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  Subjects -> PHYSICS (Total: 763 journals)
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PHYSICS (553 journals)            First | 1 2 3 4 5 6 | Last

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: 8)
Spectrochimica Acta Part B: Atomic Spectroscopy     Hybrid Journal   (Followers: 6)
Spectroscopy     Hybrid Journal   (Followers: 3)
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: 4)
Strength, Fracture and Complexity     Hybrid Journal   (Followers: 1)
Structural Dynamics     Open Access  
Studies In Applied Mathematics     Hybrid Journal   (Followers: 1)
Superconductor Science and Technology     Hybrid Journal   (Followers: 1)
Surface Review and Letters     Hybrid Journal   (Followers: 1)
Surface Science Reports     Full-text available via subscription   (Followers: 12)
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: 7)
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: 3)
The Physics Teacher     Full-text available via subscription   (Followers: 5)
Theoretical and Computational Fluid Dynamics     Hybrid Journal   (Followers: 7)
Theoretical and Mathematical Physics     Hybrid Journal   (Followers: 4)
Topological Quantum Matter     Open Access  
Transport Theory and Statistical Physics     Hybrid Journal   (Followers: 3)
Tribology International     Hybrid Journal   (Followers: 21)
Tribology Letters     Hybrid Journal   (Followers: 3)
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  
Virtual Journal of Applications of Superconductivity     Hybrid Journal   (Followers: 1)
Virtual Journal of Biological Physics Research     Hybrid Journal   (Followers: 1)
Virtual Journal of Nanoscale Science & Technology     Hybrid Journal   (Followers: 1)
Virtual Journal of Ultrafast Science     Hybrid Journal   (Followers: 7)
Western Journal of Communication     Hybrid Journal   (Followers: 4)
Women & Performance: a journal of feminist theory     Hybrid Journal   (Followers: 2)
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)

  First | 1 2 3 4 5 6 | Last

Journal Cover Ultrasound in Medicine & Biology     [SJR: 0.864]   [H-I: 85]
   [8 followers]  Follow    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0301-5629
   Published by Elsevier Homepage  [2582 journals]
  • Reliability of Ultrasound Evaluation of Hyoid–Larynx Approximation
           with Positional Change
    • Abstract: Publication date: Available online 20 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): So Young Ahn , Kang Hee Cho , Jaewon Beom , Dong Jun Park , Sungju Jee , Jin Hee Nam
      We evaluated the reliability of ultrasound evaluation of hyoid–larynx approximation with positional change. Twenty healthy volunteers (10 men, 10 women) participated in this study. The distance between the hyoid bone and thyroid cartilage was measured by ultrasound in both the sitting and supine positions. Hyoid–larynx approximation was defined as the shortest distance between the lower tip of the hyoid bone and the upper end of the thyroid cartilage during swallowing. The transducer was placed in a longitudinal position above the midline of the larynx, which allowed visualization of the hyoid bone and thyroid cartilage. Patients were given 5 mL of water and swallowed. The measurement was repeated three times to enable averaging in each position. Using the mean distance at rest and the shortest distance during swallowing, we calculated relative laryngeal elevation. There was no significant difference in resting distance between the hyoid bone and thyroid cartilage with positional change or gender, with identical relative laryngeal elevation. However, there was a negative correlation between the resting and approximation distance and body mass index. In conclusion, ultrasound evaluation in healthy volunteers revealed no difference in hyoid–laryngeal approximation on swallowing in either the supine or sitting position. This finding is likely to be of value in the investigation of dysphagia.


      PubDate: 2015-01-21T23:27:24Z
       
  • Methods for Using 3-D Ultrasound Speckle Tracking in Biaxial Mechanical
           Testing of Biological Tissue Samples
    • Abstract: Publication date: Available online 20 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Choon Hwai Yap , Dae Woo Park , Debaditya Dutta , Marc Simon , Kang Kim
      Being multilayered and anisotropic, biological tissues such as cardiac and arterial walls are structurally complex, making the full assessment and understanding of their mechanical behavior challenging. Current standard mechanical testing uses surface markers to track tissue deformations and does not provide deformation data below the surface. In the study described here, we found that combining mechanical testing with 3-D ultrasound speckle tracking could overcome this limitation. Rat myocardium was tested with a biaxial tester and was concurrently scanned with high-frequency ultrasound in three dimensions. The strain energy function was computed from stresses and strains using an iterative non-linear curve-fitting algorithm. Because the strain energy function consists of terms for the base matrix and for embedded fibers, spatially varying fiber orientation was also computed by curve fitting. Using finite-element simulations, we first validated the accuracy of the non-linear curve-fitting algorithm. Next, we compared experimentally measured rat myocardium strain energy function values with those in the literature and found a matching order of magnitude. Finally, we retained samples after the experiments for fiber orientation quantification using histology and found that the results satisfactorily matched those computed in the experiments. We conclude that 3-D ultrasound speckle tracking can be a useful addition to traditional mechanical testing of biological tissues and may provide the benefit of enabling fiber orientation computation.


      PubDate: 2015-01-21T23:27:24Z
       
  • Reliability of Automatic Vibratory Equipment for Ultrasonic Strain
           Measurement of the Median Nerve: Common Mistake
    • Abstract: Publication date: Available online 16 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Siamak Sabour



      PubDate: 2015-01-21T23:27:24Z
       
  • Global and Regional Left Ventricular Strain Indices in Post-Myocardial
           Infarction Patients with Ventricular Arrhythmias and Moderately Abnormal
           Ejection Fraction
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Bich Lien Nguyen , Lidia Capotosto , Alessandro Persi , Attilio Placanica , Asim Rafique , Gianfranco Piccirillo , Carlo Gaudio , Eli S. Gang , Robert J. Siegel , Antonio Vitarelli
      The aim of the study described here was to compare myocardial strains in ischemic heart patients with and without sustained ventricular tachycardia (VT) and moderately abnormal left ventricular ejection fraction (LVEF) to investigate which index could better predict VT on the basis of the analysis of global and regional left ventricular (LV) dysfunction. We studied 467 patients with previous myocardial infarction and LVEF >35%. Fifty-one patients had documented VT, and 416 patients presented with no VT. LV volumes and score index were obtained by 2-D echocardiography. Longitudinal, radial and circumferential strains were determined. Strains of the infarct, border and remote zones were also obtained. There were no differences in standard LV 2-D parameters between patients with and those without VT. Receiver operating characteristic values were −12.7% for global longitudinal strain (area under the curve [AUC] = 0.72), −4.8% for posterior-inferior wall circumferential strain (AUC = 0.80), 61 ms for LV mechanical dispersion (AUC = 0.84), −10.1% for longitudinal strain of the border zone (AUC = 0.86) and −9.2% for circumferential strain of the border zone (AUC = 0.89). In patients with previous myocardial infarction and moderately abnormal LVEF, peri-infarct circumferential strain was the strongest predictor of documented ventricular arrhythmias among all strain quantitative indices. Additionally, strain values from posterior-inferior wall infarctions had a higher association with arrhythmic events compared with global strain.


      PubDate: 2015-01-16T23:01:53Z
       
  • Using Critical Care Chest Ultrasonic Examination in Emergency
           Consultation: A Pilot Study
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Xiaoting Wang , Dawei Liu , Huaiwu He , Wei Du , Hongmin Zhang , Ye Liu , Wenzhao Chai , Qing Zhang , Xiang Zhou
      The purpose of this study was to investigate the effects of critical care chest ultrasonic examination (CCUE) by intensivist on the diagnosis and treatment decisions in emergent consultation for patients who may have a problem-need transfer to an intensive care unit (ICU). A total of 130 patients who required emergent consultation in the ordinary wards were included in this study. Patients were randomly divided into conventional group (n = 63) and CCUE group (n = 67, added CCUE). The two groups showed no significant differences in general clinical information or final diagnosis (p > 0.05). The CCUE group had a shorter time to preliminary diagnosis, final diagnosis, treatment response and X-ray/computed tomography examination; a delay in ICU transfer and ICU stay days (3.9 ± 1.2 vs. 5.4 ± 1.9 d, p < 0.05) and a higher diagnostic accuracy than the conventional group (p < 0.001). In conclusion, CCUE could help early diagnosis and therapy for the patient who may need to transfer to the ICU and reduce the ICU stay for in-hospital patients in emergent consultation.


