Toward An MRI-Based Method to Measure Non-Uniform Cartilage Deformation: An MRI-Cyclic Loading Apparatus System and Steady-State Cyclic Displacement of Articular Cartilage Under Compressive Loading

2003 ◽  
Vol 125 (2) ◽  
pp. 180-188 ◽  
Author(s):  
C. P. Neu ◽  
M. L. Hull
Keyword(s):  
Steady State ◽  
Articular Cartilage ◽  
Pneumatic Cylinder ◽  
Cycle Duration ◽  
Steady State Response ◽  
Time Duration ◽  
Bovine Articular Cartilage ◽  
State Response ◽  
The Mean ◽  
Phantom Material

Recent magnetic resonance imaging (MRI) techniques have shown potential for measuring non-uniform deformations throughout the volume (i.e. three-dimensional (3D) deformations) in small orthopedic tissues such as articular cartilage. However, to analyze cartilage deformation using MRI techniques, a system is required which can construct images from multiple acquisitions of MRI signals from the cartilage in both the undeformed and deformed states. The objectives of the work reported in this article were to 1) design an apparatus that could apply highly repeatable cyclic compressive loads of 400 N and operate in the bore of an MRI scanner, 2) demonstrate that the apparatus and MRI scanner can be successfully integrated to observe 3D deformations in a phantom material, 3) use the apparatus to determine the load cycle necessary to achieve a steady-state deformation response in normal bovine articular cartilage samples using a flat-surfaced and nonporous indentor in unconfined compression. Composed of electronic and pneumatic components, the apparatus regulated pressure to a double-acting pneumatic cylinder so that (1) load-controlled compression cycles were applied to cartilage samples immersed in a saline bath, (2) loading and recovery periods within a cycle varied in time duration, and (3) load magnitude varied so that the stress applied to cartilage samples was within typical physiological ranges. In addition the apparatus allowed gating for MR image acquisition, and operation within the bore of an MRI scanner without creating image artifacts. The apparatus demonstrated high repeatability in load application with a standard deviation of 1.8% of the mean 400 N load applied. When the apparatus was integrated with an MRI scanner programmed with appropriate pulse sequences, images of a phantom material in both the undeformed and deformed states were constructed by assembling data acquired through multiple signal acquisitions. Additionally, the number of cycles to reach a steady-state response in normal bovine articular cartilage was 49 for a total cycle duration of 5 seconds, but decreased to 33 and 27 for increasing total cycle durations of 10 and 15 seconds, respectively. Once the steady-state response was achieved, 95% of all displacements were within ±7.42μm of the mean displacement, indicating that the displacement response to the cyclic loads was highly repeatable. With this performance, the MRI-loading apparatus system meets the requirements to create images of articular cartilage from which 3D deformation can be determined.

scholarly journals Comparison of auditory brainstem response and auditory steady state response audiometry by evaluating the hearing thresholds obtained in children with different severity of hearing loss

2019 ◽  
Vol 35 (2) ◽  
Author(s):  
Muhammad Azeem Aslam ◽  
Adeela Javed ◽  
Abdul Moiz
Keyword(s):  
Hearing Loss ◽  
Steady State ◽  
Auditory Brainstem Response ◽  
Auditory Brainstem ◽  
Steady State Response ◽  
State Response ◽  
Hearing Thresholds ◽  
Auditory Steady State Response ◽  
Brainstem Response ◽  
The Mean

