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  Subjects -> PHYSICS (Total: 781 journals)
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PHYSICS (566 journals)            First | 1 2 3 4 5 6 | Last

Russian Physics Journal     Hybrid Journal  
Samuel Beckett Today/Aujourd'hui     Full-text available via subscription   (Followers: 2)
Science and Technology of Nuclear Installations     Open Access   (Followers: 1)
Science China : Physics, Mechanics & Astronomy     Full-text available via subscription   (Followers: 1)
Science Foundation in China     Full-text available via subscription   (Followers: 2)
Scientific Reports     Open Access   (Followers: 11)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 17)
Sensor Letters     Full-text available via subscription   (Followers: 1)
Sensors and Actuators A: Physical     Hybrid Journal   (Followers: 73)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Shock and Vibration     Hybrid Journal   (Followers: 7)
Shock Waves     Hybrid Journal   (Followers: 5)
Small     Hybrid Journal   (Followers: 10)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 27)
Solid State Physics     Full-text available via subscription  
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 4)
South African Journal for Research in Sport, Physical Education and Recreation     Full-text available via subscription   (Followers: 4)
Space Research Journal     Open Access   (Followers: 2)
Space Weather     Full-text available via subscription   (Followers: 3)
Spectral Analysis Review     Open Access  
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy     Hybrid Journal   (Followers: 7)
Spectrochimica Acta Part B: Atomic Spectroscopy     Hybrid Journal   (Followers: 7)
Spectroscopy and Spectral Analysis     Full-text available via subscription  
Spectroscopy Letters: An International Journal for Rapid Communication     Hybrid Journal   (Followers: 3)
Sri Lankan Journal of Physics     Open Access  
Strain     Hybrid Journal   (Followers: 2)
Strength of Materials     Hybrid Journal   (Followers: 5)
Structural Dynamics     Open Access  
Studies In Applied Mathematics     Hybrid Journal   (Followers: 1)
Superconductor Science and Technology     Hybrid Journal   (Followers: 1)
Surface Engineering     Hybrid Journal   (Followers: 3)
Surface Review and Letters     Hybrid Journal   (Followers: 1)
Surface Science Reports     Full-text available via subscription   (Followers: 14)
Surface Science Spectra     Hybrid Journal  
Surface Topography : Metrology and Properties     Full-text available via subscription  
Synchrotron Radiation News     Hybrid Journal   (Followers: 2)
Synthetic Metals     Hybrid Journal   (Followers: 3)
Technical Physics     Hybrid Journal  
Technical Physics Letters     Hybrid Journal  
Tectonics     Full-text available via subscription   (Followers: 9)
The Astronomy and Astrophysics Review     Hybrid Journal   (Followers: 2)
The Chemical Physics of Solid Surfaces     Full-text available via subscription  
The European Physical Journal H     Hybrid Journal   (Followers: 1)
The European Physical Journal Plus     Open Access  
The International Journal of Multiphysics     Full-text available via subscription   (Followers: 2)
The Physics of Metals and Metallography     Hybrid Journal   (Followers: 4)
The Physics Teacher     Full-text available via subscription   (Followers: 5)
Theoretical and Computational Fluid Dynamics     Hybrid Journal   (Followers: 8)
Theoretical and Mathematical Physics     Hybrid Journal   (Followers: 4)
Topological Quantum Matter     Open Access  
Transport Theory and Statistical Physics     Hybrid Journal   (Followers: 4)
Tribology International     Hybrid Journal   (Followers: 33)
Tribology Letters     Hybrid Journal   (Followers: 5)
Tribotest     Hybrid Journal   (Followers: 1)
Turkish Journal of Physics     Open Access  
Ultrasonics     Hybrid Journal   (Followers: 4)
Ultrasonics Sonochemistry     Hybrid Journal   (Followers: 2)
Ultrasound in Medicine & Biology     Full-text available via subscription   (Followers: 6)
Universal Journal of Physics and Application     Open Access  
Western Journal of Communication     Hybrid Journal   (Followers: 4)
Women & Performance: a journal of feminist theory     Hybrid Journal   (Followers: 3)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 8)
World Journal of Condensed Matter Physics     Open Access  
X-Acoustics: Imaging and Sensing : Photoacoustics, Thermoacoustics, Magnetoacoustics     Open Access  
Zeitschrift für angewandte Mathematik und Physik     Hybrid Journal   (Followers: 1)
Zeitschrift für Naturforschung A : A Journal of Physical Sciences     Open Access  

  First | 1 2 3 4 5 6 | Last

Journal Cover   Ultrasound in Medicine & Biology
  [SJR: 0.939]   [H-I: 91]   [6 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0301-5629
   Published by Elsevier Homepage  [2812 journals]
  • Calendar
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8




      PubDate: 2015-07-30T21:20:05Z
       
  • “Erratum to: “Prenatal exposure to ultrasound affects learning
           and memory in young rats,” by Li Ping, Wang pei-jun, Zhang Wei.
           Ultrasound Med Biol 2015;41:644-653
    • Abstract: Publication date: Available online 30 July 2015
      Source:Ultrasound in Medicine & Biology




      PubDate: 2015-07-30T21:20:05Z
       
  • Comparison Between Neck and Shoulder Stiffness Determined by Shear Wave
           Ultrasound Elastography and a Muscle Hardness Meter
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Ryota Akagi, Saki Kusama
      The goals of this study were to compare neck and shoulder stiffness values determined by shear wave ultrasound elastography with those obtained with a muscle hardness meter and to verify the correspondence between objective and subjective stiffness in the neck and shoulder. Twenty-four young men and women participated in the study. Their neck and shoulder stiffness was determined at six sites. Before the start of the measurements, patients rated their present subjective symptoms of neck and shoulder stiffness on a 6-point verbal scale. At all measurement sites, the correlation coefficients between the values of muscle hardness indices determined by the muscle hardness meter and shear wave ultrasound elastography were not significant. Furthermore, individuals' subjective neck and shoulder stiffness did not correspond to their objective symptoms. These results suggest that the use of shear wave ultrasound elastography is essential to more precisely assess neck and shoulder stiffness.


      PubDate: 2015-07-30T21:20:05Z
       
  • Delivering Agents Locally into Articular Cartilage by Intense MHz
           Ultrasound
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Heikki J. Nieminen, Tuomo Ylitalo, Jussi-Petteri Suuronen, Krista Rahunen, Ari Salmi, Simo Saarakkala, Ritva Serimaa, Edward Hæggström
      There is no cure for osteoarthritis. Current drug delivery relies on systemic delivery or injections into the joint. Because articular cartilage (AC) degeneration can be local and drug exposure outside the lesion can cause adverse effects, localized drug delivery could permit new drug treatment strategies. We investigated whether intense megahertz ultrasound (frequency: 1.138 MHz, peak positive pressure: 2.7 MPa, I spta: 5 W/cm2, beam width: 5.7 mm at −6 dB, duty cycle: 5%, pulse repetition frequency: 285 Hz, mechanical index: 1.1) can deliver agents into AC without damaging it. Using ultrasound, we delivered a drug surrogate down to a depth corresponding to 53% depth of the AC thickness without causing histologically detectable damage to the AC. This may be important because early osteoarthritis typically exhibits histopathologic changes in the superficial AC. In conclusion, we identify intense megahertz ultrasound as a technique that potentially enables localized non-destructive delivery of osteoarthritis drugs or drug carriers into articular cartilage.


      PubDate: 2015-07-30T21:20:05Z
       
  • Reliability and Limits of Agreement of the Supraspinatus Muscle Anatomical
           Cross-Sectional Area Assessment by Ultrasonography
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7
      Author(s): Fyllis Papatzika, Maria Papandreou, Antonis Ekizos, Chrystalla Panteli, Adamantios Arampatzis
      The purpose of this study was to evaluate the reliability and limits of agreement for assessment of the anatomical cross-sectional area (ACSA) of the supraspinatus muscle using B-mode ultrasonography. Sixteen participants were examined with two different protocols, on two different days. There were no statistically significant differences (p > 0.05) in ACSA values between days 1 and 2 or between protocols 1 and 2; the average intra-class correlation coefficient ranged from 0.93 to 0.96. The limits of agreement for supraspinatus ACSA were, in both protocols, about ± 1 cm2. Our findings revealed that both protocols had high reliability in distinguishing differences of about 1 cm2 between groups or after interventions and that ultrasonography can be used for experimental designs in which the expected changes in ACSA would be higher than 14%.