      PubDate: 2015-01-16T23:01:53Z
       
  • Diagnosis of Thyroid Nodules Using Virtual Touch Tissue Quantification
           Value and Anteroposterior/Transverse Diameter Ratio
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Tao Li , Pei Zhou , Xuming Zhang , Mingyue Ding , Ming Yuchi , Yiyong Li
      This paper proposes an effective approach to differential diagnosis of thyroid nodules using a hierarchical classification model based on the Virtual Touch tissue quantification (VTQ) value and anteroposterior/transverse diameter (A/T) ratio. One hundred twenty nodules (92 benign, 28 malignant) were analyzed using this approach by combining the quantitative elastic characteristic with the conventional sonographic feature. First, nodules were classified as benign (VTQ values <2.27 m/s), malignant (VTQ values >2.73 m/s) and indeterminate (2.27 m/s ≤ VTQ values ≤2.73 m/s) using two cutoff points selected on the basis of receiver operating characteristic analysis. Second, the indeterminate nodules were separated into malignant and benign nodules using an A/T ratio ≥1. The advantage of this approach was that it could alleviate the limitation of an overlap in VTQ values between benign and malignant nodules. According to the pathologic results, the accuracy of this approach was 95%. The proposed approach may potentially improve diagnostic accuracy.


      PubDate: 2015-01-16T23:01:53Z
       
  • Ultrasound of the Pleurae and Lungs
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Christoph F. Dietrich , Gebhard Mathis , Xin-Wu Cui , Andre Ignee , Michael Hocke , Tim O. Hirche
      The value of ultrasound techniques in examination of the pleurae and lungs has been underestimated over recent decades. One explanation for this is the assumption that the ventilated lungs and the bones of the rib cage constitute impermeable obstacles to ultrasound. However, a variety of pathologies of the chest wall, pleurae and lungs result in altered tissue composition, providing substantially increased access and visibility for ultrasound examination. It is a great benefit that the pleurae and lungs can be non-invasively imaged repeatedly without discomfort or radiation exposure for the patient. Ultrasound is thus particularly valuable in follow-up of disease, differential diagnosis and detection of complications. Diagnostic and therapeutic interventions in patients with pathologic pleural and pulmonary findings can tolerably be performed under real-time ultrasound guidance. In this article, an updated overview is given presenting not only the benefits and indications, but also the limitations of pleural and pulmonary ultrasound.


      PubDate: 2015-01-16T23:01:53Z
       
  • Masthead
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2




      PubDate: 2015-01-16T23:01:53Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2




      PubDate: 2015-01-16T23:01:53Z
       
  • Contents
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2




      PubDate: 2015-01-16T23:01:53Z
       
  • Role of Shear Wave Sonoelastography in Differentiation Between Focal
           Breast Lesions
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Katarzyna Dobruch-Sobczak , Andrzej Nowicki
      Our goal in this study was to evaluate the relevance of shear wave sonoelastography (SWE) in the differential diagnosis of masses in the breast with respect to ultrasound (US). US and SWE were performed (Aixplorer System, SuperSonic Imagine, Aix en Provence, France) in 76 women (aged 24 to 85) with 84 lesions (43 malignant, 41 benign). The study included BI-RADS-US (Breast Imaging Reporting and Data System for Ultrsound) category 3–5 lesions. In elastograms, the following values were calculated: mean elasticity in lesions (E av.l) and in fat tissue (E av.f.) and maximal (E max.adj.) and mean (E av.adj.) elasticity in lesions and adjacent tissues. The sensitivity and specificity of the BI-RADS category 4a/4b cutoff value were 97.7% and 90.2%. For an E av.adj. of 68.5 kPa, the cutoff sensitivity was 86.1% and the specificity was 87.8%, and for an E max.adj. of 124.1 kPa, 74.4% and 92.7%, respectively. For BI-RADS-US category 3 lesions, E av.l, E max.adj. and E av.adj. were below cutoff levels. On the basis of our findings, E av.adj. had lower sensitivity and specificity compared with US. E max.adj. improved the specificity of breast US with loss of sensitivity.


      PubDate: 2015-01-16T23:01:53Z
       
  • Musculoskeletal Ultrasound Ian Beggs, editor. Lippincott Williams
           &amp; Wilkins, Philadelphia, PA, USA, 2014, 339 pages. ISBN:
           978-1-4511-4498-7
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Joseph Fournier



      PubDate: 2015-01-16T23:01:53Z
       
  • Calendar
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2




      PubDate: 2015-01-16T23:01:53Z
       
  • Sonothrombolysis: The Contribution of Stable and Inertial Cavitation to
           Clot Lysis
    • Abstract: Publication date: Available online 15 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): B. Petit , Y. Bohren , E. Gaud , P. Bussat , M. Arditi , F. Yan , F. Tranquart , E. Allémann
      Microbubble-mediated sonothrombolysis (STL) is a remarkable approach to vascular occlusion therapy. However, STL remains a complex process with multiple interactions between clot, ultrasound (US), microbubbles (MB) and thrombolytic drug. The aim of this study was to evaluate the ability of combining US and MB to degrade fibrin and, more specifically, to assess the roles of both stable (SC) and inertial (IC) cavitation. Human blood clots containing radiolabeled fibrin were exposed to different combinations of recombinant tissue plasminogen activator (rtPA), US (1 MHz) and phospholipid MB. Three acoustic pressures were tested: 200, 350 and 1,300 kPa (peak-negative pressure). Clot lysis was assessed by diameter loss and release of radioactive fibrin degradation products. The combination rtPA + US + MB clearly revealed that IC (1,300 kPa) was able to enhance fibrin degradation significantly (66.3 ± 1.8%) compared with rtPA alone (51.7 ± 2.0%, p < 0.001). However, SC failed to enhance fibrin degradation at an acoustic pressure of 200 kPa. At 350 kPa, a synergistic effect between rtPA and US + MB was observed with an absolute increase of 6% compared to rtPA alone (p < 0.001). Conversely, without rtPA, the combination of US + MB was unable to degrade the fibrin network (0.3 ± 0.1%, p > 0.05 vs. control), but induced a distinct loss of red blood cells throughout the entire thickness of the clot, implying that MB were able to penetrate and cavitate inside the clot.


      PubDate: 2015-01-16T23:01:53Z
       
  • Reliability of Superficial Male Pelvic Floor Structural Measurements Using
           Linear-Array Transperineal Sonography
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Shawn C. Roll , Manku Rana , Susan M. Sigward , Moheb S. Yani , Daniel J. Kirages , Jason J. Kutch
      This study evaluated reliability of measures for superficial structures of the male pelvic floor (PF) obtained via transperineal sonography. Two embalmed cadavers were dissected to identify positioning of muscles on and around the bulb of the penis and to confirm the PF protocol. Cross-sectional area (CSA) and linear thickness of the bulb of the penis, urethra, bulbospongiosus (BS) muscles, and ischiocavernosus (IC) muscles were measured on 38 transverse images from 20 male patients by three raters with varied study knowledge and sonographic experience. Intra- and inter-rater reliability were calculated with two-way, mixed effects intra-class correlation coefficients. Measures of the bulb of the penis had the best reliability. CSA of all muscles and sagittal thickness of the BS near the central tendon had good reliability. Reliability varied for rater-identified thickest muscle region and measures of the urethra. Our study suggests that structures of the male PF can be reliably evaluated using a transperineal sonographic approach.


      PubDate: 2015-01-16T23:01:53Z
       
  • Pennation Angle Does Not Influence the Age-Related Differences in Echo
           Intensity of the Medial Gastrocnemius
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Eric D. Ryan , Joseph G. Rosenberg , Michael J. Scharville , Eric J. Sobolewski , Andrew J. Tweedell , Craig R. Kleinberg
      The reflection of an ultrasound (US) wave is strongest when the propagation direction of the wave is perpendicular to muscle fascicles. Thus, it is possible that muscle echo intensity (EI), a gray-scale US measure of muscle quality, may be influenced by the angulation of muscle fascicles. Therefore, the purpose of this study was to determine if age-related differences in muscle EI values are influenced by differences in pennation angle (PA). Medial gastrocnemius EI and PA were examined using panoramic US imaging in 24 young (19.8 ± 1.7 y) and 21 older (69.3 ± 3.3 y) men. The young men had lower EI values (young = 74.1 ± 6.3 a.u., older = 89.1 ± 8.8 a.u.) and a greater PA (young = 20.0 ± 2.9°; older = 17.2 ± 2.5°) compared with the older men (p < 0.01). In addition, there was a negative relationship (r = –0.473, p < 0.01) between PA and EI with both groups combined, but no significant relationship when the young (r = –0.334, p = 0.111) and older (r = –0.147, p = 0.525) men were examined separately. An analysis of covariance revealed that muscle EI values remained different (p < 0.01) between age groups after adjustment for differences in PA. Thus, after statistically adjusting the mean EI values for the differences in PA, there were still significant age-related differences in EI. These findings may provide further support that the age-related changes in muscle EI values reflect changes in tissue composition (i.e., increase in intramuscular fat and/or connective tissue) commonly reported in older adults.


