T2-Weighted Dixon Turbo Spin Echo for Accelerated Simultaneous Grading of Whole-Body Skeletal Muscle Fat Infiltration and Edema in Patients With Neuromuscular Diseases

Objective The assessment of fatty infiltration and edema in the musculature of patients with neuromuscular diseases (NMDs) typically requires the separate performance of T-1-weighted and fat-suppressed T-2-weighted sequences. T-2-weighted Dixon turbo spin echo (TSE) enables the generation of T-2-weighted fat- and water-separated images, which can be used to assess both pathologies simultaneously. The present study examines the diagnostic performance of T-2-weighted Dixon TSE compared with the standard sequences in 10 patients with NMDs and 10 healthy subjects. Methods Whole-body magnetic resonance imaging was performed including T-1-weighted Dixon fast field echo, T-2-weighted short-tau inversion recovery, and T-2-weighted Dixon TSE. Fatty infiltration and intramuscular edema were rated by 2 radiologists using visual semiquantitative rating scales. To assess intermethod and interrater agreement, weighted Cohen's coefficients were calculated. Results The ratings of fatty infiltration showed high intermethod and high interrater agreement (T-1-weighted Dixon fast field echo vs T-2-weighted Dixon TSE fat image). The evaluation of edematous changes showed high intermethod and good interrater agreement (T-2-weighted short-tau inversion recovery vs T-2-weighted Dixon TSE water image). Conclusions T-2-weighted Dixon TSE imaging is an alternative for accelerated simultaneous grading of whole-body skeletal muscle fat infiltration and edema in patients with NMDs

Extending the Implicit Association Test (IAT): Assessing Consumer Attitudes Based on Multi-Dimensional Implicit Associations

Background: The authors present a procedural extension of the popular Implicit Association Test (IAT; [1]) that allows for indirect measurement of attitudes on multiple dimensions (e.g., safe–unsafe; young–old; innovative–conventional, etc.) rather than on a single evaluative dimension only (e.g., good–bad). Methodology/Principal Findings: In two within-subjects studies, attitudes toward three automobile brands were measured on six attribute dimensions. Emphasis was placed on evaluating the methodological appropriateness of the new procedure, providing strong evidence for its reliability, validity, and sensitivity. Conclusions/Significance: This new procedure yields detailed information on the multifaceted nature of brand associations that can add up to a more abstract overall attitude. Just as the IAT, its multi-dimensional extension/application (dubbed md-IAT) is suited for reliably measuring attitudes consumers may not be consciously aware of, able to express, or willing to share with the researcher [2,3].Product Innovation ManagementIndustrial Design Engineerin

Localised electrochemical impedance spectroscopy with high lateral resolution by means of alternating current scanning eletrochemical microscopy

A new method for measuring local interfacial impedance properties with high lateral resolution was developed by combination of electrochemical impedance spectroscopy (EIS) with scanning electrochemical microscopy (SECM). Alternating current scanning electrochemical microscopy (AC-SECM) allowed to identify and visualise microscopic domains of different conductivity/electrochemical activities on solid/liquid interfaces immersed into an electrolyte. The performance of the method was illustrated by imaging an array of Pt-band microelectrodes in solutions of low conductivity in the absence of any redox mediator. © 2002 Elsevier Science B.V. All rights reserved

Scanning electrochemical cell microscopy : theory and experiment for quantitative high resolution spatially-resolved voltammetry and simultaneous ion-conductance measurements