      PubDate: 2015-07-30T21:20:05Z
       
  • Delayed Transcranial Echo-Contrast Bolus Arrival in Unilateral Internal
           Carotid Artery Stenosis and Occlusion
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7
      Author(s): Manuel Gómez-Choco, Stephan J. Schreiber, Markus Weih, Florian Doepp, José M. Valdueza
      Some patients with internal carotid artery (ICA) occlusion or stenosis are at risk of developing a hemodynamic stroke. Transcranial ultrasonography using an echo-contrast bolus technique might be able to assess the extent of hemodynamic compromise. We describe a transcranial Doppler sonographic method that analyzes the differences in echo-contrast bolus arrival between both middle cerebral arteries after intravenous echo-contrast application. Ten patients with 50%–79% ICA stenosis, 10 patients with 80%–99% ICA stenosis and 22 patients with ICA occlusion were studied and compared with 15 age-matched controls. There were significant increases in delayed filling of the middle cerebral artery in both 80%–99% stenoses and occlusions compared with controls. The extent of the observed delays did not correlate with vasomotor reactivity. Echo-contrast bolus arrival time can be used to gain additional information on the intracranial hemodynamic effects of extracranial carotid artery disease that seems to be independent of the established ultrasound indices.


      PubDate: 2015-07-30T21:20:05Z
       
  • Contents
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7




      PubDate: 2015-07-30T21:20:05Z
       
  • Comparing Carotid and Brachial Artery Stiffness: A First Step Toward
           Mechanical Mapping of the Arterial Tree
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7
      Author(s): Roch L. Maurice, Laurence Vaujois, Nagib Dahdah, Anne-Monique Nuyt, Jean-Luc Bigras
      Arterial stiffness is a predictor of cardiovascular mortality. It increases with age and is accelerated by hypertension and other cardiovascular risk factors. In addition to the disease state, arterial stiffness increases from the proximal to the distal arterial compartments. Concurrent assessment of various vessels from the same subjects is unavailable in the literature. The aim of this work was to quantify an intrinsic mechanical feature, namely, wall stiffness, of the common carotid artery (CCA) and brachial artery (BA). CCAs and BAs of healthy adolescents were investigated. Cine loops of CCA and BA B-mode data were digitally recorded at the same clinical examination, and arterial elastic moduli were estimated off-line with our proprietary non-invasive Imaging-based BioMarker (ImBioMark) algorithm. The 11 study subjects were 14.4 ± 1.2 years old, with normal body habitus and blood pressures 112.3 ± 10.6/63.6 ± 5.7 mm Hg. BAs had a higher elastic modulus than CCAs (arterial elastic moduli: 129.73 ± 25.67 kPa vs. 49.55 ± 14.75 kPa, p < 0.001). There was a positive correlation between the BA and CCA (slope = 0.36, intercept = 111.62 kPa, R 2 = 0.045). This article documents, for the first time, a correlation between the CCA and BA of the same subject, under the same conditions. We previously reported preliminary data for the aorta and documented the effect of aging on the CCA; we now intend to study the femoral artery as well and include age stratification to pursue our investigations. The results reported here can be seen as the first step toward mechanical mapping of the arterial tree.


      PubDate: 2015-07-30T21:20:05Z
       
  • Ultrasonographic Evaluation of Resistive Index and Renal Artery Stenosis
           
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7
      Author(s): Fabrizio Conti, Fulvia Ceccarelli, Antonietta Gigante, Carlo Perricone, Biagio Barbano, Laura Massaro, Francesca Romana Spinelli, Cristiano Alessandri, Guido Valesini, Rosario Cianci
      Renal involvement in anti-phospholipid syndrome (APS) is still relatively unknown and probably underestimated. The described lesions consist of renal artery stenosis (RAS), venous renal thrombosis and glomerular lesions. The resistive index (RI) of intra-renal arteries, expression of the degree of vascular resistance, has been analyzed in different nephropathies and observed to be associated with functional parameters and some histologic features. In contrast, there are no studies on patients with APS. We evaluated the presence of a pathologic RI and RAS in a cohort of patients with APS. The study protocol included ultrasonographic assessment to measure the RI (RIs >0.7 were considered pathologic) and to determine the presence of RAS. We enrolled 36 patients with APS, 13 with primary APS and 23 with the form associated with systemic lupus erythematosus (SLE, secondary APS). As controls, we enrolled 10 anti-phospholipid antibody carriers, 10 patients with SLE without renal involvement and 14 age- and sex-matched healthy patients. A pathologic RI was identified in five patients with APS (13.9%) and in none of the anti-phospholipid antibody carriers (p = 0.00007). Four of the five (80%) patients with a pathologic RI had secondary APS. Three patients, all with primary APS, had RAS. The almost exclusive association of a pathologic RI with secondary APS and of RAS with primary APS suggests the involvement of two pathogenic pathways in the development of these different manifestations. The hypercoagulability status driven by APS could play a central role in the determination of RAS in patients with primary APS, whereas the activation of mTORC (mammalian target of rapamycin complex) pathways could be the pathogenic mechanism inducing development of a pathologic RI.


      PubDate: 2015-07-30T21:20:05Z
       
  • Shear Wave Elastography (SWE): An Analysis of Breast Lesion
           Characterization in 83 Breast Lesions
    • Abstract: Publication date: Available online 7 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Alice Feldmann, Carole Langlois, Marion Dewailly, Elise Fréart Martinez, Loic Boulanger, Olivier Kerdraon, Nathalie Faye
      Qualitative and quantitative shear wave elastography (SWE) criteria were assessed to differentiate between malignant and benign breast lesions. This prospective study included 83 lesions. SWE features measured included maximal stiffness values inside the lesion (Elesion) and in the peri-lesion area (Eperilesion) and ratio values (Rlesion and Rperilesion) according to the formula Elesion or Eperilesion/Efat, with Efat corresponding to normal fatty tissue. We compared ultrasonography (B-mode), SWE and histologic sizes. With qualitative and quantitative SWE analysis, sensitivity was 94% and specificity 73%. Malignant lesions appeared more heterogeneous, with higher stiffness and ratio values than benign lesions (p < 0.001). For malignant lesions, SWE size was better correlated to histologic size than B-mode size. Using benign SWE signs to selectively downgrade category 4a and 4b lesions, the specificity improved from 13% to 51% without loss in sensitivity (100%) compared to ultrasound.


      PubDate: 2015-07-30T21:20:05Z
       
  • Masthead
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7




      PubDate: 2015-07-30T21:20:05Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: July 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 7




      PubDate: 2015-07-30T21:20:05Z
       
  • Sonoelastography of Plantar Fascia: Reproducibility and Pattern
           Description in Healthy Subjects and Symptomatic Subjects
    • Abstract: Publication date: Available online 9 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): José Ríos-Díaz, Jacinto J. Martínez-Payá, María Elena del Baño-Aledo, Ana de Groot-Ferrando, Paloma Botía-Castillo, David Fernández-Rodríguez
      The purpose of the work reported here was to describe the sonoelastographic appearance of the plantar fascia of healthy volunteers and patients with fasciitis. Twenty-three healthy subjects and 21 patients with plantar fasciitis were examined using B-mode and real-time sonoelastography (RTSR) scanning. B-Mode examination included fascia thickness and echotexture. Echogenicity and echovariation of the color histogram were analyzed. Fasciae were classified into type 1, blue (more elastic); type 2, blue/green (intermediate); or type 3, green (less elastic). RTSE revealed 72.7% of fasciae as type 2, with no significant association with fasciitis (χ2 = 3.6, df = 2, p = 0.17). Quantitative analysis of the color histogram revealed a significantly greater intensity of green (mean = 77.8, 95% confidence interval [CI] = 71.9–83.6) and blue (mean = 74.2, 95% CI = 69.7–78.8) in healthy subjects. Echovariation of the color red was 33.4% higher in the fasciitis group than in the healthy group (95% CI = 16.7–50.1). Sonoelastography with quantitative analysis of echovariation can be a useful tool for evaluation of plantar fascia pathology.


      PubDate: 2015-07-30T21:20:05Z
       
  • Ultrasound Fetal Weight Estimation: How Accurate Are We Now Under
           Emergency Conditions'
    • Abstract: Publication date: Available online 9 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Kaouther Dimassi, Fatma Douik, Mariem Ajroudi, Amel Triki, Mohamed Faouzi Gara
      The primary aim of this study was to evaluate the accuracy of sonographic estimation of fetal weight when performed at due date by first-line sonographers. This was a prospective study including 500 singleton pregnancies. Ultrasound examinations were performed by residents on delivery day. Estimated fetal weights (EFWs) were calculated and compared with the corresponding birth weights. The median absolute difference between EFW and birth weight was 200 g (100–330). This difference was within ±10% in 75.2% of the cases. The median absolute percentage error was 5.53% (2.70%–10.03%). Linear regression analysis revealed a good correlation between EFW and birth weight (r = 0.79, p < 0.0001). According to Bland–Altman analysis, bias was −85.06 g (95% limits of agreement: −663.33 to 494.21). In conclusion, EFWs calculated by residents were as accurate as those calculated by experienced sonographers. Nevertheless, predictive performance remains limited, with a low sensitivity in the diagnosis of macrosomia.


      PubDate: 2015-07-30T21:20:05Z
       
  • Apoptosis Induced by Microbubble-Assisted Acoustic Cavitation in K562
           Cells: The Predominant Role of the Cyclosporin A-Dependent Mitochondrial
           Permeability Transition Pore
    • Abstract: Publication date: Available online 9 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Lu Zhao, Yi Feng, Aiwei Shi, Yujin Zong, Mingxi Wan
      Acoustic cavitation of microbubbles has been described as inducing tumor cell apoptosis that is partly associated with mitochondrial dysfunction; however, the exact mechanisms have not been fully characterized. Here, low-intensity pulsed ultrasound (1 MHz, 0.3-MPa peak negative pressure, 10% duty cycle and 1-kHz pulse repetition frequency) was applied to K562 chronic myelogenous leukemia cells for 1 min with 10% (v/v) SonoVue microbubbles. After ultrasound exposure, the apoptotic index was determined by flow cytometry with annexin V–fluorescein isothiocyanate/propidium iodide. In addition, mitochondrial membrane potential (ΔΨm) was determined with the JC-1 assay. Translocation of apoptosis-associated protein cytochrome c was evaluated by Western blotting. We found that microbubble-assisted acoustic cavitation can increase the cellular apoptotic index, mitochondrial depolarization and cytochrome c release in K562 cells, compared with ultrasound treatment alone. Furthermore, mitochondrial dysfunction and apoptosis were significantly inhibited by cyclosporin A, a classic inhibitor of the mitochondrial permeability transition pore; however, the inhibitor of Bax protein, Bax-inhibiting peptide, could not suppress these effects. Our results suggest that mitochondrial permeability transition pore opening is involved in mitochondrial dysfunction after exposure to microbubble-assisted acoustic cavitation. Moreover, the release of cytochrome c from the mitochondria is dependent on cyclosporin A–sensitive mitochondrial permeability transition pore opening, but not formation of the Bax-voltage dependent anion channel complex or Bax oligomeric pores. These data provide more insight into the mechanisms underlying mitochondrial dysfunction induced by acoustic cavitation and can be used as a basis for therapy.


      PubDate: 2015-07-30T21:20:05Z
       
  • Placental Volumetry by 2-D Sonography with a New Mathematical Formula:
           Prospective Study on the Shell of a Spherical Sector Model
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Zoltan Kozinszky, Andrea Surányi, Hajnalka Péics, András Molnár, Attila Pál
      The aim of this study was to determine the utility of a new mathematical model in volumetric assessment of the placenta using 2-D ultrasound. Placental volumetry was performed in a prospective cross-sectional survey by virtual organ computer-aided analysis (VOCAL) with the help of a shell-off method in 346 uncomplicated pregnancies according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Furthermore, placental thickness, length and height were measured with the 2-D technique to estimate placental volume based on the mathematical formula for the volume of “the shell of the spherical sector.” Fetal size was also assessed by 2-D sonography. The placental volumes measured by 2-D and 3-D techniques had a correlation of 0.86. In the first trimester, the correlation was 0.82, and later during pregnancy, it was 0.86. Placental volumetry using “the circle-shaped shell of the spherical sector” mathematical model with 2-D ultrasound technique may be introduced into everyday practice to screen for placental volume deviations associated with adverse pregnancy outcome.


      PubDate: 2015-07-30T21:20:05Z
       
  • A Lipopeptide-Based αvβ3 Integrin-Targeted Ultrasound Contrast
           Agent for Molecular Imaging of Tumor Angiogenesis
    • Abstract: Publication date: Available online 10 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Fei Yan, Xiuxia Xu, Yihan Chen, Zhiting Deng, Hongmei Liu, Jianrong Xu, Jie Zhou, Guanghong Tan, Junru Wu, Hairong Zheng
      The design and fabrication of targeted ultrasound contrast agents are key factors in the success of ultrasound molecular imaging applications. Here, we introduce a transformable αvβ3 integrin-targeted microbubble (MB) by incorporation of iRGD-lipopeptides into the MB membrane for non-invasive ultrasound imaging of tumor angiogenesis. First, the iRGD-lipopeptides were synthesized by conjugating iRGD peptides to distearoylphosphatidylethanolamine–polyethylene glycol 2000–maleimide. The resulting iRGD-lipopeptides were used for fabrication of the iRGD-carrying αvβ3 integrin-targeted MBs (iRGD-MBs). The binding specificity of iRGD-MBs for endothelial cells was found to be significantly stronger than that of control MBs (p < 0.01) under in vitro static and dynamic conditions. The binding of iRGD-MBs on the endothelial cells was competed off by pre-incubation with the anti-αv or anti-β3 antibody (p < 0.01). Ultrasound images taken of mice bearing 4T1 breast tumors after intravenous injections of iRGD-MBs or control MBs revealed strong contrast enhancement within the tumors from iRGD-MBs but not from the control MBs; the mean acoustic signal intensity was 10.71 ± 2.75 intensity units for iRGD-MBs versus 1.13 ± 0.18 intensity units for the control MBs (p < 0.01). The presence of αvβ3 integrin was confirmed by immunofluorescence staining. These data indicate that iRGD-MBs can be used as an ultrasound imaging probe for the non-invasive molecular imaging of tumor angiogenesis, and may have further implications for ultrasound image-guided tumor targeting drug delivery.


      PubDate: 2015-07-30T21:20:05Z
       
  • Combination of Protoporphyrin IX-mediated Sonodynamic Treatment with
           Doxorubicin Synergistically Induced Apoptotic Cell Death of a
           Multidrug-Resistant Leukemia K562/DOX Cell Line
    • Abstract: Publication date: Available online 10 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Xiaobing Wang, Yali Jia, Xiaomin Su, Pan Wang, Kun Zhang, Xiaolan Feng, Quanhong Liu
      The main objective of this study was to evaluate the efficacy of administration of doxorubicin (DOX) in combination with protoporphyrin IX (PpIX)-assisted low-level therapeutic ultrasound (US) in K562/DOX cells as a potential strategy in cancer therapy. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to determine the cytotoxicity of different treatments. Apoptosis was analyzed using annexin V-PE/7-amino-actinomycin D staining. Changes in DNA fragmentation, intracellular reactive oxygen species production, cellular membrane permeability, P-glycoprotein expression and DOX uptake were analyzed with flow cytometry. Under optimal conditions, PpIX-US significantly aggravated DOX-induced K562/DOX cell death, compared with either monotherapy. Synergistic potentiation of DNA damage, generation of reactive oxygen species and P-glycoprotein inhibition were observed. Plasma membrane integrity changed slightly after US exposure, and DOX uptake was notably improved after PpIX-US exposure. The results indicate that PpIX-US could increase the susceptibility of tumors to antineoplastic drugs, suggesting a clinical potential method for sonodynamic therapy-mediated tumor chemotherapy.


      PubDate: 2015-07-30T21:20:05Z
       
  • Trauma Ultrasound
    • Abstract: Publication date: Available online 21 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Sirote Wongwaisayawan, Ruedeekorn Suwannanon, Thidathit Prachanukool, Pungkava Sricharoen, Nitima Saksobhavivat, Rathachai Kaewlai
      Ultrasound plays a pivotal role in the evaluation of acute trauma patients through the use of multi-site scanning encompassing abdominal, cardiothoracic, vascular and skeletal scans. In a high-speed polytrauma setting, because exsanguinations are the primary cause of trauma morbidity and mortality, ultrasound is used for quick and accurate detection of hemorrhages in the pericardial, pleural, and peritoneal cavities during the primary Advanced Trauma Life Support (ATLS) survey. Volume status can be assessed non-invasively with ultrasound of the inferior vena cava (IVC), which is a useful tool in the initial phase and follow-up evaluations. Pneumothorax can also be quickly detected with ultrasound. During the secondary survey and in patients sustaining low-speed or localized trauma, ultrasound can be used to help detect abdominal organ injuries. This is particularly helpful in patients in whom hemoperitoneum is not identified on an initial scan because findings of organ injuries will expedite the next test, often computed tomography (CT). Moreover, ultrasound can assist in detection of fractures easily obscured on radiography, such as rib and sternal fractures.


