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Foongkajornkiat S, Sokolowski K, Stephenson J, Lloyd T, Hugo HJ, Thompson EW, Momot KI. Quantitative measurement of mammographic density in breast-tissue explants using portable NMR: Precision and accuracy. Magn Reson Med 2024; 92:374-388. [PMID: 38380719 DOI: 10.1002/mrm.30040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 12/20/2023] [Accepted: 01/18/2024] [Indexed: 02/22/2024]
Abstract
PURPOSE Single-sided portable NMR (pNMR) has previously been demonstrated to be suitable for quantification of mammographic density (MD) in excised breast tissue samples. Here we investigate the precision and accuracy of pNMR measurements of MD ex vivo as compared with the gold standards. METHODS Forty-five breast-tissue explants from 9 prophylactic mastectomy patients were measured. The relative tissue water content was taken as the MD-equivalent quantity. In each sample, the water content was measured using some combination of three pNMR techniques (apparent T2, diffusion, and T1 measurements) and two gold-standard techniques (computed microtomography [μCT] and hematoxylin and eosin [H&E] histology). Pairwise correlation plots and Bland-Altman analysis were used to quantify the degree of agreement between pNMR techniques and the gold standards. RESULTS Relative water content measured from both apparent T2 relaxation spectra, and diffusion decays exhibited strong correlation with the H&E and μCT results. Bland-Altman analysis yielded average bias values of -0.4, -2.6, 2.6, and 2.8 water percentage points (pp) and 95% confidence intervals of 13.1, 7.5, 11.2, and 11.8 pp for the H&E - T2, μCT - T2, H&E - diffusion, and μCT - diffusion comparison pairs, respectively. T1-based measurements were found to be less reliable, with the Bland-Altman confidence intervals of 27.7 and 33.0 pp when compared with H&E and μCT, respectively. CONCLUSION Apparent T2-based and diffusion-based pNMR measurements enable quantification of MD in breast-tissue explants with the precision of approximately 10 pp and accuracy of approximately 3 pp or better, making pNMR a promising measurement modality for radiation-free quantification of MD.
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Affiliation(s)
- Satcha Foongkajornkiat
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Kamil Sokolowski
- Preclincal Imaging Facility, Translational Research Institute, Woolloongabba, Queensland, Australia
| | - James Stephenson
- Department of Breast and Endocrine Surgery, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
- Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Thomas Lloyd
- Department of Diagnostic Radiology, Princess Alexandra Hospital, Woolloongabba, Queensland, Australia
| | - Honor J Hugo
- School of Health and Behavioural Science, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- School of Medicine and Dentistry, Griffith University Sunshine Coast, Birtinya, Queensland, Australia
| | - Erik W Thompson
- Translational Research Institute, Woolloongabba, Queensland, Australia
- School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Konstantin I Momot
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, Queensland, Australia
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He J, Kong X, Xu Z. Improving the SNR of UMR sensor using LC resonator. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 356:107580. [PMID: 37924681 DOI: 10.1016/j.jmr.2023.107580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/06/2023]
Abstract
Single-sided or unilateral magnetic resonance (UMR) technology has various benefits, such as an open structure, low cost, portability, and nondestructive measurement, in contrast to the conventional closed magnet structure. UMR is widely used in material analysis, well logging, and biomedicine. However, its development is constrained by its poor signal-to-noise ratio (SNR). To enhance the SNR of UMR sensor, a surface coil of LC resonator is added on the Radio Frequency (RF) coil. First, a method of calculating the current in the RF coil including LC resonator is derived. Next, the equivalent AC resistance of the coil is calculated using the partial-element equivalent-circuit (PEEC) method. Finally, the SNR of a UMR sensor incorporating LC resonator is analyzed, and its sensitivity map is provided. Experimental comparisons are made between the UMR sensor with and without a LC resonator. Results show that the SNR of the UMR can be enhanced by up to three times after the LC resonator is loaded. The SNR improves within 30 mm of the coil surface, and this beneficial effect steadily diminishes as the distance increases. This study offers a useful method for improving the signal of UMR sensors.
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Affiliation(s)
- Jiali He
- School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Xiaohan Kong
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814, Japan
| | - Zheng Xu
- School of Electrical Engineering, Chongqing University, Chongqing, China.
