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Journal Cover
Ultrasound in Medicine & Biology
Journal Prestige (SJR): 0.932
Citation Impact (citeScore): 2
Number of Followers: 8  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0301-5629
Published by Elsevier Homepage  [3163 journals]
  • Visualizing Angle-Independent Principal Strains in the Longitudinal View
           of the Carotid Artery: Phantom and In Vivo Evaluation
    • Authors: Rohit Nayak; Giovanni Schifitto; Marvin M. Doyley
      Pages: 1379 - 1391
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Rohit Nayak, Giovanni Schifitto, Marvin M. Doyley
      Non-invasive vascular elastography can evaluate the stiffness of the carotid artery by visualizing the vascular strain distribution. Axial strain estimates of the longitudinal cross section of the carotid artery are sensitive to the angle between the artery and the transducer. Anatomical variations in branching and arching of the carotid artery can affect the assessment of arterial stiffness. In this study, we hypothesized that principal strain elastograms computed using compounded plane wave imaging can reliably visualize the strain distribution in the carotid artery, independent of the transducer angle. We corroborated this hypothesis by conducting phantom and in vivo studies using a commercial ultrasound scanner (Sonix RP, Ultrasonix Medical Corp., Richmond, BC, Canada). The phantom studies were conducted using a homogeneous cryogel vessel phantom. The goal of the phantom study was to assess the feasibility of visualizing the radial deformation in the longitudinal plane of the vessel phantom, independent of the transducer angle (±30°, ±20°, ±10° and 0°). The in vivo studies were conducted on 20 healthy human volunteers in the age group 50–60 y. All echo imaging was performed at a transmit frequency of 5 MHz and sampling frequency of 40 MHz. The elastograms obtained from the phantom study revealed that for straight vessels, which had their lumen parallel to the transducer, principal strains were similar to axial strains. At non-parallel configurations (angles ±30°, ±20° and ±10°), the magnitudes of the mean principal strains were within 2.5% of the parallel configuration (0° angle) estimates and, thus, were observed to be relatively unaffected by change in angle. However, in comparison, the magnitude of the axial strain decreased with increase in angle because of coordinate dependency. Further, the pilot in vivo study indicated that the principal and axial strain elastograms were similar for subjects with relatively straight arteries. However, for arteries with arched geometry, axial strains were significantly lower (p < 0.01) than the corresponding principal vascular strains, which was consistent with the results obtained from the phantom study. In conclusion, the results of the phantom and in vivo studies revealed that principal strain elastograms computed using CPW imaging could reliably visualize angle-independent vascular strains in the longitudinal plane of the carotid artery.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.012
       
  • Measurement of Wall Shear Stress Exerted by Flowing Blood in the Human
           Carotid Artery: Ultrasound Doppler Velocimetry and Echo Particle Image
           Velocimetry
    • Authors: Phillip E. Gates; Arati Gurung; Luciano Mazzaro; Kuni Aizawa; Salim Elyas; William D. Strain; Angela C. Shore; Robin Shandas
      Pages: 1392 - 1401
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Phillip E. Gates, Arati Gurung, Luciano Mazzaro, Kuni Aizawa, Salim Elyas, William D. Strain, Angela C. Shore, Robin Shandas
      Vascular endothelial cells lining the arteries are sensitive to wall shear stress (WSS) exerted by flowing blood. An important component of the pathophysiology of vascular diseases, WSS is commonly estimated by centerline ultrasound Doppler velocimetry (UDV). However, the accuracy of this method is uncertain. We have previously validated the use of a novel, ultrasound-based, particle image velocimetry technique (echo PIV) to compute 2-D velocity vector fields, which can easily be converted into WSS data. We compared WSS data derived from UDV and echo PIV in the common carotid artery of 27 healthy participants. Compared with echo PIV, time-averaged WSS was lower using UDV (28 ± 35%). Echo PIV revealed that this was due to considerable spatiotemporal variation in the flow velocity profile, contrary to the assumption that flow is steady and the velocity profile is parabolic throughout the cardiac cycle. The largest WSS underestimation by UDV was found during peak systole (118 ± 16%) and the smallest during mid-diastole (4.3± 46%). The UDV method underestimated WSS for the accelerating and decelerating systolic measurements (68 ± 30% and 24 ± 51%), whereas WSS was overestimated for end-diastolic measurements (−44 ± 55%). Our data indicate that UDV estimates of WSS provided limited and largely inaccurate information about WSS and that the complex spatiotemporal flow patterns do not fit well with traditional assumptions about blood flow in arteries. Echo PIV-derived WSS provides detailed information about this important but poorly understood stimulus that influences vascular endothelial pathophysiology.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.013
       
  • Role of Coronary Flow Velocity in Predicting Adverse Outcome in Clinical
           Practice
    • Authors: Angela Zagatina; Nadezhda Zhuravskaya; Maxim Kamenskikh; Dmitry Shmatov; Sergey Sayganov; Fausto Rigo
      Pages: 1402 - 1410
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Angela Zagatina, Nadezhda Zhuravskaya, Maxim Kamenskikh, Dmitry Shmatov, Sergey Sayganov, Fausto Rigo
      There is a lack of information on the prognostic value of local high velocity in coronary arteries during echocardiography. The aim of the study described here was to define the prognostic value of local velocity >70 cm/s in the left main, anterior or circumflex artery during echocardiography. There were 412 patients in the prospective study. Death, non-fatal myocardial infarction, acute pulmonary edema, acute coronary syndrome and revascularization were defined as major adverse cardiac events (MACEs). Over 10.5 mo, there were 207 patients with MACEs. Seventeen patients died, 10 had non-fatal acute cardiac events and 184 underwent revascularization. Deaths occurred in patients with high local velocity (6.4% vs. 0%, p < 0.009). Acute cardiac events occurred in 10% versus 0% (p < 0.003). MACEs were observed in 62% versus 0% (p < 0.0000001). Only maximal velocity was an independent prognostic predictor of death (odds ratio = 1.02, 95% confidence interval: 1.01–1.03, p < 0.02) and MACEs (odds ratio = 1.04, 95% confidence interval: 1.02–1.05, p < 0.0001). The success rate of coronary artery visualization for at least one segment was 91%.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.021
       
  • Spectral Analysis of Ultrasound Radiofrequency Backscatter for the
           Detection of Intercostal Blood Vessels
    • Authors: Jon D. Klingensmith; Asher Haggard; Russell J. Fedewa; Beidi Qiang; Kenneth Cummings; Sean DeGrande; D. Geoffrey Vince; Hesham Elsharkawy
      Pages: 1411 - 1422
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Jon D. Klingensmith, Asher Haggard, Russell J. Fedewa, Beidi Qiang, Kenneth Cummings, Sean DeGrande, D. Geoffrey Vince, Hesham Elsharkawy
      Spectral analysis of ultrasound radiofrequency backscatter has the potential to identify intercostal blood vessels during ultrasound-guided placement of paravertebral nerve blocks and intercostal nerve blocks. Autoregressive models were used for spectral estimation, and bandwidth, autoregressive order and region-of-interest size were evaluated. Eight spectral parameters were calculated and used to create random forests. An autoregressive order of 10, bandwidth of 6 dB and region-of-interest size of 1.0 mm resulted in the minimum out-of-bag error. An additional random forest, using these chosen values, was created from 70% of the data and evaluated independently from the remaining 30% of data. The random forest achieved a predictive accuracy of 92% and Youden's index of 0.85. These results suggest that spectral analysis of ultrasound radiofrequency backscatter has the potential to identify intercostal blood vessels. (jokling@siue.edu) © 2018 World Federation for Ultrasound in Medicine and Biology

