A Fundamental Evaluation of in Vivo Sound Speed Mapping Technique by Crossed Beam Method

1989 ◽  
pp. 491-498
Author(s):  
Masafumi Kondo ◽  
Kinya Takamizawa ◽  
Makoto Hirama ◽  
Kiyoshi Okazaki ◽  
Kazuhiro Iinuma ◽  
...  
Keyword(s):  
Sound Speed ◽  
Mapping Technique ◽  
Beam Method

An evaluation of an in vivo local sound speed estimation technique by the crossed beam method

1990 ◽  
Vol 16 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Masafumi Kondo ◽  
Kinya Takamizawa ◽  
Makoto Hirama ◽  
Kiyoshi Okazaki ◽  
Kazuhiro Iinuma ◽  
...  
Keyword(s):  
Sound Speed ◽  
Speed Estimation ◽  
Estimation Technique ◽  
Beam Method ◽  
Local Sound

scholarly journals Ultrasonic fat fraction quantification using in vivo adaptive sound speed estimation

2018 ◽  
Vol 63 (21) ◽  
pp. 215013 ◽  
Author(s):  
Marion Imbault ◽  
Marco Dioguardi Burgio ◽  
Alex Faccinetto ◽  
Maxime Ronot ◽  
Hanna Bendjador ◽  
...  
Keyword(s):  
Sound Speed ◽  
Speed Estimation ◽  
Fat Fraction

A new method of measuring in vivo sound speed in the reflection mode

1988 ◽  
Vol 16 (2) ◽  
pp. 87-93 ◽  
Author(s):  
Nobushige Hayashi ◽  
Nagara Tamaki ◽  
Michio Senda ◽  
Kazutaka Yamamoto ◽  
Yoshiharu Yonekura ◽  
...  
Keyword(s):  
Sound Speed ◽  
New Method ◽  
Reflection Mode

scholarly journals A Computationally Efficient Mean Sound Speed Estimation Method Based on an Evaluation of Focusing Quality for Medical Ultrasound Imaging

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1368 ◽  
Author(s):  
Lee ◽  
Yoo ◽  
Yoon ◽  
Song
Keyword(s):  
Image Quality ◽  
Sound Speed ◽  
Soft Tissues ◽  
Low Cost ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Speed Estimation ◽  
Sound Speeds ◽  
Hardware Resource

Generally, ultrasound receive beamformers calculate the focusing time delays of fixed sound speeds in human tissue (e.g., 1540 m/s). However, phase distortions occur due to variations of sound speeds in soft tissues, resulting in degradation of image quality. Thus, an optimal estimation of sound speed is required in order to improve image quality. Implementation of real-time sound speed estimation is challenging due to high computational and hardware complexities. In this paper, an optimal sound speed estimation method with a low-cost hardware resource is presented. In the proposed method, the optimal mean sound speed is determined by measuring the amplitude variance of pre-beamformed radio-frequency (RF) data. The proposed method was evaluated with phantom and in vivo experiments, and implemented on Virtex-4 with Xilinx ISE 12.4 using VHDL. Experiment results indicate that the proposed method could estimate the mean optimal sound speed and enhance spatial resolution with a negligible increase in the hardware resource usage.

scholarly journals Use of a novel S1 nuclease RNA-mapping technique to measure efficiency of transcription termination on polyomavirus DNA.

1986 ◽  
Vol 6 (5) ◽  
pp. 1624-1632 ◽  
Author(s):  
R W Tseng ◽  
N H Acheson
Keyword(s):  
Transcription Initiation ◽  
Transcription Termination ◽  
Late Phase ◽  
Full Length ◽  
Mapping Technique ◽  
S1 Nuclease ◽  
Dna Fragment ◽  
Rna Mapping ◽  
Dna Strand

We devised a strategy to measure the efficiency of transcription termination in vivo by RNA polymerase on polyomavirus DNA. Pulse-labeled nuclear RNA was hybridized with a single-stranded polyomavirus DNA fragment which spans the transcription initiation region. Hybrids were treated with RNase, bound to nitrocellulose filters, eluted with S1 nuclease, and analyzed by gel electrophoresis. The ratio of full-length to less-than-full-length DNA-RNA hybrids was used to calculate transcription termination frequency. We found that 50% of the polymerases terminated per traverse of the L DNA strand during the late phase of infection. The method for mapping in vivo pulse-labeled RNAs which we developed is potentially useful for studying unstable cellular or viral RNAs.