      PubDate: 2015-07-30T21:20:05Z
       
  • Effects of Estimators on Ultrasound Nakagami Imaging in Visualizing the
           Change in the Backscattered Statistics from a Rayleigh Distribution to a
           Pre-Rayleigh Distribution
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Po-Hsiang Tsui, Yung-Liang Wan, Dar-In Tai, Yu-Chen Shu
      Ultrasound Nakagami imaging has recently attracted interest as an imaging technique for analyzing envelope statistics. Because the presence of structures has a strong effect on estimation of the Nakagami parameter, previous studies have indicated that Nakagami imaging should be used specifically for characterization of soft tissues with fewer structures, such as liver tissues. Typically, changes in the properties of the liver parenchyma cause the backscattered statistics to transform from a Rayleigh distribution to a pre-Rayleigh distribution, and this transformation can be visualized using a Nakagami imaging technique. However, different estimators result in different estimated values; thus, the performance of a Nakagami image may depend on the type of estimator used. This study explored the effects of various estimators on ultrasound Nakagami imaging to describe the backscattered statistics as they change from a Rayleigh distribution to a pre-Rayleigh distribution. Simulations and clinical measurements involving patients with liver fibrosis (n = 85) yielded image data that were used to construct B-mode and conventional Nakagami images based on the moment estimator (denoted as m INV images) and maximum-likelihood estimator (denoted as m ML images). In addition, novel window-modulated compounding Nakagami images based on the moment estimator (denoted as m WMC images) were also obtained. The means and standard deviations of the Nakagami parameters were examined as a function of the backscattered statistics. The experimental results indicate that the m INV, m ML and m WMC images enabled quantitative visualization of the change in backscattered statistics from a Rayleigh distribution to a pre-Rayleigh distribution. Importantly, the m WMC image is superior to both m INV and m ML images because it simultaneously realizes sensitive detection of the backscattered statistics and a reduction of estimation variance for image smoothness improvement. We therefore recommend using m WMC image as a novel strategy in Nakagami imaging technique for liver tissue characterization.


      PubDate: 2015-07-30T21:20:05Z
       
  • Low-Intensity Ultrasound Promotes Clathrin-Dependent Endocytosis for Drug
           Penetration into Tumor Cells
    • Abstract: Publication date: Available online 26 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Sophie Tardoski, Evelyne Gineyts, Jacqueline Ngo, Anthony Kocot, Philippe Clézardin, David Melodelima
      Ultrasound-mediated drug delivery is a field of research with promising results, although the exact mechanisms underlying intracellular delivery of therapeutic compounds remain to be elucidated. Many studies use drug carriers and cavitation to enhance drug uptake into tumor cells. However, cavitation could induce cell lysis and remain difficult to control and predict in vivo. In this study, low-intensity ultrasound was delivered using two transducers working at 2.9 and 1.3 MHz. The maximal peak negative pressure was 0.29 MPa to avoid cavitation. Low-intensity ultrasound induced clathrin-mediated endocytosis and forced the penetration of a bisphosphonate (zoledronic acid) into MCF-7 human breast cancer cells potentially as a result of mechanical stresses. When sonication parameters were adjusted to create mild hyperthermia in addition to the mechanical stress, further significant accumulation of ZOL was observed. These results provide better insight into the role of acoustic parameters in drug uptake.


      PubDate: 2015-07-30T21:20:05Z
       
  • Ultrasonographic Visualization of Accessory Hepatic Veins and Their
           Lesions in Budd–Chiari Syndrome
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Shi-feng Cai, Yong-hao Gai, Shuang Ma, Bo Liang, Guang-chuan Wang, Qing-wei Liu
      The aim of this study was to investigate the ultrasonographic features of accessory hepatic veins (AHVs) and their lesions in Budd–Chiari syndrome (BCS). Three hundred patients with BCS were examined by ultrasonography with multifrequency (3–6 MHz) convex transducers. Sonography was performed 1 to 2 wk before digital subtraction angiography and computed tomography angiography or magnetic resonance imaging. Using sonograms, we evaluated the number, course, diameter, orifice, lesions and hemodynamics of patent and obstructed AHVs. Ultrasonography was superior to digital subtraction angiography, computed tomography angiography and magnetic resonance imaging in revealing AHV lesions and hemodynamics. Dilated AHVs were detected in 227 patients. There were 239 caudate lobe veins in 167 patients and 168 inferior right hepatic veins in 151 patients. Both caudate lobe veins and inferior right hepatic veins were found in 91 of the 227 patients. The inlets to AHVs were located mainly on the right lateral or right anterior wall of the inferior vena cava, and the remnant, on the left lateral wall. AHV lesions comprised mainly septal obstruction and segmental stenosis. The hemodynamics of AHVs varied with the condition of inferior vena cava and AHVs. Ultrasonic examination can reveal AHVs and their lesions in patients with BCS and is helpful in choosing and planning therapeutic approaches.


      PubDate: 2015-07-30T21:20:05Z
       
  • Assessment of Spectral Doppler for an Array-Based Preclinical Ultrasound
           Scanner Using a Rotating Phantom
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): David A. Kenwright, Tom Anderson, Carmel M. Moran, Peter R. Hoskins
      Velocity measurement errors were investigated for an array-based preclinical ultrasound scanner (Vevo 2100, FUJIFILM VisualSonics, Toronto, ON, Canada). Using a small-size rotating phantom made from a tissue-mimicking material, errors in pulse-wave Doppler maximum velocity measurements were observed. The extent of these errors was dependent on the Doppler angle, gate length, gate depth, gate horizontal placement and phantom velocity. Errors were observed to be up to 172% at high beam–target angles. It was found that small gate lengths resulted in larger velocity errors than large gate lengths, a phenomenon that has not previously been reported (e.g., for a beam–target angle of 0°, the error was 27.8% with a 0.2-mm gate length and 5.4% with a 0.98-mm gate length). The error in the velocity measurement with sample volume depth changed depending on the operating frequency of the probe. Some edge effects were observed in the horizontal placement of the sample volume, indicating a change in the array aperture size. The error in the velocity measurements increased with increased phantom velocity, from 22% at 2.4 cm/s to 30% at 26.6 cm/s. To minimise the impact of these errors, an angle-dependent correction factor was derived based on a simple ray model of geometric spectral broadening. Use of this angle-dependent correction factor reduces the maximum velocity measurement errors to <25% in all instances, significantly improving the current estimation of maximum velocity from pulse-wave Doppler ultrasound.


      PubDate: 2015-07-30T21:20:05Z
       
  • Panorama Ultrasound for Navigation and Guidance of Epidural Anesthesia
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Hedyeh Rafii-Tari, Victoria A. Lessoway, Allaudin A. Kamani, Purang Abolmaesumi, Robert Rohling
      Despite the common use of epidural anesthesia in obstetrics and surgery, the procedure can be challenging, especially for obese patients. We propose the use of an ultrasound guidance system employing a transducer-mounted camera to create 3-D panorama ultrasound volumes of the spine, thereby allowing identification of vertebrae and selection of puncture site, needle trajectory and depth of insertion. The camera achieves absolute position estimation of the transducer with respect to the patient using a specialized marker strip attached to the skin surface. The guidance system is validated first on a phantom against a commercial optical tracking system and then in vivo by comparing panorama images from human subjects against independent measurements by an experienced sonographer. The results for measuring depth to the epidural space, intervertebral spacing and registration of interspinous gaps to the skin prove the potential of the system for improving guidance of epidural anesthesia. The tracking and visualization are implemented in real time using the 3D Slicer software package.


      PubDate: 2015-07-30T21:20:05Z
       
  • Pulmonary Capillary Hemorrhage Induced by Fixed-Beam Pulsed Ultrasound
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Douglas L. Miller, Chunyan Dou, Krishnan Raghavendran
      The induction of pulmonary capillary hemorrhage (PCH) by pulsed ultrasound was discovered 25 y ago, but early research used fixed-beam systems rather than actual diagnostic ultrasound machines. In this study, results of exposure of rats to fixed-beam focused ultrasound for 5 min at 1.5 and 7.5 MHz were compared with recent research on diagnostic ultrasound. One exposure condition at each frequency used 10-μs pulses delivered at 25-ms intervals. Three conditions involved Gaussian modulation of the pulse amplitudes at 25-ms intervals to simulate diagnostic scanning: 7.5 MHz with 0.3- and 1.5-μs pulses at 100- and 500-μs pulse repetition periods, respectively, and 1.5 MHz with 1.7-μs pulses at 500-μs repetition periods. Four groups were tested for each condition to assess PCH areas at different exposure levels and to determine occurrence thresholds. The conditions with identical pulse timing resulted in smaller PCH areas for the smaller 7.5-MHz beam, but both had thresholds of 0.69–0.75 MPa in situ peak rarefactional pressure amplitude. The Gaussian modulation conditions for both 7.5 MHz with 0.3-μs pulses and 1.5 MHz with 1.7-μs pulses had thresholds of 1.12–1.20 MPa peak rarefactional pressure amplitude, although the relatively long 1.5-μs pulses at 7.5 MHz yielded a threshold of 0.75 MPa. The fixed-beam pulsed ultrasound exposures produced lower thresholds than diagnostic ultrasound. There was no clear tendency for thresholds to increase with increasing ultrasonic frequency when pulse timing conditions were similar.


