Ultrasound Speed of Polymer Gel Mimicked Human Soft Tissue within Three Weeks

Othman, Nur Shakila; Jaafar, Mohammad Suhaimi; Rahman, Azhar Abdul; Othman, Ernee Sazlinayati; Rozlan, Aifa Afirah

doi:10.7763/ijbbb.2011.v1.41

Cited by 14 publications

(14 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the PLGA‐PEG‐PLGA triblock copolymer, the network in the semidilute concentration range is created through packing and bridging of micelles to various intermicellar structures (these structures will be discussed in detail when the SANS results are presented); the status of this network (transient or gel network) will depend on the ratio of hydrophilic groups (PEG) and hydrophobic (PLGA) groups and the temperature. The growth of hydrophobic junction zones at higher temperatures generates connectivity of the network and a gel is formed; at sufficiently high temperatures the gel becomes turbid and eventually we have a “white gel” . The swelling effect is provided by the PEG block, but at higher temperatures this effect is weakened because PEG has a lower critical solution temperature at temperatures around 100 °C.…”

Section: Resultsmentioning

confidence: 99%

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Khorshid

Zhu

Knudsen

et al. 2016

Macromolecular Bioscience

View full text Add to dashboard Cite

The thermoresponsive amphiphilic block copolymer poly(d,l-lactic acid-co-glycolic acid)-block-poly(ethylene glycol)-block-poly(d,l-lactic acid-co-glycolic acid) (PLGA-PEG -PLGA), which exhibits a reversible temperature-induced sol-gel transition at higher polymer concentrations in aqueous solution has attached a great deal of interest because of its potential in biomedical applications. In the present work, the length of the hydrophobic PLGA blocks is kept constant, whereas the length of the hydrophilic PEG block is altered and this variation has a pronounced impact on the phase behavior of the aqueous samples and the structure of the polymer. A short PEG block promotes gelation at a low temperature, whereas a longer PEG block shifts the gelation point to higher temperature. By using a combination of turbidity, rheology, and small angle neutron scattering (SANS) methods, the authors have revealed dramatic temperature effects. In dilute solution, the SANS experiments expose asymmetric ellipsoid structures for the copolymer with the short PEG-spacer, whereas spherical core-shell structure is observed for the polymer with long PEG-spacer. In the semidilute concentration regime, SANS measurements disclose similar profiles for the two copolymers. In a broad temperature interval, the transition from spherical core-shell micelles to cylindrical structure and packing of cylinders is observed.

show abstract

Section: Resultsmentioning

confidence: 99%

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Khorshid

Zhu

Knudsen

et al. 2016

Macromolecular Bioscience

View full text Add to dashboard Cite

show abstract

“…In the B-mode image, pixels in the vicinity of wall edges were identified from the brightness change of grayscale pixels due to the acoustic impedance of the scatterer density change between the tissue-mimicking phantom and the fluid mixture. 29 Among these pixels, the wall edges were determined by the highest value of the second-order gradient of the velocity profile. Figure 3B shows the mean and standard error of the scatterer movement-versus-correlation curves in the top 2 layers (depth, 0-5.4 mm).…”

mentioning

confidence: 99%

Quantification of Ultrasound Correlation‐Based Flow Velocity Mapping and Edge Velocity Gradient Measurement