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.007
       
  • Muscle Shear Wave Elastography in Inclusion Body Myositis: Feasibility,
           Reliability and Relationships with Muscle Impairments
    • Authors: Damien Bachasson; Guillaume J.R. Dubois; Yves Allenbach; Olivier Benveniste; Jean-Yves Hogrel
      Pages: 1423 - 1432
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Damien Bachasson, Guillaume J.R. Dubois, Yves Allenbach, Olivier Benveniste, Jean-Yves Hogrel
      Degenerative muscle changes may be associated with changes in muscle mechanical properties. Shear wave elastography (SWE) allows direct quantification of muscle shear modulus (MSM). The aim of this study was to evaluate the feasibility and reliability of SWE in the severely disordered muscle as observed in inclusion body myositis. To explore the clinical relevance of SWE, potential relationships between MSM values and level muscle impairments (weakness and ultrasound-derived muscle thickness and echo intensity) were investigated. SWE was performed in the biceps brachii at 100°, 90°, 70° and 10° elbow flexion in 34 patients with inclusion body myositis. MSM was assessed before and after five passive stretch-shortening cycles at 4°/s from 70° to 10° elbow angle and after three maximal voluntary contractions to evaluate potential effects of muscle pre-conditioning. Intra-class correlation coefficients and standard errors of measurements were >0.83 and <1.74 kPa and >0.64 and <1.89 kPa for within- and between-day values, respectively. No significant effect of passive loading–unloading and maximal voluntary contractions was found (all p values  >0.18). MSM correlated to predicted muscle strength (all Spearman correlation coefficients (ρ) > 0.36; all p values < 0.05). A significant correlation was found between muscle echo intensity and muscle shear modulus at 70° only (ρ = 0.38, p < 0.05). No correlation was found between muscle thickness and MSM (all ρ values > 0.23 and all p values > 0.25, respectively). Within- and between-day reliability of muscle SWE was satisfactory and moderate, respectively. SWE shows promise for assessing changes in mechanical properties of the severely disordered muscle. Further investigations are required to clarify these findings and to refine their clinical value.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.026
       
  • Ultrasonic Cavitation-Enabled Treatment for Therapy of Hypertrophic
           Cardiomyopathy: Proof of Principle
    • Authors: Douglas L. Miller; Xiaofang Lu; Chunyan Dou; Yiying I. Zhu; Rachael Fuller; Kristina Fields; Mario L. Fabiilli; Gabe E. Owens; David Gordon; Oliver D. Kripfgans
      Pages: 1439 - 1450
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Douglas L. Miller, Xiaofang Lu, Chunyan Dou, Yiying I. Zhu, Rachael Fuller, Kristina Fields, Mario L. Fabiilli, Gabe E. Owens, David Gordon, Oliver D. Kripfgans
      Ultrasound myocardial cavitation-enabled treatment was applied to the SS-16BN rat model of hypertrophic cardiomyopathy for proof of the principle underlying myocardial reduction therapy. A focused ultrasound transducer was targeted using 10-MHz imaging (10 S, GE Vivid 7) to the left ventricular wall of anesthetized rats in a warmed water bath. Pulse bursts of 4-MPa peak rarefactional pressure amplitude were intermittently triggered 1:8 heartbeats during a 10-min infusion of a microbubble suspension. Methylprednisolone was given to reduce initial inflammation, and Losartan was given to reduce fibrosis in the healing tissue. At 28 d post therapy, myocardial cavitation-enabled treatment significantly reduced the targeted wall thickness by 16.2% (p < 0.01) relative to shams, with myocardial strain rate and endocardial displacement reduced by 34% and 29%, respectively, which are sufficient for therapeutic treatment. Premature electrocardiogram complexes and plasma troponin measurements were found to identify optimal and suboptimal treatment cohorts and would aid in achieving the desired impact. With clinical translation, myocardial cavitation-enabled treatment should fill the need for a new non-invasive hypertrophic cardiomyopathy therapy option.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.010
       
  • Effect of Microbubble-Enhanced Ultrasound on Radiofrequency Ablation of
           Rabbit Liver
    • Authors: Zhong Chen; Hongzhi Zhao; Xueyan Qiao; Cuo Yi; Shunji Gao; Wenhong Gao; Zheng Liu
      Pages: 1451 - 1459
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Zhong Chen, Hongzhi Zhao, Xueyan Qiao, Cuo Yi, Shunji Gao, Wenhong Gao, Zheng Liu
      Microbubble-enhanced ultrasound (MEUS) can non-invasively disrupt and block liver blood perfusion. It may potentially overcome the heat sink effect during a thermal ablation and consequently enhance radiofrequency ablation (RFA) of the liver. We propose a new strategy combining RFA with MEUS. For ultrasound treatment, an 831-kHz air-backed focused transducer directed 400-cycle bursts at 4.3 MPa to the liver at a 9-Hz rate. The treatment was nucleated by a lipids microbubble forming MEUS. Eighteen surgically exposed rabbit livers were treated using MEUS combined with RFA; the other 32 livers were treated using MEUS (n = 14) or RFA (n = 18) alone and served as the controls. Contrast ultrasound imaging confirmed that MEUS treatment significantly reduced liver blood perfusion by cutting contrast peak intensities in half (44.7%–54.1%) without severe liver function damage. The ablated liver volume treated using MEUS combined with RFA was 2.8 times greater than that treated using RFA alone. In conclusion, RFA of the liver can be safely and greatly enhanced by combination with MEUS pre-treatment.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.008
       
