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Special Issue "Magnetic Resonance Sensors"

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A special issue of Sensors (ISSN 1424-8220).

Deadline for manuscript submissions: closed (30 November 2013)

Special Issue Editors

Guest Editor
Dr. Robert H. Morris

Physics and Maths, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK
Website | E-Mail
Phone: +44 115 848 3123
Fax: +44 115 848 6636
Interests: Magnetic Resonance Hardware for imaging and for general sensing applications; waste water treatment and monitoring with an emphasis on constructed wetlands; Magnetic Resonance Elastography; Food process control and product stability monitoring; Extrinsic MRI contrast; Surface acoustic wave devices for fluid manipulation
Guest Editor
Dr. Michael I. Newton

Physics and Maths, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK
Website | E-Mail
Phone: 441158483365
Fax: +44 115 848 6636
Interests: Sensor applications of acoustic wave devices; Magnetic resonance based sensors; Applications of Superhydrophobic surfaces

Special Issue Information

Dear Colleagues,

Magnetic Resonance finds applications, from spectroscopy to imaging, on a routine basis in the majority of research and medical institutions. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for optimum operation. Magnetic Resonance sensors have been applied to fields as varied as petro-chemistry - with borehole logging, food engineering - with online process monitoring, emergency medicine - with point of care diagnostics and civil engineering - with sensors for monitoring cement drying. This great diversity is seeing exciting developments in magnetic resonance sensing technology published in application specific journals where they are often not seen by the wider sensor community.

It is clear that there is enormous interest in magnetic resonance sensors and this special edition of Sensors aims to address the wide distribution of relevant articles by providing a forum to disseminate cutting edge research in this field in a single open source publication.

We welcome submissions related to application-specific magnetic resonance sensor technologies, novel applications of sensors to magnetic resonance, new designs for magnetic resonance sensors or their components, new methods for acquiring or processing data collected from magnetic resonance sensors, and other topics within this field. Regular research articles and review articles are equally welcome.

Dr. Robert Morris
Dr. Michael Newton
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


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Keywords

  • magnetic resonance
  • applications
  • sensor design
  • relaxometry
  • relaxation time
  • diffusion
  • spin echo
  • pulse sequence

Published Papers (14 papers)

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Editorial

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Open AccessEditorial Magnetic Resonance Sensors
Sensors 2014, 14(11), 21722-21725; doi:10.3390/s141121722
Received: 7 November 2014 / Accepted: 13 November 2014 / Published: 17 November 2014
PDF Full-text (628 KB) | HTML Full-text | XML Full-text
Abstract
Magnetic Resonance finds countless applications, from spectroscopy to imaging, routinely in almost all research and medical institutions across the globe. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for a dedicated application.
[...] Read more.
Magnetic Resonance finds countless applications, from spectroscopy to imaging, routinely in almost all research and medical institutions across the globe. It is also becoming more frequently used for specific applications in which the whole instrument and system is designed for a dedicated application. With beginnings in borehole logging for the petro-chemical industry Magnetic Resonance sensors have been applied to fields as varied as online process monitoring for food manufacture and medical point of care diagnostics. This great diversity is seeing exciting developments in magnetic resonance sensing technology published in application specific journals where they are often not seen by the wider sensor community. It is clear that there is enormous interest in magnetic resonance sensors which represents a significant growth area. The aim of this special edition of Sensors was to address the wide distribution of relevant articles by providing a forum to disseminate cutting edge research in this field in a single open source publication.[...] Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available

