scholarly journals Oligomerization of Paramagnetic Substrates Result in Signal Amplification and Can be Used for MR Imaging of Molecular Targets

2002 ◽  
Vol 1 (1) ◽  
pp. 153535002002000 ◽  
Author(s):  
Alexei Bogdanov ◽  
Lars Matuszewski ◽  
Christoph Bremer ◽  
Alexander Petrovsky ◽  
Ralph Weissleder
Keyword(s):  
Signal Amplification ◽  
Imaging Modality ◽  
Functional Characterization ◽  
Molecular Targets ◽  
Transgenic Animals ◽  
Rotational Correlation Time ◽  
In Vivo Detection ◽  
Noninvasive Imaging Modality ◽  
Magnetic Resonance Imaging Mri

Magnetic resonance imaging (MRI) has evolved into a sophisticated, noninvasive imaging modality capable of high-resolution anatomical and functional characterization of transgenic animals. To expand the capabilities MRI, we have developed a novel MR signal amplification (MRamp) strategy based on enzyme-mediated polymerization of paramagnetic substrates into oligomers of higher magnetic relaxivity. The substrates consist of chelated gadolinium covalently bound to phenols, which then serve as electron donors during enzymatic hydrogen peroxide reduction by peroxidase. The converted monomers undergo rapid condensation into paramagnetic oligomers leading to a threefold increase in atomic relaxivity ( R1/Gd). The observed relaxivity changes are largely due to an increase in the rotational correlation time τr of the lanthanide. Three applications of the developed system are demonstrated: (1) imaging of nanomolar amounts of an oxidoreductase (peroxidase); (2) detection of a model ligand using an enzyme-linked immunoadsorbent assay format; and (3) imaging of E-selectin on the surface of endothelial cells probed for with an anti-E-selectin – peroxidase conjugate. The development of “enzyme sensing” probes is expected to have utility for a number of applications including in vivo detection of specific molecular targets. One particular advantage of the MRamp technique is that the same paramagnetic substrate can be potentially used to identify different molecular targets by attaching enzymes to various antibodies or other target-seeking molecules.

scholarly journals In vivo detection of connectivity between cortical and white matter lesions in early MS

2016 ◽  
Vol 23 (7) ◽  
pp. 973-981 ◽  
Author(s):  
Jan-Mendelt Tillema ◽  
Stephen D Weigand ◽  
Jay Mandrekar ◽  
Yunhong Shu ◽  
Claudia F Lucchinetti ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
White Matter Lesions ◽  
Cortical Lesion ◽  
In Vivo Detection ◽  
Relapsing Remitting ◽  
Mri Scans ◽  
Healthy Control ◽  
Magnetic Resonance Imaging Mri

Background: The relationship between cortical lesions (CLs) and white matter lesions (WMLs) in multiple sclerosis (MS) is poorly understood. Pathological studies support a topographical association between CLs and underlying subcortical WMLs and suggest CLs may play a role in both disease initiation and progression. We hypothesized that cortical MS lesions are physically connected to white matter MS lesions via axonal connections. Objective: To assess the presence of CL-WML connectivity utilizing novel magnetic resonance imaging (MRI) methodology. Methods: In all, 28 relapsing-remitting MS patients and 25 controls received 3 T MRI scans, including double inversion recovery (DIR) for CL detection coupled with diffusion tensor imaging (DTI). CL and WML maps were created, and DTI was used to calculate inter-lesional connectivity and volumetric connectivity indices. Results: All patients showed inter-lesional WML connectivity (median 76% of WMLs connected to another WML; interquartile range (IQR), 58%–88%). On average, 52% of detected CLs per patient were connected to at least one WML (IQR, 42%–71%). Volumetric connectivity analysis showed significantly elevated cortical lesion ratios in MS patients (median, 2.3; IQR, 1.6–3.3) compared to null MS and healthy control datasets ( p < 0.001). Conclusion: These findings provide strong evidence of inter-lesional connectivity between CLs and WMLs, supporting our hypothesis of intrinsic CL-WML connectivity.

scholarly journals A new method for accurate in vivo mapping of human brain connections using microstructural and anatomical information

2020 ◽  
Vol 6 (31) ◽  
pp. eaba8245 ◽  
Author(s):  
Simona Schiavi ◽  
Mario Ocampo-Pineda ◽  
Muhamed Barakovic ◽  
Laurent Petit ◽  
Maxime Descoteaux ◽  
...  
Keyword(s):  
Human Brain ◽  
Imaging Modality ◽  
Brain Anatomy ◽  
Major Step ◽  
Wide Range ◽  
Noninvasive Imaging Modality ◽  
Novel Processing ◽  
Brain Data ◽  
Anatomical Information