scholarly journals Metacognitive ability predicts hippocampal and prefrontal microstructure

2016 ◽  
Author(s):  
Micah Allen ◽  
James C. Glen ◽  
Daniel Müllensiefen ◽  
Dietrich Samuel Schwarzkopf ◽  
Martina F. Callaghan ◽  
...  
Keyword(s):  
Grey Matter ◽  
Brain Volume ◽  
Brain Network ◽  
Auditory Memory ◽  
Brain Maturation ◽  
Mapping Technique ◽  
Theoretic Model ◽  
The Relationship ◽  
Metacognitive Ability

AbstractThe ability to introspectively evaluate our experiences to form accurate metacognitive beliefs, or insight, is an essential component of decision-making. Previous research suggests individuals vary substantially in their level of insight, and that this variation predicts brain volume and function, particularly in the anterior prefrontal cortex (aPFC). However, the neurobiological mechanisms underlying these effects are unclear, as qualitative, macroscopic measures such as brain volume can be related to a variety of microstructural features. Here we used a newly developed, high-resolution (800µm isotropic) multi-parameter mapping technique in 48 healthy individuals to delineate quantitative markers of in vivo histological features underlying metacognitive ability. Specifically, we examined how neuroimaging markers of local grey matter myelination, macromolecular and iron content relate to insight. Extending previous volumetric findings, we found that metacognitive ability, as determined by a signal-detection theoretic model, was positively related to the myelo-architectural integrity of aPFC grey matter. Interestingly, perceptual metacognition predicted decreased macromolecule content coupled with increased iron in the hippocampus and precuneus, areas previously implicated in meta-memory rather than meta-perception. Further, the relationship of hippocampal-precuneus and prefrontal microstructure to an auditory memory measure was respectively mediated or suppressed by metacognitive ability, suggesting a dynamic trade-off between participant’s memory and metacognition. These results point towards a novel understanding of the relationship between memory, brain microstructure, and metacognition.Significance StatementBy combining a signal-theoretic model of individual metacognitive ability with state of the art quantitative neuroimaging, our results shed new light on the neurobiological mechanisms underlying introspective insight. Myelination and iron are core determinants of both healthy brain maturation and neurodegeneration; particularly in the hippocampus where iron accumulation is linked to oxidative stress and inflammation. Our results may thus indicate that metacognition depends upon the development and integrity of a memory-related brain network, potentially revealing novel biomarkers of neurodegeneration. These results highlight the power of quantitative mapping to reveal neurobiological correlates of behaviour.

Clinical Sound Speed Measurement in Liver and Spleen in Vivo

1987 ◽  
Vol 9 (4) ◽  
pp. 221-235 ◽  
Author(s):  
C.F. Chen ◽  
D.E. Robinson ◽  
L.S. Wilson ◽  
K.A. Griffiths ◽  
A. Manoharan ◽  
...  
Keyword(s):  
Sound Speed ◽  
Disease Status ◽  
Clinical Results ◽  
General Purpose ◽  
Clinical Role ◽  
Speed Measurement ◽  
Clinical Confidence ◽  
Signal Processing Methods

The paper describes an implementation of clinical sound speed measurement using either a commercial water path scanner or a specially developed dual transducer real time scanner, each interfaced to a general purpose minicomputer for off-line analysis. It describes the examination technique to obtain suitable in vivo clinical data from the liver and the spleen. It develops signal processing methods to achieve clinical confidence in individual measurements. Forty-five liver patients and 46 spleen patients were examined. Sound speed was found to correlate closely with fibrosis content in both the liver and the spleen with an increase in fibrosis resulting in a decrease in sound speed. Sound speed in various pathological conditions are discussed. Clinical results of sequential examinations on patients under treatment are presented and successful monitoring of the disease status is demonstrated. The potential clinical role of sound speed measurement is suggested.

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