Permanent magnet based magnetic resonance sensors

In 2006 patent EP2069769A2 described using magnetic resonance (MR), instead of fluorescence, as the detection method for microarrays. This covered the concept of binding magnetic particles, such as Superparamagnetic Iron Oxide (SPIO), to a surface in order to change the MR signal that would normally be expected from the fluid covering the surface to which the particles were bound. In this thesis, measurement techniques are presented, utilising both pulsed and continuous wave nuclear magnetic resonance (CWNMR), where surface bound magnetic nanoparticles disrupt the MR signal that would normally be detected in the fluid covering the surface, using low magnetic field sensors constructed from permanent magnets. A pulsed technique is presented with a sensor constructed using permanent magnets in a Halbach arrangement. Using a technique called Magnetic Resonance Disruption (MaRDi), it is shown that the T2eff relaxation time of a test liquid, polydimethylsiloxane (PDMS), reduces as the proportion of the surface area covered with SPIO increases. In addition, a linear decrease in the signal amplitude from the PDMS as a function of SPIO coverage, which is observed both for an integral over 4096 NMR echoes and even just in the first echo. The latter result suggests the potential for a technique to be developed with simplified and low cost electronics. A CWNMR technique is also presented by revisiting the Look and Locker’s tone-burst experiments but modified to use a commercial marginal oscillator. Though observing the transient effect when a sweep coil is switched on, a parameter Tx can be determined that is related to relaxation time T1 that can subsequently be calculated with the aid of calibration samples. This Transient Effect Determination of Spin Lattice relaxation time (TEDSpiL) was automated using low cost microcontrollers. A potential industrial application of detecting moisture uptake through improperly stored dehydrated milk powder is also presented

A Low Cost Magnetic Resonance Relaxometry Sensor

Magnetic resonance relaxometry, conducted by measuring relaxation parameters at different field strengths, has become an increasingly popular technique in recent years. This technique, known as field cycling, often uses expensive and large electromagnets. In this work we present a small, portable field cycling sensor. Fast field cycling is a technique that uses a varying magnetic field applied to a sample, polarising it at a high field, allowing it time to develop at a lower field and then collecting the data at the same initial high field. This causes changes in T1 and can reveal interesting proper ties of the samples not seen by traditional methods. A prototype portable magnetic resonance sensor that undertakes relaxometry measurements using fast field cycling has been developed using a combination of permanent magnets which has been used to conduct preliminary studies on a water sample. We demonstrate the effectiveness of this sensor by conducting measurements of T1 at different field strengths

A magnetic resonance disruption (MaRDi) technique for the detection of surface immobilised magnetic nanoparticles

There are numerous assays that result in a surface with bound magnetic nanoparticles (MNP) whose number is proportional to the concentration of the analyte of interest. The techniques used to explore such assays are typically complex and costly. Since the presence of such MNP disrupts the pulsed magnetic resonance signal that would normally be detected from a fluid covering the surface, we present a measurement technique to quantify such assays. In this work we identify and characterise a suitable fluid for such measurements, namely 10 cSt viscosity PDMS oil of thickness 250 μm. We demonstrate that the Teff2 relaxation time from the PDMS reduces as the proportion of the surface area covered with MNP increases. Most significant however, is a linear decrease in the signal amplitude from the PDMS as a function of MNP coverage. This is observed both for the integral over 4096 echoes and also in the first echo promising simplified console electronics for rapid measurements

A microcontroller system for the automation of transient effect determination of the spin-lattice relaxation time using continuous wave NMR

A simple transient effect method for the determination of the spin-lattice relaxation time using continuous wave NMR (TEDSpiL) with a marginal oscillator was recently reported (doi:10.1002/mrc.4594). Such a system measures a parameter, called Tx, that is related to T1 and allows T1 to be determined with the aid of calibration samples. For such a system, the process of making the Tx measurement does not require variable parameters and so is ideal for implementing in microcontroller code. In this article, we demonstrate that TEDSpiL may be automated using two microcontrollers from the Teensy family to make a low power and portable system

Assessment of health care needs and utilization in a mixed public-private system: the case of the Athens area

BACKGROUND: Given the public-private mix of the Greek health system, the purpose of this study was to assess whether variations in the utilisation of health services, both primary and inpatient care, were associated with underlying health care needs and/or various socio-economic factors. METHODS: Data was obtained from a representative sample (N = 1426) residing in the broader Athens area (response rate 70.6%). Perceived health-related quality of life (HRQOL), as measured by the physical and mental summary component scores of the SF-36 Health Survey, was used as a proxy of health care need. Health care utilization was measured by a) last-month visits to public sector physicians, b) last-month visits to private sector physicians, c) last-year visits to hospital emergency departments and d) last-year hospital admissions. Statistical analysis involved the implementation of logistic regression models. RESULTS: Health care need was the factor most strongly associated with all measures of health care utilization, except for visits to public physicians. Women, elderly, less wealthy and individuals of lower physical health status visited physicians contracted to their insurance fund (public sector). Women, well educated and those once again of lower physical health status were more likely to visit private providers. Visits to hospital emergency departments and hospital admissions were related to need and no socio-economic factor was related to the use of those types of care. CONCLUSION: This study has demonstrated a positive relationship between health care need and utilisation of health services within a mixed public-private health care system. Concurrently, interesting differences are evident in the utilization of various types of services. The results have potential implications in health policy-making and particularly in the proper allocation of scarce health resources

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac