A variety of magnetic resonance imaging acoustic radiation force imaging (MR-ARFI) pulse sequences as the means for image guidance of focused ultrasound therapy have been recently developed and tested ex vivo and in animal models. To successfully translate MR-ARFI guidance into human applications, ensuring that MR-ARFI provides satisfactory image quality in the presence of patient motion and deposits safe amount of ultrasound energy during image acquisition is necessary. The first aim of this work was to study the effect of motion on in vivo displacement images of the brain obtained with 2D Fourier transform spin echo MR-ARFI. Repeated bipolar displacement encoding configuration was shown less sensitive to organ motion. The optimal signal-to-noise ratio of displacement images was found for the duration of encoding gradients of 12 ms. The second aim was to further optimize the displacement signal-to-noise ratio for a particular tissue type by setting the time offset between the ultrasound emission and encoding based on the tissue response to acoustic radiation force. A method for measuring tissue response noninvasively was demonstrated. Finally, a new method for simultaneous monitoring of tissue heating during MR-ARFI acquisition was presented to enable timely adjustment of the ultrasound energy aimed at ensuring the safety of the MR-ARFI acquisition.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4028045 | PMC |
| http://dx.doi.org/10.1002/mrm.24308 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Effects of stimuli and contralateral noise levels on auditory cortical potentials recorded in school-age children.
PLoS One
January 2025
Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brazil.
Background And Objective: One of the functions attributed to the auditory efferent system is related to the processing of acoustic stimuli in noise backgrounds. However, clinical implications and the neurophysiological mechanisms of this system are not yet understood, especially on higher regions of the central nervous system. Only a few researchers studied the effects of noise on cortical auditory evoked potentials (CAEP), but the lack of studies in this area and the contradictory results, especially in children, point to the need to investigate different protocols and parameters that could allow the study of top-down activity in humans.
View Article and Find Full Text PDFTheoretical modeling and modal analysis of multi-element coupled transducers.
J Acoust Soc Am
January 2025
National Key Laboratory of Underwater Acoustic Technology, Harbin Engineering University, Harbin 150001, China.
Low-frequency transducers are considerably smaller than the wavelength. When multiple low-frequency transducers are closely packed, they couple with the surrounding water and form a transducer-water-transducer coupling structure called multi-element coupled transducers (MCT). This study presents a theoretical model of the MCT based on radiation and mutual radiation theory and analyzes it under multiple resonance frequencies and vibration modes.
View Article and Find Full Text PDFThrush nightingales adjust the peak frequency and structure of their songs in response to different types of experimental noise.
Sci Rep
January 2025
Department of Behavioural Ecology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, Poznan, 61614, Poland.
Animals employ various strategies to minimize the overlap of their vocalizations with other sounds, thereby enhancing the effectiveness of their communication. However, little attention has been given to experimentally examining how the structure of the acoustic signal changes in response to various kinds of disturbances in the soundscape. In this study, I experimentally investigated whether male thrush nightingales (Luscinia luscinia) adjust their singing rate, song frequency, and song type in response to different types of artificial sounds.
View Article and Find Full Text PDFLow-vibration cryogenic test facility for next generation of ground-based gravitational-wave observatories.
Rev Sci Instrum
January 2025
OzGrav-ANU, ARC Centre for Gravitational Astrophysics, College of Science, The Australian National University, Canberra ACT2601, Australia.
We present the design and commissioning of a cryogenic low-vibration test facility that measures displacement noise from a gram-scale silicon cantilever at the level of 10-16m/Hz at 1 kHz. This sensitivity is necessary for future tests of thermal noise models on cross sections of silicon suspension samples proposed for future gravitational-wave detectors. A volume of ∼36 l is enclosed by radiation shields cooling an optical test cavity that is suspended from a multi-stage pendulum chain providing isolation from acoustic and environmental noise.
View Article and Find Full Text PDFSound enrichment helps persons suffering from low frequency phantom sounds.
J Acoust Soc Am
January 2025
Applied Health Research (TGO), University Medical Center Groningen (UMCG), Groningen, the Netherlands.
Low frequency noise (LFN) of unknown origin can be disturbing, especially at night, and affect sleep and relaxation. If reduction of the LFN is impossible, adding sound can mask the troubling noise or detract attention from it to reduce distress. To assess the effectiveness of this, a survey was set up consisting of three questionnaires: the first when a person requested a masking sound and follow-ups after 1 and 3 months.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!