Objectives: To compare the hearing thresholds obtained with auditory brainstem response (ABR) and auditory steady state response (ASSR) audiometry in children with hearing loss. Methods: Hearing thresholds were obtained by ABR and ASSR in children who presented with suspicion of deafness at Ear, nose & throat department of Al-Nafees Medical College Hospital Islamabad, between January to August 2018. The mean hearing thresholds obtained by two tests were compared within each category of severity of deafness. Time taken by both tests was also compared. Results: A total of 57 patients (114 ears) were included in the study. Among them 27 (47.4%) were male and 30 (52.6%) were female. The mean age of patients at presentation was 42 months (±30.9) with age range from one to 12 years. Mean hearing thresholds obtained by click ABR, chirp ABR, ASSR (1, 2, 4 kHz) & ASSR (0.5, 1, 2, 4 kHz) was 56.25 (±27.61), 58.88 (±27.44), 58.03 (±21.26) & 56.35 (±22.86) respectively. Mean thresholds were comparable between click ABR & ASSR (1, 2, 4 kHz) and between chirp ABR & ASSR (0.5, 1, 2, 4 kHz) in all degrees of hearing loss categories except in those patients with normal hearing thresholds. The mean time taken by clicks ABR, chirp ABR and ASSR were four minutes seven seconds, three minutes 15 seconds and 16 minutes and 7 seconds respectively. Conclusions: Hearing thresholds obtained by ABR and ASSR are comparable in all categories of severity of hearing loss. The time taken by ABR is less as compared to ASSR. How to cite this:Aslam MA, Javed A, Moiz A. Comparison of auditory brainstem response and auditory steady state response audiometry by evaluating the hearing thresholds obtained in children with different severity of hearing loss. Pak J Med Sci. 2019;35(2):---------.   doi: https://doi.org/10.12669/pjms.35.2.688 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Air-Conduction Auditory Steady-State Response: Comparison of Interchannel Recording Using Two Modulation Frequencies

2008 ◽  
Vol 19 (09) ◽  
pp. 696-707 ◽  
Author(s):  
Wafaa A. Kaf ◽  
Ali A. Danesh
Keyword(s):  
Steady State ◽  
Carrier Frequency ◽  
Young Female ◽  
Response Amplitude ◽  
Normal Female ◽  
Steady State Response ◽  
State Response ◽  
Auditory Steady State Response ◽  
The Mean ◽  
Contralateral Response

Background: Two-channel auditory steady-state response (ASSR) recording at high and low MF (modulation frequency) most likely provides an insight about the response amplitude and latency from different directions at the brainstem level and at the thalamus or cortical level. Little is known about the combined relationship between MF (39 and 79 Hz) and electrode montages (ipsilateral and contralateral) to single AM (amplitude modulation) tones on the ASSR amplitude and latency. Purpose: To determine if ipsilateral versus contralateral response asymmetries are present at the brainstem level (79 Hz ASSR) and at the thalamus or cortical levels (39 Hz ASSR). Research Design: Descriptive and inferential statistics for interchannel ipsilateral and contralateral ASSR amplitude and latency to 79 and 39 Hz. Study Sample: Twenty-five normal-hearing, right-handed young female adults participated in the study. All participants were right-handed, and their age ranged between 18 to 28 years (mean 24.5 ± 1.6 years). Data Collection and Analysis: Ipsilateral and contralateral ASSR to 39 and 79 Hz MF and 100% AM stimuli were recorded at 500, 2000, and 4000 Hz carrier frequencies at 65 dB SPL. The ASSR amplitudes and phases were determined for each MF across Fc (carrier frequency) for the two channels to the test (right) ear. ASSR amplitude and latency between recording montages for each MF and across carrier frequency were compared by computing two-way repeated measures ANOVA. Results: The mean ipsilateral ASSR amplitudes to 39 Hz across frequency were slightly larger (228.6 ± 61.6 µV) than the contralateral response amplitude (223.2 ± 78 µV) while the mean ipsilateral 79 Hz amplitudes were smaller (127.3 ± 114.8) compared to contralateral 79 Hz amplitude (154.6 ± 112.7 µV). For latency response, the mean ipsilateral/contralateral latency difference, on average, was 1 msec or less for both MFs. Results, in normal female adults, indicated no significant interchannel ASSR asymmetries for amplitude and latency (p > 0.05) at the brainstem (79 Hz ASSR) and at the thalamus or cortical levels (39 Hz ASSR). Conclusions: Interchannel ipsilateral and contralateral ASSR amplitude and latency to 79 and 39 Hz are not significantly different in normal, young female adults. Two-channel recording of ASSR to different MFs may be of clinical value in otoneurologic assessment.