  • Dual-Targeted Microbubbles Specific to Integrin αVβ3 and Vascular
           Endothelial Growth Factor Receptor 2 for Ultrasonography Evaluation of
           Tumor Angiogenesis
    • Authors: Hai-xia Yuan; Wen-ping Wang; Jie-xian Wen; Le-wu Lin; Agata A. Exner; Pei-shan Guan; Xue-jun Chen
      Pages: 1460 - 1467
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Hai-xia Yuan, Wen-ping Wang, Jie-xian Wen, Le-wu Lin, Agata A. Exner, Pei-shan Guan, Xue-jun Chen
      Aggressive tumors are characterized by angiogenesis that promotes the migration and dissemination of tumor cells. Our aim was to develop a dual-targeted microbubble system for non-invasive evaluation of tumor angiogenesis in ultrasound. Avidinylated microbubbles were conjugated with biotinylated arginylglycylaspartic acid and vascular endothelial growth factor receptor 2 (VEGFR2) antibodies. Subcutaneous MHCC-97H liver carcinoma models were established. Non-targeted, αvβ3-targeted, VEGFR2-targeted and dual-targeted microbubbles was intravenously injected in series while acquiring ultrasound images of the tumor. The microbubbles were destroyed by a high-mechanical-index pulse 4 min after the injection. Peak intensity (PI) before and after the destructive pulse was recorded to compare contrast enhancement by different microbubbles. The targeting rates of the integrin-targeted, VEGFR2-targeted and dual-targeted groups were 95.02%, 96.04% and 94.23%, respectively, with no significant differences. Tumors in all groups were significantly enhanced. The time–intensity curve indicated no significant differences in arrival time, PI, area under the curve, amplitude and mean transit time. The difference in ultrasound signal intensity before and after the destructive pulse (⊿PI) for all targeted microbubble groups was significantly greater than that for the non-targeted microbubble group (all p values < 0.05), and the difference for the dual-targeted microbubble group was significantly greater than those of both mono-targeted groups (p < 0.05).

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.022
       
  • Macrophages as Drug Delivery Carriers for Acoustic Phase-Change Droplets
    • Authors: Ching-Hsiang Fan; Ya-Hsuan Lee; Yi-Ju Ho; Chung-Hsin Wang; Shih-Tsung Kang; Chih-Kuang Yeh
      Pages: 1468 - 1481
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Ching-Hsiang Fan, Ya-Hsuan Lee, Yi-Ju Ho, Chung-Hsin Wang, Shih-Tsung Kang, Chih-Kuang Yeh
      The major challenges in treating malignant tumors are transport of therapeutic agents to hypoxic regions and real-time assessment of successful drug release via medical imaging modalities. In this study, we propose the use of macrophages (RAW 264.7 cells) as carriers of drug-loaded phase-change droplets to penetrate ischemic or hypoxic regions within tumors. The droplets consist of perfluoropentane, lipid and the chemotherapeutic drug doxorubicin (DOX, DOX-droplets). The efficiency of DOX-droplet uptake, migration mobility and viability of DOX-droplet-loaded macrophages (DLMs) were measured using a transmembrane cell migration assay, the alamarBlue assay and flow cytometric analysis, respectively. Our results indicate the feasibility of utilizing macrophages as DOX-droplet carriers (DOX payload of DOX-droplets: 459.3 ± 35.8 µg/mL, efficiency of cell uptake DOX-droplets: 88.8 ± 3.5%). The migration mobility (total number of migrated microphages) of DLMs decreased to 32.3% compared with that of healthy macrophages, but the DLMs provided contrast-enhanced ultrasound imaging (1.7-fold enhancement) and anti-tumor effect (70.9% cell viability) after acoustic droplet vaporization, suggesting the potential theranostic applications of DLMs. Future work will assess the tumor penetration ability of DLMs, mechanical effect of droplet vaporization on in vivo anti-tumor therapy and the release of the carried drug by ultrasound-triggered vaporization.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.009
       
  • Monodisperse Versus Polydisperse Ultrasound Contrast Agents: Non-Linear
           Response, Sensitivity, and Deep Tissue Imaging Potential
    • Authors: Tim Segers; Pieter Kruizinga; Maarten P. Kok; Guillaume Lajoinie; Nico de Jong; Michel Versluis
      Pages: 1482 - 1492
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Tim Segers, Pieter Kruizinga, Maarten P. Kok, Guillaume Lajoinie, Nico de Jong, Michel Versluis
      It has been proposed that monodisperse microbubble ultrasound contrast agents further increase the signal-to-noise ratio of contrast-enhanced ultrasound imaging. Here, the sensitivity of a polydisperse pre-clinical agent was compared experimentally with that of its size- and acoustically sorted derivatives by using narrowband pressure- and frequency-dependent scattering and attenuation measurements. The sorted monodisperse agents had up to a two-orders-of-magnitude increase in sensitivity, that is, in the average scattering cross section per bubble. Moreover, we found, for the first time, that the highly non-linear response of acoustically sorted microbubbles can be exploited to confine scattering and attenuation to the focal region of ultrasound fields used in clinical imaging. This property is a result of minimal pre-focal scattering and attenuation and can be used to minimize shadowing effects in deep tissue imaging. Moreover, it potentially allows for more localized therapy using microbubbles through the spatial control of resonant microbubble oscillations.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.019
       
  • Analysis of Transient Shear Wave in Lossy Media
    • Authors: Kevin J. Parker; Juvenal Ormachea; Scott Will; Zaegyoo Hah
      Pages: 1504 - 1515
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Kevin J. Parker, Juvenal Ormachea, Scott Will, Zaegyoo Hah
      The propagation of shear waves from impulsive forces is an important topic in elastography. Observations of shear wave propagation can be obtained with numerous clinical imaging systems. Parameter estimations of the shear wave speed in tissues, and more generally the viscoelastic parameters of tissues, are based on some underlying models of shear wave propagation. The models typically include specific choices of the spatial and temporal shape of the impulsive force and the elastic or viscoelastic properties of the medium. In this work, we extend the analytical treatment of 2-D shear wave propagation in a biomaterial. The approach applies integral theorems relevant to the solution of the generalized Helmholtz equation, and does not depend on a specific rheological model of the tissue's viscoelastic properties. Estimators of attenuation and shear wave speed are derived from the analytical solutions, and these are applied to an elastic phantom, a viscoelastic phantom and in vivo liver using a clinical ultrasound scanner. In these samples, estimated shear wave group velocities ranged from 1.7 m/s in the liver to 2.5 m/s in the viscoelastic phantom, and these are lower-bounded by independent measurements of phase velocity.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.014
       
  • Validation of Musculoskeletal Ultrasound in the Assessment of Experimental
           Gout Synovitis
    • Authors: Esperanza Naredo; Juan Pablo Medina; Sandra Pérez-Baos; Aranzazu Mediero; Gabriel Herrero-Beaumont; Raquel Largo
      Pages: 1516 - 1524
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Esperanza Naredo, Juan Pablo Medina, Sandra Pérez-Baos, Aranzazu Mediero, Gabriel Herrero-Beaumont, Raquel Largo
      The objective of this study was to validate musculoskeletal ultrasound (US) in a rabbit model of acute gout. Acute gout was induced by intra-articular injection of monosodium urate (MSU) crystals in 10 rabbits; the 3 controls received vehicle. Rabbit knees were assessed by B-mode and power Doppler (PD) US 24 and 72 h after injections. After 72 h, all rabbits were euthanized. US discriminated between the MSU-injected and control groups with respect to the different inflammatory findings at both at 24 and 72 h and for MSU crystal-related findings after 24 h of injection. US synovial thickening, intra-synovial power Doppler signal and global joint distension significantly correlated with the synovial global histopathological score (r = 0.47, p = 0.0188), tissue vascularization measured by CD31 immunohistochemical-positive staining (r = 0.46, p = 0.0172) and tissue levels of interleukin-1β (r = 0.53, p = 0.0078), respectively. US is a valid method for assessment of synovial inflammation in experimental gouty arthritis in rabbits.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.018
       