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NMR Profiling of Reaction and Transport in Thin Layers: A Review. Polymers (Basel) 2022; 14:polym14040798. [PMID: 35215714 PMCID: PMC8963059 DOI: 10.3390/polym14040798] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/25/2022] [Accepted: 02/14/2022] [Indexed: 02/04/2023] Open
Abstract
Reaction and transport processes in thin layers of between 10 and 1000 µm are important factors in determining their performance, stability and degradation. In this review, we discuss the potential of high-gradient Nuclear Magnetic Resonance (NMR) as a tool to study both reactions and transport in these layers spatially and temporally resolved. As the NMR resolution depends on gradient strength, the high spatial resolution required in submillimeter layers can only be achieved with specially designed high-gradient setups. Three different high-gradient setups exist: STRAFI (STRay FIeld), GARField (Gradient-At-Right-angles-to-Field) and MOUSE (MObile Universal Surface Explorer). The aim of this review is to provide a detailed overview of the three techniques and their ability to visualize reactions and transport processes using physical observable properties such as hydrogen density, diffusion, T1- and T2-relaxation. Finally, different examples from literature will be presented to illustrate the wide variety of applications that can be studied and the corresponding value of the techniques.
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Wald LL, McDaniel PC, Witzel T, Stockmann JP, Cooley CZ. Low-cost and portable MRI. J Magn Reson Imaging 2020; 52:686-696. [PMID: 31605435 PMCID: PMC10644353 DOI: 10.1002/jmri.26942] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/04/2019] [Indexed: 11/16/2023] Open
Abstract
Research in MRI technology has traditionally expanded diagnostic benefit by developing acquisition techniques and instrumentation to enable MRI scanners to "see more." This typically focuses on improving MRI's sensitivity and spatiotemporal resolution, or expanding its range of biological contrasts and targets. In complement to the clear benefits achieved in this direction, extending the reach of MRI by reducing its cost, siting, and operational burdens also directly benefits healthcare by increasing the number of patients with access to MRI examinations and tilting its cost-benefit equation to allow more frequent and varied use. The introduction of low-cost, and/or truly portable scanners, could also enable new point-of-care and monitoring applications not feasible for today's scanners in centralized settings. While cost and accessibility have always been considered, we have seen tremendous advances in the speed and spatial-temporal capabilities of general-purpose MRI scanners and quantum leaps in patient comfort (such as magnet length and bore diameter), but only modest success in the reduction of cost and siting constraints. The introduction of specialty scanners (eg, extremity, brain-only, or breast-only scanners) have not been commercially successful enough to tilt the balance away from the prevailing model: a general-purpose scanner in a centralized healthcare location. Portable MRI scanners equivalent to their counterparts in ultrasound or even computed tomography have not emerged and MR monitoring devices exist only in research laboratories. Nonetheless, recent advances in hardware and computational technology as well as burgeoning markets for MRI in the developing world has created a resurgence of interest in the topic of low-cost and accessible MRI. This review examines the technical forces and trade-offs that might facilitate a large step forward in the push to "jail-break" MRI from its centralized location in healthcare and allow it to reach larger patient populations and achieve new uses. Level of Evidence: 5 Technical Efficacy Stage: 6 J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2020;52:686-696.