Research

Jump to: Editorial, Review

Open AccessArticle Simultaneous Magnetic Resonance Imaging and Consolidation Measurement of Articular Cartilage
Sensors 2014, 14(5), 7940-7958; doi:10.3390/s140507940
Received: 19 December 2013 / Revised: 22 April 2014 / Accepted: 24 April 2014 / Published: 5 May 2014
Cited by 5 | PDF Full-text (888 KB) | HTML Full-text | XML Full-text
Abstract
Magnetic resonance imaging (MRI) offers the opportunity to study biological tissues and processes in a non-disruptive manner. The technique shows promise for the study of the load-bearing performance (consolidation) of articular cartilage and changes in articular cartilage accompanying osteoarthritis. Consolidation of articular cartilage
[...] Read more.
Magnetic resonance imaging (MRI) offers the opportunity to study biological tissues and processes in a non-disruptive manner. The technique shows promise for the study of the load-bearing performance (consolidation) of articular cartilage and changes in articular cartilage accompanying osteoarthritis. Consolidation of articular cartilage involves the recording of two transient characteristics: the change over time of strain and the hydrostatic excess pore pressure (HEPP). MRI study of cartilage consolidation under mechanical load is limited by difficulties in measuring the HEPP in the presence of the strong magnetic fields associated with the MRI technique. Here we describe the use of MRI to image and characterize bovine articular cartilage deforming under load in an MRI compatible consolidometer while monitoring pressure with a Fabry-Perot interferometer-based fiber-optic pressure transducer. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Figures