      PubDate: 2015-07-30T21:20:05Z
       
  • VEGFR2-Targeted Contrast-Enhanced Ultrasound to Distinguish between Two
           Anti-Angiogenic Treatments
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Thomas Payen, Alexandre Dizeux, Capucine Baldini, Delphine Le Guillou-Buffello, Michele Lamuraglia, Eva Comperat, Olivier Lucidarme, S. Lori Bridal
      The aim of this study was to evaluate the capacity of BR55, an ultrasound contrast agent specifically targeting vascular endothelial growth factor receptor 2 (VEGFR2), to distinguish the specific anti-VEGFR2 therapy effect of sunitinib from other anti-angiogenic effects of a therapy (imatinib) that does not directly inhibit VEGFR2. Sunitinib, imatinib and placebo were administered daily for 11 d (264 h) to 45 BalbC mice bearing ectopic CT26 murine colorectal carcinomas. During the course of therapy, B-mode ultrasound, contrast-enhanced ultrasound and VEGFR2-targeted contrast-enhanced ultrasound were performed to assess tumor morphology, vascularization and VEGFR2 expression, respectively. The angiogenic effects on these three aspects were characterized using tumor volume, contrast-enhanced area and differential targeted enhancement. Necrosis, microvasculature and expression of VEGFR2 were also determined by histology and immunostaining. B-Mode imaging revealed that tumor growth was significantly decreased in sunitinib-treated mice at day 11 (p < 0.05), whereas imatinib did not affect growth. Functional evaluation revealed that the contrast-enhanced area decreased significantly (p < 0.02) and by similar amounts under both anti-angiogenic treatments by day 8 (192 h): −23% for imatinib and −21% for sunitinib. No significant decrease was observed in the placebo group. Targeted contrast-enhanced imaging revealed lower differential targeted enhancement, that is, lower levels of VEGFR2 expression, in sunitinib-treated mice relative to placebo-treated mice from 24 h (p < 0.05) and relative to both placebo- and imatinib-treated mice from 48 h (p < 0.05). Histologic assessment of tumors after the final imaging indicated that necrotic area was significantly higher for the sunitinib group (21%) than for the placebo (8%, p < 0.001) and imatinib (11%, p < 0.05) groups. VEGFR2-targeted ultrasound was able to sensitively differentiate the anti-VEGFR2 effect from the reduced area of tumor with functional flow produced by both anti-angiogenic agents. BR55 molecular imaging was, thus, able both to detect early therapeutic response to sunitinib in CT26 tumors as soon as 24 h after the beginning of the treatment and to provide early discrimination (48 h) between tumor response during anti-angiogenic therapy targeting VEGFR2 expression and response during anti-angiogenic therapy not directly acting on this receptor.


      PubDate: 2015-07-30T21:20:05Z
       
  • Quantitative Contrast-Enhanced Ultrasonic Imaging Reflects
           Microvascularization in Hepatocellular Carcinoma and Prognosis after
           Resection
    • Abstract: Publication date: Available online 23 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Ru-Hai Zou, Qing-Guang Lin, Wei Huang, Xiao-Ling Li, Yun Cao, Jing Zhang, Jian-Hua Zhou, An-Hua Li, Laura Beretta, Chao-Nan Qian
      Our aim was to evaluate the correlation between tumor vasculature detected by pre-surgical contrast-enhanced ultrasonography and the post-surgical prognosis of patients with hepatocellular carcinoma. One hundred ninety-five patients with hepatocellular carcinoma who had undergone curative resection and pre-operative contrast-enhanced ultrasonography were enrolled. Intra-tumoral microvessels were evaluated by immunohistochemical staining for anti-CD31 and anti-CD34. On the basis of the immunohistochemical staining and morphology patterns, tumors were divided into capillary-like and sinusoid-like microvessel subtypes. The rise time of tumors was shorter in the capillary-like microvessel subtype than in the sinusoid-like microvasculature subtype (p = 0.026). Intra-tumor microvascular density (p < 0.001, hazard ratio = 0.137) and rise time (p = 0.006, hazard ratio = 2.475) were independent factors corresponding to different microvasculature types. Microvascular density, vascular invasion and wash-in perfusion index were determined to be independent factors in recurrence-free survival and overall survival. In conclusion, contrast-enhanced ultrasonography may serve as a means of non-invasive assessment of tumor angiogenesis and may be associated with the survival of patients with hepatocellular carcinoma after resection.


      PubDate: 2015-07-30T21:20:05Z
       
  • Automated Computed Tomography–Ultrasound Cross-Modality 3-D
           Contouring Algorithm for Prostate
    • Abstract: Publication date: Available online 21 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Denis Ermacora, Silvia Pesente, Francesco Pascoli, Sebastian Raducci, Rudy Mauro, Imad Abu Rumeileh, Frank Verhaegen, Davide Fontanarosa
      A novel fully automated algorithm is introduced for 3-D cross-modality image segmentation of the prostate, based on the simultaneous use of co-registered computed tomography (CT) and 3-D ultrasound (US) images. By use of a Gabor feature detector, the algorithm can outline in three dimensions and in cross-modality the prostate, and it can be trained and optimized on specific patient populations. We applied it to 16 prostate cancer patients and evaluated the conformity between the automatically segmented prostate contours and the contours manually outlined by an experienced physician, on the CT–US fusion, using the mean distance to conformity (MDC) index. When only the CT scans were used, the average MDC value was 4.5 ± 1.7 mm (maximum value = 9.0 mm). When the US scans also were considered, the mean ± standard deviation was reduced to 3.9 ± 0.7 mm (maximum value = 5.5 mm). The cross-modality approach acted on all the largest distance values, reducing them to acceptable discrepancies.


      PubDate: 2015-07-30T21:20:05Z
       
  • High-Frequency Acoustic Impedance Imaging of Cancer Cells
    • Abstract: Publication date: Available online 10 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Muhannad N. Fadhel, Elizabeth S.L. Berndl, Eric M. Strohm, Michael C. Kolios
      Variations in the acoustic impedance throughout cells and tissue can be used to gain insight into cellular microstructures and the physiologic state of the cell. Ultrasound imaging can be used to create a map of the acoustic impedance, on which fluctuations can be used to help identify the dominant ultrasound scattering source in cells, providing information for ultrasound tissue characterization. The physiologic state of a cell can be inferred from the average acoustic impedance values, as many cellular physiologic changes are linked to an alteration in their mechanical properties. A recently proposed method, acoustic impedance imaging, has been used to measure the acoustic impedance maps of biological tissues, but the method has not been used to characterize individual cells. Using this method to image cells can result in more precise acoustic impedance maps of cells than obtained previously using time-resolved acoustic microscopy. We employed an acoustic microscope using a transducer with a center frequency of 375 MHz to calculate the acoustic impedance of normal (MCF-10 A) and cancerous (MCF-7) breast cells. The generated acoustic impedance maps and simulations suggest that the position of the nucleus with respect to the polystyrene substrate may have an effect on the measured acoustic impedance value of the cell. Fluorescence microscopy and confocal microscopy were used to correlate acoustic impedance images with the position of the nucleus within the cell. The average acoustic impedance statistically differed between normal and cancerous breast cells (1.636 ± 0.010 MRayl vs. 1.612 ± 0.006 MRayl), indicating that acoustic impedance could be used to differentiate between normal and cancerous cells.