      PubDate: 2015-01-16T23:01:53Z
       
  • The Role of Viscosity Estimation for Oil-in-gelatin Phantom in Shear Wave
           Based Ultrasound Elastography
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Ying Zhu , Changfeng Dong , Yin Yin , Xin Chen , Yanrong Guo , Yi Zheng , Yuanyuan Shen , Tianfu Wang , Xinyu Zhang , Siping Chen
      Shear wave based ultrasound elastography utilizes mechanical excitation or acoustic radiation force to induce shear waves in deep tissue. The tissue response is monitored to obtain elasticity information about the tissue. During the past two decades, tissue elasticity has been extensively studied and has been used in clinical disease diagnosis. However, biological soft tissues are viscoelastic in nature. Therefore, they should be simultaneously characterized in terms of elasticity and viscosity. In this study, two shear wave-based elasticity imaging methods, shear wave dispersion ultrasound vibrometry (SDUV) and acoustic radiation force impulsive (ARFI) imaging, were compared. The discrepancy between the measurements obtained by the two methods was analyzed, and the role of viscosity was investigated. To this end, four types of gelatin phantoms containing 0%, 20%, 30% and 40% castor oil were fabricated to mimic different viscosities of soft tissue. For the SDUV method, the shear elasticity μ1 was 3.90 ± 0.27 kPa, 4.49 ± 0.16 kPa, 2.41 ± 0.33 kPa and 1.31 ± 0.09 kPa; and the shear viscosity μ2 was 1.82 ± 0.31 Pa•s, 2.41 ± 0.35 Pa•s, 2.65 ± 0.13 Pa•s and 2.89 ± 0.14 Pa•s for 0%, 20%, 30% and 40% oil, respectively in both cases. For the ARFI measurements, the shear elasticity μ was 7.30 ± 0.20 kPa, 8.20 ± 0.31 kPa, 7.42 ± 0.21 kPa and 5.90 ± 0.36 kPa for 0%, 20%, 30% and 40% oil, respectively. The SDUV results demonstrated that the elasticity first increased from 0% to 20% oil and then decreased for the 30% and 40% oil. The viscosity decreased consistently as the concentration of castor oil increased from 0% to 40%. The elasticity measured by ARFI showed the same trend as that of the SDUV but exceeded the results measured by SDUV. To clearly validate the impact of viscosity on the elasticity estimation, an independent measurement of the elasticity and viscosity by dynamic mechanical analysis (DMA) was conducted on these four types of gelatin phantoms and then compared with SDUV and ARFI results. The shear elasticities obtained by DMA (3.44 ± 0.31 kPa, 4.29 ± 0.13 kPa, 2.05 ± 0.29 kPa and 1.06 ± 0.18 kPa for 0%, 20%, 30% and 40% oil, respectively) were lower than those by SDUV, whereas the shear viscosities obtained by DMA (2.52 ± 0.32 Pa·s, 3.18 ± 0.12 Pa·s, 3.98 ± 0.19 Pa·s and 4.90 ± 0.20 Pa·s for 0%, 20%, 30% and 40% oil, respectively) were greater than those obtained by SDUV. However, the DMA results showed that the trend in the elasticity and viscosity data was the same as that obtained from the SDUV and ARFI. The SDUV results demonstrated that adding castor oil changed the viscoelastic properties of the phantoms and resulted in increased dispersion of the shear waves. Viscosity can provide important and independent information about the inner state of the phantoms, in addition to the elasticity. Because the ARFI method ignores the dispersion of the shear waves, namely viscosity, it may bias the estimation of the true elasticity. This study sheds further light on the significance of the viscosity measurements in shear wave based elasticity imaging methods.


      PubDate: 2015-01-16T23:01:53Z
       
  • Quantification of Elastic Heterogeneity Using Contourlet-Based Texture
           Analysis in Shear-Wave Elastography for Breast Tumor Classification
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Qi Zhang , Yang Xiao , Shuai Chen , Congzhi Wang , Hairong Zheng
      Ultrasound shear-wave elastography (SWE) has become a valuable tool for diagnosis of breast tumors. The purpose of this study was to quantify the elastic heterogeneity of breast tumors in SWE by using contourlet-based texture features and evaluating their diagnostic performance for classification of benign and malignant breast tumors, with pathologic results as the gold standard. A total of 161 breast tumors in 125 women who underwent B-mode and SWE ultrasonography before biopsy were included. Five quantitative texture features in SWE images were extracted from the directional subbands after the contourlet transform, including the mean (T mean), maximum (T max), median (T med), third quartile (T qt), and standard deviation (T sd) of the subbands. Diagnostic performance of the texture features and the classic features was compared using the area under the receiver operating characteristic curve (AUC) and the leave-one-out cross validation with Fisher classifier. The feature T mean achieved the highest AUC (0.968) among all features and it yielded a sensitivity of 89.1%, a specificity of 94.3% and an accuracy of 92.5% for differentiation between benign and malignant tumors via the leave-one-out cross validation. Compared with the best classic feature, i.e., the maximum elasticity, T mean improved the AUC, sensitivity, specificity and accuracy by 3.5%, 12.7%, 2.8% and 6.2%, respectively. The T med, T qt and T sd were also superior to the classic features in terms of the AUC and accuracy. The results demonstrated that the contourlet-based texture features captured the tumor's elastic heterogeneity and improved diagnostic performance contrasted with the classic features.


      PubDate: 2015-01-16T23:01:53Z
       
  • Validity of Ultrasound Prediction Equations for Total and Regional
           Muscularity in Middle-aged and Older Men and Women
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Takashi Abe , Jeremy P. Loenneke , Kaelin C. Young , Robert S. Thiebaud , Vinayak K. Nahar , Kaitlyn M. Hollaway , Caitlin D. Stover , M. Allison Ford , Martha A. Bass , Mark Loftin
      To test the validity of published equations, 79 Caucasian adults (40 men and 39 women) aged 50–78 y had muscle thickness (MT) measured by ultrasound at nine sites of the body. Fat-free mass (FFM), lean soft tissue mass (LM) and total muscle mass (TMM) were estimated from MT using equations previously published in the literature. Appendicular LM (aLM) was estimated using dual-energy X-ray absorptiometry (DXA) and this method served as the reference criterion. There were strong correlations (range r = 0.85–0.94) between DXA-derived aLM and estimated FFM, leg LM or TMM. Total error between DXA-derived aLM and TMM (∼2 kg) was lower compared with the three other selected equations (6–10 kg). A Bland-Altman plot revealed that there was no systematic bias between aLM and TMM; however, the other three equations included systematic error. Our results suggest that an ultrasound equation for TMM is appropriate and useful for evaluating skeletal muscle mass in the body.


      PubDate: 2015-01-16T23:01:53Z
       
  • Measurement of the Doppler Power of Flowing Blood Using Ultrasound Doppler
           Devices
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Chih-Chung Huang , Hung-Lung Chou , Pay-Yu Chen
      Measurement of the Doppler power of signals backscattered from flowing blood (henceforth referred to as the Doppler power of flowing blood) and the echogenicity of flowing blood have been used widely to assess the degree of red blood cell (RBC) aggregation for more than 20 y. Many studies have used Doppler flowmeters based on an analogue circuit design to obtain the Doppler shifts in the signals backscattered from flowing blood; however, some recent studies have mentioned that the analogue Doppler flowmeter exhibits a frequency-response problem whereby the backscattered energy is lost at higher Doppler shift frequencies. Therefore, the measured Doppler power of flowing blood and evaluations of RBC aggregation obtained using an analogue Doppler device may be inaccurate. To overcome this problem, the present study implemented a field-programmable gate array-based digital pulsed-wave Doppler flowmeter to measure the Doppler power of flowing blood, in the aim of providing more accurate assessments of RBC aggregation. A clinical duplex ultrasound imaging system that can acquire pulsed-wave Doppler spectrograms is now available, but its usefulness for estimating the ultrasound scattering properties of blood is still in doubt. Therefore, the echogenicity and Doppler power of flowing blood under the same flow conditions were measured using a laboratory pulser–receiver system and a clinical ultrasound system, respectively, for comparisons. The experiments were carried out using porcine blood under steady laminar flow with both RBC suspensions and whole blood. The experimental results indicated that a clinical ultrasound system used to measure the Doppler spectrograms is not suitable for quantifying Doppler power. However, the Doppler power measured using a digital Doppler flowmeter can reveal the relationship between backscattering signals and the properties of blood cells because the effects of frequency response are eliminated. The measurements of the Doppler power and echogenicity of flowing blood were compared with those obtained in several previous studies.