Open AccessArticle Degradation of Phosphate Ester Hydraulic Fluid in Power Station Turbines Investigated by a Three-Magnet Unilateral Magnet Array
Sensors 2014, 14(4), 6797-6805; doi:10.3390/s140406797
Received: 3 December 2013 / Revised: 25 March 2014 / Accepted: 28 March 2014 / Published: 14 April 2014
Cited by 4 | PDF Full-text (537 KB) | HTML Full-text | XML Full-text
Abstract
A three-magnet array unilateral NMR sensor with a homogeneous sensitive spot was employed for assessing aging of the turbine oils used in two different power stations. The Carr-Purcell-Meiboom-Gill (CPMG) sequence and Inversion Recovery-prepared CPMG were employed for measuring the 1H-NMR transverse and
[...] Read more.
A three-magnet array unilateral NMR sensor with a homogeneous sensitive spot was employed for assessing aging of the turbine oils used in two different power stations. The Carr-Purcell-Meiboom-Gill (CPMG) sequence and Inversion Recovery-prepared CPMG were employed for measuring the 1H-NMR transverse and longitudinal relaxation times of turbine oils with different service status. Two signal components with different lifetimes were obtained by processing the transverse relaxation curves with a numeric program based on the Inverse Laplace Transformation. The long lifetime components of the transverse relaxation time T2eff and longitudinal relaxation time T1 were chosen to monitor the hydraulic fluid aging. The results demonstrate that an increase of the service time of the turbine oils clearly results in a decrease of T2eff,long and T1,long. This indicates that the T2eff,long and T1,long relaxation times, obtained from the unilateral magnetic resonance measurements, can be applied as indices for degradation of the hydraulic fluid in power station turbines. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessArticle Towards Using NMR to Screen for Spoiled Tomatoes Stored in 1,000 L, Aseptically Sealed, Metal-Lined Totes
Sensors 2014, 14(3), 4167-4176; doi:10.3390/s140304167
Received: 28 November 2013 / Revised: 12 February 2014 / Accepted: 20 February 2014 / Published: 3 March 2014
Cited by 1 | PDF Full-text (331 KB) | HTML Full-text | XML Full-text
Abstract
Nuclear magnetic resonance (NMR) spectroscopy is used to track factory relevant tomato paste spoilage. It was found that spoilage in tomato paste test samples leads to longer spin lattice relaxation times T1 using a conventional low magnetic field NMR system. The increase
[...] Read more.
Nuclear magnetic resonance (NMR) spectroscopy is used to track factory relevant tomato paste spoilage. It was found that spoilage in tomato paste test samples leads to longer spin lattice relaxation times T1 using a conventional low magnetic field NMR system. The increase in T1 value for contaminated samples over a five day room temperature exposure period prompted the work to be extended to the study of industry standard, 1,000 L, non-ferrous, metal-lined totes. NMR signals and T1 values were recovered from a large format container with a single-sided NMR sensor. The results of this work suggest that a handheld NMR device can be used to study tomato paste spoilage in factory process environments. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessArticle Optimal Configuration for Relaxation Times Estimation in Complex Spin Echo Imaging
Sensors 2014, 14(2), 2182-2198; doi:10.3390/s140202182
Received: 27 November 2013 / Revised: 9 January 2014 / Accepted: 9 January 2014 / Published: 28 January 2014
Cited by 10 | PDF Full-text (2322 KB) | HTML Full-text | XML Full-text
Abstract
Many pathologies can be identified by evaluating differences raised in the physical parameters of involved tissues. In a Magnetic Resonance Imaging (MRI) framework, spin-lattice T1 and spin-spin T2 relaxation time parameters play a major role in such an identification. In this
[...] Read more.
Many pathologies can be identified by evaluating differences raised in the physical parameters of involved tissues. In a Magnetic Resonance Imaging (MRI) framework, spin-lattice T1 and spin-spin T2 relaxation time parameters play a major role in such an identification. In this manuscript, a theoretical study related to the evaluation of the achievable performances in the estimation of relaxation times in MRI is proposed. After a discussion about the considered acquisition model, an analysis on the ideal imaging acquisition parameters in the case of spin echo sequences, i.e., echo and repetition times, is conducted. In particular, the aim of the manuscript consists in providing an empirical rule for optimal imaging parameter identification with respect to the tissues under investigation. Theoretical results are validated on different datasets in order to show the effectiveness of the presented study and of the proposed methodology. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessCommunication Detection of Virgin Olive Oil Adulteration Using Low Field Unilateral NMR
Sensors 2014, 14(2), 2028-2035; doi:10.3390/s140202028
Received: 29 November 2013 / Revised: 20 January 2014 / Accepted: 23 January 2014 / Published: 24 January 2014
Cited by 7 | PDF Full-text (290 KB) | HTML Full-text | XML Full-text
Abstract
The detection of adulteration in edible oils is a concern in the food industry, especially for the higher priced virgin olive oils. This article presents a low field unilateral nuclear magnetic resonance (NMR) method for the detection of the adulteration of virgin olive
[...] Read more.
The detection of adulteration in edible oils is a concern in the food industry, especially for the higher priced virgin olive oils. This article presents a low field unilateral nuclear magnetic resonance (NMR) method for the detection of the adulteration of virgin olive oil that can be performed through sealed bottles providing a non-destructive screening technique. Adulterations of an extra virgin olive oil with different percentages of sunflower oil and red palm oil were measured with a commercial unilateral instrument, the profile NMR-Mouse. The NMR signal was processed using a 2-dimensional Inverse Laplace transformation to analyze the transverse relaxation and self-diffusion behaviors of different oils. The obtained results demonstrated the feasibility of detecting adulterations of olive oil with percentages of at least 10% of sunflower and red palm oils. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessArticle Calibrationless Parallel Magnetic Resonance Imaging: A Joint Sparsity Model
Sensors 2013, 13(12), 16714-16735; doi:10.3390/s131216714
Received: 10 October 2013 / Revised: 22 November 2013 / Accepted: 25 November 2013 / Published: 5 December 2013
Cited by 4 | PDF Full-text (805 KB) | HTML Full-text | XML Full-text
Abstract
State-of-the-art parallel MRI techniques either explicitly or implicitly require certain parameters to be estimated, e.g., the sensitivity map for SENSE, SMASH and interpolation weights for GRAPPA, SPIRiT. Thus all these techniques are sensitive to the calibration (parameter estimation) stage. In this work, we
[...] Read more.
State-of-the-art parallel MRI techniques either explicitly or implicitly require certain parameters to be estimated, e.g., the sensitivity map for SENSE, SMASH and interpolation weights for GRAPPA, SPIRiT. Thus all these techniques are sensitive to the calibration (parameter estimation) stage. In this work, we have proposed a parallel MRI technique that does not require any calibration but yields reconstruction results that are at par with (or even better than) state-of-the-art methods in parallel MRI. Our proposed method required solving non-convex analysis and synthesis prior joint-sparsity problems. This work also derives the algorithms for solving them. Experimental validation was carried out on two datasets—eight channel brain and eight channel Shepp-Logan phantom. Two sampling methods were used—Variable Density Random sampling and non-Cartesian Radial sampling. For the brain data, acceleration factor of 4 was used and for the other an acceleration factor of 6 was used. The reconstruction results were quantitatively evaluated based on the Normalised Mean Squared Error between the reconstructed image and the originals. The qualitative evaluation was based on the actual reconstructed images. We compared our work with four state-of-the-art parallel imaging techniques; two calibrated methods—CS SENSE and l1SPIRiT and two calibration free techniques—Distributed CS and SAKE. Our method yields better reconstruction results than all of them. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessArticle Software Defined Radio (SDR) and Direct Digital Synthesizer (DDS) for NMR/MRI Instruments at Low-Field
Sensors 2013, 13(12), 16245-16262; doi:10.3390/s131216245
Received: 3 October 2013 / Revised: 21 November 2013 / Accepted: 22 November 2013 / Published: 27 November 2013
Cited by 3 | PDF Full-text (314 KB) | HTML Full-text | XML Full-text
Abstract
A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital
[...] Read more.
A proof-of-concept of the use of a fully digital radiofrequency (RF) electronics for the design of dedicated Nuclear Magnetic Resonance (NMR) systems at low-field (0.1 T) is presented. This digital electronics is based on the use of three key elements: a Direct Digital Synthesizer (DDS) for pulse generation, a Software Defined Radio (SDR) for a digital receiving of NMR signals and a Digital Signal Processor (DSP) for system control and for the generation of the gradient signals (pulse programmer). The SDR includes a direct analog-to-digital conversion and a Digital Down Conversion (digital quadrature demodulation, decimation filtering, processing gain…). The various aspects of the concept and of the realization are addressed with some details. These include both hardware design and software considerations. One of the underlying ideas is to enable such NMR systems to “enjoy” from existing advanced technology that have been realized in other research areas, especially in telecommunication domain. Another goal is to make these systems easy to build and replicate so as to help research groups in realizing dedicated NMR desktops for a large palette of new applications. We also would like to give readers an idea of the current trends in this field. The performances of the developed electronics are discussed throughout the paper. First FID (Free Induction Decay) signals are also presented. Some development perspectives of our work in the area of low-field NMR/MRI will be finally addressed. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Figures