      PubDate: 2015-07-30T21:20:05Z
       
  • Acoustic Cavitation-Mediated Delivery of Small Interfering Ribonucleic
           Acids with Phase-Shift Nano-Emulsions
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Mark T. Burgess, Tyrone M. Porter
      Localized, targeted delivery of small interfering ribonucleic acid (siRNA) has been the foremost hurdle in the use of siRNA for the treatment of various diseases. Major advances have been achieved in the synthesis of siRNA, which have led to greater target messenger RNA (mRNA) silencing and stability under physiologic conditions. Although numerous delivery strategies have shown promise, there are still limited options for targeted delivery and release of siRNA administered systemically. In this in vitro study, phase-shift nano-emulsions (PSNE) were explored as cavitation nuclei to facilitate free siRNA delivery to cancer cells via sonoporation. A cell suspension containing varying amounts of PSNE and siRNA was exposed to 5-MHz pulsed ultrasound at fixed settings (6.2-MPa peak negative pressure, 5-cycle pulses, 250-Hz pulse repetition frequency (PRF) and total exposure duration of 100 s). Inertial cavitation emissions were detected throughout the exposure using a passive cavitation detector. Successful siRNA delivery was achieved (i.e., >50% cell uptake) with high (>80%) viability. The percentage of cells with siRNA uptake was correlated with the amount of inertial cavitation activity generated from vaporized PSNE. The siRNA remained functional after delivery, significantly reducing expression of green fluorescent protein in a stably transfected cell line. These results indicate that vaporized PSNE can facilitate siRNA entry into the cytosol of a majority of sonicated cells and may provide a non-endosomal route for siRNA delivery.


      PubDate: 2015-07-30T21:20:05Z
       
  • A Computerized System to Assess Axillary Lymph Node Malignancy from
           Sonographic Images
    • Abstract: Publication date: Available online 21 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Aneta Chmielewski, Paul Dufort, Anabel M. Scaranelo
      A computational approach to classifying axillary lymph node metastasis in sonographic images is described. One hundred five ultrasound images of axillary lymph nodes from patients with breast cancer were evaluated (81 benign and 24 malignant), and each lymph node was manually segmented, delineating both the whole lymph node and internal hilum surfaces. Normalized signed distance transforms were computed from the segmented boundaries of both structures, and each pixel was then assigned coordinates in a 3-D feature space according to the pixel's intensity, its signed distance to the node boundary and its signed distance to the hilum boundary. Three-dimensional histograms over the feature space were accumulated for each node by summing over all pixels, and the bin counts served as predictor inputs to a support vector machine learning algorithm. Repeated random sampling of 80/25 train/test splits was used to estimate generalization performance and generate receiver operating characteristic curves. The optimal classifier had an area under the receiver operating characteristic curve of 0.95 and sensitivity and specificity of 0.90 and 0.90. Our results indicate the feasibility of axillary nodal staging with computerized analysis.


      PubDate: 2015-07-30T21:20:05Z
       
  • Signal of Interest Selection Standard for Ultrasonic Backscatter in
           Cancellous Bone Evaluation
    • Abstract: Publication date: Available online 23 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Chengcheng Liu, Tao Tang, Feng Xu, Dean Ta, Mami Matsukawa, Bo Hu, Weiqi Wang
      The aim of this study was to examine the effect of the backscattered signal of interest (SOI) on ultrasonic cancellous bone evaluation. In vitro backscatter measurements were performed using 16 bovine cancellous bone specimens and six different transducers with central frequencies of 0.5, 1, 2.25, 3.5, 5 and 10 MHz. The SOI for signal analysis was selected by a rectangular window. The delay (T1) and duration (T2) of the time window were varied, and the apparent integrated backscatter (AIB) and its correlation to bone volume fraction (BV/TV) were calculated. The results indicate that in addition to affecting the measured value of AIB, the SOI influences the observed correlation between AIB and BV/TV. Strong positive correlations were observed for short T1 (0.5 MHz: ≤6 μs, 1 MHz: ≤3 μs, 2.25 and 3.5 MHz: ≤2 μs, 5 and 10 MHz: ≤1 μs). However, strong negative correlations were observed when T1 was long (0.5 MHz: >9 μs, 1 MHz: >7 μs, 2.25 and 3.5 MHz: >3 μs, 5 and 10 MHz: >2 μs). The T2 value, especially low values (≤3 μs), also influenced the correlation coefficients. Positive correlations were more commonly observed at lower frequencies (i.e., 0.5–1 MHz), whereas negative correlations were more common at higher frequencies (i.e., 2.25–10 MHz). An explicit standard for in vitro SOI selection and cancellous bone assessment was proposed for a broad frequency range (0.5–10 MHz). Current conflicting findings are explained, and constructive suggestions for ultrasonic backscatter cancellous bone evaluation are provided.


      PubDate: 2015-07-30T21:20:05Z
       
  • In Vivo Measures of Shear Wave Speed as a Predictor of Tendon
           Elasticity and Strength
    • Abstract: Publication date: Available online 26 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Jack A. Martin, Adam H. Biedrzycki, Kenneth S. Lee, Ryan J. DeWall, Sabrina H. Brounts, William L. Murphy, Mark D. Markel, Darryl G. Thelen
      The purpose of this study was to assess the potential for ultrasound shear wave elastography (SWE) to measure tissue elasticity and ultimate stress in both intact and healing tendons. The lateral gastrocnemius (Achilles) tendons of 41 New Zealand white rabbits were surgically severed and repaired with growth factor coated sutures. SWE imaging was used to measure shear wave speed (SWS) in both the medial and lateral tendons pre-surgery, and at 2 and 4 wk post-surgery. Rabbits were euthanized at 4 wk, and both medial and lateral tendons underwent mechanical testing to failure. SWS significantly (p < 0.001) decreased an average of 17% between the intact and post-surgical state across all tendons. SWS was significantly (p < 0.001) correlated with both the tendon elastic modulus (r = 0.52) and ultimate stress (r = 0.58). Thus, ultrasound SWE is a potentially promising non-invasive technology for quantitatively assessing the mechanical integrity of pre-operative and post-operative tendons.


      PubDate: 2015-07-30T21:20:05Z
       
  • Single-Camera Closed-Form Real-Time Needle Tracking
           for Ultrasound-Guided Needle Insertion
    • Abstract: Publication date: Available online 26 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Mohammad Najafi, Purang Abolmaesumi, Robert Rohling
      Many common needle intervention procedures are performed with ultrasound guidance because it is a flexible, cost-effective and widely available intra-operative imaging modality. In a needle insertion procedure with ultrasound guidance, real-time calculation and visualization of the needle trajectory can help to guide the choice of puncture site and needle angle to reach the target depicted in the ultrasound image. We found that it is feasible to calculate the needle trajectory with a single camera mounted directly on the ultrasound transducer by using the needle markings. Higher accuracy is achieved compared with other similar transducer-mounted needle trackers. We used an inexpensive, real-time and easy-to-use tracking method based on an automatic feature extraction algorithm and a closed-form method for pose estimation of the needle. The overall accuracy was 0.94 ± 0.46 mm.


      PubDate: 2015-07-30T21:20:05Z
       
  • Simulation of Low-Intensity Ultrasound Propagating in a Beagle Dog
           Dentoalveolar Structure to Investigate the Relations between Ultrasonic
           Parameters and Cementum Regeneration
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Behzad Vafaeian, Saleh Al-Daghreer, Marwan El-Rich, Samer Adeeb, Tarek El-Bialy
      The therapeutic effect of low-intensity pulsed ultrasound on orthodontically induced inflammatory root resorption is believed to be brought about through mechanical signals induced by the low-intensity pulsed ultrasound. However, the stimulatory mechanism triggering dental cell response has not been clearly identified yet. The aim of this study was to evaluate possible relations between the amounts of new cementum regeneration and ultrasonic parameters such as pressure amplitude and time-averaged energy density. We used the finite-element method to simulate the previously published experiment on ultrasonic wave propagation in the dentoalveolar structure of beagle dogs. Qualitative relations between the thickness of the regenerated cementum in the experiment and the ultrasonic parameters were observed. Our results indicated that the areas of the root surface with greater ultrasonic pressure were associated with larger amounts of cementum regeneration. However, the establishment of reliable quantitative correlations between ultrasound parameters and cementum regeneration requires more experimental data and simulations.


      PubDate: 2015-07-30T21:20:05Z
       
  • Experimental and Numerical Determination of the Local Temperature
           Distribution during Phacoemulsification and Comparison of Different
           Surgery Situations within Enucleated Porcine Eyes
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Steffen Buschschlüter, Jörn von Eicken, Christian Koch, Helmut Höh
      Phacoemulsification, a common treatment for cataract, is accompanied by cell damage at the corneal endothelium. Thermal exposure during treatment has been considered a reason for this damage, but a thorough experimental and theoretical assessment of the local temperature distribution inside the eye had not yet been conducted. Measurements in porcine eyes and a finite-element simulation enabled such an assessment and localized the highest temperature rise very close to the probe. The results described in this study indicate that a distance of 1 mm between the probe and the endothelium should be maintained during treatment as a safety margin, especially when fluid flow is blocked. The highest measured temperature rise with surgically reasonable system settings and unblocked fluid flow was 1.11°C. The finite-element simulation described here is able to calculate the temperature rise at the endothelium and could serve as a tool for comparing arbitrary surgical situations with respect to thermal exposure of the endothelium.