      PubDate: 2015-01-16T23:01:53Z
       
  • An Ultrasound-Driven Kinematic Model for Deformation of the Infarcted
           Mouse Left Ventricle Incorporating a Near-Incompressibility Constraint
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Dan Lin , Brent A. French , Yaqin Xu , John A. Hossack , Jeffrey W. Holmes
      Mathematical models of varying complexity have proved useful in fitting and interpreting regional cardiac displacements obtained from imaging methods such as ultrasound speckle tracking or MRI tagging. Simpler models, such as the classic thick-walled cylinder model of the left ventricle (LV), can be solved quickly and are easy to implement, but they ignore regional geometric variations and are difficult to adapt to the study of regional pathologies like myocardial infarctions. Complex, anatomically accurate finite-element models work well, but are computationally intensive and require specialized expertise to implement. We developed a kinematic model that offers a compromise between these two traditional approaches, assuming only that displacements in the left ventricle are polynomial functions of initial position and that the myocardium is nearly incompressible, while allowing myocardial motion to vary spatially as would be expected in an ischemic or dyssynchronous LV. Model parameters were determined using an objective function with adjustable weights to account for confidence in individual displacement components and desired strength of the incompressibility constraint. The model accurately represented the motion of both normal and infarcted mouse LVs during the cardiac cycle, with normalized root mean square errors in predicted deformed positions of 8.2 ± 2.3% and 7.4 ± 2.1% for normal and infarcted hearts, respectively.


      PubDate: 2015-01-16T23:01:53Z
       
  • Validation of a Computer-Aided Diagnosis System for the Automatic
           Identification of Carotid Atherosclerosis
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Lilla Bonanno , Silvia Marino , Placido Bramanti , Fabrizio Sottile
      Carotid atherosclerosis represents one of the most important causes of brain stroke. The degree of carotid stenosis is, up to now, considered one of the most important features for determining the risk of brain stroke. Ultrasound (US) is a non-invasive, relatively inexpensive, portable technique, which has an excellent temporal resolution. Computer-aided diagnosis (CAD) has become one of the major research fields in medical and diagnostic imaging. We studied US images of 44 patients, 22 patients with and 22 without carotid artery stenosis, by using US examination and applying a CAD system, an automatic prototype software to detect carotid plaques. We obtained 287 regions: 60 were classified as plaques, with an average signal echogenicity of 244.1 ± 20.0 and 227 were classified as non-plaques, with an average signal echogenicity of 193.8 ± 38.6 compared with the opinion of an expert neurologist (golden test). The receiver operating characteristic (ROC) analysis revealed a highly significant area under the ROC curve difference from 0.5 (null hypothesis) in the discrimination between plaques and non-plaques; the diagnostic accuracy was 89% (95% CI: 0.85–0.92), with an appropriate cut-off value of 236.8, sensitivity was 83% and specificity reached a value of 85%. The experimental results showed that the proposed method is feasible and has a good agreement with the expert neurologist. Without the need of any user-interaction, this method generates a detection out-put that may be useful in second opinion.


      PubDate: 2015-01-16T23:01:53Z
       
  • Fully Automated Carotid Plaque Segmentation in Combined Contrast-Enhanced
           and B-Mode Ultrasound
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Zeynettin Akkus , Diego D.B. Carvalho , Stijn C.H. van den Oord , Arend F.L. Schinkel , Wiro J. Niessen , Nico de Jong , Antonius F.W. van der Steen , Stefan Klein , Johan G. Bosch
      Carotid plaque segmentation in B-mode ultrasound (BMUS) and contrast-enhanced ultrasound (CEUS) is crucial to the assessment of plaque morphology and composition, which are linked to plaque vulnerability. Segmentation in BMUS is challenging because of noise, artifacts and echo-lucent plaques. CEUS allows better delineation of the lumen but contains artifacts and lacks tissue information. We describe a method that exploits the combined information from simultaneously acquired BMUS and CEUS images. Our method consists of non-rigid motion estimation, vessel detection, lumen–intima segmentation and media–adventitia segmentation. The evaluation was performed in training (n = 20 carotids) and test (n = 28) data sets by comparison with manually obtained ground truth. The average root-mean-square errors in the training and test data sets were comparable for media–adventitia (411 ± 224 and 393 ± 239 μm) and for lumen–intima (362 ± 192 and 388 ± 200 μm), and were comparable to inter-observer variability. To the best of our knowledge, this is the first method to perform fully automatic carotid plaque segmentation using combined BMUS and CEUS.


      PubDate: 2015-01-16T23:01:53Z
       
  • A Theoretical Study of Inertial Cavitation from Acoustic Radiation Force
           Impulse Imaging and Implications for the Mechanical Index1
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Charles C. Church , Cecille Labuda , Kathryn Nightingale
      The mechanical index (MI) attempts to quantify the likelihood that exposure to diagnostic ultrasound will produce an adverse biological effect by a non-thermal mechanism. The current formulation of the MI implicitly assumes that the acoustic field is generated using the short pulse durations appropriate to B-mode imaging. However, acoustic radiation force impulse (ARFI) imaging employs high-intensity pulses up to several hundred acoustic periods long. The effect of increased pulse durations on the thresholds for inertial cavitation was studied computationally in water, urine, blood, cardiac and skeletal muscle, brain, kidney, liver and skin. The results indicate that, although the effect of pulse duration on cavitation thresholds in the three liquids can be considerable, reducing them by, for example, 6%–24% at 1 MHz, the effect on tissue is minor. More importantly, the frequency dependence of the MI appears to be unnecessarily conservative; that is, the magnitude of the exponent on frequency could be increased to 0.75. Comparison of these theoretical results with experimental measurements suggests that some tissues do not contain the pre-existing, optimally sized bubbles assumed for the MI. This means that in these tissues, the MI is not necessarily a strong predictor of the probability of an adverse biological effect.


      PubDate: 2015-01-16T23:01:53Z
       
  • Subharmonic, Non-linear Fundamental and Ultraharmonic Imaging of
           Microbubble Contrast at High Frequencies
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Verya Daeichin , Johan G. Bosch , Andrew Needles , F. Stuart Foster , Antonius van der Steen , Nico de Jong
      There is increasing use of ultrasound contrast agent in high-frequency ultrasound imaging. However, conventional contrast detection methods perform poorly at high frequencies. We performed systematic in vitro comparisons of subharmonic, non-linear fundamental and ultraharmonic imaging for different depths and ultrasound contrast agent concentrations (Vevo 2100 system with MS250 probe and MicroMarker ultrasound contrast agent, VisualSonics, Toronto, ON, Canada). We investigated 4-, 6- and 10-cycle bursts at three power levels with the following pulse sequences: B-mode, amplitude modulation, pulse inversion and combined pulse inversion/amplitude modulation. The contrast-to-tissue (CTR) and contrast-to-artifact (CAR) ratios were calculated. At a depth of 8 mm, subharmonic pulse-inversion imaging performed the best (CTR = 26 dB, CAR = 18 dB) and at 16 mm, non-linear amplitude modulation imaging was the best contrast imaging method (CTR = 10 dB). Ultraharmonic imaging did not result in acceptable CTRs and CARs. The best candidates from the in vitro study were tested in vivo in chicken embryo and mouse models, and the results were in a good agreement with the in vitro findings.