Open AccessArticle Embedded NMR Sensor to Monitor Compressive Strength Development and Pore Size Distribution in Hydrating Concrete
Sensors 2013, 13(12), 15985-15999; doi:10.3390/s131215985
Received: 8 October 2013 / Revised: 12 November 2013 / Accepted: 14 November 2013 / Published: 25 November 2013
Cited by 5 | PDF Full-text (1842 KB) | HTML Full-text | XML Full-text
Abstract
In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials.
[...] Read more.
In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials. The sensor consists of two NdFeB magnets having their North and South poles facing each other, separated by 7 mm to allow space for a Faraday cage containing a Teflon tube and an ellipsoidal RF coil. To account for magnetic field changes due to temperature variations, and/or the presence of steel rebars, or frequency variation due to sample impedance, an external tuning circuit was employed. The sensor performance was evaluated by analyzing the transverse magnetization decay obtained with a CPMG measurement from different materials, such as a polymer phantom, fresh white and grey cement pastes with different w/c ratios and concrete with low (0.30) and high (0.6) w/c ratios. The results indicated that the sensor is capable of detecting changes in water content in fresh cement pastes and porosity refinement caused by cement hydration in hardened materials, even if they are prepared with a low w/c ratio (w/c = 0.30). The short lifetime component of the transverse relaxation rate is directly proportional to the compressive strength of concrete determined by destructive testing. The r2 (0.97) from the linear relationship observed is similar to that obtained using T2 data from a commercial Oxford Instruments 12.9 MHz spectrometer. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessArticle Sensing Lanthanide Metal Content in Biological Tissues with Magnetic Resonance Spectroscopy
Sensors 2013, 13(10), 13732-13743; doi:10.3390/s131013732
Received: 22 August 2013 / Revised: 22 September 2013 / Accepted: 27 September 2013 / Published: 11 October 2013
Cited by 2 | PDF Full-text (509 KB) | HTML Full-text | XML Full-text
Abstract
The development and validation of MRI contrast agents consisting of a lanthanide chelate often requires a determination of the concentration of the agent in ex vivo tissue. We have developed a protocol that uses 70% nitric acid to completely digest tissue samples that
[...] Read more.
The development and validation of MRI contrast agents consisting of a lanthanide chelate often requires a determination of the concentration of the agent in ex vivo tissue. We have developed a protocol that uses 70% nitric acid to completely digest tissue samples that contain Gd(III), Dy(III), Tm(III), Eu(III), or Yb(III) ions, or the MRI contrast agent gadodiamide. NMR spectroscopy of coaxial tubes containing a digested sample and a separate control solution of nitric acid was used to rapidly and easily measure the bulk magnetic susceptibility (BMS) shift caused by each lanthanide ion and gadodiamide. Each BMS shift was shown to be linearly correlated with the concentration of each lanthanide ion and gadodiamide in the 70% nitric acid solution and in digested rat kidney and liver tissues. These concentration measurements had outstanding precision, and also had good accuracy for concentrations ³10 mM for Tm(III) Eu(III), and Yb(III), and ³3 mM for Gd(III), gadodiamide, and Dy(III). Improved sample handling methods are needed to improve measurement accuracy for samples with lower concentrations. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Figures