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Affiliation(s)
- Lawrence L. Wald
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
- Division of Health Sciences and Technology, Harvard – Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Patrick C. McDaniel
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Thomas Witzel
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Jason P. Stockmann
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
| | - Clarissa Zimmerman Cooley
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
- Harvard Medical School, Boston, Massachusetts, USA
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Ansari F, McGuiness C, Zhang B, Dauskardt RH. Effect of emulsifiers on drying stress and intercellular cohesion in human stratum corneum. Int J Cosmet Sci 2020; 42:581-589. [PMID: 32567061 DOI: 10.1111/ics.12643] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Emulsifier molecules, with their amphiphilic character, are ubiquitous in moisturizing creams and primarily serve to disperse the water-insoluble molecules such as emollients, oils, lipids and fats in water. The objective of this study was to investigate the effect of emulsifier molecules on the barrier and biomechanical properties of human stratum corneum (SC) and to compare the efficacy of emulsifier molecules when used in a fully formulated moisturizing cream. METHODS We employed methods based on thin-film mechanics to measure the drying stress and intercellular cohesion in the SC. The emulsifier molecules or moisturizing creams formulated with them were applied to a fully hydrated SC adhered to a glass substrate. In-plane stress developed in the SC during drying was then measured by tracking changes in the curvature of the glass substrate. The intercellular cohesion within the SC was measured by means of a double cantilever beam (DCB) set-up, where the treated or untreated SC was sandwiched between two substrates, and the delamination energy calculated by measuring the force required to drive a crack through the SC. Moisturizing cream diffusivity through the stratum corneum was measured by spectroscopic technique and related to internal SC stress and fracture energy. RESULTS We observe significant differences in the biomechanical behaviour of SC when moisturizing creams with different emulsifier molecules are applied on isolated stratum corneum ex vivo. The reduction in maximum stress varied between 12% and 26% depending on the emulsifier molecules used in the formulation. The intercellular cohesion and the diffusion of molecules in the formulated moisturizing creams through the SC were also found to be strongly dependent on the type of emulsifier molecule used in the formulation. CONCLUSIONS The biomechanical and barrier properties of the human stratum corneum show strong dependence on the emulsifier molecule used in the moisturizing creams, even when the creams included only ~3 weight% emulsifier molecules. Moreover, we found that the reduction in SC peak stress was strongly correlated with the formulation diffusivity into the SC. The moisturizing creams diffusing fastest into the SC had the largest reduction in peak stress and vice versa.
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Affiliation(s)
- F Ansari
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - C McGuiness
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA.,Solvay USA Inc, 350 George Patterson Blvd, Bristol, PA, 19007, USA
| | - B Zhang
- Solvay Inc, Jindu Road 3966, Xinzhuang Industrial zone, Shanghai, 201108, China
| | - R H Dauskardt
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
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Bergman E, Yeredor A, Nevo U. An estimation method of MR signal parameters for improved image reconstruction in unilateral scanner. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 237:92-99. [PMID: 24184709 DOI: 10.1016/j.jmr.2013.09.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 09/24/2013] [Accepted: 09/26/2013] [Indexed: 06/02/2023]
Abstract
Unilateral NMR devices are used in various applications including non-destructive testing and well logging, but are not used routinely for imaging. This is mainly due to the inhomogeneous magnetic field (B0) in these scanners. This inhomogeneity results in low sensitivity and further forces the use of the slow single point imaging scan scheme. Improving the measurement sensitivity is therefore an important factor as it can improve image quality and reduce imaging times. Short imaging times can facilitate the use of this affordable and portable technology for various imaging applications. This work presents a statistical signal-processing method, designed to fit the unique characteristics of imaging with a unilateral device. The method improves the imaging capabilities by improving the extraction of image information from the noisy data. This is done by the use of redundancy in the acquired MR signal and by the use of the noise characteristics. Both types of data were incorporated into a Weighted Least Squares estimation approach. The method performance was evaluated with a series of imaging acquisitions applied on phantoms. Images were extracted from each measurement with the proposed method and were compared to the conventional image reconstruction. All measurements showed a significant improvement in image quality based on the MSE criterion - with respect to gold standard reference images. An integration of this method with further improvements may lead to a prominent reduction in imaging times aiding the use of such scanners in imaging application.
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Affiliation(s)
- Elad Bergman
- The Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Arie Yeredor
- The Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Uri Nevo
- The Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel.
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7
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Liberman A, Bergman E, Sarda Y, Nevo U. Faster imaging with a portable unilateral NMR device. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 231:72-78. [PMID: 23597948 DOI: 10.1016/j.jmr.2013.03.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 03/18/2013] [Accepted: 03/21/2013] [Indexed: 06/02/2023]
Abstract
Unilateral NMR devices are important tools in various applications such as non-destructive testing and well logging, but are not applied routinely for imaging, primarily because B0 inhomogeneity in these scanners leads to a relatively low signal and requires use of the slow single point imaging scan scheme. Enabling high quality, fast imaging could make this affordable and portable technology practical for various imaging applications as well as for new applications that are not yet feasible with MRI technology. The goal of this work was to improve imaging times in a portable unilateral NMR scanner. Both Compressed Sensing and Fast Spin Echo were modified and applied to fit the unique characteristics of a unilateral device. Two printed phantoms, allowing high resolution images, were scanned with both methods and compared to a standard scan and to a low pass scan to evaluate performance. Both methods were found to be feasible with a unilateral device, proving ways to accelerate single point imaging in such scanners. This outcome encourages us to explore how to further accelerate imaging times in unilateral NMR devices so that this technology might become clinically applicable in the future.