      PubDate: 2015-01-16T23:01:53Z
       
  • Electrophysiological Changes Correlated with Temperature Increases Induced
           by High-Intensity Focused Ultrasound Ablation
    • Abstract: Publication date: February 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 2
      Author(s): Ziqi Wu , Ronald E. Kumon , Jacob I. Laughner , Igor R. Efimov , Cheri X. Deng
      To gain better understanding of the detailed mechanisms of high-intensity focused ultrasound (HIFU) ablation for cardiac arrhythmias, we investigated how the cellular electrophysiological (EP) changes were correlated with temperature increases and thermal dose (cumulative equivalent minutes [CEM 43 ]) during HIFU application using Langendorff-perfused rabbit hearts. Employing voltage-sensitive dye di-4-ANEPPS, we measured the EP and temperature during HIFU using simultaneous optical mapping and infrared imaging. Both action potential amplitude (APA) and action potential duration at 50% repolarization (APD50) decreased with temperature increases, and APD50 was more thermally sensitive than APA. EP and tissue changes were irreversible when HIFU-induced temperature increased above 52.3 ± 1.4°C and log10(CEM 43 ) above 2.16 ± 0.51 (n = 5), but were reversible when temperature was below 50.1 ± 0.8°C and log10(CEM 43 ) below –0.9 ± 0.3 (n = 9). EP and temperature/thermal dose changes were spatially correlated with HIFU-induced tissue necrosis surrounded by a transition zone.


      PubDate: 2015-01-16T23:01:53Z
       
  • Erratum
    • Abstract: Publication date: Available online 6 January 2015
      Source:Ultrasound in Medicine & Biology




      PubDate: 2015-01-07T22:38:59Z
       
  • Meshless Bubble Filter Using Ultrasound for Extracorporeal Circulation and
           its Effect on Blood
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Koji Mino , Masato Imura , Daisuke Koyama , Masayoshi Omori , Shigeki Kawarabata , Masafumi Sato , Yoshiaki Watanabe
      A bubble filter with no mesh structure for extracorporeal circulation using ultrasound was developed. Hemolysis was evaluated by measuring free hemoglobin (FHb). FHb in 120 mL of bovine blood was measured in acoustic standing-wave fields. With a sound pressure amplitude of 60 kPa at driving frequencies of 1 MHz, 500 kHz and 27 kHz for 15 min. FHb values were 641.6, 2575 and 8903 mg/dL, respectively. Thus, hemolysis was inhibited with higher driving frequencies when the same sound pressure amplitude was applied. An ultrasound bubble filter with a resonance frequency of 1 MHz was designed. The filtering characteristics of the flowing microbubbles were investigated with a circulation system using bovine blood with a flow rate of 5.0 L/min. Approximately 99.1% of microbubbles were filtered with 250 kPa and a flow of 5.0 L/min. Hemolysis decreased as the sound pressure decreased; FHb values were 225.8 and 490.7 mg/dL when using 150 and 200 kPa, respectively.


      PubDate: 2014-12-24T21:18:15Z
       
  • Diagnostic Ultrasound Imaging: Inside Out (Second Edition) Thomas L.
           Szabo. Academic Press, Kidlington, Oxford, UK, 2014. 832 pages. ISBN
           number 978 012 396487 8.
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Christian Kollmann



      PubDate: 2014-12-24T21:18:15Z
       
  • Treatment of Microvascular Micro-embolization Using Microbubbles and
           Long-Tone-Burst Ultrasound: An in Vivo Study
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): John J. Pacella , Judith Brands , Frederick G. Schnatz , John J. Black , Xucai Chen , Flordeliza S. Villanueva
      Despite epicardial coronary artery reperfusion by percutaneous coronary intervention, distal micro-embolization into the coronary microcirculation limits myocardial salvage during acute myocardial infarction. Thrombolysis using ultrasound and microbubbles (sonothrombolysis) is an approach that induces microbubble oscillations to cause clot disruption and restore perfusion. We sought to determine whether this technique could restore impaired tissue perfusion caused by thrombotic microvascular obstruction. In 16 rats, an imaging transducer was placed on the biceps femoris muscle, perpendicular to a single-element 1-MHz treatment transducer. Ultrasound contrast perfusion imaging was performed at baseline and after micro-embolization. Therapeutic ultrasound (5000 cycles, pulse repetition frequency = 0.33 Hz, 1.5 MPa) was delivered to nine rats for two 10-min sessions during intra-arterial infusion of lipid-encapsulated microbubbles; seven control rats received no ultrasound–microbubble therapy. Ultrasound contrast perfusion imaging was repeated after each treatment or control period, and microvascular volume was measured as peak video intensity. There was a 90% decrease in video intensity after micro-embolization (from 8.6 ± 4.8 to 0.7 ± 0.8 dB, p < 0.01). The first and second ultrasound–microbubble sessions were respectively followed by video intensity increases of 5.8 ± 5.1 and 8.7 ± 5.7 dB (p < 0.01, compared with micro-embolization). The first and second control sessions, respectively, resulted in no significant increase in video intensity (2.4 ± 2.3 and 3.6 ± 4.9) compared with micro-embolization (0.6 ± 0.7 dB). We have developed an in vivo model that simulates the distal thrombotic microvascular obstruction that occurs after primary percutaneous coronary intervention. Long-pulse-length ultrasound with microbubbles has a therapeutic effect on microvascular perfusion and may be a valuable adjunct to reperfusion therapy for acute myocardial infarction.


      PubDate: 2014-12-24T21:18:15Z
       
  • Strokes and TIAs during and after Carotid Artery Doppler: Cause or
           Coincidence'
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Vasileios Papavasileiou , Haralampos Milionis , Lorenz Hirt , Patrik Michel
      The aim of the present study was to explore the prevalence of acute cerebrovascular symptoms temporally related to carotid Doppler examination (DEx), in order to increase the awareness and recording of such events and to discuss possible mechanisms. All adult patients who complained of acute onset neurologic symptoms during or shortly after a carotid DEx, between 01/2003 and 12/2011 in the University Hospital of Lausanne were prospectively collected. We identified four consecutive patients with acute onset neurologic symptoms during or shortly after a carotid DEx among approximately 13,500 patients who underwent carotid DEx in our facility during the nine-year period (0.015% of all examined carotids). Clinical data, imaging reports and CTA (CT angiography) or/and ultrasound images are presented for each patient. Ischemic cerebrovascular events during or immediately after cervical Doppler could be due to chance or to several physical factors. They should be promptly recognized by Doppler personnel and properly treated, but do not put into question the overwhelming benefits of Doppler in cerebrovascular patients.


      PubDate: 2014-12-24T21:18:15Z
       
  • Near Real-Time Robust Non-rigid Registration of Volumetric Ultrasound
           Images for Neurosurgery
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Hassan Rivaz , D. Louis Collins
      Ultrasound images are acquired before and after the resection of brain tumors to help the surgeon to localize the tumor and its extent and to minimize the amount of residual tumor after the resection. Because the brain undergoes large deformation between these two acquisitions, deformable image-based registration of these data sets is of substantial clinical importance. In this work, we present an algorithm for non-rigid registration of ultrasound images (RESOUND) that models the deformation with free-form cubic B-splines. We formulate a regularized cost function that uses normalized cross-correlation as the similarity metric. To optimize the cost function, we calculate its analytic derivative and use the stochastic gradient descent technique to achieve near real-time performance. We further propose a robust technique to minimize the effect of non-corresponding regions such as the resected tumor and possible hemorrhage in the post-resection image. Using manually labeled corresponding landmarks in the pre- and post-resection ultrasound volumes, we illustrate that our registration algorithm reduces the mean target registration error from an initial value of 3.7 to 1.5 mm. We also compare RESOUND with the previous work of Mercier et al. (2013) and illustrate that it has three important advantages: (i) it is fully automatic and does not require a manual segmentation of the tumor, (ii) it produces smaller registration errors and (iii) it is about 30 times faster. The clinical data set is available online on the BITE database website.