      PubDate: 2015-07-30T21:20:05Z
       
  • Comparison of Ultrasound Corticomedullary Strain with Doppler Parameters
           in Assessment of Renal Allograft Interstitial Fibrosis/Tubular Atrophy
    • Abstract: Publication date: Available online 26 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Jing Gao, Jonathan M. Rubin, William Weitzel, Jun Lee, Darshana Dadhania, Sandip Kapur, Robert Min
      To compare the capability of ultrasound strain and Doppler parameters in the assessment of renal allograft interstitial fibrosis/tubular atrophy (IF/TA), we prospectively measured ultrasound corticomedullary strain (strain) and intra-renal artery Doppler end-diastolic velocity (EDV), peak systolic velocity (PSV) and resistive index (RI) in 45 renal transplant recipients before their kidney biopsies. We used 2-D speckle tracking to estimate strain, the deformation ratio of renal cortex to medulla produced by external compression using the ultrasound transducer. We also measured Doppler EDV, PSV and RI at the renal allograft inter-lobar artery. Using the Banff scoring system for renal allograft IF/TA, 45 patients were divided into the following groups: group 1 with ≤5% (n = 12) cortical IF/TA; group 2 with 6%–25% (n = 12); group 3 with 26%–50% (n = 11); and group 4 with >50% (n = 10). We performed receiver operating characteristic curve analysis to test the accuracy of these ultrasound parameters and duration of transplantation in determining >26% cortical IF/TA. In our results, strain was statistically significant in all paired groups (all p < 0.005) and inversely correlated with the grade of cortical IF/TA (p < 0.001). However, the difference in PSV and EDV was significant only between high-grade (>26%, including 26%–50% and >50%) and low-grade (≤25%, including <5% and 6%–25%) cortical IF/TA (p < 0.001). RI did not significantly differ in any paired group (all p > 0.05). The areas under the receiver operating characteristic curve for strain, EDV, PSV, RI and duration of transplantation in determining >26% cortical IF/TA were 0.99, 0.94, 0.88, 0.52 and 0.92, respectively. Our results suggest that corticomedullary strain seems to be superior to Doppler parameters and duration of transplantation in assessment of renal allograft cortical IF/TA.


      PubDate: 2015-07-30T21:20:05Z
       
  • Ultrasonographic Features of the Major Salivary Glands
           after Radioactive Iodine Ablation in Patients with Papillary Thyroid
           Carcinoma
    • Abstract: Publication date: Available online 26 July 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Dong Wook Kim
      The aim of this study was to evaluate the ultrasonographic features of the major salivary glands (MSGs) after post-operative radioactive iodine ablation (RIA) in patients with papillary thyroid carcinoma (PTC). The study population comprised 202 consecutively registered PTC patients who had undergone total thyroidectomy, RIA and follow-up neck ultrasonography. The ultrasonographic features of the MSGs in each patient were retrospectively evaluated by a single radiologist, and the presence of post-RIA changes was determined by direct comparisons of pre- and post-RIA follow-up ultrasonographic scans. Of the 202 patients, 94 (46.5%) had post-RIA changes in the MSGs on follow-up ultrasonography. RIA dose was closely associated with the prevalence of post-RIA changes. Post-RIA changes were more common in the parotid glands (n = 93, 46.0%) than in the submandibular glands (n = 7, 3.5%). Common ultrasonographic findings representing post-RIA changes in MSGs included coarse echotexture, decreased echogenicity, lobulated margin and decreased gland size.


      PubDate: 2015-07-30T21:20:05Z
       
  • Histotripsy Lesion Formation Using an Ultrasound Imaging Probe Enabled by
           a Low-Frequency Pump Transducer
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Kuang-Wei Lin, Timothy L. Hall, Zhen Xu, Charles A. Cain
      When histotripsy pulses shorter than 2 cycles are applied, the formation of a dense bubble cloud relies only on the applied peak negative pressure (p−) exceeding the “intrinsic threshold” of the medium (absolute value of 26–30 MPa in most soft tissues). It has been found that a sub-threshold high-frequency probe pulse (3 MHz) can be enabled by a sub-threshold low-frequency pump pulse (500 kHz) where the sum exceeds the intrinsic threshold, thus generating lesion-producing dense bubble clouds (“dual-beam histotripsy”). Here, the feasibility of using an imaging transducer to provide the high-frequency probe pulse in the dual-beam histotripsy approach is investigated. More specifically, an ATL L7-4 imaging transducer (Philips Healthcare, Andover, MA, USA), pulsed by a V-1 Data Acquisition System (Verasonics, Redmond, WA, USA), was used to generate the high-frequency probe pulses. The low-frequency pump pulses were generated by a 20-element 345-kHz array transducer, driven by a custom high-voltage pulser. These dual-beam histotripsy pulses were applied to red blood cell tissue-mimicking phantoms at a pulse repetition frequency of 1 Hz, and optical imaging was used to visualize bubble clouds and lesions generated in the red blood cell phantoms. The results indicated that dense bubble clouds (and resulting lesions) were generated when the p− of the sub-threshold pump and probe pulses combined constructively to exceed the intrinsic threshold. The average size of the smallest reproducible lesions using the imaging probe pulse enabled by the sub-threshold pump pulse was 0.7 × 1.7 mm, whereas that using the supra-threshold pump pulse alone was 1.4 × 3.7 mm. When the imaging transducer was steered laterally, bubble clouds and lesions were steered correspondingly until the combined p− no longer exceeded the intrinsic threshold. These results were also validated with ex vivo porcine liver experiments. Using an imaging transducer for dual-beam histotripsy can have two advantages: (i) lesion steering can be achieved using the steering of the imaging transducer (implemented with the beamformer of the accompanying programmable ultrasound system), and (ii) treatment can be simultaneously monitored when the imaging transducer is used in conjunction with an ultrasound imaging system.


      PubDate: 2015-07-30T21:20:05Z
       
  • Effects of Ultrasound Frequency on Nanodroplet-Mediated Histotripsy
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Eli Vlaisavljevich, Omer Aydin, Yasemin Yuksel Durmaz, Kuang-Wei Lin, Brian Fowlkes, Mohamed ElSayed, Zhen Xu
      Nanodroplet-mediated histotripsy (NMH) is a targeted ultrasound ablation technique combining histotripsy with nanodroplets that can be selectively delivered to tumor cells for targeted tumor ablation. In a previous study, it was reported that by use of extremely short, high-pressure pulses, histotripsy cavitation bubbles were generated in regions containing nanodroplets at significantly lower pressure (∼10.8 MPa) than without nanodroplets (∼28 MPa) at 500 kHz. Furthermore, it was hypothesized that lower frequency would improve the effectiveness of NMH by increasing the size of the focal region, increasing bubble expansion, and decreasing the cavitation threshold. In this study, we investigated the effects of ultrasound frequency (345 kHz, 500 kHz, 1.5 MHz, and 3 MHz) on NMH. First, the NMH cavitation threshold was measured in tissue phantoms with and without nanodroplets, with results indicating that the NMH threshold was significantly below the histotripsy intrinsic threshold at all frequencies. Results also indicated that the NMH threshold decreased at lower frequency, ranging from 7.4 MPa at 345 kHz to 13.2 MPa at 3 MHz. In the second part of this study, the effects of frequency on NMH bubble expansion were investigated, with results indicating larger expansion at lower frequency, even at a lower pressure. In the final part of this study, the ability of perfluoropentane-encapsulated nanodroplets to act as sustainable cavitation nuclei over multiple pulses was investigated, with results indicating that the nanodroplets are destroyed by the cavitation process and only function as cavitation nuclei for the first few pulses, with this effect being most pronounced at higher frequencies. Overall, the results of this study support our hypothesis that using a lower frequency will improve the effectiveness of NMH by increasing the size of the focal region, increasing bubble expansion and decreasing the cavitation threshold.