Diffusion magnetic resonance imaging is a noninvasive imaging modality that has been extensively used in the literature to study the neuronal architecture of the brain in a wide range of neurological conditions using tractography. However, recent studies highlighted that the anatomical accuracy of the reconstructions is inherently limited and challenged its appropriateness. Several solutions have been proposed to tackle this issue, but none of them proved effective to overcome this fundamental limitation. In this work, we present a novel processing framework to inject into the reconstruction problem basic prior knowledge about brain anatomy and its organization and evaluate its effectiveness using both simulated and real human brain data. Our results indicate that our proposed method dramatically increases the accuracy of the estimated brain networks and, thus, represents a major step forward for the study of connectivity.

scholarly journals MIMoSA: A Method for Inter-Modal Segmentation Analysis

2017 ◽  
Author(s):  
Alessandra M. Valcarcel ◽  
Kristin A. Linn ◽  
Simon N. Vandekar ◽  
Theodore D. Satterthwaite ◽  
Peter A. Calabresi ◽  
...  
Keyword(s):  
Imaging Modality ◽  
Covariance Structure ◽  
White Matter Lesions ◽  
Imaging Modalities ◽  
Automated Segmentation ◽  
Tissue Properties ◽  
Segmentation Analysis ◽  
Magnetic Resonance Imaging Mri ◽  
Thresholding Algorithm

AbstractMagnetic resonance imaging (MRI) is crucial for in vivo detection and characterization of white matter lesions (WML) in multiple sclerosis. While these lesions have been studied for over two decades using MRI technology, automated segmentation remains challenging. Although the majority of statistical techniques for the automated segmentation of WML are based on a single imaging modality, recent advances have used multimodal techniques for identifying WML. Complementary imaging modalities emphasize different tissue properties, which can help identify and characterize interrelated features of lesions. However, prior work has ignored relationships between imaging modalities, which may be informative in this clinical context. To harness the coherent changes in these measurements, we utilized inter-modal coupling regression (IMCo) to estimate the covariance structure across modalities. We then used a local logistic regression, MIMoSA, which leverages new covariance features from IMCo regression as well as the mean structure of each imaging modality in order to model the probability that any voxel is part of a lesion. Finally, we introduced a novel thresholding algorithm to fully automate the estimation of the probability maps to generate fully automated segmentations masks for 94 subjects. To evaluate the performance of the automated segmentations generated using MIMoSA we compared results with gold standard manual segmentations. We demonstrate the superiority of MIMoSA to other automated segmentation techniques by comparing it to the OASIS algorithm as well as LesionTOADS. MIMoSA resulted in statistically significant improvement in lesion segmentation.

The Use of Magnetic Resonance Imaging (MRI) for the Study of the Velopharynx

2017 ◽  
Vol 2 (5) ◽  
pp. 35-52 ◽  
Author(s):  
Kazlin Mason ◽  
Jamie Perry
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Acoustic Analysis ◽  
Imaging Modality ◽  
Resonance Imaging ◽  
Advantages And Disadvantages ◽  
Magnetic Resonance Imaging Mri ◽  
Outcomes For Children ◽  
Posterior Pharynx

Magnetic resonance imaging (MRI) has contributed significantly to our understanding of the velopharyngeal mechanism and is the only imaging modality that allows for visualization of the internal musculature in vivo. Although velopharyngeal dysfunction often can be perceived through indirect assessments such as perceptual ratings, acoustic analysis, and pressure-flow assessment, these indirect methods can fail to identify the underlying cause of hypernasality or velopharyngeal dysfunction due to the inability to visualize the primary muscles responsible for speech. Direct imaging methods, such as nasendoscopy or videofluoroscopy, present drawbacks and are limited in the information that is provided within the oral and nasal cavities, as well as the posterior pharynx. MRI studies have enhanced our knowledge of the velopharyngeal system and offer a foundation to establish the utility of using MRI clinically to improve speech outcomes for children with cleft palate and craniofacial anomalies. The purpose of this paper is to provide an overview of the underlying principles of MRI, describe the advantages and disadvantages of MRI, and discusses a standard protocol for assessing velopharyngeal anatomy.

scholarly journals Is MRI as safe as we think?

