scholarly journals Multifrequency magnetic resonance elastography-based tomoelastography of the parotid glands–feasibility and reference values

2021 ◽  
pp. 20210337
Author(s):  
Fabian Henry Jürgen Elsholtz ◽  
Rolf Reiter ◽  
Stephan Rodrigo Marticorena Garcia ◽  
Jürgen Braun ◽  
Ingolf Sack ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Reference Values ◽  
Viscoelastic Properties ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Parotid Glands ◽  
Retest Reliability ◽  
Shear Wave Speed ◽  
Test Retest Reliability ◽  
Healthy Participants

Objectives: Accurate radiological differentiation of parotid tumors remains challenging despite recent technical advances in quantitative medical imaging. Multifrequency magnetic resonance elastography (MRE) could provide additional information on viscoelastic properties of normal and abnormal biological tissues. This study investigates the feasibility of MRE of the parotid glands in healthy participants and provides first reference values. Methods: 20 healthy participants underwent multifrequency MRE of both parotid glands at 3 Tesla. Shear waves at frequencies of 25, 30, 40, and 50 Hz were introduced into the participants' heads through the occiput using pressurized-air actuators. Shear wave speed (SWS) and loss angle of the shear modulus (φ) were reconstructed by tomoelastography post-processing as surrogate parameters for tissue stiffness and viscosity or fluidity. 10 participants underwent repeated MRE to determine test–retest reliability based on intraclass correlation coefficients. Results: All MRE datasets acquired could be included in the analysis. Mean SWS was 0.97 ± 0.13 m/s, and mean φ was 0.59 ± 0.05 rad, each for both sides combined and without notable lateral difference (p = 0.88/0.87). Test–retest reliability was good for SWS (ICC = 0.84 for both sides/ICC = 0.77 for the right side/ICC = 0.79 for the left side) and good to excellent for φ(ICC = 0.94/0.86/0.90). Conclusions: Multifrequency MRE of the parotid glands is feasible and reliable. This technique, therefore, is a promising method for investigating the viscoelastic properties of salivary gland tumors in future studies.

scholarly journals Comparative analysis of indentation and magnetic resonance elastography for measuring viscoelastic properties

2021 ◽  
Author(s):  
Yu Chen ◽  
Suhao Qiu ◽  
Zhao He ◽  
Fuhua Yan ◽  
Ruokun Li ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Viscoelastic Properties ◽  
Soft Tissues ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Small Samples ◽  
Model Parameters ◽  
In Vivo Measurement ◽  
Pathological Behavior

Abstract Measurement the viscoelastic properties is important for studying the developmental and pathological behavior of soft biological tissues. Magnetic resonance elastography (MRE) is a non-invasive method for in vivo measurement of tissue viscoelasticity. As a flexible method capable of testing small samples, indentation has been widely used for characterizing soft tissues. Using 2nd-order Prony series and dimensional analysis, we analyzed and compared the model parameters estimated from both indentation and MRE. Conversions of the model parameters estimated from the two methods were established. We found that the indention test is better at capturing the dynamic response of tissues at a frequency less than 10 Hz, while MRE is better for describing the frequency responses at a relatively higher range. The results provided helpful information for testing soft tissues using indentation and MRE. The models analyzed are also helpful for quantifying the frequency response of viscoelastic tissues. Graphic Abstract

scholarly journals Lorentz force induced shear waves for magnetic resonance elastography applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillaume Flé ◽  
Guillaume Gilbert ◽  
Pol Grasland-Mongrain ◽  
Guy Cloutier
Keyword(s):  
Magnetic Resonance ◽  
Shear Wave ◽  
Lorentz Force ◽  
Wave Attenuation ◽  
Shear Waves ◽  
Estimation Method ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Motion Generation ◽  
Wave Source

AbstractQuantitative mechanical properties of biological tissues can be mapped using the shear wave elastography technique. This technology has demonstrated a great potential in various organs but shows a limit due to wave attenuation in biological tissues. An option to overcome the inherent loss in shear wave magnitude along the propagation pathway may be to stimulate tissues closer to regions of interest using alternative motion generation techniques. The present study investigated the feasibility of generating shear waves by applying a Lorentz force directly to tissue mimicking samples for magnetic resonance elastography applications. This was done by combining an electrical current with the strong magnetic field of a clinical MRI scanner. The Local Frequency Estimation method was used to assess the real value of the shear modulus of tested phantoms from Lorentz force induced motion. Finite elements modeling of reported experiments showed a consistent behavior but featured wavelengths larger than measured ones. Results suggest the feasibility of a magnetic resonance elastography technique based on the Lorentz force to produce an shear wave source.

scholarly journals The Brief International Cognitive Assessment in Multiple Sclerosis (BICAMS): Validation in Arabic and Lebanese Normative Values