  • Selection Strategies for Atlas-Based Mosaicing of Left Atrial 3-D
           Transesophageal Echocardiography Data
    • Authors: Harriët W. Mulder; Marijn van Stralen; Ben Ren; Alexander Haak; Gerard van Burken; Max A. Viergever; Johan G. Bosch; Josien P.W. Pluim
      Pages: 1533 - 1543
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Harriët W. Mulder, Marijn van Stralen, Ben Ren, Alexander Haak, Gerard van Burken, Max A. Viergever, Johan G. Bosch, Josien P.W. Pluim
      Three-dimensional transesophageal echocardiography (TEE) provides real-time soft tissue information, but its use is hampered by its limited field of view. The mosaicing of multiple TEE views makes it possible to visualize a large structure, like the left atrium, in a single volume. To this end, an automatic registration method is required. Similarly to atlas-based segmentation approaches, atlas-based mosaicing (ABM) uses a full volume atlas set to moderate the onerous registration of the individual TEE views. The performance of ABM depends both on the quality of the involved registrations and on the selection of the optimal transformation from the candidate transformations that result from the various atlases. The study described here explored the performance of different selection strategies on multiview TEE data of the left atrium. We found that by incorporating two stages of transformation selection, using the image similarity and the conformity between the candidate transformations as selection criteria, the average registration error dropped below 3 mm with respect to manual registration of these data. Finally, we used this method for the automatic construction of a wide-view TEE volume of the left atrium.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.004
       
  • Echocardiographic Analysis of Cardiac Function after Infarction in Mice:
           Validation of Single-Plane Long-Axis View Measurements and the Bi-Plane
           Simpson Method
    • Authors: Andre Heinen; Annika Raupach; Friederike Behmenburg; Nina Hölscher; Ulrich Flögel; Malte Kelm; Wolfgang Kaisers; Rianne Nederlof; Ragnar Huhn; Axel Gödecke
      Pages: 1544 - 1555
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Andre Heinen, Annika Raupach, Friederike Behmenburg, Nina Hölscher, Ulrich Flögel, Malte Kelm, Wolfgang Kaisers, Rianne Nederlof, Ragnar Huhn, Axel Gödecke
      Although echocardiography is commonly used to analyze cardiac function in small animal models of cardiac remodeling after myocardial infarction, the different echocardiographic methods are validated poorly. End-diastolic volume, end-systolic volume and ejection fraction were analyzed using either standard single-plane analysis from parasternal long-axis B-mode views (PSLAX) or the bi-plane Simpson method (using PSLAX and three short-axis views) and validated using magnetic resonance imaging as standard. Ejection fraction measured by PSLAX was moderately correlated with a coefficient of R 2 = 0.49. The standard deviation of residuals was 9.91. Simpson analysis revealed an improved correlation coefficient of R 2 = 0.77 and a reduction in standard deviation of residuals by 45% (5.45 vs. 9.92, p = 0.014). Subgroup analysis revealed that the high variation in PSLAX is due to changes in ventricular geometry after myocardial infarction. Our results indicate that the bi-plane Simpson method is advantageous for the assessment of cardiac function after myocardial infarction.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.020
       
  • A Novel Technique for the Standardized Application of Shock Waves in
           Experimental Research: The Diver Box
    • Authors: Heiko Sorg; Daniel J. Tilkorn; Jonas Kolbenschlag; Inga Zwetzich; Joerg Hauser; Ole Goertz; Nick Spindler; Stefan Langer; Andrej Ring
      Pages: 1563 - 1568
      Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7
      Author(s): Heiko Sorg, Daniel J. Tilkorn, Jonas Kolbenschlag, Inga Zwetzich, Joerg Hauser, Ole Goertz, Nick Spindler, Stefan Langer, Andrej Ring
      The Diver Box is designed to prevent impedance differences, energy loss or damage to neighboring structures caused by the use of shock waves with application gels. The Diver Box is an acrylic glass container filled with tempered water and includes a coupling membrane to prevent the impedance jump from air to water and to avoid the continuous propagation of shock waves into the tissue, maintaining wave dynamics. Different modes of extracorporeal shock waves can be applied to a mouse skin wound without energy loss and protected from harmful phase-reversed waves. Macroscopic changes were seen in only 5% to 12% of tested specimens. Hazardous phase reversal, back reflection and mechanical tissue damage can be avoided by use of the Diver Box, ensuring standardized extracorporeal shock wave application.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.006
       
  • Ultrasound Molecular Imaging of Atherosclerosis Using Small-Peptide
           Targeting Ligands Against Endothelial Markers of Inflammation and
           Oxidative Stress
    • Authors: Federico Moccetti; Craig C. Weinkauf; Brian P. Davidson; J. Todd Belcik; Edmund R. Marinelli; Evan Unger; Jonathan R. Lindner
      Pages: 1155 - 1163
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Federico Moccetti, Craig C. Weinkauf, Brian P. Davidson, J. Todd Belcik, Edmund R. Marinelli, Evan Unger, Jonathan R. Lindner
      The aim of this study was to evaluate a panel of endothelium-targeted microbubble (MB) ultrasound contrast agents bearing small peptide ligands as a human-ready approach for molecular imaging of markers of high-risk atherosclerotic plaque. Small peptide ligands with established affinity for human P-selectin, VCAM-1, LOX-1 and von Willebrand factor (VWF) were conjugated to the surface of lipid-stabilized MBs. Contrast-enhanced ultrasound (CEUS) molecular imaging of the thoracic aorta was performed in wild-type and gene-targeted mice with advanced atherosclerosis (DKO). Histology was performed on carotid endarterectomy samples from patients undergoing surgery for unstable atherosclerosis to assess target expression in humans. In DKO mice, CEUS signal for all four targeted MBs was significantly higher than that for control MBs, and was three to sevenfold higher than in wild-type mice, with the highest signal achieved for VCAM-1 and VWF. All molecular targets were present on the patient plaque surface but expression was greatest for VCAM-1 and VWF. We conclude that ultrasound contrast agents bearing small peptide ligands feasible for human use can be targeted against endothelial cell adhesion molecules for inflammatory cells and platelets for imaging advanced atherosclerotic disease.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.01.001
       