      PubDate: 2014-12-24T21:18:15Z
       
  • Changes in Backscattered Ultrasonic Envelope Statistics as a Function of
           Thrombus Age: An in Vitro Study
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Jui Fang , Chin-Kuo Chen , Ju-Yi Peng , Chung-Hsin Hsu , Yung-Ming Jeng , Yu-Hsin Lee , Jen-Jen Lin , Po-Hsiang Tsui
      It is necessary to determine the age of thrombi in planning clinical treatment for thrombolysis. Ultrasound imaging can potentially be used to evaluate thrombus age in real time. The backscattered signals from thrombi may contain useful information regarding their age. On the basis of the randomness of ultrasound backscattering, this study explored changes in backscattered US statistics as a function of thrombus age. Porcine blood samples were used for the in vitro induction of fresh thrombi (day 0) with hematocrits ranging from 0%–40% and aged thrombi (days 0–8) with a hematocrit of 40%. Each thrombus was imaged using a pulse-echo ultrasound scanner equipped with a 7.5-MHz linear array transducer to acquire raw backscattered signals for B-mode and Nakagami imaging, by which the backscattered statistics were visualized. Hematoxylin and eosin staining and scanning electron microscopy were used to observe the histology of fresh and aged thrombi. The results indicated that a decrease in the number of red blood cells in the thrombus caused by the aging effect was observed in the in vitro model, indicating that the proposed model could simulate the structural changes in the thrombus during aging. Compared with fresh thrombi with various hematocrits, the aged thrombi exhibited a trend toward more substantial decreases in the Nakagami parameter with increasing thrombus age (the Nakagami parameter decreased from 1.1 to 0.6 as thrombus age increased from day 0 to day 8), indicating that thrombus aging causes the backscattered statistics to follow a pre-Rayleigh distribution to a high degree. This finding may be applied to the determination of thrombus age using conventional ultrasound imaging in the future.


      PubDate: 2014-12-24T21:18:15Z
       
  • Effect of Biological Characteristics of Different Types of Uterine
           Fibroids, as Assessed with T2-Weighted Magnetic Resonance Imaging, on
           Ultrasound-Guided High-Intensity Focused Ultrasound Ablation
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Wen-Peng Zhao , Jin-Yun Chen , Wen-Zhi Chen
      The aims of this study were to assess the effects of the biological characteristics of different types of uterine fibroids, as assessed with T2-weighted magnetic resonance imaging (MRI), on ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation. Thirty-five patients with 39 symptomatic uterine fibroids who underwent myomectomy or hysterectomy were enrolled. Before surgery, the uterine fibroids were subdivided into hypo-intense, iso-intense, heterogeneous hyper-intense and homogeneous hyper-intense categories based on signal intensity on T2-weighted MRI. Tissue density and moisture content were determined in post-operative samples and normal uterine tissue, the isolated uterine fibroids were subjected to USgHIFU, and the extent of ablation was measured using triphenyltetrazolium chloride. Hematoxylin and eosin staining and sirius red staining were undertaken to investigate the organizational structure of the uterine fibroids. Estrogen and progesterone receptor expression was assayed via immunohistochemical staining. The mean diameter of uterine fibroids was 6.9 ± 2.8 cm. For all uterine fibroids, the average density and moisture content were 10.7 ± 0.7 mg/mL and 75.7 ± 2.4%, respectively; and for the homogeneous hyper-intense fibroids, 10.3 ± 0.5 mg/mL and 76.6 ± 2.3%. The latter subgroup had lower density and higher moisture content compared with the other subgroups. After USgHIFU treatment, the extent of ablation of the hyper-intense fibroids was 102.7 ± 42.1 mm2, which was significantly less than those of the hypo-intense and heterogeneous hyper-intense fibroids. Hematoxylin and eosin staining and sirius red staining revealed that the homogeneous hyper-intense fibroids had sparse collagen fibers and abundant cells. Immunohistochemistry results revealed that estrogen and progesterone receptors were highly expressed in the homogeneous hyper-intense fibroids. This study revealed that lower density, higher moisture content, sparse collagen fibers, abundant cells and overexpression of estrogen and progesterone receptors are important biological characteristics that resulted in poor efficacy in the treatment of homogeneous hyper-intense fibroids.


      PubDate: 2014-12-24T21:18:15Z
       
  • Mammographic and Sonographic Features of Triple-Negative Invasive
           Carcinoma of No Special Type
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Hyun Kyung Jung , Kyunghwa Han , Yeo Jin Lee , Hee Jung Moon , Eun-Kyung Kim , Min Jung Kim
      The aim of this study was to compare the mammography, ultrasound (US) and histologic features of triple-negative (TN) invasive carcinoma of no special type (NST) to non-TN invasive carcinoma of NST. The second aim was to assess whether the distinct imaging characteristics of TN breast cancer would persist after controlling for the histologic features. A total of 344 invasive carcinomas of NST in 337 patients from January 2007 to February 2008 were included in this study. Two radiologists retrospectively reviewed the mammography and US findings using the American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) lexicon and our institution's criteria. On mammography, TN invasive carcinoma of NST most commonly presented as a mass with round shape and non-spiculated margin. On US, it was more likely to have internal hypoechogenicity, an abrupt boundary and posterior acoustic enhancement. TNBC lacked major suspicious imaging findings such as an irregular shape, spiculated margin and calcification.


      PubDate: 2014-12-24T21:18:15Z
       
  • Defining the Optimal Age for Focal Lesioning in a Rat Model
           of Transcranial HIFU
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Yanrong Zhang , Jean-François Aubry , Junfeng Zhang , Yi Wang , Jack Roy , Jaime F. Mata , Wilson Miller , Erik Dumont , Mingxing Xie , Kevin Lee , Zhiyi Zuo , Max Wintermark
      This study aimed at determining the optimal age group for high-intensity focused ultrasound (HIFU) experiments for producing lesions in rats. Younger rats have thinner skulls, allowing for the acoustic waves to propagate easily through the skull without causing burns of the skin and brain surface. Younger rats however, have a smaller brain that can make HIFU focusing in the brain parenchyma challenging because of the focus size. In this study, we conducted transcranial HIFU sonications in rat pups of different ages (from 9 to 43 d) with a 1.5MHz MR compatible transducer. The electric power was selected to always reach a target temperature of at least 50°C in the parenchyma. The thickness of the skull and of the brain parenchyma was measured using T2-weighted MR imaging. Results showed that the thickness of the brain parenchyma increased quickly from P9 to P12, reaching 8.5 mm at P16, and then increasing gradually along with age. The skull thickness increased gradually from P9 to P26, and then more quickly after P30. The ratio between brain parenchyma thickness and skull thickness decreased gradually with age. For the pups at 30 d, the temperature in the brain tissue adjacent to the skull increased to 48.9°C, and those from the rodents older than 33 d reached 60°C or higher, which can produce undesired irreversible damage in this location. We conclude that young rats aged 16–26 d are optimal for experiments producing transcranial HIFU lesions in rats with an intact skull.


      PubDate: 2014-12-24T21:18:15Z
       
  • Hepatic Angiomyolipomas: Ultrasonic Characteristics of 25 Patients from a
           Single Center
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Baohua Wang , Zhengdu Ye , Yan Chen , Qiyu Zhao , Min Huang , Fen Chen , Yanyuan Li , Tian'an Jiang
      Twenty-five pathologically proven hepatic angiomyolipomas (AMLs) were included in the study. Ultrasonic features of hepatic AMLs were reviewed. Three types of echogenicity were observed on ultrasound examination: (i) strong hyper-echogenicity, (ii) moderate hyper-echogenicity and (iii) hypo-echogenicity. Vascular signals within tumors could be detected in 22 (88.00%) tumors as multiple punctiform, filiform or dendriform signals by color Doppler flow imaging. Based on the enhancement patterns in the arterial, portal and late phases, the features of hepatic AMLs on contrast-enhanced ultrasound were divided into four subtypes: (i) “fast in slow out” (68.00%, n = 17); (ii) “fast in same out” (16%, n = 4); (iii) “fast in fast out” (12.00%, n = 3); and (iv) “fast in uneven out” (4.00%, n = 1). Contrast-enhanced ultrasound diagnosed 22 (88.00%) tumors as benign tumors and 13 (52.00%) as hepatic AMLs. Four cases were misdiagnosed as hepatic hemangioma, five cases as focal nodular hyperplasia (total = 36.00%). The rate of correct diagnosis of hepatic AMLs increased significantly from 24.00% for ultrasound alone to 52.00% for contrast-enhanced ultrasound. Therefore, information obtained from ultrasound, color Doppler flow imaging and contrast-enhanced ultrasound should be combined to improve diagnosis.


