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PHYSICS (564 journals)            First | 1 2 3 4 5 6 | Last

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: 10)
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: 62)
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: 23)
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: 8)
Spectrochimica Acta Part B: Atomic Spectroscopy     Hybrid Journal   (Followers: 7)
Spectroscopy     Hybrid Journal   (Followers: 3)
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)
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 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: 7)
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: 32)
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: 5)
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)

  First | 1 2 3 4 5 6 | Last

Journal Cover   Ultrasound in Medicine & Biology
  [SJR: 0.939]   [H-I: 91]   [8 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0301-5629
   Published by Elsevier Homepage  [2586 journals]
  • Waveform Patterns and Peak Reversed Velocity in Vertebral Arteries Predict
           Severe Subclavian Artery Stenosis and Occlusion
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Shun-Ping Chen , Yuan-Ping Hu
      This study investigated the value of analyzing spectral Doppler waveform patterns and measuring the peak reversed velocity (PRV) of the vertebral artery (VA) in predicting proximal severe subclavian artery (SA) stenosis and occlusion. Fifty-one patients with proximal SA stenosis were studied retrospectively. Based on the depth of the mid-systolic notch, the Doppler waveforms of the ipsilateral VA were divided into five subtypes (type I, n = 8; type II, n = 8; type III, n = 6; type IV, n = 13; and type V, n = 16). PRV was also measured. PRV receiver operating characteristic curves were constructed to obtain the best cutoff value for predicting severe SA stenosis or complete SA occlusion. The results indicated that both VA Doppler waveform and PRV were associated with the degree of SA stenosis (p < 0.05). PRV and the Doppler waveform in the VA had similar accuracy in predicting SA occlusion (84.3%, 43/51). PRV was more accurate than VA waveforms in predicting severe SA stenosis (98%, 50/51 vs. 94.1%, 48/51). However, no significant differences between the two methods in predicting severe SA stenosis were observed (p = 0.84). Thus, with severe obstruction of the SA, typical Doppler waveform patterns of the VA could be observed. PRV is a helpful criterion in predicting severe stenosis and occlusion of the SA.


      PubDate: 2015-04-12T21:33:54Z
       
  • Wavelet Entropy of Doppler Ultrasound Blood Velocity Flow Waveforms
           Distinguishes Nitric Oxide-Modulated States
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Christina E. Agnew , Paul K. Hamilton , Aaron J. McCann , R. Canice McGivern , Gary E. McVeigh
      Wavelet entropy assesses the degree of order or disorder in signals and presents this complex information in a simple metric. Relative wavelet entropy assesses the similarity between the spectral distributions of two signals, again in a simple metric. Wavelet entropy is therefore potentially a very attractive tool for waveform analysis. The ability of this method to track the effects of pharmacologic modulation of vascular function on Doppler blood velocity waveforms was assessed. Waveforms were captured from ophthalmic arteries of 10 healthy subjects at baseline, after the administration of glyceryl trinitrate (GTN) and after two doses of N G-nitro-L-arginine-methyl ester (L-NAME) to produce vasodilation and vasoconstriction, respectively. Wavelet entropy had a tendency to decrease from baseline in response to GTN, but significantly increased after the administration of L-NAME (mean: 1.60 ± 0.07 after 0.25 mg/kg and 1.72 ± 0.13 after 0.5 mg/kg vs. 1.50 ± 0.10 at baseline, p < 0.05). Relative wavelet entropy had a spectral distribution from increasing doses of L-NAME comparable to baseline, 0.07 ± 0.04 and 0.08 ± 0.03, respectively, whereas GTN had the most dissimilar spectral distribution compared with baseline (0.17 ± 0.08, p = 0.002). Wavelet entropy can detect subtle changes in Doppler blood velocity waveform structure in response to nitric-oxide-mediated changes in arteriolar smooth muscle tone.


      PubDate: 2015-04-12T21:33:54Z
       
  • Measurement of Internal Diameter Changes and Pulse Wave Velocity in Fetal
           Descending Aorta Using the Ultrasonic Phased-Tracking Method in Normal and
           Growth-Restricted Fetuses
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Susumu Miyashita , Jun Murotsuki , Jin Muromoto , Katsusuke Ozawa , Nobuo Yaegashi , Hideyuki Hasegawa , Hiroshi Kanai
      Phased tracking (PT) is an ultrasound-based technique that enables precise measurement of a target velocity. The aims of this study were to use PT to evaluate arterial pulse waveform, pulse wave velocity and fetal pulse pressure in normal and growth-restricted fetuses. One hundred fetuses with normal development and 15 fetuses with growth restriction were analyzed. Ultrasonic raw radiofrequency signals were captured from a direction perpendicular to the vascular axis at the fetal diaphragmatic level for the difference in internal dimensions (DID), or simultaneously from different directions for the pulse wave velocity. Pulsatile movement of the proximal and distal intima of the vessels was analyzed using PT. The fetal DID exhibited no significant changes in growth-restricted fetuses. Pulse wave velocity (3.8 ± 0.32 m/s vs. 2.2 ± 0.069 m/s, p < 0.001) and estimated pulse pressure (6.9 ± 0.90 kPa vs. 2.5 ± 0.18 kPa, p < 0.001) were significantly elevated in growth-restricted fetuses. Assessment of DID and pulse wave velocity of the descending aorta using PT is a feasible, non-invasive approach to evaluation of fetal hemodynamics.


      PubDate: 2015-04-12T21:33:54Z
       
  • Contrast-Enhanced Ultrasound in the Characterization of Complex Cystic
           Focal Liver Lesions
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): A. Corvino , O. Catalano , S.V. Setola , F. Sandomenico , F. Corvino , A. Petrillo
      Complex cystic focal liver lesions (FLLs) found at non-contrast ultrasound (US) may turn out to be malignant. In this prospective, monocentric study we investigated the value of contrast-enhanced US (CEUS) in the differential diagnosis of complex cystic FLLs. In the past 3 years, all patients with complex cystic FLLs unclassifiable at US underwent CEUS with low-transmit insonation power. We evaluated 36 consecutive patients with 61 FLLs (1–6/patient, mean = 2). The diameter of the lesions ranged from 1.1 to 7.9 cm (mean = 3.9 cm). Sixteen patients had an extrahepatic malignancy. There were 42 malignant lesions and 19 benign lesions. No lesion had a certain diagnosis at conventional US, whereas 16 FLLs were classified as probable (benign or malignant) and 45 as uncertain. CEUS correctly categorized 95% of the malignant cases. CEUS was not able to differentiate the biliary cystadenoma from its malignant counterpart and misdiagnosed two abscesses. Complete non-enhancement throughout three phases or sustained enhancement in the portal/late phase was exhibited in most benign complex cystic FLLs, except for 1 (of the 3) cystadenomas and in 2 (of the 4) abscesses. On the other hand, all malignant lesions presented a contrast washout with a hypo-enhancing appearance. CEUS may provide added diagnostic value in all complex cystic FLLs found uncertain at conventional US, potentially avoiding the use of more invasive and expensive imaging modalities.