Park

Kruger

Rubin

et al. 2013

J of Ultrasound Medicine

View full text Add to dashboard Cite

he blood flow velocity profile is important for diagnosis of cardiovascular diseases, which are associated with abnormal blood flow in arteries due to hemodynamic changes in patients. 1 The blood flow velocity gradient at the wall edge has been used to estimate the vascular wall shear stress, which has a key role in vascular physiology as well as the pathophysiologic mechanisms of vascular diseases. 2 Based on Poiseuille theory, the blood flow velocity profile is parabolic, and high-velocity gradients occur at the vascular wall in steady-state and fully developed laminar flow in normal conduit vessels. 3 In areas with vascular tortuosity, branching, and the presence of vascular plaque, the blood flow velocity profile is asymmetric. 1 Ultrasound imaging has been the preferred noninvasive technique for measuring blood flow velocity profiles.Multigate Doppler ultrasound measurement has been applied to estimate the blood flow velocity in vessels. 4 Using multigate Doppler measurements, the blood flow velocity profile and blood flow velocity gradient at the wall edge were determined from longitudinal (along the blood flow directions) views of blood vessels. [5][6][7][8] Dae Woo Park, PhD, Grant H. Kruger, PhD, Jonathan M. Rubin, MD, PhD, James Hamilton, PhD, Paul Gottschalk, PhD, Robert E. Dodde, PhD, Albert J. Shih, PhD, William F. Weitzel, MD Received January 1, 2013, This study investigated the use of ultrasound speckle decorrelation-and correlationbased lateral speckle-tracking methods for transverse and longitudinal blood velocity profile measurement, respectively. By studying the blood velocity gradient at the vessel wall, vascular wall shear stress, which is important in vascular physiology as well as the pathophysiologic mechanisms of vascular diseases, can be obtained. Decorrelationbased blood velocity profile measurement transverse to the flow direction is a novel approach, which provides advantages for vascular wall shear stress measurement over longitudinal blood velocity measurement methods. Blood flow velocity profiles are obtained from measurements of frame-to-frame decorrelation. In this research, both decorrelation and lateral speckle-tracking flow estimation methods were compared with Poiseuille theory over physiologic flows ranging from 50 to 1000 mm/s. The decorrelation flow velocity measurement method demonstrated more accurate prediction of the flow velocity gradient at the wall edge than the correlation-based lateral speckle-tracking method. The novelty of this study is that speckle decorrelation-based flow velocity measurements determine the blood velocity across a vessel. In addition, speckle decorrelation-based flow velocity measurements have higher axial spatial resolution than Doppler ultrasound measurements to enable more accurate measurement of blood velocity near a vessel wall and determine the physiologically important wall shear.

show abstract

“…Some studies have recommended other TM materials such as agar with suspended graphite, polyurethane foam, and magnesium silicate gels (7) or TM materials such as agar (polysaccharide), oil gel, polyvinyl alcohol gel (PVA), and polyacrylamide gel (PAA) (6). Unfortunately, the cost of phantoms is a major limiting problem for imaging centers, which is why the use of phantoms is sometimes construed as extra unnecessary work.…”

Section: Objectivesmentioning

confidence: 99%

“…In addition, recent advances have raised concern amongs the medical community about the safety of diagnostic ultrasound applications (3). Evaluation of the accuracy and performance of ultrasound systems usually needs tissue-mimicking (TM) phantoms (6). These materials should mimic the acoustic properties of the tissue (with regard to the speed of sound, average attenuation, etc.)…”

Section: Introductionmentioning

confidence: 99%

A New Sonographic Phantom for Quality Control and Training Purposes

Bitarafan-Rajabi¹,

Hasanzadeh²,

Jahangiri³

et al. 2014

Arch Cardiovasc Imaging

View full text Add to dashboard Cite

Background: Evaluation of the accuracy and performance of sonography units needs tissue-mimicking phantoms. These phantoms play an important role by simulating soft tissues, obviating the need to experiment on humans or animals. Objectives: To present a simple sonographic phantom for quality control and training purposes. Materials and Methods:The presented phantom consists of a two-part Plexiglas box. The larger part is filled with a mixture of ethanol (9.5 ± 0.25%) in distilled water and a solution of sodium nitrite (0.1 M) to prevent rusting. The second part is filled with a combination of 3.85% by wt. % agar, and 50 g/L of powdered graphite as the background material. In this study, chrome-plated electric guitar strings, 0.52 mm in diameter, were used. Several objects were considered as tissue-equivalent material, and their images were obtained at different times. Criteria for the selection of suitable objects comprised similarity between the obtained image and the corresponding tissues in the human body, minimal shrinkage, and change in brightness level at different times. In addition to quantitative analysis obtained from image processing, a blind qualitative study was done by a radiologist. Results:Both results of quantitative analysis using MATLAB software and independent qualitative analysis showed that the commercial rubber and agar were appropriate as solid and cystic objects, respectively. Moreover, quantitative analysis done with MATLAB on images obtained from the phantom showed that the commercial rubber and agar had a 5% and 2% change in image pixel intensity (brightness) after 2 months, respectively. Conclusions: The presented phantom not only has lower cost and complexity, which make it suitable for educational centers, but also is capable of providing good images of cystic and solid objects for quality control and training purposes. Furthermore, it confers reliable stability for at least 2 months, as was assessed in the present study.

show abstract

Ultrasound Speed of Polymer Gel Mimicked Human Soft Tissue within Three Weeks

Cited by 14 publications

References 10 publications

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Quantification of Ultrasound Correlation‐Based Flow Velocity Mapping and Edge Velocity Gradient Measurement

A New Sonographic Phantom for Quality Control and Training Purposes

Contact Info

Product

Resources

About