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Affiliation(s)
- Asaf Liberman
- Department of Biomedical Engineering, The Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
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Windbergs M, Hansen S, Schroeter A, Schaefer U, Lehr CM, Bouwstra J. From the Structure of the Skin Barrier and Dermal Formulations to in vitro Transport Models for Skin Absorption: Skin Research in the Netherlands and in Germany. Skin Pharmacol Physiol 2013; 26:317-30. [DOI: 10.1159/000351936] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 03/03/2013] [Indexed: 11/19/2022]
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9
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Rawlings AV, Lombard KJ. A review on the extensive skin benefits of mineral oil. Int J Cosmet Sci 2012; 34:511-8. [PMID: 22994201 DOI: 10.1111/j.1468-2494.2012.00752.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 08/14/2012] [Indexed: 11/28/2022]
Abstract
This review was initially prepared in 2011 before Professor Johann Wiechers tragically passed away. It has been updated and is being published in his memory. It discusses the importance of mineral oil and its benefits to skin. Its source, structure, properties and efficacy are discussed. Mineral oil has been shown to improve skin softness and barrier function better than some other emollients using the gas-bearing dynamometer and standard water vapour transmission testing as well as in vivo studies showing its effects on suppressing transepidermal water loss (TEWL). It has also been subjected to the rigour of the newer in vivo confocal microscopic measurements now used for testing the performance of moisturizers by following the swelling characteristics of the stratum corneum and been found favourable compared with many vegetable oils. Its introduction as a cosmetic oil was in the late 1800s, and still today, it is used as one of the main components of moisturizers, a true testament to its cost to efficacy window. Naturally, it has physical effects on the stratum corneum, but it is expected that these will translate into biological effects simply through its mechanism of hydrating and occluding the stratum corneum from which many benefits are derived.
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Koptyug IV. MRI of mass transport in porous media: drying and sorption processes. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 65:1-65. [PMID: 22781314 DOI: 10.1016/j.pnmrs.2011.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 12/05/2011] [Indexed: 06/01/2023]
Affiliation(s)
- Igor V Koptyug
- International Tomography Center, SB RAS, 3A Institutskaya Str., Novosibirsk 630090, Russian Federation.
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11
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Ciampi E, van Ginkel M, McDonald PJ, Pitts S, Bonnist EYM, Singleton S, Williamson AM. Dynamic in vivo mapping of model moisturiser ingress into human skin by GARfield MRI. NMR IN BIOMEDICINE 2011; 24:135-144. [PMID: 20842757 DOI: 10.1002/nbm.1562] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 04/12/2010] [Accepted: 04/12/2010] [Indexed: 05/29/2023]
Abstract
We describe the development of in vivo one-dimensional MRI (profiling) using a GARField (Gradient At Right angles to Field) magnet for the characterisation of side-of-hand human skin. For the first time and in vivo, we report measurements of the NMR longitudinal and transverse relaxation parameters and self-diffusivity of the upper layers of human skin with a nominal spatial resolution better than 10 µm. The results are correlated with in vivo confocal Raman spectroscopy measurements of water concentration and natural moisturiser factors, and discussed in terms of known skin biology and microstructure of the stratum corneum and viable epidermis. The application of model moisturiser solutions to the skin is followed and their dynamics of ingress are characterised using the MRI methodology developed. Selected hydrophilic and lipophilic formulations are studied. The results are corroborated by standard in vivo measurements of transepidermal water loss and hydration status. A further insight into moisturisation mechanisms is gained. The effect of two different penetration enhancers on a commonly used skin care oil is also discussed, and different timescales of oil penetration into the skin are reported depending on the type of enhancer.
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Abstract
A thorough examination of the skin is essential to screen various diseases accurately, evaluate the effectiveness of topically applied drugs and assess the results of dermatological surgeries such as skin grafts. The assessment of skin properties is also crucial in the cosmetics industry, where it is important to evaluate the effects skin care products have on these properties. The simplest and most widely used method of skin evaluation, the 'naked eye' assessment, enables researchers to assess only the skin surface and involves a large amount of inter-observer variability. Thanks to a great progress that has been made in physics, electronics and computer engineering in recent years, sophisticated imaging methods are increasingly available in day-to-day studies. The aim of this review was to present one of these techniques, namely the magnetic resonance imaging (MRI), and to discuss its possible use in skin examination and analysis. We present basic principles of MRI, as well as several interesting applications in the field of dermatology, and discuss the advantages and limitations of this method.