Open AccessArticle Fetal Electrocardiogram (fECG) Gated MRI
Sensors 2013, 13(9), 11271-11279; doi:10.3390/s130911271
Received: 20 July 2013 / Revised: 12 August 2013 / Accepted: 22 August 2013 / Published: 23 August 2013
Cited by 1 | PDF Full-text (412 KB) | HTML Full-text | XML Full-text
Abstract
We have developed a Magnetic Resonance Imaging (MRI)-compatible system to enable gating of a scanner to the heartbeat of a foetus for cardiac, umbilical cord flow and other possible imaging applications. We performed radiofrequency safety testing prior to a fetal electrocardiogram (fECG) gated
[...] Read more.
We have developed a Magnetic Resonance Imaging (MRI)-compatible system to enable gating of a scanner to the heartbeat of a foetus for cardiac, umbilical cord flow and other possible imaging applications. We performed radiofrequency safety testing prior to a fetal electrocardiogram (fECG) gated imaging study in pregnant volunteers (n = 3). A compact monitoring device with advanced software capable of reliably detecting both the maternal electrocardiogram (mECG) and fECG simultaneously was modified by the manufacturer (Monica Healthcare, Nottingham, UK) to provide an external TTL trigger signal from the detected fECG which could be used to trigger a standard 1.5 T MR (GE Healthcare, Milwaukee, WI, USA) gating system with suitable attenuation. The MR scanner was tested by triggering rapidly during image acquisition at a typical fetal heart rate (123 beats per minute) using a simulated fECG waveform fed into the gating system. Gated MR images were also acquired from volunteers who were attending for a repeat fetal Central Nervous System (CNS) examination using an additional rapid cardiac imaging sequence triggered from the measured fECG. No adverse safety effects were encountered. This is the first time fECG gating has been used with MRI and opens up a range of new possibilities to study a developing foetus. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Figures

Review

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Open AccessReview Hyperpolarized NMR Probes for Biological Assays
Sensors 2014, 14(1), 1576-1597; doi:10.3390/s140101576
Received: 28 November 2013 / Revised: 20 December 2013 / Accepted: 7 January 2014 / Published: 16 January 2014
Cited by 16 | PDF Full-text (3202 KB) | HTML Full-text | XML Full-text
Abstract
During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized) molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and
[...] Read more.
During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized) molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and detected with high sensitivity and contrast against background signals using high resolution NMR spectroscopy. A variety of natural, derivatized and designed hyperpolarized probes has emerged for diverse biological studies including assays of intracellular reaction progression, pathway kinetics, probe uptake and export, pH, redox state, reactive oxygen species, ion concentrations, drug efficacy or oncogenic signaling. These probes are readily used directly under natural conditions in biofluids and are often directly developed and optimized for cellular assays, thus leaving little doubt about their specificity and utility under biologically relevant conditions. Hyperpolarized molecular probes for biological NMR spectroscopy enable the unbiased detection of complex processes by virtue of the high spectral resolution, structural specificity and quantifiability of NMR signals. Here, we provide a survey of strategies used for the selection, design and use of hyperpolarized NMR probes in biological assays, and describe current limitations and developments. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Figures