      PubDate: 2015-07-30T21:20:05Z
       
  • Evaluation of the Temporal Acoustic Window for Transcranial Doppler in a
           Multi-Ethnic Population in Brazil
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Rodrigo Bazan, Gabriel Pereira Braga, Gustavo José Luvizutto, João Carlos Hueb, Newton Key Hokama, Silméia Garcia Zanati Bazan, Hélio Rubens de Carvalho Nunes, João Pereira Leite, Octávio Marques Pontes-Neto
      The aim of this study was to relate the presence of a temporal acoustic window (TAW) to the variables sex, age and race. This observational study was conducted in patients under etiologic investigation after stroke, sickle-cell anemia and hospitalization in an intensive therapy neurologic unit. TAW presence was confirmed by bilateral assessment by two neurologists via transcranial Doppler (TCD). Multiple logistic regression was performed to explain the presence of the window as a function of sex, age and race. In 20% of the 262 patients evaluated, a TAW was not present. The incidence of TAW presence was greater in men (odds ratio [OR] = 5.4, 95% confidence interval [CI] = 2.5–11.7, p < 0.01); lower with increased age (OR = 0.9, 95% CI = 0.92–0.97, p < 0.01); and lower among those of African and Asian descent (OR = 0.32, 95% CI = 0.14–0.70, p = 0.005). On the basis of the results, more men than women had TAWs, and the decrease in TAWs was associated with increased age and African or Asian descent.


      PubDate: 2015-07-30T21:20:05Z
       
  • Associations between Handgrip Strength and Ultrasound-Measured Muscle
           Thickness of the Hand and Forearm in Young Men and Women
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Takashi Abe, Brittany R. Counts, Brian E. Barnett, Scott J. Dankel, Kofan Lee, Jeremy P. Loenneke
      It is unknown whether muscle size of intrinsic hand muscles is associated with handgrip strength. To investigate the relationships between handgrip strength and flexor muscle size of the hand and forearm, muscle thickness (MT) of 86 young adults (43 men and 43 women) between the ages of 18 and 34 y was measured by ultrasound. Two MTs (forearm radius and forearm ulna MT) in the anterior forearm, two MTs (lumbrical and dorsal interosseous MT) in the anterior hand and handgrip strength were measured on the right side. Linear regression with part (also referred to as semipartial) correlation coefficients revealed that forearm ulna MT positively correlated with handgrip strength in both men (part = 0.379, p = 0.001) and women (part = 0.268, p = 0.002). Dorsal interosseous MT correlated with handgrip strength in women only (part = 0.289, p = 0.001). Our results suggest that the forearm ulna and dorsal interosseous MTs for women and forearm ulna MTs for men are factors contributing to prediction of handgrip strength in young adults.


      PubDate: 2015-07-30T21:20:05Z
       
  • Ultrasound-Guided Perineural Injection at Guyon's Tunnel: An Anatomic
           Feasibility Study
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Stefan Meng, Ines Tinhofer, Wolfgang Grisold, Wolfgang J. Weninger
      Compression of the ulnar nerve (UN) at the wrist causes neuropathy in the ulnar tunnel (UT), or Guyon's tunnel. In the absence of trauma and motor syndromes, primarily conservative treatment is considered. As in carpal tunnel syndrome, a perineural injection of corticosteroids may be beneficial. The aim of this study was to investigate the feasibility of ultrasound-guided injections at the UT. We performed ultrasound-guided injections of ink at the UN within the UT in 21 limbs from 11 non-embalmed cadavers. In all cases, we stained the perineural sheath of the superficial branch of the ulnar nerve within the UT. No ink was found inside the nerve or in adjacent structures such as blood vessels and tendons. In conclusion, perineural injection of the UN in the UT seems to be a technically feasible procedure. On the basis of these anatomic data, clinical trials are needed to prove the concept for routine use.


      PubDate: 2015-07-30T21:20:05Z
       
  • Tissue Doppler-Derived Myocardial Acceleration during Isovolumetric
           Contraction Predicts Pulmonary Capillary Wedge Pressure in Patients with
           Significant Mitral Regurgitation
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Alaa Mabrouk Salem Omar, Mohamed Ahmed Abdel-Rahman, Hazem Khorshid, Mostafa Helmy, Hala Raslan, Osama Rifaie
      The aim of this study was to determine whether isovolumic contraction velocity (IVV) and acceleration (IVA) predict pulmonary capillary wedge pressure (PCWP) in mitral regurgitation. Forty-four patients with mitral regurgitation were studied. PCWP was invasively measured. IVV, IVA and the ratio IVRT/T e′–E (where IVRT = isovolumic relaxation time, and T e′–E  = time difference between the onset of mitral annular e′ and mitral flow E waves) were measured. Mean age was 59.2 ± 13.3 y. Twenty-six patients had an ejection fraction ≥55%, and 18 patients had an ejection fraction <55%. IVRT/T e′–E was impossible in 11 patients because T e′–E  = zero. PCWP correlated with IVV, IVA and IVRT/T e′–E ; overall (r = −0.714, −0.892 and, −0.752, all p < 0.001), ejection fraction ≥55 (r = −0.467, −0.749, −0.639, p = 0.016, <0.001, 0.003) and ejection fraction <55% (r = −0.761, −0.911 and −0.833, all p < 0.001). Similar correlations were found for sinus and atrial fibrillation. Our study suggests that IVV and IVA correlate with PCWP in patients with mitral regurgitation irrespective of systolic function or rhythms and, thus, can be alternatives to the tedious IVRT/T e′–E, especially when impossible because T e′–E  = 0.


      PubDate: 2015-07-30T21:20:05Z
       
  • Adding Ultrasound to the Evaluation of Patients with Pathologic Nipple
           Discharge to Diagnose Additional Breast Cancers: Preliminary Data
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8
      Author(s): Haesung Yoon, Jung Hyun Yoon, Eun-Kyung Kim, Hee Jung Moon, Byeong-Woo Park, Min Jung Kim
      The aim of this study was to assess the malignancy yield of ultrasound Breast Imaging Reporting and Data System (BI-RADS) classification and the diagnostic value of adding ultrasound to diagnosis of breast cancer in patients with pathologic nipple discharge. Of 267 patients with pathologic nipple discharge seen from February 2003 to March 2011, 198 with histopathologic confirmation and follow-up data were included. Ultrasound images and mammograms were analyzed according to BI-RADS. The malignancy rate for each BI-RADS category and the difference in diagnostic performance resulting from the addition of ultrasound to mammography were calculated. Of the 198 enrolled patients, 34 were diagnosed with a malignancy. The malignancy rates obtained with the addition of ultrasound to mammography were 0.0% (0 of 27) for category 1, 5.9% (1/17) for category 2, 9.4% (5/53) for category 3, 21.5% (20/93) for category 4 and 100% (8/8) for category 5. The malignancy rates for mammography alone were 7.7%–9.0% for categories 1–3, 68.5% (13/19) for category 4 and 100.0% (5/5) for category 5. Adding US to mammography did not significantly increase sensitivity compared with mammography alone. Other diagnostic performance markers such as specificity and positive predictive value were not improved. Among patients for whom mammograms were available, ultrasound detected 5 breast cancers (26.3%) in addition to the 19 breast cancers found by positive mammography. Although it did not increase overall diagnostic performance in patients with pathologic nipple discharge, addition of ultrasound to mammography did detect an additional 26.3% of malignant lesions.


      PubDate: 2015-07-30T21:20:05Z
       
  • Contents
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8




      PubDate: 2015-07-30T21:20:05Z
       
  • Masthead
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8




      PubDate: 2015-07-30T21:20:05Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: August 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 8




      PubDate: 2015-07-30T21:20:05Z
       
  • Liver Stiffness: A Significant Relationship with the Waveform Pattern in
           the Hepatic Vein
    • Abstract: Publication date: Available online 6 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Tadashi Sekimoto , Hitoshi Maruyama , Soichiro Kiyono , Takayuki Kondo , Taro Shimada , Masanori Takahashi , Osamu Yokosuka , Tadashi Yamaguchi
      The aim of this prospective study was to assess the relationship between liver stiffness and hepatic vein waveform patterns in 42 patients with chronic hepatitis and 55 with cirrhosis. Liver stiffness measurement (LSM) values (FibroScan, Echosens, Paris, France) were significantly lower in the triphasic pattern group (11.3 ± 8.4 kPa) than in the monophasic pattern (32.5 ± 23.5 kPa, p = 0.001) and biphasic pattern (25.6 ± 18.1 kPa, p = 0.001) groups, indicating no significant relationship with portal pressure. The ability to diagnose cirrhosis represented by the highest area under the receiver operating characteristic curve was 0.921 (83.6% sensitivity, 90.5% specificity, best cutoff value: 16.9 kPa) by LSM and 1.000 (best cutoff value: 19.4 kPa) by LSM combined with the monophasic pattern. This study revealed a close linkage between liver stiffness and hepatic vein waveform findings, resulting in a better understanding of hepatic vein hemodynamics and wider application of its analysis.


      PubDate: 2015-04-12T21:33:54Z
       
  • In Memoriam: Floyd Dunn (1924–2015)
    • Abstract: Publication date: Available online 2 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Andi Dunn , Roo Dunn , Bill O'Brien



      PubDate: 2015-04-12T21:33:54Z
       
 
 
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