2021 ◽  
pp. 1-10
Author(s):  
Hala Darwish ◽  
Pia Zeinoun ◽  
Natali Farran ◽  
Husam Ghusn ◽  
Bassem Yamout ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Psychometric Properties ◽  
Cognitive Assessment ◽  
Healthy Subjects ◽  
Good Evidence ◽  
Normative Values ◽  
Arabic Version ◽  
Retest Reliability ◽  
Test Retest Reliability ◽  
Healthy Participants

Abstract Objective: Multiple sclerosis (MS) is often associated with cognitive deficits. Accurate evaluation of the MS patients’ cognitive performance is essential for diagnosis and treatment recommendation. The Brief International Cognitive Assessment in Multiple Sclerosis (BICAMS), widely used cognitive testing battery, examines processing speed, verbal and visuospatial learning, and memory. Our study aims to examine the psychometric properties of an Arabic version of the BICAMS and to provide normative values in a Lebanese sample. Method: The BICAMS, comprised of the Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMT-R), and a newly developed verbal learning/memory test, the Verbal Memory Arabic Test (VMAT), were administered on healthy subjects and MS patients. The sample consisted of 180 healthy individuals, of whom 63 were retested after 2–3 weeks. Forty-three MS patients matched with 43 healthy subjects based on age, sex, and years of education were assessed. A sample of 10 MS patients was also examined on two occasions. Test–retest reliability and criterion-related validity were examined, and regression-based norms were derived. Results: The test–retest correlations showed good evidence of reliability with coefficients ranging between 0.64 and 0.73 in the healthy sample, and between 0.43 and 0.92 in the MS sample. The BICAMS was able to discriminate between MS patients and matched healthy participants on the SDMT and BVMT-R. Normative data were comparable to other studies. Conclusions: This new Arabic version of the BICAMS shows initial good psychometric properties. While good evidence of VMAT’s reliability was shown in the healthy participants, less test–retest reliability in this tool was seen in the MS group, and partial criterion-related validity was evident. This renders further examination of the VMAT. We provide regression-based norms for a Lebanese sample and encourage the use of this battery in both research and clinical settings.

The Minnesota Manual Dexterity Test: Reliability, Validity and Reference Values Studies with Healthy Elderly People

1997 ◽  
Vol 64 (5) ◽  
pp. 270-276 ◽  
Author(s):  
Johanne Desrosiers ◽  
Annie Rochette ◽  
Réjean Hébert ◽  
Gina Bravo
Keyword(s):  
Elderly People ◽  
Reference Values ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Manual Dexterity ◽  
Test Reliability ◽  
Retest Reliability ◽  
Healthy Elderly ◽  
Block Test ◽  
Test Retest Reliability

Several dexterity tests have been developed, including the Minnesota Rate of Manipulation Test (MRMT) and a new version, the Minnesota Manual Dexterity Test (MMDT). The objectives of the study were: a) to verify the test-retest reliability of the MMDT; b) to compare the MRMT and the MMDT; c) to study the concurrent validity of the MMDT; and d) to establish reference values for elderly people with the MMDT. Two hundred and forty-seven community-living healthy elderly were evaluated with the MMDT, and two other dexterity tests, the Box and Block Test (BBT) and the Purdue Pegboard (PP). Thirty-five of them were evaluated twice with the MMDT and 44 were evaluated with both the MMDT and MRMT. The results show that the test-retest reliability of the MMDT is acceptable to high (intraclass correlation coefficients of 0.79 to 0.87, depending on the subtest) and the validity of the test is demonstrated by significant correlations between the MMDT, the BBT and the PP (0.63 to 0.67). There is a high correlation (0.85 to 0.95) between the MMDT and the MMRT in spite of different results. The reference values will help occupational therapists to differentiate better between real dexterity difficulties and those that may be attributed to normal aging.

Test–retest reliability of grip strength measurement in full elbow extension to evaluate maximum grip strength

2012 ◽  
Vol 38 (2) ◽  
pp. 183-186 ◽  
Author(s):  
C. Savva ◽  
C. Karagiannis ◽  
A. Rushton
Keyword(s):  
Grip Strength ◽  
Elbow Extension ◽  
Strength Measurement ◽  
Retest Reliability ◽  
Maximum Grip Strength ◽  
Grip Strength Measurement ◽  
Test Retest Reliability ◽  
Standard Error Of Measurement ◽  
Healthy Participants ◽  
Maximum Grip

The objective of this study was to investigate the test–retest reliability of measurement of grip strength in full elbow extension. The grip strengths of 19 healthy participants were measured using the Jamar dynamometer by the same rater on two occasions with an interval of 7 days between measures. Test–retest reliability of grip strength measurement was excellent in full elbow extension and associated with low values of standard error of measurement and small variations in the differences between the two measurements in both testing sessions.

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