Optically detunable, inductively coupled coil for self-gating in small animal magnetic resonance imaging

2010 ◽  
Vol 65 (3) ◽  
pp. 882-888 ◽  
Author(s):  
Matthias Korn ◽  
Reiner Umathum ◽  
Jessica Schulz ◽  
Wolfhard Semmler ◽  
Michael Bock
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Small Animal ◽  
Resonance Imaging ◽  
Inductively Coupled

scholarly journals Numerical Analysis of a Flexible Dual Loop Coil and its Experimental Validation for pre-Clinical Magnetic Resonance Imaging of Rodents at 7 T

2016 ◽  
Vol 16 (6) ◽  
pp. 294-299 ◽  
Author(s):  
S. Solis-Najera ◽  
F. Vazquez ◽  
R. Hernandez ◽  
O. Marrufo ◽  
A.O. Rodriguez
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Imaging System ◽  
Ex Vivo ◽  
Small Animal ◽  
Magnetic Resonance Imaging System ◽  
External Diameter ◽  
Rf Coil ◽  
Resonance Imaging ◽  
Clinical Magnetic Resonance Imaging

Abstract A surface radio frequency coil was developed for small animal image acquisition in a pre-clinical magnetic resonance imaging system at 7 T. A flexible coil composed of two circular loops was developed to closely cover the object to be imaged. Electromagnetic numerical simulations were performed to evaluate its performance before the coil construction. An analytical expression of the mutual inductance for the two circular loops as a function of the separation between them was derived and used to validate the simulations. The RF coil is composed of two circular loops with a 5 cm external diameter and was tuned to 300 MHz and 50 Ohms matched. The angle between the loops was varied and the Q factor was obtained from the S11 simulations for each angle. B1 homogeneity was also evaluated using the electromagnetic simulations. The coil prototype was designed and built considering the numerical simulation results. To show the feasibility of the coil and its performance, saline-solution phantom images were acquired. A correlation of the simulations and imaging experimental results was conducted showing a concordance of 0.88 for the B1 field. The best coil performance was obtained at the 90° aperture angle. A more realistic phantom was also built using a formaldehyde-fixed rat phantom for ex vivo imaging experiments. All images showed a good image quality revealing clearly defined anatomical details of an ex vivo rat.

scholarly journals Agreement of Magnetic Resonance Imaging With Computed Tomography in the Assessment for Acute Skull Fractures in a Canine and Feline Cadaver Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Silke Hecht ◽  
Kimberly M. Anderson ◽  
Aude Castel ◽  
John F. Griffin ◽  
Adrien-Maxence Hespel ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Magnetic Resonance ◽  
Head Trauma ◽  
Imaging Modality ◽  
Small Animal ◽  
Skull Fractures ◽  
Resonance Imaging ◽  
Significant Difference ◽  
Mri Sequences

Computed tomography (CT) is the imaging modality of choice to evaluate patients with acute head trauma. However, magnetic resonance imaging (MRI) may be chosen in select cases. The objectives of this study were to evaluate the agreement of MRI with CT in the assessment for presence or absence of acute skull fractures in a canine and feline cadaver model, compare seven different MRI sequences (T1-W, T2-W, T2-FLAIR, PD-W, T2*-W, “SPACE” and “VIBE”), and determine agreement of four different MRI readers with CT data. Pre- and post-trauma CT and MRI studies were performed on 10 canine and 10 feline cadaver heads. Agreement of MRI with CT as to presence or absence of a fracture was determined for 26 individual osseous structures and four anatomic regions (cranium, face, skull base, temporomandibular joint). Overall, there was 93.5% agreement in assessing a fracture as present or absent between MRI and CT, with a significant difference between the pre and post trauma studies (99.4 vs. 87.6%; p < 0.0001; OR 0.042; 95% CI 0.034–0.052). There was no significant difference between dogs and cats. The agreement for the different MRI sequences with CT ranged from 92.6% (T2*-W) to 94.4% (PD-W). There was higher agreement of MRI with CT in the evaluation for fractures of the face than other anatomic regions. Agreement with CT for individual MRI readers ranged from 92.6 to 94.7%. A PD-W sequence should be added to the MR protocol when evaluating the small animal head trauma patient.

scholarly journals Magnetic Resonance Imaging in Animal Models of Alzheimer’s Disease Amyloidosis