  • Role of Virtual Touch Tissue Quantification in Hashimoto's Thyroiditis
    • Authors: Zi-mei Lin; Yao Wang; Chun-mei Liu; Cao-xin Yan; Pin-tong Huang
      Pages: 1164 - 1169
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Zi-mei Lin, Yao Wang, Chun-mei Liu, Cao-xin Yan, Pin-tong Huang
      We investigated the role of the virtual touch tissue quantification (VTQ) technique in diagnosing Hashimoto's thyroiditis (HT) and in distinguishing various HT-related thyroid dysfunctions. Two hundred HT patients and 100 healthy volunteers (the control group) were enrolled. The diagnostic performance of VTQ in predicting HT was calculated as the area under the receiver operating characteristic curve (AZ ). The HT patients were further classified into three subgroups on the basis of serologic tests of thyroid function: hyperthyroidism, euthyroidism and hypothyroidism. Comparisons of shear wave velocity (SWV) between three subgroups were evaluated by analysis of variance. The mean SWV of the control group was significantly lower than that of the HT group (1.93 ± 0.33 m/s vs. 2.32 ± 0.49 m/s, p < 0.001). Az was 0.734 with a cut-off value of 1.86 m/s for performance of SWV in distinguishing between HT and a healthy thyroid; the sensitivity and specificity were 82.5% and 50.0%, respectively. Mean SWV values in the three HT subgroups (hyperthyroidism [2.07 ± 0.37 cm/s] vs. euthyroidism [2.20 ± 0.40 cm/s] vs. hypothyroidism [2.49 ± 0.46 cm/s]) were significantly different (p < 0.05). Our results suggest that VTQ is a promising technique for assessing HT and HT-related thyroid dysfunction.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.005
       
  • Artifacts in Shear Wave Elastography Images of Thyroid Nodules
    • Authors: Manjiri Dighe; Daniel S. Hippe; Jeff Thiel
      Pages: 1170 - 1176
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Manjiri Dighe, Daniel S. Hippe, Jeff Thiel
      The purpose of the study described here was to evaluate the presence and types of artifacts seen in color elastograms in thyroid elastography using shear wave elastography. This Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant study was approved by the ethics committee of our institution, and all patients provided written informed consent. One hundred seventy-eight patients (40 men and 138 women; mean age, 49 y; range, 19–84 y) were enrolled for a total of 241 thyroid nodules. After a short ultrasound (US) examination, SWE images were acquired at multiple levels in the nodule in transverse and longitudinal orientations. A total of 1297 images were obtained from 241 nodules for an average of 5.4 ±  2.7 (mean ± standard deviation) images per nodule. A retrospective review of all images was performed by one reviewer experienced in thyroid elastography. Two hundred eighty images (21.6%) were rated as good quality, and 112 (8.6%) were rated as moderate quality without artifacts. A total of 905 (69.8%) images had some artifact present, though most of these images (73.4%) were still interpretable. Two hundred forty-one images (18.6% of all images) were considered uninterpretable because of artifact. The most common types of artifacts were due to operator error (44.6% of all images), primarily compression (36.5% of all images). Other artifacts seen were due to anatomy (presence of carotid pulsation or adjacent to thyroid or location in isthmus, 11% of all images), nodule characteristics (cystic and calcified nodules or large nodules with lack of penetration, 17% of all images) and other artifacts that could not be explained by the prior mentioned causes (13% of all images). Our study indicates that artifacts are common in elastography images. Operator error was the most common type of artifact we saw. This should be easily correctable by adequate knowledge and recognition with subsequent correction of the artifacts.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.007
       
  • Acoustic Structure Quantification Versus Point Shear Wave Speed
           Measurement for the Assessment of Liver Fibrosis in Viral Hepatitis B
    • Authors: Jianxue Liu; Wei Ren; Hong Ai; Guoliang Dun; Yonghao Ji; Yaoren Zhang; Qinyun Wan; Shumei Lin
      Pages: 1177 - 1186
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Jianxue Liu, Wei Ren, Hong Ai, Guoliang Dun, Yonghao Ji, Yaoren Zhang, Qinyun Wan, Shumei Lin
      This study was conducted to evaluate the value of acoustic structure quantification (ASQ) technology versus that of point shear wave speed measurement (PSWSM) imaging technology for the assessment of liver fibrosis stage. A total of 104 patients with chronic hepatitis B (CHB) and 30 healthy control patients underwent ASQ and PSWSM examinations. Seven quantitative parameters were obtained from ASQ, and a principal component analysis was used to establish the integrative indicators. A quantitative parameter, known as the shear wave speed (SWS, m/s), was obtained from the PSWSM. The METAVIR scores for the assessment of pathologic liver fibrosis were used as a benchmark. Liver fibrosis stages exhibited a good correlation with the integrative indicators and SWS (r = 0.682, p < 0.001; r = 0.651, p < 0.001). The areas under the receiver operating characteristic curves for ASQ and PSWSM were 0.705 and 0.854 for mild liver fibrosis (F ≥ 1, p = 0.045), 0.813 and 0.743 for significant liver fibrosis (F ≥ 2, p = 0.115), 0.839 and 0.857 for severe liver fibrosis (F ≥ 3, p = 0.417) and 0.874 and 0.971 for liver cirrhosis (F = 4, p = 0.016), respectively. In conclusion, both ASQ and PSWSM were promising ultrasonic methods for assessing liver fibrosis in patients with CHB; however, PSWSM was more valuable for identifying mild liver fibrosis (F ≥ 1) and cirrhosis (F = 4) than ASQ, and the combination of PSWSM and ASQ improved the accuracy of diagnosing severe liver fibrosis (F ≥ 3).

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.010
       
  • 20-MHz Ultrasound for Measurements of Flow-Mediated Dilation and Shear
           Rate in the Radial Artery
    • Authors: Andrzej Nowicki; Zbigniew Trawinski; Barbara Gambin; Wojciech Secomski; Michał Szubielski; Marzena Parol; Robert Olszewski
      Pages: 1187 - 1197
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Andrzej Nowicki, Zbigniew Trawinski, Barbara Gambin, Wojciech Secomski, Michał Szubielski, Marzena Parol, Robert Olszewski
      A high-frequency scanning system consisting of a 20-MHz linear array transducer combined with a 20-MHz pulsed Doppler probe was introduced to evaluate the degree of radial artery flow-mediated dilation (FMD [%]) in two groups of patients after 5 min of controlled forearm ischemia followed by reactive hyperemia. In group I, comprising 27 healthy volunteers, FMD (mean ± standard deviation) was 15.26 ± 4.90% (95% confidence interval [CI]: 13.32%–17.20%); in group II, comprising 17 patients with chronic coronary artery disease, FMD was significantly less at 4.53 ± 4.11% (95% CI: 2.42%–6.64%). Specifically, the ratio FMD/SR (mean ± standard deviation), was equal to 5.36 × 10−4 ± 4.64 × 10−4 (95% CI: 3.54 × 10−4 to 7.18 × 10−4) in group I and 1.38 × 10−4 ± 0.89 × 10−4 (95% CI: 0.70 × 10−4 to 2.06 × 10−4) in group II. Statistically significant differences between the two groups were confirmed by a Wilcoxon–Mann–Whitney test for both FMD and FMD/SR (p < 0.01). Areas under receiver operating characteristic curves for FMD and FMD/SR were greater than 0.9. The results confirm the usefulness of the proposed measurements of radial artery FMD and SR in differentiation of normal patients from those with chronic coronary artery disease.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.011
       