      PubDate: 2014-12-24T21:18:15Z
       
  • User-Guided Segmentation of Preterm Neonate Ventricular System from 3-D
           Ultrasound Images Using Convex Optimization
    • Abstract: Publication date: Available online 23 December 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Wu Qiu , Jing Yuan , Jessica Kishimoto , Jonathan McLeod , Yimin Chen , Sandrine de Ribaupierre , Aaron Fenster
      A three-dimensional (3-D) ultrasound (US) system has been developed to monitor the intracranial ventricular system of preterm neonates with intraventricular hemorrhage (IVH) and the resultant dilation of the ventricles (ventriculomegaly). To measure ventricular volume from 3-D US images, a semi-automatic convex optimization-based approach is proposed for segmentation of the cerebral ventricular system in preterm neonates with IVH from 3-D US images. The proposed semi-automatic segmentation method makes use of the convex optimization technique supervised by user-initialized information. Experiments using 58 patient 3-D US images reveal that our proposed approach yielded a mean Dice similarity coefficient of 78.2% compared with the surfaces that were manually contoured, suggesting good agreement between these two segmentations. Additional metrics, the mean absolute distance of 0.65 mm and the maximum absolute distance of 3.2 mm, indicated small distance errors for a voxel spacing of 0.22 × 0.22 × 0.22 mm3. The Pearson correlation coefficient (r = 0.97, p < 0.001) indicated a significant correlation of algorithm-generated ventricular system volume (VSV) with the manually generated VSV. The calculated minimal detectable difference in ventricular volume change indicated that the proposed segmentation approach with 3-D US images is capable of detecting a VSV difference of 6.5 cm3 with 95% confidence, suggesting that this approach might be used for monitoring IVH patients' ventricular changes using 3-D US imaging. The mean segmentation times of the graphics processing unit (GPU)- and central processing unit-implemented algorithms were 50 ± 2 and 205 ± 5 s for one 3-D US image, respectively, in addition to 120 ± 10 s for initialization, less than the approximately 35 min required by manual segmentation. In addition, repeatability experiments indicated that the intra-observer variability ranges from 6.5% to 7.5%, and the inter-observer variability is 8.5% in terms of the coefficient of variation of the Dice similarity coefficient. The intra-class correlation coefficient for ventricular system volume measurements for each independent observer ranged from 0.988 to 0.996 and was 0.945 for three different observers. The coefficient of variation and intra-class correlation coefficient revealed that the intra- and inter-observer variability of the proposed approach introduced by the user initialization was small, indicating good reproducibility, independent of different users.


      PubDate: 2014-12-24T21:18:15Z
       
  • Contents
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1




      PubDate: 2014-12-16T19:46:08Z
       
  • Factors that Influence Kidney Shear Wave Speed Assessed by Acoustic
           
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Simona Bota , Flaviu Bob , Ioan Sporea , Roxana Şirli , Alina Popescu
      Our aim was to assess kidney shear wave speed by means of acoustic radiation force impulse (ARFI) elastography in patients without kidney pathology (“normal” patients) and to identify the factors that influence it. We analyzed 91 “normal” patients in whom kidney shear wave speed was assessed by means of ARFI elastography. Five valid ARFI elastographic measurements were obtained in all “normal” patients in both kidneys. In univariate analysis, age (r = −0.370, p = 0.003), gender (female vs. male, r = −0.305, p = 0.003) and measurement depth (r = −0.285, p = 0.01) were significantly correlated with kidney shear wave speed values assessed by ARFI elastography, whereas body mass index, kidney length and renal parenchyma thickness were not correlated. In multivariate analysis, only age (p = 0.006) and gender (p = 0.03) were significantly correlated with kidney shear wave speed values. In conclusion, kidney shear wave speed values assessed by ARFI elastography in “normal” patients are influenced mainly by age and gender and less by measurement depth.


      PubDate: 2014-12-16T19:46:08Z
       
  • Ultrasound Quantification of Acetabular Rounding in Hip Dysplasia:
           Reliability and Correlation to Treatment Decisions in a Retrospective
           Study
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Edwin Cheng , Myles Mabee , Vimarsha G. Swami , Yeli Pi , Richard Thompson , Sukhdeep Dulai , Jacob L. Jaremko
      Currently, acetabular rounding is only subjectively assessed on ultrasound for developmental dysplasia of the hip. We tested whether acetabular rounding can be quantified reliably and can distinguish between hips requiring and not requiring treatment. Consecutive infants (n = 90) suspected of having dysplasia of the hip, seen at a pediatric orthopedic clinic, were separated into four diagnostic categories (normal, borderline but resolved, treated by brace, treated surgically). Acetabular rounding was assessed by semi-quantitative grade (0 = nil, 1 = mild, 2 = moderate, 3 = severe) by three observers and by direct measurement of acetabular radius of curvature (AROC) by two observers. Inter-observer reliability of rounding grade was poor (κ = 0.30–0.37). AROC had an inter-observer intra-class correlation coefficient of 0.84 and coefficient of variation of 29%–34%. Mean AROC was significantly higher for hips requiring treatment than for those not requiring treatment (3.3 mm vs. 1.6 mm, p = 0.007). AROC reliably quantifies an observation currently being made subjectively by radiologists and surgeons, and may be useful as a supplementary ultrasound index of dysplasia of the hip in future prospective studies.


      PubDate: 2014-12-16T19:46:08Z
       
  • Ultrasound Diagnosis of Carotid Artery Stiffness in Patients with Ischemic
           Leukoaraiosis
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Monika Turk , Janja Pretnar-Oblak , Matija Zupan , Bojana Zvan , Marjan Zaletel
      The pathophysiology of ischemic leukoaraiosis (ILA) is unknown. It was recently found that ILA patients have increased aortic stiffness. Carotid stiffness is a more specific parameter and could have value as a non-invasive diagnostic value for ILA. Therefore, using color-coded duplex sonography, we compared local carotid stiffness parameters of 59 patients with ILA with those of 45 well-matched controls. The diagnosis of ILA was based on exclusion of other causes of white matter changes seen on magnetic resonance imaging. Pulse wave velocity β (PWVβ, m/s), pressure–strain elasticity modulus (E p, kPa), β index and augmentation index (A ix, %) values were higher and arterial compliance (AC, mm2/kPa) values were lower in the ILA group; however, only E p and PWVβ reached statistical significance (p ≤ 0.05). β, E p and PWVβ exhibited an increasing trend with higher Fazekas score, though only E p reached significance (p = 0.05). The main conclusion was that E p and PWVβ could have a diagnostic role in patients with ILA.


      PubDate: 2014-12-16T19:46:08Z
       
  • Diagnostic Evaluation of Ductal Carcinoma in Situ of the Breast:
           Ultrasonographic, Mammographic and Histopathologic Correlations
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Zhan-Qiang Jin , Mei-Ying Lin , Wan-Qing Hao , Hua-Tang Jiang , Li Zhang , Wen-Hua Hu , Miao Zhang
      The aims of the study described here were to illustrate the spectrum of ultrasonographic features of ductal carcinoma in situ (DCIS) and to evaluate the ability of ultrasonography (US) to predict the grade and recurrence of DCIS on the basis of mammographic and histopathologic findings. We retrospectively evaluated the ultrasonographic features of 129 DCIS lesions from 127 consecutive women and compared these with their mammographic and histopathologic features. The mean size of DCISs on ultrasonography and mammography (MMG) was 3.67 ± 1.40 and 4.00 ± 1.74 cm, respectively, which do not differ statistically (p = 0.09). Despite the statistical difference in Breast Imaging Reporting and Data System (BI-RADS) classification on US and MMG (p = 0.000), the median BI-RADS classification is category 4c on both US and MMG (p = 0.01). There was no statistically significant difference in the distribution of microcalcification on MMG and US. Clusters <5 mm in greatest diameter are easily seen on MMG. At US, a scattered/linear distribution on MMG had a higher level of visibility than clustered distribution on MMG. The correlation between tumor size and DCIS with micro-invasion evaluated using US is higher than that obtained using MMG (p = 0.001 and 0.024, respectively). When US was used for the detection of DCIS, diagnostic accuracy was significantly associated with higher Van Nuys groups, the presence of micro-invasion and comedo carcinoma (p = 0.000, 0.022 and 0.011, respectively). However, mammographic diagnostic accuracy was found not to associate with higher Van Nuys groups, the presence of micro-invasion and comedo carcinoma (p = 0.054, 0.093 and 0.256, respectively). Ultrasonography may play an important role both in detecting DCIS and in evaluating its histopathologic features. Detection of DCIS using MMG alone may be suboptimal for patients with dense breasts, especially among Chinese women.