      PubDate: 2015-04-12T21:33:54Z
       
  • Masthead
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5




      PubDate: 2015-04-12T21:33:54Z
       
  • Pre-operative Ultrasound Diagnosis of Nodal Metastasis in Papillary
           Thyroid Carcinoma Patients According to Nodal Compartment
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Yoo Jin Lee , Dong Wook Kim , Ha Kyoung Park , Do Hun Kim , Soo Jin Jung , Minkyung Oh , Sang Kyun Bae
      The aim of this study was to assess the accuracy of ultrasound (US) and individual US features in the diagnosis of nodal metastasis in patients with papillary thyroid carcinoma (PTC) with respect to nodal compartment. US diagnoses and individual US features of nodal metastases with respect to nodal compartment were investigated in 184 consecutive PTC patients who underwent pre-operative US. Histopathologic results were used as a reference standard. One hundred thirty-six of 368 (37.0%) central compartments contained one or more metastatic nodes, whereas 44 of 48 (91.7%) lateral compartments had one or more metastatic nodes. The malignancy rates of suspicious US diagnoses in the central and lateral compartments were 66.3% (53/80) and 93.3% (42/45), respectively. The central and lateral compartments differed significantly in nodal composition, echogenicity, calcification, shape, hilar echogenicity and vascularity. The accuracy of US in the diagnosis of nodal metastases from PTC was lower in the central compartment than in the lateral compartment.


      PubDate: 2015-04-12T21:33:54Z
       
  • Vascularity Assessment of Thyroid Nodules by Quantitative Color Doppler
           Ultrasound
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Laith R. Sultan , Hui Xiong , Hanna M. Zafar , Susan M. Schultz , Jill E. Langer , Chandra M. Sehgal
      Our objective was to assess the role of quantitative Doppler vascularity in differentiating malignant and benign thyroid nodules. Color Doppler images of 100 nodules were analyzed for three metrics: vascular fraction area, mean flow velocity index and flow volume index in three regions (nodule center, nodule rim and surrounding parenchyma). Vascular fraction area and flow volume index were higher in malignant than benign nodules in both the central and rim regions, whereas flow velocity index was equivalent in both regions. Of the three vascularity metrics studied, the vascular fraction area of the central region was most effective in predicting malignancy, with a sensitivity of 0.90 ± 0.05, specificity of 0.88 ± 0.13, positive predictive value of 0.84 ± 0.14, negative predictive value of 0.92 ± 0.03 and accuracy of 0.89 ± 0.08. Quantitative Doppler vascularity of the nodule center yielded a high level of discrimination between benign and malignant nodules and, thus, has the greatest potential to contribute to gray-scale assessment of thyroid cancer.


      PubDate: 2015-04-12T21:33:54Z
       
  • Role of Portal Vein Tumor Thrombosis in Quantitative Perfusion Analysis of
           Contrast-Enhanced Ultrasound of Hepatocellular Carcinoma
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Zhu Wang , GuangJian Liu , Ming-De Lu , XiaoYan Xie , Ming Kuang , Wei Wang , ZuoFeng Xu , ManXia Lin , LiDa Chen
      The goal of our study was to evaluate the differences between quantitative parameters of hepatocellular carcinoma (HCC) with or without portal vein tumor thrombosis (PVTT) on contrast-enhanced ultrasound (CEUS). Twenty-four patients with HCC with PVTT and 48 without PVTT underwent CEUS using sulfur hexafluoride microbubbles. Dynamic images were analyzed with quantification software. Time–intensity curves were obtained for HCC and surrounding liver parenchyma, and parameters including the intensity maximum (IMAX), rising time (RT), mean transit time and time to peak (TTP) were compared within and between the PVTT and control groups, respectively. RT and TTP of HCC were significantly faster than those of surrounding liver parenchyma in both the PVTT and control groups. IMAX of HCC was significantly stronger than that of surrounding liver in the control group, but not significantly different from that of liver parenchyma in the PVTT group. RT and TTP of HCC and surrounding liver were significantly faster in the PVTT group compared with the control group, whereas IMAX values of HCC in the PVTT group were lower than those in the control group. HCC with PVTT presents different hemodynamic parameters, with faster RT and TTP and lower IMAX than those for HCC without PVTT. Quantitative perfusion analysis of CEUS may be a potential method for predicting PVTT.


      PubDate: 2015-04-12T21:33:54Z
       
  • Reconstruction of the Descending Thoracic Aorta by Multiview Compounding
           of 3-D Transesophageal Echocardiographic Aortic Data Sets for Improved
           Examination and Quantification of Atheroma Burden
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Maria Chiara Carminati , Concetta Piazzese , Lynn Weinert , Wendy Tsang , Gloria Tamborini , Mauro Pepi , Roberto Miguel Lang , Enrico Gianluca Caiani
      A robust and efficient approach to reconstruction of the descending thoracic aorta from contiguous 3-D transesophageal echocardiographic (TEE) images is proposed. An ad hoc image acquisition protocol was designed to acquire ordered and partially overlapped 3-D TEE data sets, followed by dedicated image processing to align and fuse all acquired data sets. Alignment strategy implemented pairwise rigid registration guided by a priori knowledge, and it was validated using artificially misaligned images. Image fusion was finally performed to enable visualization and analysis of extended field-of-view of the acquired aorta. The application of different fusion techniques was also investigated. The method was applied to a population of 17 consecutive patients. Qualitative and quantitative results supported the feasibility and accuracy of the proposed approach. In a clinical scenario, its application could allow the quantitative assessment of aortic plaque burden in the descending thoracic aorta from 3-D TEE images.


      PubDate: 2015-04-12T21:33:54Z
       
  • Ultrasonographic Assessment of Optic Nerve Sheath Diameter during
           Pediatric Laparoscopy
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Ji Young Min , Jeong-Rim Lee , Jung-Tak Oh , Min-Soo Kim , Eun-Kyung Jun , Jiwon An
      This study investigated the extent of the raised intracranial pressure resulting from carbon dioxide (CO2) pneumoperitoneum by ultrasonographically measuring optic nerve sheath diameter (ONSD) in children undergoing laparoscopic surgery. Twenty-five children aged less than 9 y (53.1 ± 23.3 mo, mean ± standard deviation) and scheduled for an elective laparoscopic surgery participated. ONSD was assessed using ocular ultrasonography 10 min after induction of anesthesia (T0), 10 min after induction of CO2 pneumoperitoneum at 10 mm Hg intra-abdominal pressure (T1) and in an anesthetized state without CO2 pneumoperitoneum at the conclusion of the surgery (T2). During CO2 pneumoperitoneum, ONSD increased significantly compared with ONSD after anesthesia induction (T0: 4.3 ± 0.3 mm, T1: 4.6 ± 0.3 mm, p < 0.05). In all enrolled patients, any neurologic complications were not observed during the intra-operative or post-operative period. In children undergoing laparoscopic surgery, an increase in ONSD was ascertained during CO2 pneumoperitoneum, and thus the corresponding increase in intracranial pressure could be predicted.


      PubDate: 2015-04-12T21:33:54Z
       
  • Transcranial Ultrasound to Detect Elevated Intracranial Pressure:
           Comparison of Septum Pellucidum Undulations and Optic Nerve Sheath
           Diameter
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Susanne Bolesch , Frederic von Wegner , Christian Senft , Matthias W. Lorenz
      Two ultrasound tests that can be used to assess increased intracranial pressure (ICP) at the bedside are described. In outpatients receiving lumbar puncture and in intensive care patients with invasive ICP monitoring, we measured the optic nerve sheath diameter (ONSD) with transbulbar B-mode sonography and septum pellucidum undulation (SPU) induced by repeated passive head rotation with transtemporal M-mode sonography. We assessed the sensitivity and specificity of ONSD and SPU in the prediction of ICP >20 cm H2O. For ONSD, sensitivity was 53% and specificity 100% (n = 35, p < 0.001). The sensitivity of the SPU test was 75% and the specificity 100% (n = 32, p < 0.001). Although the SPU test may not feasible in some patients, it has high sensitivity and specificity comparable to those of ONSD measurement. The SPU test and ONSD may be useful alternatives to fundoscopy in clinical routine, preferably in combination.