  • Bi-Atrial Function before and after Percutaneous Closure of Atrial Septum
           in Patients with and without Paroxysmal Atrial Fibrillation: A 2-D and 3-D
           Speckle Tracking Echocardiographic Study
    • Authors: Antonio Vitarelli; Carlo Gaudio; Enrico Mangieri; Lidia Capotosto; Gaetano Tanzilli; Serafino Ricci; Nicola Viceconte; Attilio Placanica; Giuseppe Placanica; Rasul Ashurov
      Pages: 1198 - 1211
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Antonio Vitarelli, Carlo Gaudio, Enrico Mangieri, Lidia Capotosto, Gaetano Tanzilli, Serafino Ricci, Nicola Viceconte, Attilio Placanica, Giuseppe Placanica, Rasul Ashurov
      Our aim was to analyze atrial function with 2-D (2-D-STE) and 3-D (3-D-STE) speckle tracking echocardiography in patients with atrial septal devices and paroxysmal atrial fibrillation (PAF). One hundred sixteen patients and a subgroup of 22 patients who developed PAF after device insertion were studied. Left atrial and right atrial peak longitudinal strain and standard deviations of time to peak strain (TPS) were calculated using 2-D-STE. The left atrial/right atrial emptying fraction and expansion index were determined using 3-D-STE. By multivariate analysis, pre-closure 3-D right atrial expansion index, left atrial time to peak strain, and 3-D left atrial expansion index were independently associated with PAF. Compared with the other indices, receiver operating characteristic analysis revealed better diagnostic accuracy for the combination of pre-closure time to peak strain and 3-D expansion index in detecting PAF. Patients with atrial septal devices have pre-existing left and right atrial dilation and dysfunction as assessed by 2-D-STE and 3-D-STE that appear sensitive for the stratification of PAF risk in this population.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.015
       
  • Sources of Variability in the Detection of B-Lines, Using Lung Ultrasound
    • Authors: Emanuele Pivetta; Federico Baldassa; Serena Masellis; Federica Bovaro; Enrico Lupia; Milena M. Maule
      Pages: 1212 - 1216
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Emanuele Pivetta, Federico Baldassa, Serena Masellis, Federica Bovaro, Enrico Lupia, Milena M. Maule
      Lung ultrasound (LUS) is a largely employed diagnostic tool but an operational protocol for implementation has never been proposed. The lack of standardization clearly introduces variability in LUS results. We enrolled adult patients presenting for acute dyspnea with a clinical suspect of etiology related to heart failure. We calculated agreement among four providers in assessing B-lines. We varied probes, depth, evaluation time and scanning areas and we estimated the importance of each factors on B-lines assessment. Overall agreement among raters varied from a kappa of 0.70 to 0.81. The mean number of B-lines was 5.44 (95% confidence interval, CI, 4.1–6.8). This estimate did not suffer variation by the depth used (0.03, 95% CI –0.2–0.2, more B-lines, using 19 cm versus 10 cm). The use of a convex probe and expertise in LUS reduced the number of artifacts by 1.7 (95% CI 1.5–1.9) and 1.1 in comparison with a phased array probe and naive operators. Evaluation time increased estimates by 1.2 (95% CI 1–1.5) and 2.9 (95% CI 2.7–3.9) B-lines for 4” and 7” clips (reference was 2” clips). This study suggests that the probe, the evaluation time and the level of expertise might affect the results of quantitative assessment of B-lines.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.018
       
  • Activation of Piezo1 but Not NaV1.2 Channels by Ultrasound at 43 MHz
    • Authors: Martin Loynaz Prieto; Kamyar Firouzi; Butrus T. Khuri-Yakub; Merritt Maduke
      Pages: 1217 - 1232
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Martin Loynaz Prieto, Kamyar Firouzi, Butrus T. Khuri-Yakub, Merritt Maduke
      Ultrasound (US) can modulate the electrical activity of the excitable tissues, but the mechanisms underlying this effect are not understood at the molecular level or in terms of the physical modality through which US exerts its effects. Here, we report an experimental system that allows for stable patch-clamp recording in the presence of US at 43 MHz, a frequency known to stimulate neural activity. We describe the effects of US on two ion channels proposed to be involved in the response of excitable cells to US: the mechanosensitive Piezo1 channel and the voltage-gated sodium channel NaV1.2. Our patch-clamp recordings, together with finite-element simulations of acoustic field parameters indicate that Piezo1 channels are activated by continuous wave US at 43 MHz and 50 or 90 W/cm2 through cell membrane stress caused by acoustic streaming. NaV1.2 channels were not affected through this mechanism at these intensities, but their kinetics could be accelerated by US-induced heating.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2017.12.020
       
  • Blocking the Glycolytic Pathway Sensitizes Breast Cancer to Sonodynamic
           Therapy
    • Authors: Lifen Xie; Xiaolan Feng; Yin Shi; Meng He; Pan Wang; Xiaobing Wang; Zeyuan Mi; Quanhong Liu; Kun Zhang
      Pages: 1233 - 1243
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Lifen Xie, Xiaolan Feng, Yin Shi, Meng He, Pan Wang, Xiaobing Wang, Zeyuan Mi, Quanhong Liu, Kun Zhang
      Inhibition of the increased aerobic glycolysis in cancer cells is a promising methodology for various malignant tumor therapies but is limited by systemic toxicity, at least in part. Recent studies suggest that dual restriction of glycolysis and mitochondrial function may overcome this issue. Sonodynamic therapy (SDT), a prospective therapeutic modality for cancers, has been reported to induce mitochondria-dependent cell damage. Here, we investigated the combined effect of SDT and 2-deoxyglucose (2DG), an anti-glycolytic agent, on breast cancer both in vitro and in vivo. In vitro, we found that, compared with a single treatment, SDT + 2DG co-treatment significantly decreased cell viability and increased cell apoptosis. Moreover, the generation of reactive oxygen species was enhanced and mitochondrial membrane potential (MMP) was reduced after SDT + 2DG co-treatment. Furthermore, the oxidative phosphorylation was also restrained after SDT + 2DG co-treatment, further to cause the blockage of ATP provision. In vivo, SDT + 2DG markedly reduced tumor volume and weight, consistent with the in vitro findings. Furthermore, toxicology tests concurrently indicated that the dosages of sinoporphyrin sodium and 2DG were comparatively tolerable. Generally, these results indicated that SDT + 2DG combination therapy may be an available, promising therapy for highly metastatic breast cancer.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.01.020
       
