Parametric Amplification of Magnetic Resonance Images

Syms, R.R.A.; Floume, Timmy; Young, I. R.; Solymár, L.; Rea, Marc

doi:10.1109/jsen.2011.2176928

Cited by 12 publications

(10 citation statements)

References 43 publications

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“…Qian et al amplification (23). Since the WAND is decoupled from the transmit field by a combination of static frequency offset (4 MHz) and dynamic resonance modulation, there was little B 1 distortion around the resonator, as evidenced by the homogeneous B 1 profile of the transmit coil in column 6.…”

Section: Technical Developments: Wireless Amplified Nuclear Mr Detectmentioning

confidence: 99%

Wireless Amplified Nuclear MR Detector (WAND) for High-Spatial-Resolution MR Imaging of Internal Organs: Preclinical Demonstration in a Rodent Model

Cui¹,

Yu²,

Chen³

et al. 2013

Radiology

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Purpose:To assess the feasibility of imaging deep-lying internal organs at high spatial resolution by imaging kidney glomeruli in a rodent model with use of a newly developed, wireless amplified nuclear magnetic resonance (MR) detector. Materials and Methods:This study was approved by the Animal Care and Use Committee at the National Institutes of Health/National Institute of Neurologic Disorder and Stroke. As a preclinical demonstration of this new detection technology, five different millimeter-scale wireless amplified nuclear MR detectors configured as double frequency resonators were chronically implanted on the medial surface of the kidney in five Sprague-Dawley rats for MR imaging at 11.7 T. Among these rats, two were administered gadopentetate dimeglumine to visualize renal tubules on T1-weighted gradient-refocused echo (GRE) images, two were administered cationized ferritin to visualize glomeruli on T2*-weighted GRE images, and the remaining rat was administered both gadopentetate dimeglumine and cationized ferritin to visualize the interleaved pattern of renal tubules and glomeruli. The image intensity in each pixel was compared with the local tissue signal intensity average to identify regions of hyper-or hypointensity. Results:T1-weighted images with 70-mm in-plane resolution and 200-mm section thickness were obtained within 3.2 minutes to image renal tubules, and T2*-weighted images of the same resolution were obtained within 5.8 minutes to image the glomeruli. Hyperintensity from gadopentetate dimeglumine enabled visualization of renal tubules, and hypointensity from cationic ferritin enabled visualization of the glomeruli. Conclusion:High-spatial-resolution images have been obtained to observe kidney microstructures in vivo with a wireless amplified nuclear MR detector.q RSNA, 2013 Supplemental material: http://radiology.rsna.org/lookup /suppl

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Section: Technical Developments: Wireless Amplified Nuclear Mr Detectmentioning

confidence: 99%

Wireless Amplified Nuclear MR Detector (WAND) for High-Spatial-Resolution MR Imaging of Internal Organs: Preclinical Demonstration in a Rodent Model

Cui¹,

Yu²,

Chen³

et al. 2013

Radiology

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“…A WAND can be implemented as a nonlinear multi-frequency resonator [ 20 ], [ 21 ]. By making the sum of its two lower resonance frequencies approximately equal to the highest resonance frequency, the resonator can utilize the wireless pumping signal at ω 3 (that is provided near its highest resonance frequency) to amplify the MR signal at ω 1 (that is detected near one of its lower resonance frequencies).…”

Section: Operation Principlementioning

confidence: 99%

Wireless Reconfigurable RF Detector Array for Focal and Multiregional Signal Enhancement

Qian

Cui

2020

IEEE Access

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Wirelessly Amplified NMR Detectors (WAND) can utilize wireless pumping power to amplify MRI signals in situ for sensitivity enhancement of deep-lying tissues that are difficult to access by conventional surface coils. To reconfigure between selective and simultaneous activation in a multielement array, each WAND has a dipole resonance mode for MR signal acquisition and two butterfly modes that support counter-rotating current circulation. Because detectors in the same row share the same lower butterfly frequency but different higher butterfly frequency, a pumping signal at the sum frequency of the dipole mode and the higher butterfly mode can selectively activate individual resonators, leading to 4-fold sensitivity gain over passive coupling. Meanwhile, a pumping signal at the sum frequency of the dipole mode and the lower butterfly mode can simultaneously activate multiple resonators in the same row, leading to 3-fold sensitivity gain over passive coupling. When multiple rows of detectors are parallelly aligned, each row has a unique lower butterfly frequency for consecutive activation during the acquisition interval of the others. This wireless detector array can be embedded beneath a headpost that is normally required for multi-modal brain imaging, enabling easy reconfiguration between focal imaging of individual vessels and multiregional mapping of brain connectivity.

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“…This amplified output at ω 2 can mix back with the pumping signal at ω 3 to create a second amplified output at ω 1 with phase Φ 3 −(Φ 3 −Φ 1 ), which can be detected by a standard external receiving coil (Fig. 1) [28], [29]. Basically, the enhancement procedure suggests that the pumping signal provides power needed for inphase signal amplification at the input frequency.…”

Section: A Operation Principlementioning

confidence: 99%

A Novel Expandable Catheter Wireless Amplified NMR Detector for MR Sensitivity Accessing the Kidney in Rodent Model

Timilsina

Cui

2019

IEEE Trans. Biomed. Circuits Syst.

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This article demonstrates the enlarged effective range for MRI sensitivity enhancement with a deformable catheter MRI coils integrated with a wirelessly powered amplifier. The expandable balloon Wireless Amplified Nuclear magnetic resonance Detector (WAND) is constructed on a copper-clad polyimide film to resonate at the first and second harmonics of the proton Larmor frequency at 7 Tesla. The WAND is then mounted on a balloon catheter system for easy delivery inside confined orifice. Upon reaching the region of interest, it is unfolded out of the sheath tube to increase its effective size. Magnetic Resonance (MR) imaging experiments with and without the WAND are performed both in a water phantom and in a live rat to evaluate the WAND's sensitivity advantage. Expanded from a 3 mm diameter in its folded state, this deformable WAND can change its width by > 100% in its inflated state to at least 6 mm, leading to a sensitive detection region extending to up to 20 mm in the transverse direction. When the deformable WAND is placed in an artery in the region of the kidney of a live rat, it could achieve at least a 10-fold SNR gain over images acquired by a standard external detector of 22 mm diameter, even though the region of interest is separated from the WAND's surface by a distance larger than the WAND's own width. The proposed expandable catheter WAND could significantly enlarge the effective range for MR sensitivity enhancement in-vivo, enabling versatile applications in interventional MRI.

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Parametric Amplification of Magnetic Resonance Images

Cited by 12 publications

References 43 publications

Wireless Amplified Nuclear MR Detector (WAND) for High-Spatial-Resolution MR Imaging of Internal Organs: Preclinical Demonstration in a Rodent Model

Wireless Amplified Nuclear MR Detector (WAND) for High-Spatial-Resolution MR Imaging of Internal Organs: Preclinical Demonstration in a Rodent Model

Wireless Reconfigurable RF Detector Array for Focal and Multiregional Signal Enhancement

A Novel Expandable Catheter Wireless Amplified NMR Detector for MR Sensitivity Accessing the Kidney in Rodent Model

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