      PubDate: 2015-04-12T21:33:54Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5




      PubDate: 2015-04-12T21:33:54Z
       
  • Contents
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5




      PubDate: 2015-04-12T21:33:54Z
       
  • Foreword to the WFUMB Guidelines and Recommendations on the Clinical Use
           of Ultrasound Elastography
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Masatoshi Kudo



      PubDate: 2015-04-12T21:33:54Z
       
  • WFUMB Guidelines and Recommendations for Clinical Use of Ultrasound
           Elastography: Part 1: Basic Principles and Terminology
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Tsuyoshi Shiina , Kathryn R. Nightingale , Mark L. Palmeri , Timothy J. Hall , Jeffrey C. Bamber , Richard G. Barr , Laurent Castera , Byung Ihn Choi , Yi-Hong Chou , David Cosgrove , Christoph F. Dietrich , Hong Ding , Dominique Amy , Andre Farrokh , Giovanna Ferraioli , Carlo Filice , Mireen Friedrich-Rust , Kazutaka Nakashima , Fritz Schafer , Ioan Sporea , Shinichi Suzuki , Stephanie Wilson , Masatoshi Kudo
      Conventional diagnostic ultrasound images of the anatomy (as opposed to blood flow) reveal differences in the acoustic properties of soft tissues (mainly echogenicity but also, to some extent, attenuation), whereas ultrasound-based elasticity images are able to reveal the differences in the elastic properties of soft tissues (e.g., elasticity and viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathologic lesions. Typically, all elasticity measurement and imaging methods introduce a mechanical excitation and monitor the resulting tissue response. Some of the most widely available commercial elasticity imaging methods are ‘quasi-static’ and use external tissue compression to generate images of the resulting tissue strain (or deformation). In addition, many manufacturers now provide shear wave imaging and measurement methods, which deliver stiffness images based upon the shear wave propagation speed. The goal of this review is to describe the fundamental physics and the associated terminology underlying these technologies. We have included a questions and answers section, an extensive appendix, and a glossary of terms in this manuscript. We have also endeavored to ensure that the terminology and descriptions, although not identical, are broadly compatible across the WFUMB and EFSUMB sets of guidelines on elastography (Bamber et al. 2013; Cosgrove et al. 2013).


      PubDate: 2015-04-12T21:33:54Z
       
  • Reliability of Ultrasound Evaluation of Hyoid–Larynx Approximation
           with Positional Change
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      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: 2015-04-12T21:33:54Z
       
  • Comparison of Three Methods for the Confirmation of Laryngeal Mask Airway
           Placement in Female Patients Undergoing Gynecologic Surgery
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Zhen-feng Zhou , Chen-zhong Xia , Meng Wu , Li-na Yu , Guo-zhang Yan , Qiu-sheng Ren , Ci-xian Hu , Min Yan
      The laryngeal mask airway (LMA) is a supraglottic device that is commonly used to provide lung ventilation during general anesthesia. LMA placement needs to be confirmed to provide adequate lung ventilation. To investigate the feasibility of using ultrasound examination, compared with clinical tests and fiberoptic laryngoscopy, to confirm LMA placement, we performed a clinical study of 64 female patients classified as American Society of Anesthesiologists Physical Status I or II who were scheduled for gynecologic surgery with LMA insertion for airway management. After insertion, placement of the LMA was confirmed by clinical tests, ultrasound examination and fiberoptic laryngoscopy. Of the 64 women, placement was confirmed as acceptable in 89.1% by clinical tests, in 59.4% by fiberoptic laryngoscope assessment and in 67.2% by ultrasound examination. With respect to patients with oropharyngeal leaks classified as high, there were no differences in confirmation of acceptable placement between clinical tests and ultrasound examinations (p = 0.092), but the number of patients determined to have acceptable placement by ultrasound examination was greater than that determined by fiberoptic laryngoscopy (p = 0.034). Thus, ultrasound examination is a superior technique for confirming the seal on the LMA.


      PubDate: 2015-04-12T21:33:54Z
       
  • Role of 3-D Ultrasound in Clinical Obstetric Practice: Evolution Over
           20 Years
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Gabriele Tonni , Wellington P. Martins , Hélio Guimarães Filho , Edward Araujo Júnior
      The use of 3-D ultrasound in obstetrics has undergone dramatic development over the past 20 years. Since the first publications on this application in clinical practice, several 3-D ultrasound techniques and rendering modes have been proposed and applied to the study of fetal brain, face and cardiac anatomy. In addition, 3-D ultrasound has improved calculations of the volume of fetal organs and limbs and estimations of fetal birth weight. And furthermore, angiographic patterns of fetal organs and the placenta have been assessed using 3-D power Doppler ultrasound quantification. In this review, we aim to summarize current evidence on the clinical relevance of these methodologies and their application in obstetric practice.


      PubDate: 2015-04-12T21:33:54Z
       
  • WFUMB Guidelines and Recommendations for Clinical Use of Ultrasound
           Elastography: Part 3: Liver
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Giovanna Ferraioli , Carlo Filice , Laurent Castera , Byung Ihn Choi , Ioan Sporea , Stephanie R. Wilson , David Cosgrove , Christoph F. Dietrich , Dominique Amy , Jeffrey C. Bamber , Richard Barr , Yi-Hong Chou , Hong Ding , Andre Farrokh , Mireen Friedrich-Rust , Timothy J. Hall , Kazutaka Nakashima , Kathryn R. Nightingale , Mark L. Palmeri , Fritz Schafer , Tsuyoshi Shiina , Shinichi Suzuki , Masatoshi Kudo
      The World Federation for Ultrasound in Medicine and Biology (WFUMB) has produced these guidelines for the use of elastography techniques in liver disease. For each available technique, the reproducibility, results, and limitations are analyzed, and recommendations are given. Finally, recommendations based on the international literature and the findings of the WFUMB expert group are established as answers to common questions. The document has a clinical perspective and is aimed at assessing the usefulness of elastography in the management of liver diseases.


      PubDate: 2015-04-12T21:33:54Z
       
  • WFUMB Guidelines and Recommendations for Clinical Use of Ultrasound
           Elastography: Part 2: Breast
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Richard G. Barr , Kazutaka Nakashima , Dominique Amy , David Cosgrove , Andre Farrokh , Fritz Schafer , Jeffrey C. Bamber , Laurent Castera , Byung Ihn Choi , Yi-Hong Chou , Christoph F. Dietrich , Hong Ding , Giovanna Ferraioli , Carlo Filice , Mireen Friedrich-Rust , Timothy J. Hall , Kathryn R. Nightingale , Mark L. Palmeri , Tsuyoshi Shiina , Shinichi Suzuki , Ioan Sporea , Stephanie Wilson , Masatoshi Kudo
      The breast section of these Guidelines and Recommendations for Elastography produced under the auspices of the World Federation of Ultrasound in Medicine and Biology (WFUMB) assesses the clinically used applications of all forms of elastography used in breast imaging. The literature on various breast elastography techniques is reviewed, and recommendations are made on evidence-based results. Practical advice is given on how to perform and interpret breast elastography for optimal results, with emphasis placed on avoiding pitfalls. Artifacts are reviewed, and the clinical utility of some artifacts is discussed. Both strain and shear wave techniques have been shown to be highly accurate in characterizing breast lesions as benign or malignant. The relationship between the various techniques is discussed, and recommended interpretation based on a BI-RADS-like malignancy probability scale is provided. This document is intended to be used as a reference and to guide clinical users in a practical way.