  • Effects of Low-Intensity Pulsed Ultrasound for Preventing Joint Stiffness
           in Immobilized Knee Model in Rats
    • Authors: Nobuyuki Itaya; Yutake Yabe; Yoshihiro Hagiwara; Kenji Kanazawa; Masashi Koide; Takuya Sekiguchi; Shinichirou Yoshida; Yasuhito Sogi; Toshihisa Yano; Masahiro Tsuchiya; Yoshihumi Saijo; Eiji Itoi
      Pages: 1244 - 1256
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Nobuyuki Itaya, Yutake Yabe, Yoshihiro Hagiwara, Kenji Kanazawa, Masashi Koide, Takuya Sekiguchi, Shinichirou Yoshida, Yasuhito Sogi, Toshihisa Yano, Masahiro Tsuchiya, Yoshihumi Saijo, Eiji Itoi
      The purpose of this study was to examine the effect of low-intensity pulsed ultrasound (LIPUS) in preventing joint stiffness. Unilateral knee joints were immobilized in two groups of rats (n = 6/period/group). Under general anesthesia, the immobilized knee joints were exposed to LIPUS for 20 min/d, 5 d/wk, using an existing LIPUS device (LIPUS group, 1.5-MHz frequency, 1.0-kHz repetition cycle, 200-µs burst width and 30-mW/cm2 power output) until endpoints (2, 4 or 6 wk). In the control group, general anesthesia alone was administered in the same manner as in the other group. The variables compared between the groups included joint angles; histologic, histomorphometric and immunohistochemical analyses; quantitative reverse transcription polymerase chain reactions; and tissue elasticity. LIPUS had a preventive effect on joint stiffness, resulting in decreased adhesion, fibrosis and inflammation and hypoxic response after joint immobilization.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.002
       
  • Pre-Treatment with Either L-Carnitine or Piracetam Increases
           Ultrasound-Mediated Gene Transfection by Reducing Sonoporation-Associated
           Apoptosis
    • Authors: Wei-Hao Liao; Chueh-Hung Wu; Wen-Shiang Chen
      Pages: 1257 - 1265
      Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6
      Author(s): Wei-Hao Liao, Chueh-Hung Wu, Wen-Shiang Chen
      Sonoporation, the use of ultrasound to alter the permeability of cell membranes, is a non-viral technique used to facilitate gene delivery, possibly by opening transient pores in the cell membrane. However, sonoporation may have negative bio-effects on cells, such as causing apoptosis, which limits its efficacy in gene delivery. In this study, we investigated whether pre-treatment with either L-carnitine or piracetam could protect cells from undergoing apoptosis after sonoporation and the possible mechanisms. We found that either L-carnitine or piracetam can promote gene transfection without reducing cell viability, possibly by reducing cavitation-induced reactive oxygen species generation, reversing alterations of mitochondrial membrane potential, preventing caspase-3/7 activity and facilitating mitochondrial ATP production. In conclusion, pre-treatment with either L-carnitine or piracetam could protect cells from sonoporation-associated apoptosis by preserving mitochondrial function.

      PubDate: 2018-05-29T08:25:15Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.003
       
  • Viscoelasticity Measurement in Rat Livers Using Shear-Wave US Elastography
    • Abstract: Publication date: Available online 21 June 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Katsutoshi Sugimoto, Fuminori Moriyasu, Hisashi Oshiro, Hirohito Takeuchi, Yu Yoshimasu, Yoshitaka Kasai, Yoshihiro Furuichi, Takao Itoi
      To investigate the usefulness of shear-wave speed and dispersion slope measurements obtained, using an ultrasound elastography system in rat livers with various degrees of necroinflammation and fibrosis. A total of 25 male Sprague Dawley rats were randomly divided into 5 groups of 5 rats each: G0 (control), G1 (CCl4 injected twice a week for 1 wk), G2 (CCl4 injected four times a wk for 1 wk), G3 (CCl4 injected twice a wk for 6 wk) and G4 (CCl4 injected twice a wk for 10 wk). The shear-wave speed (m/s) and the dispersion slope ([m/s]/kHz) were measured. Histologic features (inflammation, necrosis and fibrosis) were used as reference standards. In multivariable analysis with histologic features as independent variables, the fibrosis grade was significantly related to shear-wave speed (p < 0.05) and the necrosis grade was significantly related to dispersion slope (p < 0.05). Dispersion slope is more useful than shear-wave speed for predicting the degree of necroinflammation.

      PubDate: 2018-06-22T13:03:14Z
       
  • Efficacy of Superb Microvascular Imaging for Diagnosing Acute
           Cholecystitis: Comparison with Conventional Ultrasonography
    • Abstract: Publication date: Available online 21 June 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Joon Chul Ra, Eun Sun Lee, Hyun Jeong Park, Hee Sung Kim, Jong Beum Lee, Jae Hyuk Do, Sung Bin Park, Byung Ihn Choi
      We evaluated the diagnostic performance of ultrasonography (US) plus superb microvascular imaging (SMI) compared with conventional US alone for diagnosing acute cholecystitis. We included 54 patients with suspected biliary disease. The SMI pixel count showing flow signal was measured in the region of interest of the gallbladder bed of the liver. Two radiologists independently evaluated imaging features and rated five-point diagnostic likelihood level before versus after the additional SMI using the cutoff SMI pixel count. The SMI pixel count was significantly higher in acute than in non-acute cholecystitis (169.84 vs. 27.48, p < 0.001). The optimal SMI cutoff pixel count for predicting acute cholecystitis obtained by receiver operating characteristic curve was 56.67(82.8% sensitivity, 92.0% specificity). The area under the curve value was significantly higher after the additional SMI than before (0.798–0.863 vs. 0.701–0.736, p < 0.05). US plus SMI could objectively improve diagnostic performance compared with conventional US for acute cholecystitis.

      PubDate: 2018-06-22T13:03:14Z
       
  • Study of THP-1 Macrophage Viability after Sonodynamic Therapy Using Methyl
           Ester of 5-Aminolevulinic Acid Gold Nanoparticles
    • Abstract: Publication date: Available online 20 June 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Karina de Oliveira Gonçalvez, Daniel Perez Vieira, Lilia Coronato Courrol
      Sonodynamic therapy (SDT) is emerging as new atherosclerosis treatment. The use of gold nanoparticles (AuNPs) as the vehicle for a sensitizer delivery improves reactive oxygen species formation. In this study, methyl ester of aminolevulinic acid (MALA) gold nanoparticles (MALA:AuNPs) functionalized with polyethylene glycol (PEG) were synthesized by photoreduction and characterized by ultraviolet/visible optical absorption, zeta potential and electron microscopy. The reactive oxygen species generation induced by ultrasound irradiation of MALA:AuNPs solutions was studied by observing the decrease in the 1,3-diphenylisobenzofuran emission band. The potential use of MALA:AuNPs as sensitizer for sonodynamic therapy was investigated on THP-1 macrophages. The cytotoxicity test was also described. The findings suggested that ultrasound combined with MALA:AuNPs provides impressive results in in vitro studies. Sonodynamic therapy with MALA:AuNPs through 2 minutes of ultrasound exposure (1MHz and 1 W/cm2) culminated with total macrophage reduction. Thus, sonodynamic therapy combined with MALA:AuNPs has potential as a treatment for atherosclerosis.