2008 ◽  
Vol 12 (2) ◽  
pp. 50
Author(s):  
S Wahab ◽  
R A Khan ◽  
E Ullah ◽  
A Wahab
Keyword(s):  
Magnetic Field ◽  
Imaging Modality ◽  
Biological Effects ◽  
Conclusive Evidence ◽  
Clear Understanding ◽  
Gradient Magnetic Field ◽  
Mr Contrast Agents ◽  
Noninvasive Imaging Modality ◽  
Magnetic Resonance Imaging Mri ◽  
Mri Diagnostics

Magnetic resonance imaging (MRI) is nowadays widely used as a noninvasive imaging modality for a wide variety of diseases and disorders. A patient placed in the MR system for scanning remains under the influence of powerful static magnetic field, rapidly varying gradient magnetic field and radiofrequency field in addition to the risk factors associated with gadolinium based MR contrast agents. At present, there is no conclusive evidence for adverse biological effects in patients undergoing MRI. However, a clear understanding of the various bioeffects associated with MRI diagnostics is necessary in order to ensure the safety of the patient as well as to justify its clinical use.

Size-Tunable Magnetofluorescent Nanoparticles as In Vivo Imaging

2014 ◽  
Vol 1660 ◽  
Author(s):  
Keisuke Sato ◽  
Kenji Hirakuri ◽  
Kouki Fujioka ◽  
Yoshinobu Manome ◽  
Hiroaki Sukegawa ◽  
...  
Keyword(s):  
Imaging Modality ◽  
Ferromagnetic Behavior ◽  
Synthetic Approach ◽  
Resonance Imaging ◽  
Green Fluorescence ◽  
Mean Diameter ◽  
Magnetic Guidance ◽  
Good Biocompatibility ◽  
Magnetic Resonance Imaging Mri

ABSTRACTMagnetic/fluorescent (magnetofluorescent) materials have become one of the most important tools in the imaging modality in vivo using magnetic resonance imaging (MRI) and fluorescence imaging. We succeeded in fabricating magnetofluorescent nanoparticles (MFNPs) consisting of silicon/magnetite composite nanoparticles. Our unique synthetic approach can control simultaneously the magnetic and fluorescence behaviors by varying the particle size, demonstrating the superparamagnetic behavior and green fluorescence for the MFNPs having mean diameter of 3.0 nm, and the ferromagnetic behavior without fluorescence for the MFNPs having mean diameter more than 5.0 nm. More intriguingly, the MFNPs with superparamagnetism can detect green fluorescence even after the magnetic guidance of MFNPs by the commercial neodymium magnet. Additionally, the MFNPs having two magnetic behaviors also possess good biocompatibility.

scholarly journals Diffusion Tensor Imaging for In Vivo Detection of Degenerated Optic Radiation

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Georg Michelson ◽  
Tobias Engelhorn ◽  
Simone Waerntges ◽  
Arnd Doerfler
Keyword(s):  
Diffusion Tensor Imaging ◽  
Diffusion Tensor ◽  
Open Angle Glaucoma ◽  
Optic Radiation ◽  
New Approach ◽  
Transneuronal Degeneration ◽  
In Vivo Detection ◽  
Magnetic Resonance Imaging Mri ◽  
Diffusion Tensor Imaging Dti

Glaucomatous optic nerve atrophy may continue to the linked optic radiation by transneuronal degeneration, as described in animal models of glaucoma. In vivo visualization of the visual pathway represents a new challenge in the field of ophthalmology. We present a new approach for illustration of the optic radiation by diffusion tensor imaging (DTI) based on magnetic resonance imaging (MRI). The DTI was established by use of a 3T high-field scanner. The case of a patient with primary open-angle glaucoma is opposed to this one of a healthy subject to demonstrate the visible rarefication of the optic radiation. The goal was to introduce the technique of the DTI also in ophthalmology and to demonstrate that it may be useful to judge glaucoma-related differences.

Advanced Magnetic Resonance Imaging in Epilepsy

US Neurology ◽  
2014 ◽  
Vol 10 (02) ◽  
pp. 104 ◽  
Author(s):  
Heath Pardoe ◽  
Ruben Kuzniecky ◽  
◽  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Imaging Modality ◽  
Brain Regions ◽  
Network Activity ◽  
Resonance Imaging ◽  
Multiple Channel ◽  
Epilepsy Diagnosis ◽  
Noninvasive Imaging Modality ◽  
Magnetic Resonance Imaging Mri

Magnetic resonance imaging (MRI) is the most commonly used noninvasive imaging modality for epilepsy diagnosis, etiologic classification, and management. The availability of 3T scanners and multiple channel coils mean isotropic T2-weighted MRI can also be readily obtained with a similar spatial resolution to T1w MRI. These acquisitions in combination with quantitative morphometric techniques can be used to detect subtle cortical and subcortical brain abnormalities associated with epilepsy. Functional MRI (fMRI) methods including electroencephalography (EEG)-fMRI and resting state imaging have been used to study network activity, such as language and memory in surgical candidates. Diffusion MRI can be used to map white matter pathways and provide an alternative structural view of connections between brain regions. These techniques will increase the yield of abnormalities in epilepsy patients previously considered nonlesional.

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