      PubDate: 2015-04-12T21:33:54Z
       
  • An Ultrasonographic Technique to Assess the Jugular Venous Pulse: A Proof
           of Concept
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Francesco Sisini , Mirko Tessari , Giacomo Gadda , Giovanni Di Domenico , Angelo Taibi , Erica Menegatti , Mauro Gambaccini , Paolo Zamboni
      The purpose of the work described here was to investigate the feasibility of assessing the jugular venous pulse (JVP) using ultrasound (US) equipment. Three young healthy subjects underwent a B-mode US scan of the internal jugular vein (IJV) to acquire a sonogram sequence in the transverse plane. On each acquired sonogram, the IJV contour was manually traced, and both the cross-sectional area (CSA) and the perimeter were measured. The CSA data set represents the US jugular diagram (USJD). The arterial distension waveform of the subjects was compared with its USJD. The correlation between the CSA and the perimeter was assessed during the cardiac cycle to verify IJV distension. For each subject, a short sonogram sequence of a few seconds was recorded, and the USJD obtained exhibited periodic behavior. Furthermore, for all subjects, the CSA was found to be correlated with the perimeter (Pearson coefficient, R > 0.9), indicating that the IJV in supine position is distended. We compared 390 manually traced contours of the IJV cross-sectional area with corresponding values semi-automatically calculated by an algorithm developed in-house. For all subjects, the sensitivity, specificity and accuracy were around 95%, 85% and 90% respectively. We found that a diagram reflecting the JVP can be obtained by analyzing a B-mode sonogram sequence of the IJV; such a diagram can result in a new methodology to assess the IJV functionality.


      PubDate: 2015-04-12T21:33:54Z
       
  • Profound Increase in Longitudinal Displacements of the Porcine Carotid
           Artery Wall Can Take Place Independently of Wall Shear Stress: A
           Continuation Report
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Åsa Rydén Ahlgren , Stig Steen , Simon Segstedt , Tobias Erlöv , Kjell Lindström , Trygve Sjöberg , Hans W. Persson , Stefano Ricci , Piero Tortoli , Magnus Cinthio
      The mechanisms underlying longitudinal displacements of the arterial wall, that is, displacements of the wall layers along the artery, and the resulting intramural shear strain remain largely unknown. We have already found that these displacements undergo profound changes in response to catecholamines. Wall shear stress, closely related to wall shear rate, represents the viscous drag exerted on the vessel wall by flowing blood. The aim of the work described here was to study possible relations between the wall shear rate and the longitudinal displacements. We investigated the carotid arteries of five anesthetized pigs in different hemodynamic situations using in-house developed non-invasive ultrasound techniques. The study protocol included administration of epinephrine, norepinephrine and β-blockade (metoprolol). No significant correlation between longitudinal displacement of the intima–media complex and wall shear rate was found. This result suggests that one or multiple pulsatile forces other than wall shear stress are also working along arteries, strongly influencing arterial wall behavior.


      PubDate: 2015-04-12T21:33:54Z
       
  • Comparison of Carotid Artery Blood Velocity Measurements by Vector and
           Standard Doppler Approaches
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Piero Tortoli , Matteo Lenge , Daniele Righi , Gabriele Ciuti , Hervé Liebgott , Stefano Ricci
      Although severely affected by the angle dependency, carotid artery peak systolic velocity measurements are widely used for assessment of stenosis. In this study, blood peak systolic velocities in the common and internal carotid arteries of both healthy volunteers and patients with internal carotid artery stenosis were measured by two vector Doppler (VD) methods and compared with measurements obtained with the conventional spectral Doppler approach. Although the two VD techniques were completely different (using the transmission of focused beams and plane waves, respectively), the measurement results indicate that these techniques are nearly equivalent. The peak systolic velocities measured in 22 healthy common carotid arteries by the two VD techniques were very close (according to Bland–Altman analysis, the average difference was 3.2%, with limits of agreement of ±8.6%). Application of Bland–Altman analysis to comparison of either VD technique with the spectral Doppler method provided a 21%–25% average difference with ±13%–15% limits of agreement. Analysis of the results obtained from 15 internal carotid arteries led to similar conclusions, indicating significant overestimation of peak systolic velocity with the spectral Doppler method. Inter- and intra-operator repeatability measurements performed in a group of 8 healthy volunteers provided equivalent results for all of the methods (coefficients of variability in the range 2.7%–6.9%), even though the sonographers were not familiar with the VD methods. The results of this study suggest that the introduction of vector Doppler methods in commercial machines may finally be considered mature and capable of overcoming the angle-dependent overestimation typical of the standard spectral Doppler approach.


      PubDate: 2015-04-12T21:33:54Z
       
  • Effects of Low-Intensity Ultrasound on Oxidative Damage in Retinal Pigment
           Epithelial Cells in vitro
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Na Kyeong Kim , Chan Yun Kim , Min Joo Choi , So Ra Park , Byung Hyune Choi
      Oxidative stress in retinal pigment epithelium (RPE) is one of the key causative factors of RPE injury in age-related macular degeneration (AMD). Low-intensity ultrasound (LIUS) less than 1 W/cm2 in intensity has been found to have cytoprotective and anti-inflammatory effects in many cell types and diseases. In this study, we investigated for the first time the feasibility of using LIUS to protect RPE cells from oxidative damage. ARPE-19 cells were treated with H2O2 (an exogenous source of reactive oxygen species) or L-buthionine-(S,R)-sulfoximine (BSO), a glutathione synthase inhibitor, and exposed immediately to LIUS at intensities of 50, 100 and 200 mW/cm2 and a frequency of 1 MHz for 20 min. Both H2O2 and BSO increased the percentage of cells positive for mitochondrial reactive oxygen species at 1 h, but not at 24 h. Co-treatment with LIUS clearly repressed these cells similarly at all intensities by approximately 34%–43% for H2O2 and 24%–25% for BSO (p < 0.05). The percentage of cells with mitochondrial membrane depolarization also increased with H2O2 and BSO treatment, particularly at 1 h, and decreased by approximately 60% with LIUS at 100 mW/cm2 (p < 0.05). The amount of intracellular calcium ion ([Ca2+]i) was elevated only by BSO at 24 h and was also significantly diminished, by approximately 45%, by LIUS at 100 mW/cm2 (p < 0.05). Both H2O2 and BSO significantly hampered cell viability at 24 h, but LIUS at 100 mW/cm2 restored only BSO-induced cell viability by approximately 2.7-fold (p < 0.05). This study illustrated that LIUS has a protective effect on RPE cells against oxidative damage caused by BSO, an endogenous mitochondrial reactive oxygen species generator. We speculate that LIUS has the potential to treat oxidative damage and related pathologic changes in RPE.