Open AccessReview Optical Fiber-Based MR-Compatible Sensors for Medical Applications: An Overview
Sensors 2013, 13(10), 14105-14120; doi:10.3390/s131014105
Received: 30 July 2013 / Revised: 6 September 2013 / Accepted: 9 October 2013 / Published: 18 October 2013
Cited by 39 | PDF Full-text (414 KB) | HTML Full-text | XML Full-text
Abstract
During last decades, Magnetic Resonance (MR)—compatible sensors based on different techniques have been developed due to growing demand for application in medicine. There are several technological solutions to design MR-compatible sensors, among them, the one based on optical fibers presents several attractive features.
[...] Read more.
During last decades, Magnetic Resonance (MR)—compatible sensors based on different techniques have been developed due to growing demand for application in medicine. There are several technological solutions to design MR-compatible sensors, among them, the one based on optical fibers presents several attractive features. The high elasticity and small size allow designing miniaturized fiber optic sensors (FOS) with metrological characteristics (e.g., accuracy, sensitivity, zero drift, and frequency response) adequate for most common medical applications; the immunity from electromagnetic interference and the absence of electrical connection to the patient make FOS suitable to be used in high electromagnetic field and intrinsically safer than conventional technologies. These two features further heightened the potential role of FOS in medicine making them especially attractive for application in MRI. This paper provides an overview of MR-compatible FOS, focusing on the sensors employed for measuring physical parameters in medicine (i.e., temperature, force, torque, strain, and position). The working principles of the most promising FOS are reviewed in terms of their relevant advantages and disadvantages, together with their applications in medicine. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available
Open AccessReview Magnetic Resonance Imaging of Ischemia Viability Thresholds and the Neurovascular Unit
Sensors 2013, 13(6), 6981-7003; doi:10.3390/s130606981
Received: 16 February 2013 / Revised: 2 May 2013 / Accepted: 6 May 2013 / Published: 27 May 2013
Cited by 9 | PDF Full-text (1424 KB) | HTML Full-text | XML Full-text
Abstract
Neuroimaging has improved our understanding of the evolution of stroke at discreet time points helping to identify irreversibly damaged and potentially reversible ischemic brain. Neuroimaging has also contributed considerably to the basic premise of acute stroke therapy which is to salvage some portion
[...] Read more.
Neuroimaging has improved our understanding of the evolution of stroke at discreet time points helping to identify irreversibly damaged and potentially reversible ischemic brain. Neuroimaging has also contributed considerably to the basic premise of acute stroke therapy which is to salvage some portion of the ischemic region from evolving into infarction, and by doing so, maintaining brain function and improving outcome. The term neurovascular unit (NVU) broadens the concept of the ischemic penumbra by linking the microcirculation with neuronal-glial interactions during ischemia reperfusion. Strategies that attempt to preserve the individual components (endothelium, glia and neurons) of the NVU are unlikely to be helpful if blood flow is not fully restored to the microcirculation. Magnetic resonance imaging (MRI) is the foremost imaging technology able to bridge both basic science and the clinic via non-invasive real time high-resolution anatomical delineation of disease manifestations at the molecular and ionic level. Current MRI based technologies have focused on the mismatch between perfusion-weighted imaging (PWI) and diffusion weighted imaging (DWI) signals to estimate the tissue that could be saved if reperfusion was achieved. Future directions of MRI may focus on the discordance of recanalization and reperfusion, providing complimentary pathophysiological information to current compartmental paradigms of infarct core (DWI) and penumbra (PWI) with imaging information related to cerebral blood flow, BBB permeability, inflammation, and oedema formation in the early acute phase. In this review we outline advances in our understanding of stroke pathophysiology with imaging, transcending animal stroke models to human stroke, and describing the potential translation of MRI to image important interactions relevant to acute stroke at the interface of the neurovascular unit. Full article
(This article belongs to the Special Issue Magnetic Resonance Sensors) Print Edition available

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