Scanning electrochemical cell microscopy (SECCM) is a high resolution electrochemical scanning probe technique that employs a dual-barrel theta pipet probe containing electrolyte solution and quasi-reference counter electrodes (QRCE) in each barrel. A thin layer of electrolyte protruding from the tip of the pipet ensures that a gentle meniscus contact is made with a substrate surface, which defines the active surface area of an electrochemical cell. The substrate can be an electrical conductor, semiconductor, or insulator. The main focus here is on the general case where the substrate is a working electrode, and both ion-conductance measurements between the QRCEs in the two barrels and voltammetric/amperometric measurements at the substrate can be made simultaneously. In usual practice, a small perpendicular oscillation of the probe with respect to the substrate is employed, so that an alternating conductance current (ac) develops, due to the change in the dimensions of the electrolyte contact (and hence resistance), as well as the direct conductance current (dc). It is shown that the dc current can be predicted for a fixed probe by solving the Nernst-Planck equation and that the ac response can also be derived from this response. Both responses are shown to agree well with experiment. It is found that the pipet geometry plays an important role in controlling the dc conductance current and that this is easily measured by microscopy. A key feature of SECCM is that mass transport to the substrate surface is by diffusion and, for charged analytes, ion migration which can be controlled and varied quantifiably via the bias between the two QRCEs. For a working electrode substrate this means that charged redox-active analytes can be transported to the electrode/solution interface in a well-defined and controllable manner and that relatively fast heterogeneous electron transfer kinetics can be studied. The factors controlling the voltammetric response are determined by both simulation and experiment. Experiments demonstrate the realization of simultaneous quantitative voltammetric and ion conductance measurements and also identify a general rule of thumb that the surface contacted by electrolyte is of the order of the pipet probe dimensions

Active sites for outer-sphere, inner-sphere, and complex multistage electrochemical reactions at polycrystalline boron-doped diamond electrodes (pBDD) revealed with scanning electrochemical cell microscopy (SECCM)

The local rate of heterogeneous electron transfer (HET) at polycrystalline boron-doped diamond (pBDD) electrodes has been visualized at high spatial resolution for various aqueous electrochemical reactions, using scanning electrochemical cell microscopy (SECCM), which is a technique that uses a mobile pipet-based electrochemical cell as an imaging probe. As exemplar systems, three important classes of electrode reactions have been investigated: outer-sphere (one-electron oxidation of ferrocenylmethyltrimethylammonium (FcTMA+)), inner-sphere (one-electron oxidation of Fe2+), and complex processes with coupled electron transfer and chemical reactions (oxidation of serotonin). In all cases, the pattern of reactivity is similar: the entire pBDD surface is electroactive, but there are variations in activity between different crystal facets which correlate directly with differences in the local dopant level, as visualized qualitatively by field-emission scanning electron microscopy (FE-SEM). No evidence was found for enhanced activity at grain boundaries for any of the reactions. The case of serotonin oxidation is particularly interesting, as this process is known to lead to deterioration of the electrodes, because of blocking by reaction products, and therefore cannot be studied with conventional scanning electrochemical probe microscopy (SEPM) techniques. Yet, we have found this system nonproblematic to study, because the meniscus of the scanning pipet is only in contact with the surface investigated for a brief time and any blocking product is left behind as the pipet moves to a new location. Thus, SECCM opens up the possibility of investigating and visualizing much more complex heterogeneous electrode reactions than possible presently with other SEPM techniques

Acceleration of chemical shift encoding-based water fat MRI for liver proton density fat fraction and T2* mapping using compressed sensing.

ObjectivesTo evaluate proton density fat fraction (PDFF) and T2* measurements of the liver with combined parallel imaging (sensitivity encoding, SENSE) and compressed sensing (CS) accelerated chemical shift encoding-based water-fat separation.MethodsSix-echo Dixon imaging was performed in the liver of 89 subjects. The first acquisition variant used acceleration based on SENSE with a total acceleration factor equal to 2.64 (acquisition labeled as SENSE). The second acquisition variant used acceleration based on a combination of CS with SENSE with a total acceleration factor equal to 4 (acquisition labeled as CS+SENSE). Acquisition times were compared between acquisitions and proton density fat fraction (PDFF) and T2*-values were measured and compared separately for each liver segment.ResultsTotal scan duration was 14.5 sec for the SENSE accelerated image acquisition and 9.3 sec for the CS+SENSE accelerated image acquisition. PDFF and T2* values did not differ significantly between the two acquisitions (paired Mann-Whitney and paired t-test P>0.05 in all cases). CS+SENSE accelerated acquisition showed reduced motion artifacts (1.1%) compared to SENSE acquisition (12.3%).ConclusionCS+SENSE accelerates liver PDFF and T2*mapping while retaining the same quantitative values as an acquisition using only SENSE and reduces motion artifacts