      PubDate: 2015-04-12T21:33:54Z
       
  • Real-Time Feedback of Histotripsy Thrombolysis Using Bubble-Induced Color
           Doppler
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Xi Zhang , Ryan M. Miller , Kuang-Wei Lin , Albert M. Levin , Gabe E. Owens , Hitinder S. Gurm , Charles A. Cain , Zhen Xu
      Histotripsy thrombolysis is a non-invasive, drug-free, image-guided therapy that fractionates blood clots using well-controlled acoustic cavitation alone. Real-time quantitative feedback is highly desired during histotripsy thrombolysis treatment to monitor the progress of clot fractionation. Bubble-induced color Doppler (BCD) monitors the motion after cavitation generated by each histotripsy pulse, which has been found in gel and ex vivo liver tissue to be correlated with histotripsy fractionation. We investigated the potential of BCD to quantitatively monitor histotripsy thrombolysis in real time. To visualize clot fractionation, transparent three-layered fibrin clots were developed. Results indicated that a coherent motion follows the cavitation generated by each histotripsy pulse with a push and rebound pattern. The temporal profile of this motion expands and saturates as treatment progresses. A strong correlation exists between the degree of histotripsy clot fractionation and two metrics extracted from BCD: time of peak rebound velocity (t PRV) and focal mean velocity at a fixed delay (V f,delay). The saturation of clot fractionation (i.e., treatment completion) matches well the saturations detected using t PRV and V f,delay. The mean Pearson correlation coefficients between the progression of clot fractionation and the two BCD metrics were 93.1% and 92.6%, respectively. To validate BCD feedback in in vitro clots, debris volumes from histotripsy thrombolysis were obtained at different therapy doses and compared with V f,delay. There is also good agreement between the increasing and saturation trends of debris volume and V f,delay. Finally, a real-time BCD feedback algorithm to predict complete clot fractionation during histotripsy thrombolysis was developed and tested. This work illustrates the potential of BCD to monitor histotripsy thrombolysis treatment in real time.


      PubDate: 2015-04-12T21:33:54Z
       
  • Sonothrombolysis: The Contribution of Stable and Inertial Cavitation to
           Clot Lysis
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      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: 2015-04-12T21:33:54Z
       
  • Non-linear Response and Viscoelastic Properties of Lipid-Coated
           Microbubbles: DSPC versus DPPC
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Tom van Rooij , Ying Luan , Guillaume Renaud , Antonius F.W. van der Steen , Michel Versluis , Nico de Jong , Klazina Kooiman
      For successful in vivo contrast-enhanced ultrasound imaging (CEUS) and ultrasound molecular imaging, detailed knowledge of stability and acoustical properties of the microbubbles is essential. Here, we compare these aspects of lipid-coated microbubbles that have either 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) as their main lipid; the other components were identical. The microbubbles were investigated in vitro over the frequency range 1–4 MHz at pressures between 10 and 100 kPa, and their response to the applied ultrasound was recorded using ultrahigh-speed imaging (15 Mfps). Relative to DPPC-coated microbubbles, DSPC-coated microbubbles had (i) higher acoustical stability; (ii) higher shell elasticity as derived using the Marmottant model (DSPC: 0.26 ± 0.13 N/m, DPPC: 0.06 ± 0.06 N/m); (iii) pressure amplitudes twice as high at the second harmonic frequency; and (iv) a smaller amount of microbubbles that responded at the subharmonic frequency. Because of their higher acoustical stability and higher non-linear response, DSPC-coated microbubbles may be more suitable for contrast-enhanced ultrasound.


      PubDate: 2015-04-12T21:33:54Z
       
  • Photoacoustic Spectrum Analysis for Microstructure Characterization in
           Biological Tissue: Analytical Model
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Guan Xu , J. Brian Fowlkes , Chao Tao , Xiaojun Liu , Xueding Wang
      Photoacoustic spectrum (PA) analysis (PASA) has been found to have the ability to identify the microstructures in phantoms and biological tissues. PASA adopts the procedures in ultrasound spectrum analysis, although the signal generation mechanisms related to ultrasound backscatter and PA wave generation differ. The purpose of this study was to theoretically validate PASA. The analytical solution to the power spectrum of PA signals generated by identical microspheres following discrete uniform random distribution in space was derived. The simulation and experiment validation of the analytical solution include: (i) the power spectrum profile of a single microsphere with a diameter of 300 μm, and (ii) the PASA parameters of the PA signals generated by randomly distributed microspheres 100, 200, 300, 400 and 500 μm in diameter, at concentrations of 30, 60, 120, 240, 480 per 1.53 cm3 in the observation range 0.5–13 MHz.


      PubDate: 2015-04-12T21:33:54Z
       
  • What Do We Know About Shear Wave Dispersion in Normal and Steatotic
           Livers'
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Kevin J. Parker , Alexander Partin , Deborah J. Rubens
      A number of new approaches to measure the viscoelastic properties of the liver are now available to clinicians, many involving shear waves. However, we are at an early stage in understanding the physical processes that govern shear wave propagation in normal liver, with more unknowns added when pathologies such as steatosis are present. This technical note focuses on what is known about the characterization of normal and steatotic (or fatty) livers, with a particular focus on dispersion. Some studies in phantoms and mouse livers support the hypothesis that, starting with a normal liver, increasing accumulations of micro- and macrosteatosis will increase the lossy viscoelastic properties of shear waves in a medium. This results in an increased dispersion (or slope) of shear wave speed and attenuation in the steatotic livers. Theoretical and empirical findings across a number of studies are summarized.


      PubDate: 2015-04-12T21:33:54Z
       
  • Do Not Forget to Calculate the Mean Shear Wave Speed as Assessed by
           Acoustic Radiation Force Impulse Elastography as a Harmonic Mean, Not an
           Arithmetical Mean
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Fuat Ozkan , Sema Yildiz , Mehmet Sait Menzilcioglu , Mahmut Duymus , Serhat Avcu



      PubDate: 2015-04-12T21:33:54Z
       
  • Reply to the Letter to the Editor Regarding do Not Forget to Calculate the
           Mean Shear Wave Speed as Assessed by Acoustic Radiation Force Impulse
           Elastography as a Harmonic Mean, Not an Arithmetical Mean
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5
      Author(s): Simona Bota , Flaviu Bob



      PubDate: 2015-04-12T21:33:54Z
       
  • Calendar
    • Abstract: Publication date: May 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 5




      PubDate: 2015-04-12T21:33:54Z
       
  • Repeatability and Minimal Detectable Change in Longitudinal Median Nerve
           Excursion Measures During Upper Limb Neurodynamic Techniques in a Mixed
           Population: A Pilot Study Using Musculoskeletal Ultrasound Imaging
    • Abstract: Publication date: Available online 11 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Philippe Paquette , Martin Lamontagne , Johanne Higgins , Dany H. Gagnon
      This study determined test–retest reliability and minimum detectable change in longitudinal median nerve excursion during upper limb neurodynamic tests (ULNTs). Seven participants with unilateral or bilateral carpal tunnel syndrome and 11 healthy participants were randomly tested with two ULNTs (i.e., tensioner and slider). Each ULNT was performed three times each at 45° and 90° of shoulder abduction on two separate visits. Video sequences of median nerve excursion, recorded by a physical therapist using ultrasound imaging, were quantified using computer software. The generalizability theory, encompassing a G-Study and a D-study, measured the dependability coefficient (Φ) along with standard error of measurement (SEM) accuracy and allowed various testing protocols to be proposed. The highest reliability (Φ = 0.84) and lowest minimal measurement error (SEM = 0.58 mm) of the longitudinal median nerve excursion were reached during the ULNT-slider performed with 45° of shoulder abduction and when measures obtained from three different image sequences recorded during a single visit were averaged. It is recommended that longitudinal median nerve excursion measures computed from three separate image sequences recorded during a single visit be averaged in clinical practice. Ideally, adding a second visit (six image sequences) is also suggested in research protocols.