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Affiliation(s)
- J Stefanowska
- Department of Pharmaceutical Technology, Medical University of Gdansk, Gdansk, Poland
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Andrew Chan KL, Kazarian SG. Chemical imaging of the stratum corneum under controlled humidity with the attenuated total reflection Fourier transform infrared spectroscopy method. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:044010. [PMID: 17867814 DOI: 10.1117/1.2754686] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Attenuated total reflection Fourier transform infrared spectroscopic imaging was applied to study human stratum corneum (SC) tissue, the outermost layer of the skin. This imaging approach was combined with a controlled environment cell to demonstrate the possibility of obtaining chemical images of SC exposed to a wide range of relative humidities and diffusion of ethanol through the SC tissue with a specially designed liquid cell. The effect of water vapor sorbed into the SC on the distribution of other components in the SC was studied. Principal component analysis was applied in conjunction with univariate analysis to differentiate the distribution of different components in the SC. Swelling of the SC, a heterogeneous distribution of natural moisturizing factor and water, was detected upon the increase of relative humidity. The approach to image the penetration of liquid ethanol into the SC was also demonstrated and showed good potential and implications for studying transdermal drug delivery.
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Affiliation(s)
- K L Andrew Chan
- Imperial College London, Department of Chemical Engineering, London, SW7 2AZ, United Kingdom
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McDonald PJ, Aptaker PS, Mitchell J, Mulheron M. A unilateral NMR magnet for sub-structure analysis in the built environment: the Surface GARField. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2007; 185:1-11. [PMID: 17123850 DOI: 10.1016/j.jmr.2006.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 10/31/2006] [Accepted: 11/01/2006] [Indexed: 05/12/2023]
Abstract
A new, portable NMR magnet with a tailored magnetic field profile and a complementary radio frequency sensor have been designed and constructed for the purpose of probing in situ the sub-surface porosity of cement based materials in the built environment. The magnet is a one sided device akin to a large NMR-MOUSE with the additional design specification of planes of constant field strength /B0/ parallel to the surface. There is a strong gradient G in the field strength perpendicular to these planes. As with earlier GARField magnets, the ratio G//:B0/ is a system constant although the method of achieving this condition is substantially different. The new magnet as constructed is able to detect signals 50mm (1H NMR at 3.2 MHz) away from the surface of the magnet and can profile the surface layers of large samples to a depth of 35-40 mm by moving the magnet, and hence the resonant plane of the polarising field, relative to the sample surface. The matching radio frequency excitation/detector coil has been designed to complement the static magnetic field such that the polarising B0 and sensing B1 fields are, in principal, everywhere orthogonal. Preliminary spatially resolved measurements are presented of cement based materials, including two-dimensional T1-T2 relaxation correlation spectra.
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Affiliation(s)
- P J McDonald
- School of Electronics and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.
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Garidel P. Monitoring the Penetration and Distribution of Topically Applied Formulations through the Skin in Relation to the Skin Protein/Lipid Morphological Characteristics. ACTA ACUST UNITED AC 2006. [DOI: 10.1159/000088011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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McDonald PJ, Akhmerov A, Backhouse LJ, Pitts S. Magnetic resonance profiling of human skin in vivo using GARField magnets. J Pharm Sci 2005; 94:1850-60. [PMID: 15986454 DOI: 10.1002/jps.20401] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It is shown that one-dimensional magnetic resonance imaging (MRI-profiling) of human forearm and side-of-hand skin in vivo is possible using GARField magnets. Strong profile contrast originating from differing molecular mobility is seen for stratum corneum and viable epidermis. The first in vivo spatially-resolved field-gradient measurements of water self-diffusivity, D, in the stratum corneum (2.0 x 10(-6) cm(2)/s) and viable epidermis (8.5 x 10(-6) cm(2)/s) are reported. Also reported are spatially resolved measurements of the (1)H spin-lattice relaxation time, T(1), the spin-spin relaxation time, T(2). It is further shown that the application of moisturizing agents to the skin noticeably affects the profiles. However, universal behavior is not seen as both signal increases and decreases are observed dependent on agent and volunteer.
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Affiliation(s)
- P J McDonald
- Department of Physics, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom.
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