      PubDate: 2014-12-16T19:46:08Z
       
  • Evaluation of the Development of the Fetal Anal Sphincter with Tomography
           Ultrasonography Imaging
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Yang Guang , Xi Wang , Ai-Lu Cai , Li-Mei Xie , Hai-Long Ding , Xin-Yue Meng
      The aim of the study described here was to examine the potential of tomography ultrasonography imaging (TUI) in evaluation of the fetal anal sphincter. In this prospective cross-sectional study of the fetal anal sphincter with TUI, 326 singleton pregnancies (mean age = 28 y, range: 22–38 y) were scanned at 19–40 wk of gestation. The fetal anal region and ischium were revealed in 320 of 326 patients (98.2%). The normal fetal anal sphincter diameter and ischial space reached maximums of 15 and 39 mm, respectively. The normal fetal anal sphincter diameter and the ischial space were plotted as a function of gestational age (GA) on a linear curve, and the regression equations for normal fetal anal sphincter diameter and ischial space as a function of GA in weeks were obtained. A scatterplot was also created that revealed a significant positive relationship between normal fetal anal sphincter diameter and ischial space. On the basis of these criteria, imperforate anus was diagnosed in one fetus. Ultrasonographic assessment of the fetal anal sphincter and the ischium with TUI is feasible. The reference values reported in this article may be useful in prenatal diagnosis of fetal anal sphincter abnormalities.


      PubDate: 2014-12-16T19:46:08Z
       
  • Acoustic Output Measured by Thermal and Mechanical Indices during Fetal
           Echocardiography at the Time of the First Trimester Scan
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Dragos Nemescu , Anca Berescu
      We measured acoustic output, expressed as the thermal index (TI) and mechanical index (MI), during fetal echocardiography at the time of the first trimester scan. TI and MI were retrieved from the saved displays during gray-mode, high-definition color flow Doppler and pulsed-wave Doppler (tricuspid flow) ultrasound examinations of the fetal heart and from the ductus venosus assessment. A total of 399 fetal cardiac examinations were evaluated. There was a significant increase in TI values from B-mode studies (0.07 ± 0.04 [mean ± SD]) to color flow mapping (0.2 ± 0.0) and pulsed-wave Doppler studies (0.36 ± 0.05). The TI from ductus venosus assessment (0.1 ± 0.01) was significantly lower than those from Doppler examinations of the heart. MI values from B-mode scans (0.65 ± 0.12) and color flow mapping (0.71 ± 0.11) were comparable, although different, and both values were higher than those from pulsed-wave Doppler tricuspid evaluation (0.39 ± 0.03). There were no differences in MI values from power Doppler assessment between the tricuspid flow and ductus venosus. Safety indices were remarkably stable and were largely constant, especially for color Doppler (TI), tricuspid flow (MI) and ductus venosus assessment (TI, MI). We acquired satisfactory Doppler images and/or signals at acoustic levels that were lower than the actual recommendations and never reached a TI of 0.5.


      PubDate: 2014-12-16T19:46:08Z
       
  • Diagnostic Performance of Axial-Strain Sonoelastography in Confirming
           Clinically Diagnosed Achilles Tendinopathy: Comparison with B-Mode
           Ultrasound and Color Doppler Imaging
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1
      Author(s): Chin Chin Ooi , Michal Elisabeth Schneider , Peter Malliaras , Martine Chadwick , David Alister Connell
      This primary aim of this study was to evaluate the diagnostic performance of axial-strain sonoelastography (ASE), B-mode ultrasound (US) and color Doppler US in confirming clinically symptomatic Achilles tendinopathy. The secondary aim was to establish the relationship between the strain ratio during sonoelastography and Victorian Institute of Sport Assessment—Achilles (VISA-A) scores. The VISA-A questionnaire is a validated clinical rating scale that evaluates the symptoms and dysfunction of the Achilles tendon. One hundred twenty Achilles tendons of 120 consecutively registered patients with clinical symptoms of Achilles tendinopathy and another 120 gender- and age-matched, asymptomatic Achilles tendons of 120 healthy volunteers were assessed with B-mode US, ASE and color Doppler US. Symptomatic patients had significantly higher strain ratio scores and softer Achilles tendon properties compared with controls (p < 0.001). The strain ratio was moderately correlated with VISA-A scores (r = −0.62, p < 0.001). The diagnostic accuracy of B-mode US, ASE and color Doppler US in confirming clinically symptomatic Achilles tendinopathy was 94.7%, 97.8% and 82.5% respectively. There was excellent correlation between the clinical reference standard and the grade of tendon quality on ASE (κ = 0.91, p < 0.05), compared with B-mode US (κ = 0.74, p < 0.05) and color Doppler imaging (κ = 0.49, p < 0.05). ASE is an accurate clinical tool in the evaluation of Achilles tendinopathy, with results comparable to those of B-mode US and excellent correlation with clinical findings. The strain ratio may offer promise as a supplementary tool for the objective evaluation of Achilles tendon properties.


      PubDate: 2014-12-16T19:46:08Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1




      PubDate: 2014-12-16T19:46:08Z
       
  • Masthead
    • Abstract: Publication date: January 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 1




      PubDate: 2014-12-16T19:46:08Z
       
  • Comparison of Acoustic Radiation Force Impulse Imaging and Transient
           Elastography for Non-invasive Assessment of Liver Fibrosis in Patients
           with Chronic Hepatitis B
    • Abstract: Publication date: Available online 11 October 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Dakun Zhang , Min Chen , Ruifang Wang , Yang Liu , Dedong Zhang , Liping Liu , Guangde Zhou
      The aims of this study were to compare the performance of acoustic radiation force impulse (ARFI) elastography and transient elastography (TE) in the assessment of liver fibrosis in patients with chronic hepatitis B and to evaluate the impact of elevated alanine transaminase levels on liver stiffness assessment using ARFI elastography. One hundred eighty consecutive patients with chronic hepatitis B were enrolled in this study and evaluated with respect to histologic and biochemical features. All patients underwent ARFI elastography and TE. ARFI elastography and TE correlated significantly with histologically assessed fibrosis (r = 0.599, p < 0.001, for ARFI elastography; r = 0.628, p < 0.001, for TE) and necro-inflammatory activity (r = 0.591, p < 0.001, for ARFI elastography; r = 0.616, p < 0.001, for TE). Areas under the receiver operating characteristic curves for ARFI elastography and TE were 0.764 and 0.813 (p = 0.302, ≥stage 2), 0.852 and 0.852 (p = 1.000, ≥stage 3) and 0.825 and 0.799 (p = 0.655, S = 4), respectively. The optimum cutoff values for ARFI elastography were 1.63 m/s for stage ≥2, 1.74 m/s for stage ≥3 and 2.00 m/s for stage 4 in patients for whom alanine transaminase levels were evaluated. The cutoff values decreased to 1.24 m/s for ≥ stage 2, 1.32 m/s for ≥ stage 3 and 1.41 m/s for stage 4 in patients with normal alanine transaminase levels. ARFI elastography may be a reliable method for diagnosing the stage of liver fibrosis with diagnostic performance similar to that of TE in patients with chronic hepatitis B. In addition, liver stiffness values obtained with ARFI elastography, like those obtained with TE, may be influenced by alanine transaminase levels.


      PubDate: 2014-10-12T23:27:04Z
       
  • Reliability of Contrast-Enhanced Ultrasound for the Assessment of Muscle
           Perfusion in Health and Peripheral Arterial Disease
    • Abstract: Publication date: Available online 11 October 2014
      Source:Ultrasound in Medicine & Biology
      Author(s): Kate N. Thomas , James D. Cotter , Samuel J.E. Lucas , Brigid G. Hill , André M. van Rij
      We investigated the reliability of contrast-enhanced ultrasound (CEUS) in assessing calf muscle microvascular perfusion in health and disease. Response to a post-occlusive reactive hyperaemia test was repeated on two occasions >48 h apart in healthy young (28 ± 7 y) and elderly controls (70 ± 5 y), and in peripheral arterial disease patients (PAD, 69 ± 7 y; n = 10, 9 and 8 respectively). Overall, within-individual reliability was poor (coefficient of variation [CV] range: 15–87%); the most reliable parameter was time to peak (TTP, 15–48% CV). Nevertheless, TTP was twice as long in elderly controls and PAD compared to young (19.3 ± 10.4 and 22.0 ± 8.6 vs. 8.9 ± 6.2 s respectively; p < 0.01), and area under the curve for contrast intensity post-occlusion (a reflection of blood volume) was ∼50% lower in elderly controls (p < 0.01 versus PAD and young). Thus, CEUS assessment of muscle perfusion during reactive hyperaemia demonstrated poor reliability, yet still distinguished differences between PAD patients, elderly and young controls.


      PubDate: 2014-10-12T23:27:04Z
       
 
 
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