The Auditory Steady-State Response: Full-Term and Premature Neonates

2002 ◽  
Vol 13 (05) ◽  
pp. 260-269 ◽  
Author(s):  
Barbara Cone-Wesson ◽  
John Parker ◽  
Nina Swiderski ◽  
Field Rickards
Keyword(s):  
Steady State ◽  
Premature Infants ◽  
Modulation Frequency ◽  
Otoacoustic Emission ◽  
Full Term ◽  
Steady State Response ◽  
Pass Rates ◽  
Term Infants ◽  
State Response ◽  
Auditory Steady State Response

Two studies were aimed at developing the auditory steady-state response (ASSR) for universal newborn hearing screening. First, neonates who had passed auditory brainstem response, transient evoked otoacoustic emission, and distortion-product otoacoustic emission tests were also tested with ASSRs using modulated tones that varied in frequency and level. Pass rates were highest (> 90%) for amplitude-modulated tones presented at levels ≥ 69 dB SPL. The effect of modulation frequency on ASSR for 500- and 2000-Hz tones was evaluated in full-term and premature infants in the second study. Full-term infants had higher pass rates for 2000-Hz tones amplitude modulated at 74 to 106 Hz compared with pass rates for a 500-Hz tone modulated at 58 to 90 Hz. Premature infants had lower pass rates than full-term infants for both carrier frequencies. Systematic investigation of ASSR threshold and the effect of modulation frequency in neonates is needed to adapt the technique for screening.

scholarly journals Steady State Response of Linear Time Invariant Systems Modeledby Multibond Graphs

2021 ◽  
Vol 11 (4) ◽  
pp. 1717
Author(s):  
Gilberto Gonzalez Avalos ◽  
Noe Barrera Gallegos ◽  
Gerardo Ayala-Jaimes ◽  
Aaron Padilla Garcia
Keyword(s):  
Steady State ◽  
Linear Time ◽  
Direct Determination ◽  
The State ◽  
Steady State Response ◽  
State Variables ◽  
Linear Time Invariant ◽  
State Response ◽  
Time Invariant

The direct determination of the steady state response for linear time invariant (LTI) systems modeled by multibond graphs is presented. Firstly, a multiport junction structure of a multibond graph in an integral causality assignment (MBGI) to get the state space of the system is introduced. By assigning a derivative causality to the multiport storage elements, the multibond graph in a derivative causality (MBGD) is proposed. Based on this MBGD, a theorem to obtain the steady state response is presented. Two case studies to get the steady state of the state variables are applied. Both cases are modeled by multibond graphs, and the symbolic determination of the steady state is obtained. The simulation results using the 20-SIM software are numerically verified.

Decreased Gamma Auditory Steady-State Response Is Associated With Impaired Real-World Functioning in Unmedicated Patients at Clinical High Risk for Psychosis

2020 ◽  
pp. 155005942098270
Author(s):  
Sarah Ahmed ◽  
Jennifer R. Lepock ◽  
Romina Mizrahi ◽  
R. Michael Bagby ◽  
Cory J. Gerritsen ◽  
...  
Keyword(s):  
Steady State ◽  
High Risk ◽  
Functional Impairment ◽  
Real World ◽  
Steady State Response ◽  
Clinical High Risk ◽  
State Response ◽  
Auditory Steady State Response ◽  
Gamma Synchrony ◽  
40 Hz

Aim Deficits in synchronous, gamma-frequency neural oscillations may contribute to schizophrenia patients’ real-world functional impairment and can be measured electroencephalographically using the auditory steady-state response (ASSR). Gamma ASSR deficits have been reported in schizophrenia patients and individuals at clinical high risk (CHR) for developing psychosis. We hypothesized that, in CHR patients, gamma ASSR would correlate with real-world functioning, consistent with a role for gamma synchrony deficits in functional impairment. Methods A total of 35 CHR patients rated on Global Functioning: Social and Role scales had EEG recorded while listening to 1-ms, 93-dB clicks presented at 40 Hz in 500-ms trains, in response to which 40-Hz evoked power and intertrial phase-locking factor (PLF) were measured. Results In CHR patients, lower 40-Hz PLF correlated with lower social functioning. Conclusions Gamma synchrony deficits may be a biomarker of real-world impairment at early stages of the schizophrenia disease trajectory.

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