      PubDate: 2015-04-12T21:33:54Z
       
  • Development of a New Ultrasound-Based System for Tracking Motion of the
           Human Lumbar Spine: Reliability, Stability and Repeatability during
           Forward Bending Movement Trials
    • Abstract: Publication date: Available online 8 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Antonio I. Cuesta-Vargas
      The aim of this study was to develop a new method for quantifying intersegmental motion of the spine in an instrumented motion segment L4–L5 model using ultrasound image post-processing combined with an electromagnetic device. A prospective test–retest design was employed, combined with an evaluation of stability and within- and between-day intra-tester reliability during forward bending by 15 healthy male patients. The accuracy of the measurement system using the model was calculated to be ± 0.9° (standard deviation = 0.43) over a 40° range and ± 0.4 cm (standard deviation = 0.28) over 1.5 cm. The mean composite range of forward bending was 15.5 ± 2.04° during a single trial (standard error of the mean = 0.54, coefficient of variation = 4.18). Reliability (intra-class correlation coefficient = 2.1) was found to be excellent for both within-day measures (0.995–0.999) and between-day measures (0.996–0.999). Further work is necessary to explore the use of this approach in the evaluation of biomechanics, clinical assessments and interventions.


      PubDate: 2015-04-12T21:33:54Z
       
  • Improved Segmentation of Multiple Cavities of the Heart in Wide-View 3-D
           Transesophageal Echocardiograms
    • Abstract: Publication date: Available online 8 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Alexander Haak , Ben Ren , Harriët W. Mulder , Gonzalo Vegas-Sánchez-Ferrero , Gerard van Burken , Antonius F.W. van der Steen , Marijn van Stralen , Josien P.W. Pluim , Theo van Walsum , Johannes G. Bosch
      Minimally invasive interventions in the heart such as in electrophysiology are becoming more and more important in clinical practice. Currently, preoperative computed tomography angiography (CTA) is used to provide anatomic information during electrophysiology interventions, but this does not provide real-time feedback and burdens the patient with additional radiation and side effects of the contrast agent. Three-dimensional transesophageal echocardiography (TEE) is an excellent modality for visualization of anatomic structures and instruments in real time, but some cavities, especially the left atrium, suffer from the limited coverage of the 3-D TEE volumes. This leads to difficulty in segmenting the left atrium. We propose replacing or complementing pre-operative CTA imaging with wide-view TEE. We tested this proposal on 20 patients for which TEE image volumes covering the left atrium and CTA images were acquired. The TEE images were manually registered, and wide-view volumes were generated. Five heart cavities in single-view and wide-view TEE were segmented and compared with atlas based-segmentations derived from the CTA images. We found that the segmentation accuracy (Dice coefficients) improved relative to segmentation of single-view images by 5, 15 and 9 percentage points for the left atrium, right atrium and aorta, respectively. Average anatomic coverage was improved by 2, 29, 62 and 49 percentage points for the right ventricle, left atrium, right atrium and aorta, respectively. This finding confirms that wide-view 3-D TEE can be useful in supporting electrophysiology interventions.


      PubDate: 2015-04-12T21:33:54Z
       
  • Quantification of Microvascular Tortuosity during Tumor Evolution Using
           Acoustic Angiography
    • Abstract: Publication date: Available online 7 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Sarah E. Shelton , Yueh Z. Lee , Mike Lee , Emmanuel Cherin , F. Stuart Foster , Stephen R. Aylward , Paul A. Dayton
      The recent design of ultra-broadband, multifrequency ultrasound transducers has enabled high-sensitivity, high-resolution contrast imaging, with very efficient suppression of tissue background using a technique called acoustic angiography. Here we perform the first application of acoustic angiography to evolving tumors in mice predisposed to develop mammary carcinoma, with the intent of visualizing and quantifying angiogenesis progression associated with tumor growth. Metrics compared include vascular density and two measures of vessel tortuosity quantified from segmentations of vessels traversing and surrounding 24 tumors and abdominal vessels from control mice. Quantitative morphologic analysis of tumor vessels revealed significantly increased vascular tortuosity abnormalities associated with tumor growth, with the distance metric elevated approximately 14% and the sum of angles metric increased 60% in tumor vessels versus controls. Future applications of this imaging approach may provide clinicians with a new tool in tumor detection, differentiation or evaluation, though with limited depth of penetration using the current configuration.


      PubDate: 2015-04-12T21:33:54Z
       
  • 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
       
  • Attenuation Correction and Normalisation for Quantification of Contrast
           Enhancement in Ultrasound Images of Carotid Arteries
    • Abstract: Publication date: Available online 3 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Wing Keung Cheung , Dorothy M. Gujral , Benoy N. Shah , Navtej S. Chahal , Sanjeev Bhattacharyya , David O. Cosgrove , Robert J. Eckersley , Kevin J. Harrington , Roxy Senior , Christopher M. Nutting , Meng-Xing Tang
      An automated attenuation correction and normalisation algorithm was developed to improve the quantification of contrast enhancement in ultrasound images of carotid arteries. The algorithm first corrects attenuation artefact and normalises intensity within the contrast agent-filled lumen and then extends the correction and normalisation to regions beyond the lumen. The algorithm was first validated on phantoms consisting of contrast agent-filled vessels embedded in tissue-mimicking materials of known attenuation. It was subsequently applied to in vivo contrast-enhanced ultrasound (CEUS) images of human carotid arteries. Both in vitro and in vivo results indicated significant reduction in the shadowing artefact and improved homogeneity within the carotid lumens after the correction. The error in quantification of microbubble contrast enhancement caused by attenuation on phantoms was reduced from 55% to 5% on average. In conclusion, the proposed method exhibited great potential in reducing attenuation artefact and improving quantification in contrast-enhanced ultrasound of carotid arteries.


      PubDate: 2015-04-12T21:33:54Z
       
  • Cavitation-Enhanced Back Projection for Acoustic Rib Detection and
           Attenuation Mapping
    • Abstract: Publication date: Available online 2 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Pascal Ramaekers , Martijn de Greef , Chrit T.W. Moonen , Mario G. Ries
      High-intensity focused ultrasound allows for minimally invasive, highly localized cancer therapies that can complement surgical procedures or chemotherapy. For high-intensity focused ultrasound interventions in the upper abdomen, the thoracic cage obstructs and aberrates the ultrasonic beam, causing undesired heating of healthy tissue. When a phased array therapeutic transducer is used, such complications can be minimized by applying an apodization law based on analysis of beam path obstructions. In this work, a rib detection method based on cavitation-enhanced ultrasonic reflections is introduced and validated on a porcine tissue sample containing ribs. Apodization laws obtained for different transducer positions were approximately 90% similar to those obtained using image analysis. Additionally, the proposed method provides information on attenuation between transducer elements and the focus. This principle was confirmed experimentally on a polymer phantom. The proposed methods could, in principle, be implemented in real time for determination of the optimal shot position in intercostal high-intensity focused ultrasound therapy.


