, which could increase the signal-to-noise ratio by 100 relative to these results to enable a new class of gas imaging applications. Magn Reson Med 60:14,20, 2008. © 2008 Wiley-Liss, Inc. [source] Non-invasive tracking of avian development in vivo by MRINMR IN BIOMEDICINE, Issue 4 2009Bianca Hogers Abstract Conventional microscopic techniques, to study embryonic development, require large numbers of embryos and are invasive, making follow-up impossible. We explored the use of in vivo MRI to study embryonic development, in general, and cardiovascular development in particular, over time. Wild-type quail embryos (n,=,11) were imaged at embryonic days 3, 5, 7, 9, and 11, covering the main time course of embryonic heart development. On each imaging day cardiac morphology was evaluated and embryonic length was measured. MRI-embryos as well as control embryos (n,=,11) were sacrificed at day 11 and scored for external malformations, while embryonic wet weight and stage were determined. In addition, venous clipped embryos (n,=,4), known to develop cardiovascular malformations, were scanned at regular intervals and sacrificed at day 9 for histological analysis ex vivo. We were able to follow heart development of individual quail embryos inside their shell non-invasively over time, with sufficient detail to study cardiac morphology in vivo. We did not find any adverse effect of the repeated MRI examinations on morphology, length, or weight. Prenatally diagnosed malformations, like ventricular septal defects and aortic arch interruptions were confirmed by histology. In conclusion, micro-MRI can be used to evaluate in vivo early embryonic development and to diagnose cardiovascular malformations prenatally. Copyright © 2008 John Wiley & Sons, Ltd. [source] Quantitative MRI-pathology correlations of brain white matter lesions developing in a non-human primate model of multiple sclerosisNMR IN BIOMEDICINE, Issue 2 2007Erwin L. A. Blezer Abstract Experimental autoimmune encephalomyelitis (EAE) induced with recombinant human myelin/oligodendrocyte glycoprotein in the common marmoset is a useful preclinical model of multiple sclerosis in which white matter lesions can be well visualized with MRI. In this study we characterized lesion progression with quantitative in vivo MRI (4.7,T; T1 relaxation time,±,Gd-DTPA; T2 relaxation time; magnetization transfer ratio, MTR, imaging) and correlated end stage MRI presentation with quantitative ex vivo MRI (formaldehyde fixed brains; T1 and T2 relaxation times; MTR) and histology. The histopathological characterization included axonal density measurements and the numeric quantification of infiltrated macrophages expressing markers for early active [luxol fast blue (LFB) or migration inhibition factor-related protein-14 positive] or late active/inactive [periodic acid Schiff (PAS) positive] demyelinating lesion. MRI experiments were done every two weeks until the monkeys were sacrificed with severe EAE-related motor deficits. Compared with the normal appearing white matter, lesions showed an initial increase in T1 relaxation times, leakage of Gd-DTPA and decrease in MTR values. The progressive enlargement of lesions was associated with stabilized T1 values, while T2 initially increased and stabilized thereafter and MTR remained decreased. Gd-DTPA leakage was highly variable throughout the experiment. MRI characteristics of the cortex and (normal appearing) white matter did not change during the experiment. We observed that in vivo MTR values correlated positively with the number of early active (LFB+) and negatively with late active (PAS+) macrophages. Ex vivo MTR and relaxation times correlated positively with the number of PAS-positive macrophages. None of the investigated MRI parameters correlated with axonal density. Copyright © 2006 John Wiley & Sons, Ltd. [source] Detailed Visualization of the Functional Regions of the Rat Pituitary Gland by High-Resolution T2-Weighted MRIANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2010E. Theunissen With 5 figures and 1 table Summary This high-resolution MRI study focuses on the visualization of the detailed morphology of the rat's pituitary gland by means of post-mortem as well as in vivo MRI at 9.4 T. Determination of the local T1- and T2-relaxation decay times allows to explain the regional image intensities which reflects the degree of tissue organization at the molecular level. Detailed characterization of the molecular level of the pituitary gland, as provided by the relaxation decay times, can offer a rigid platform with respect to functional or pathological explorations. It is demonstrated that T1-weighted imaging, as is routinely used in the clinic, can differentiate between the posterior and anterior lobe but not between the posterior and intermediate lobe. T2-weighted images, however, clearly show the three distinct lobes of the rat pituitary gland without the use of contrast agents, i.e. the posterior, the intermediate and the anterior lobe. Histological analysis of the rat's pituitary gland confirms the morphological structures seen on the MR images. Although the intermediate lobe is less defined in humans and can neither be differentiated by T1-weighted MRI, its clinical visualization might be possible in T2-weighted images. [source] Gestational Hypoxia Induces White Matter Damage in Neonatal Rats: A New Model of Periventricular LeukomalaciaBRAIN PATHOLOGY, Issue 1 2004Olivier Baud In the premature infant, periventricular leukomalacia, usually related to hypoxic-ischemic white matter damage, is the main cause of neurological impairment. We hypothesized that protracted prenatal hypoxia might induce white matter damage during the perinatal period. Pregnant Sparague-Dawley rats were placed in a chamber supplied with hypoxic gas (10% O2 -90% N2) from embryonic day 5(E5) to E20. Neonatal rat brains were investigated by histology, immunocytochemistry, western blotting, in situ hybridization, DNA fragmentation analysis, and in vivo magnetic resonance imaging (MRI). Body weight of pups subjected to prenatal hypoxia was 10 to 30% lower from p0 to P14 than in controls. Specific white matter cysts wear detected between p0 and p7 in pups subjected to prenatal hypoxia, in addition to abnormal extra-cellular matrix, increased lipid peroxidation, white matter cell death detected by TUNEL and increased activated macrophage counts in white matter. Subsequently, gliotic scars and delayed myelination primarily involving immature oligodendrocytes were seen In vivo MRI with T1, T2, and diffusion sequences disclosed similar findings immediately after birth, showing strong correlations with histological abnormalities. We speculate that protracted prenatal hypoxia in rat induces abnormalities. We speculate that protracted prenatal hypoxia in rat induces white matter damage occurring through local inflammatory response and oxidative stress linked to re-oxygenation during the perinatal period. [source] The development of the subplate and thalamocortical connections in the human foetal brainACTA PAEDIATRICA, Issue 8 2010Ivica Kostovi Abstract The aim of this review is to present clinically relevant data on prenatal development of thalamocortical connections in the human brain. The analysis is based on extensive Zagreb Neuroembryological Collection, including more than 500 prenatal human brains stained with various classical neurohistological, as well as modern histochemical and immunohistochemical methods. The connection of thalamocortical axons during the ,waiting' period with transient cortical subplate zone and subsequent synaptic engagement in the cortical plate is the main connectivity event in the late foetus and preterm infant. This connectivity is the structural substrate for the endogeneous subplate and sensory-driven circuitry generating transient electrical phenomena and may represent a transient network in the developmental history of consciousness. Conclusion:, Findings presented in this review should be considered in the management of pain in preterm infants, in searching for the vulnerability of the subplate zone in diagnostic procedures using the in vivo MRI and in revealing the developmental origin of cognitive and mental disorders. [source] | |||||||||||||