2021 ◽  
Author(s):  
Ruiqing Ni
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Animal Models ◽  
Amyloid Beta ◽  
High Field ◽  
Diffusion Tensor ◽  
Small Animal ◽  
Resonance Imaging ◽  
Magnetic Resonance Imaging Mri

Amyloid-beta plays an important role in the pathogenesis of Alzheimer’s disease. Aberrant amyloid-beta and tau accumulation induce neuroinflammation, cerebrovascular alterations, synaptic deficits, functional deficits, and neurodegeneration, leading to cognitive impairment. Animal models recapitulating the amyloid-beta pathology such as transgenic, knock-in mouse and rat models have facilitated the understanding of disease mechanisms and development of therapeutics targeting at amyloid-beta. There is a rapid advance in high-field MR in small animals. Versatile high-field magnetic resonance imaging (MRI) sequences such as diffusion tensor imaging, arterial spin labelling, resting-state functional MRI, anatomical MRI, MR spectroscopy as well as contrast agents have been developed for the applications in animal models. These tools have enabled high-resolution in vivo structural, functional, and molecular readouts with a whole brain field-of-view. MRI have been utilized to visualize non-invasively the amyloid-beta deposits, synaptic deficits, regional brain atrophy, impairment in white matter integrity, functional connectivity, cerebrovascular and glymphatic system in animal models of amyloidosis. Many of the readouts are translational in clinical MRI in the brain of patients with Alzheimer’s disease. In this review, we summarize the recent advance of using MRI for visualizing the pathophysiology in amyloidosis animal model. We discuss the outstanding challenges in brain imaging using MRI in small animal and propose future outlook in visualizing amyloid-beta-related alterations in brain of animal models.

scholarly journals Improvement of magnetic resonance imaging using a wireless radiofrequency resonator array

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Akbar Alipour ◽  
Alan C. Seifert ◽  
Bradley N. Delman ◽  
Philip M. Robson ◽  
Raj Shrivastava ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
High Field ◽  
Simple Structure ◽  
7 Tesla ◽  
Resonance Imaging ◽  
Array Design ◽  
Inductively Coupled ◽  
Signal Sensitivity ◽  
Field Uniformity

AbstractIn recent years, new human magnetic resonance imaging systems operating at static magnetic fields strengths of 7 Tesla or higher have become available, providing better signal sensitivity compared with lower field strengths. However, imaging human-sized objects at such high field strength and associated precession frequencies is limited due to the technical challenges associated with the wavelength effect, which substantially disturb the transmit field uniformity over the human body when conventional coils are used. Here we report a novel passive inductively-coupled radiofrequency resonator array design with a simple structure that works in conjunction with conventional coils and requires only to be tuned to the scanner’s operating frequency. We show that inductive-coupling between the resonator array and the coil improves the transmit efficiency and signal sensitivity in the targeted region. The simple structure, flexibility, and cost-efficiency make the proposed array design an attractive approach for altering the transmit field distribution specially at high field systems, where the wavelength is comparable with the tissue size.

scholarly journals An Automated Open-Source Workflow for Standards-Compliant Integration of Small Animal Magnetic Resonance Imaging Data

2019 ◽  
Author(s):  
Horea-Ioan Ioanas ◽  
Markus Marks ◽  
Clément M. Garin ◽  
Marc Dhenain ◽  
Mehmet Fatih Yanik ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Data Structure ◽  
Magnetic Resonance ◽  
Open Source ◽  
Large Scale ◽  
Free Field ◽  
Small Animal ◽  
Field Operator ◽  
Imaging Data ◽  
Resonance Imaging

AbstractLarge-scale research integration is contingent on seamless access to data in standardized formats. Standards enable researchers to understand external experiment structures, pool results, and apply homogeneous preprocessing and analysis workflows. Particularly, they facilitate these features without the need for numerous potentially confounding compatibility add-ons. In small animal magnetic resonance imaging, an overwhelming proportion of data is acquired via the ParaVision software of the Bruker Corporation. The original data structure is predominantly transparent, but fundamentally incompatible with modern pipelines. Additionally, it sources metadata from free-field operator input, which diverges strongly between laboratories and researchers. In this article we present an open-source workflow which automatically converts and reposits data from the ParaVision structure into the widely supported and openly documented Brain Imaging Data Structure (BIDS). Complementing this workflow we also present operator guidelines for appropriate ParaVision data input, and a programmatic walk-through detailing how preexisting scans with uninterpretable metadata records can easily be made compliant after the acquisition.

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