      PubDate: 2015-04-12T21:33:54Z
       
  • Intensity-Invariant Texture Analysis for Classification of BI-RADS
           Category 3 Breast Masses
    • Abstract: Publication date: Available online 2 April 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Chung-Ming Lo , Woo Kyung Moon , Chiun-Sheng Huang , Jeon-Hor Chen , Min-Chun Yang , Ruey-Feng Chang
      Radiologists likely incorrectly classify benign masses as Breast Imaging Reporting and Data System (BI-RADS) category 3. A computer-aided diagnosis (CAD) system was developed in this study as a second viewer to avoid misclassification of carcinomas. Sixty-nine biopsy-proven BI-RADS category 3 masses, including 21 malignant and 48 benign masses, were used to evaluate the CAD system. To improve the texture features, gray-scale variations between images were reduced by transforming pixels into intensity-invariant ranklet coefficients. The textures of the tumor and speckle pixels were extracted from the transformed ranklet images to provide more robust features than in conventional CAD systems. As a result, tumor texture and speckle texture with ranklet transformation achieved significantly better areas under the receiver operating characteristic curve (Az) compared with those without ranklet transformation (Az = 0.83 vs. 0.58 and Az = 0.80 vs. 0.56, p value < 0.05). The improved CAD system can be a second reader to confirm the classification of BI-RADS category 3 masses.


      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
       
  • Masthead
    • Abstract: Publication date: April 2015
      Source:Ultrasound in Medicine & Biology, Volume 41, Issue 4




      PubDate: 2015-04-12T21:33:54Z
       
  • Hemodynamic Effects of Proximal Supra-aortic Artery Stenosis on Anterior
           Cerebral Artery
    • Abstract: Publication date: Available online 29 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Nicolás López-Hernández , Alejandro García-Escrivá , Federico Ballenilla , Jose Ignacio Gallego-Leon
      Alternating flow in the anterior cerebral artery is a rare finding, associated with innominate artery stenosis. We present a series of four patients with this finding on transcranial color coded sonography, under basal conditions. In all of these patients, vascular studies detected an ipsilateral proximal stenosis, three in the innominate artery and, for the first time, one at the left common carotid artery origin. Successful angioplasties with stenting were performed, resulting for the first time in the normalization of orthograde flow in all cases. We conclude that an early systolic hemodynamic compromise in the first segment of the anterior cerebral artery, in the form of alternating flow, is an indirect indicator of ipsilateral proximal stenosis in the supra-aortic arteries, either in the innominate artery or at the origin of the left common carotid artery.


      PubDate: 2015-02-06T01:04:43Z
       
  • Investigation into the Mechanisms of Tissue Atomization by High-Intensity
           Focused Ultrasound
    • Abstract: Publication date: Available online 3 February 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Julianna C. Simon , Oleg A. Sapozhnikov , Yak-Nam Wang , Vera A. Khokhlova , Lawrence A. Crum , Michael R. Bailey
      Ultrasonic atomization, or the emission of a fog of droplets, was recently proposed to explain tissue fractionation in boiling histotripsy. However, even though liquid atomization has been studied extensively, the mechanisms underlying tissue atomization remain unclear. In the work described here, high-speed photography and overpressure were used to evaluate the role of bubbles in tissue atomization. As static pressure increased, the degree of fractionation decreased, and the ex vivo tissue became thermally denatured. The effect of surface wetness on atomization was also evaluated in vivo and in tissue-mimicking gels, where surface wetness was found to enhance atomization by forming surface instabilities that augment cavitation. In addition, experimental results indicated that wetting collagenous tissues, such as the liver capsule, allowed atomization to breach such barriers. These results highlight the importance of bubbles and surface instabilities in atomization and could be used to enhance boiling histotripsy for transition to clinical use.


      PubDate: 2015-02-06T01:04:43Z
       
  • Bas-Relief Map Using Texture Analysis with Application to Live Enhancement
           of Ultrasound Images
    • Abstract: Publication date: Available online 29 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Huarui Du , Rui Ma , Xiaoying Wang , Jue Zhang , Jing Fang
      For ultrasound imaging, speckle is one of the most important factors in the degradation of contrast resolution because it masks meaningful texture and has the potential to interfere with diagnosis. It is expected that researchers would explore appropriate ways to reduce the speckle noise, to find the edges of structures and enhance weak borders between different organs in ultrasound imaging. Inspired by the principle of differential interference contrast microscopy, a “bas-relief map” is proposed that depicts the texture structure of ultrasound images. Based on a bas-relief map, an adaptive bas-relief filter was developed for ultrafast despeckling. Subsequently, an edge map was introduced to enhance the edges of images in real time. The holistic bas-relief map approach has been used experimentally with synthetic phantoms and digital ultrasound B-scan images of liver, kidney and gallbladder. Based on the visual inspection and the performance metrics of the despeckled images, it was found that the bas-relief map approach is capable of effectively reducing the speckle while significantly enhancing contrast and tissue boundaries for ultrasonic images, and its speckle reduction ability is comparable to that of Kuan, Lee and Frost filters. Meanwhile, the proposed technique could preserve more intra-region details compared with the popular speckle reducing anisotropic diffusion technique and more effectively enhance edges. In addition, the adaptive bas-relief filter was much less time consuming than the Kuan, Lee and Frost filter and speckle reducing anisotropic diffusion techniques. The bas-relief map strategy is effective for speckle reduction and live enhancement of ultrasound images, and can provide a valuable tool for clinical diagnosis.


      PubDate: 2015-02-06T01:04:43Z
       
  • Quantifying Activation of Perfluorocarbon-Based Phase-Change Contrast
           Agents Using Simultaneous Acoustic and Optical Observation
    • Abstract: Publication date: Available online 2 February 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Sinan Li , Shengtao Lin , Yi Cheng , Terry O. Matsunaga , Robert J. Eckersley , Meng-Xing Tang
      Phase-change contrast agents in the form of nanoscale droplets can be activated into microbubbles by ultrasound, extending the contrast beyond the vasculature. This article describes simultaneous optical and acoustical measurements for quantifying the ultrasound activation of phase-change contrast agents over a range of concentrations. In experiments, decafluorobutane-based nanodroplets of different dilutions were sonicated with a high-pressure activation pulse and two low-pressure interrogation pulses immediately before and after the activation pulse. The differences between the pre- and post-interrogation signals were calculated to quantify the acoustic power scattered by the microbubbles activated over a range of droplet concentrations. Optical observation occurred simultaneously with the acoustic measurement, and the pre- and post-microscopy images were processed to generate an independent quantitative indicator of the activated microbubble concentration. Both optical and acoustic measurements revealed linear relationships to the droplet concentration at a low concentration range <108/mL when measured at body temperature. Further increases in droplet concentration resulted in saturation of the acoustic interrogation signal. Compared with body temperature, room temperature was found to produce much fewer and larger bubbles after ultrasound droplet activation.


      PubDate: 2015-02-06T01:04:43Z
       
  • Quantitative Ultrasound Assessment of the Facet Joint in the Lumbar Spine:
           A Feasibility Study
    • Abstract: Publication date: Available online 28 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Da Liu , Ying Huang , Dan Tian , Jing Yin
      This study was designed to determine the feasibility and accuracy of a sonographic approach to assessment of facet joints of the lumbar spine in healthy populations. Five facet joints (L1–S1) on each side of 30 volunteers, for a total of 300 facet joints, were examined and evaluated by sonography and computed tomography. Parameters of the facet joints (height and width) were established to assess the facet joint in the parasagittal and transverse planes on all volunteers. Differences between means of continuous variables including age, height, weight, body surface area, body mass index and joint parameters were evaluated with Student's t-test. Stepwise multiple regression analysis was used to evaluate the associations between the mean values of facet joint parameters and age, height, body surface area and body mass index. In general, sonography revealed that facet joints had a clear and smooth border. There were no significant differences in width and height between the left and right facet joints at the same level by sonography. Stepwise multiple regression analysis revealed that body mass index and age (p < 0.05) were the only independent factors modulating height of the facet joint. Facet joint width was independently influenced by age (p < 0.01). There were no significant differences between ultrasound and computed tomography in mean measurements of height (1.23 ± 0.15 vs. 1.25 ± 0.07, p > 0.05) and width (0.17 ± 0.08 vs. 0.18 ± 0.07, p > 0.05) of the facet joint, respectively. In this article, we describe a feasible, accurate and simple technique for identification and depiction of facet joints of the lumbar spine in healthy populations.


      PubDate: 2015-01-30T00:19:25Z
       
  • Improved Correlation between Carotid and Coronary Atherosclerosis SYNTAX
           Score Using Automated Ultrasound Carotid Bulb Plaque IMT Measurement
    • Abstract: Publication date: Available online 28 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Nobutaka Ikeda , Ajay Gupta , Nilanjan Dey , Soumyo Bose , Shoaib Shafique , Tadashi Arak , Elisa Cuadrado Godia , Luca Saba , John R. Laird , Andrew Nicolaides , Jasjit S. Suri
      Described here is a detailed novel pilot study on whether the SYNTAX (Synergy between percutaneous coronary intervention with TAXUS and cardiac surgery) score, a measure of coronary artery disease complexity, could be better predicted with carotid intima–media thickness (cIMT) measures using automated IMT all along the common carotid and bulb plaque compared with manual IMT determined by sonographers. Three hundred seventy consecutive patients who underwent carotid ultrasound and coronary angiography were analyzed. SYNTAX score was determined from coronary angiograms by two experienced interventional cardiologists. Unlike most methods of cIMT measurement commonly used by sonographers, our method involves a computerized automated cIMT measurement all along the carotid artery that includes the bulb region and the region proximal to the bulb (under the class of AtheroEdge systems from AtheroPoint, Roseville, CA, USA). In this study, the correlation between automated cIMT that includes bulb plaque and SYNTAX score was found to be 0.467 (p < 0.0001), compared with 0.391 (p < 0.0001) for the correlation between the sonographer's IMT reading and SYNTAX score. The correlation between the automated cIMT and the sonographer's IMT was 0.882. When compared against the radiologist's manual tracings, automated cIMT system performance had a lumen–intima error of 0.007818 ± 0.0071 mm, media–adventitia error of 0.0179 ± 0.0125 mm and automated cIMT error of 0.0099 ± 0.00988 mm. The precision of automated cIMT against the manual radiologist's reading was 98.86%. This current automated algorithm revealed a significantly stronger correlation between cIMT and coronary SYNTAX score as compared with the sonographer's cIMT measurements with multiple cardiovascular risk factors. We benchmarked our correlation between the automated cIMT that includes bulb plaque and SYNTAX score against a previously published (Ikeda et al. 2013) AtheroEdgeLink (AtheroPoint) correlation between the automated cIMT that does not include bulb plaque and SYNTAX score and had an improvement of 44.58%. By sampling cIMT in the bulb region, the automated cIMT technique improves the degree of correlation between coronary artery disease lesion complexity and carotid atherosclerosis characteristics.


      PubDate: 2015-01-30T00:19:25Z
       
  • Delivery of Molecules to the Lymph Node via Lymphatic Vessels Using
           Ultrasound and Nano/Microbubbles
    • Abstract: Publication date: Available online 28 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Shigeki Kato , Yuko Shirai , Hiroyuki Kanzaki , Maya Sakamoto , Shiro Mori , Tetsuya Kodama
      Lymph node (LN) dissection is the primary option for head and neck cancer when imaging modalities and biopsy confirm metastasis to the sentinel LN. However, there are no effective alternative treatments to dissection for LN metastasis. Here, we describe a novel drug delivery system combining nano/microbubbles (NMBs) with ultrasound (US) that exhibits considerable potential for the delivery of exogenous molecules into LNs through the lymphatic vessels. A solution containing fluorophores (as a model of a therapeutic molecule) and NMBs was injected into the subiliac LNs of MXH10/Mo-lpr/lpr mice, which develop systemic swelling of LNs (up to 13 mm in diameter, similar to human LNs). It was found that the NMBs were delivered to the entire area of the proper axillary LN (proper-ALN) via the lymphatic channels and that these were retained there for more than 8 min. Furthermore, exposure to US in the presence of NMBs enhanced the delivery of fluorophores into the lymphocytes near the lymphatic channels, compared with exposure to US in the absence of NMBs. It is proposed that a system using US and NMBs to deliver therapeutic drugs via lymphatic vessels can serve as a new treatment method for LN metastasis.


      PubDate: 2015-01-30T00:19:25Z
       
  • Measurement of Quantitative Viscoelasticity of Bovine Corneas Based on
           Lamb Wave Dispersion Properties
    • Abstract: Publication date: Available online 28 January 2015
      Source:Ultrasound in Medicine & Biology
      Author(s): Xinyu Zhang , Yin Yin , Yanrong Guo , Ning Fan , Haoming Lin , Fulong Liu , Xianfen Diao , Changfeng Dong , Xin Chen , Tianfu Wang , Siping Chen
      The viscoelastic properties of the human cornea can provide valuable information for clinical applications such as the early detection of corneal diseases, better management of corneal surgery and treatment and more accurate measurement of intra-ocular pressure. However, few techniques are capable of quantitatively and non-destructively assessing corneal biomechanics in vivo. The cornea can be regarded as a thin plate in which the vibration induced by an external vibrator propagates as a Lamb wave, the properties of which depend on the thickness and biomechanics of the tissue. In this study, pulses of ultrasound radiation force with a repetition frequency of 100 or 200 Hz were applied to the apex of corneas, and the linear-array transducer of a SonixRP system was used to track the tissue motion in the radial direction. Shear elasticity and viscosity were estimated from the phase velocities of the A0 Lamb waves. To assess the effectiveness of the method, some of the corneas were subjected to collagen cross-linking treatment, and the changes in mechanical properties were validated with a tensile test. The results indicated that the shear modulus was 137 ± 37 kPa and the shear viscosity was 3.01 ± 2.45 mPa·s for the group of untreated corneas and 1145 ± 267 kPa and was 0.16 ± 0.11 mPa·s for the treated group, respectively, implying a significant increase in elasticity and a significant decrease in viscosity after collagen cross-linking treatment. This result is in agreement with the results of the mechanical tensile test and with reports in the literature. This initial investigation illustrated the ability of this ultrasound-based method, which uses the velocity dispersion of low-frequency A0 Lamb waves, to quantitatively assess both the elasticity and viscosity of corneas. Future studies could discover ways to optimize this system and to determine the feasibility of using this method in clinical situations.


      PubDate: 2015-01-30T00:19:25Z
       
 
 
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