      PubDate: 2018-06-22T13:03:14Z
       
  • Impact of Encapsulation on in vitro and in vivo Performance of Volatile
           Nanoscale Phase-Shift Perfluorocarbon Droplets
    • Abstract: Publication date: Available online 19 June 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Kimoon Yoo, Wesley R. Walker, Ross Williams, Charles Tremblay-Darveau, Peter N. Burns, Paul S. Sheeran
      Phase-shift droplets can be converted by sound from low-echogenicity, liquid-core agents into highly echogenic microbubbles. Many proposed applications in imaging and therapy take advantage of the high spatiotemporal control over this dynamic transition. Although some studies have reported increased circulation time of the droplets compared with microbubbles, few have directly explored the impact of encapsulation on droplet performance. With the goal of developing nanoscale droplets with increased circulatory persistence, we first evaluate the half-life of several candidate phospholipid encapsulations in vitro at clinical frequencies. To evaluate in vivo circulatory persistence, we develop a technique to periodically measure droplet vaporization from high-frequency B-mode scans of a mouse kidney. Results show that longer acyl chain phospholipids can dramatically reduce droplet degradation, increasing median half-life in vitro to 25.6 min—a 50-fold increase over droplets formed from phospholipids commonly used for clinical microbubbles. In vivo, the best-performing droplet formulations showed a median half-life of 18.4 min, more than a 35-fold increase in circulatory half-life compared with microbubbles with the same encapsulation in vivo. These findings also point to possible refinements that may improve nanoscale phase-shift droplet performance beyond those measured here.

      PubDate: 2018-06-19T12:21:16Z
       
  • Iterative Minimum Variance Beamformer with Low Complexity for Medical
           Ultrasound Imaging
    • Authors: Ali Mohades; Deylami Babak Mohammadzadeh Asl
      Abstract: Publication date: Available online 4 June 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Ali Mohades Deylami, Babak Mohammadzadeh Asl
      Minimum variance beamformer (MVB) improves the resolution and contrast of medical ultrasound images compared with delay and sum (DAS) beamformer. The weight vector of this beamformer should be calculated for each imaging point independently, with a cost of increasing computational complexity. The large number of necessary calculations limits this beamformer to application in real-time systems. A beamformer is proposed based on the MVB with lower computational complexity while preserving its advantages. This beamformer avoids matrix inversion, which is the most complex part of the MVB, by solving the optimization problem iteratively. The received signals from two imaging points close together do not vary much in medical ultrasound imaging. Therefore, using the previously optimized weight vector for one point as initial weight vector for the new neighboring point can improve the convergence speed and decrease the computational complexity. The proposed method was applied on several data sets, and it has been shown that the method can regenerate the results obtained by the MVB while the order of complexity is decreased from O(L 3) to O(L 2).

      PubDate: 2018-06-07T10:35:29Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7


      PubDate: 2018-05-29T08:25:15Z
       
  • Calendar
    • Abstract: Publication date: July 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 7


      PubDate: 2018-05-29T08:25:15Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: June 2018
      Source:Ultrasound in Medicine & Biology, Volume 44, Issue 6


      PubDate: 2018-05-29T08:25:15Z
       
  • Anisotropy and Spatial Heterogeneity in Quantitative Ultrasound
           Parameters: Relevance to the Study of the Human Cervix
    • Authors: Quinton W. Guerrero; Helen Feltovich; Ivan M. Rosado-Mendez; Lindsey C. Carlson; Geng Li; Timothy J. Hall
      Abstract: Publication date: Available online 13 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Quinton W. Guerrero, Helen Feltovich, Ivan M. Rosado-Mendez, Lindsey C. Carlson, Geng Li, Timothy J. Hall
      Imaging biomarkers based on quantitative ultrasound can offer valuable information about properties that inform tissue function and behavior such as microstructural organization (e.g., collagen alignment) and viscoelasticity (i.e., compliance). For example, the cervix feels softer as its microstructure remodels during pregnancy, an increase in compliance that can be objectively quantified with shear wave speed and therefore shear wave speed estimation is a potential biomarker of cervical remodeling. Other proposed biomarkers include parameters derived from the backscattered echo signal, such as attenuation and backscattered power loss, because such parameters can provide insight into tissue microstructural alignment and organization. Of these, attenuation values for the pregnant cervix have been reported, but large estimate variance reduces their clinical value. That said, parameter estimates based on the backscattered echo signal may be incorrect if assumptions they rely on, such as tissue isotropy and homogeneity, are violated. For that reason, we explored backscatter and attenuation parameters as potential biomarkers of cervical remodeling via careful investigation of the assumptions of isotropy and homogeneity in cervical tissue. Specifically, we estimated the angle- and spatial-dependence of parameters of backscattered power and acoustic attenuation in the ex vivo human cervix, using the reference phantom method and electronic steering of the ultrasound beam. We found that estimates are anisotropic and spatially heterogeneous, presumably because the tissue itself is anisotropic and heterogeneous. We conclude that appropriate interpretation of imaging biomarkers of cervical remodeling must account for tissue anisotropy and heterogeneity.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.008
       
  • Quantitative Measurement of Erythrocyte Aggregation as a Systemic
           Inflammatory Marker by Ultrasound Imaging: A Systematic Review
    • Authors: Prajwal Gyawali; Daniela Ziegler; Jean-François Cailhier; André Denault; Guy Cloutier
      Abstract: Publication date: Available online 13 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Prajwal Gyawali, Daniela Ziegler, Jean-François Cailhier, André Denault, Guy Cloutier
      This systematic review is aimed at answering two questions: (i) Is erythrocyte aggregation a useful biomarker in assessing systemic inflammation' (ii) Does quantitative ultrasound imaging provide the non-invasive option to measure erythrocyte aggregation in real time' The search was executed through bibliographic electronic databases CINAHL, EMB Review, EMBASE, MEDLINE, PubMed and the grey literature. The majority of studies correlated elevated erythrocyte aggregation with inflammatory blood markers for several pathologic states. Some studies used “erythrocyte aggregation” as an established marker of systemic inflammation. There were limited but promising articles regarding the use of quantitative ultrasound spectroscopy to monitor erythrocyte aggregation. Similarly, there were limited studies that used other ultrasound techniques to measure systemic inflammation. The quantitative measurement of erythrocyte aggregation has the potential to be a routine clinical marker of inflammation as it can reflect the cumulative inflammatory dynamics in vivo, is relatively simple to measure, is cost-effective and has a rapid turnaround time. Technologies like quantitative ultrasound spectroscopy that can measure erythrocyte aggregation non-invasively and in real time may offer the advantage of continuous monitoring of the inflammation state and, thus, may help in rapid decision making in a critical care setup.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.020
       
  • Can Biannual Ultrasound Surveillance Detect Smaller Second Cancers or
           Detect Cancers Earlier in Patients with Breast Cancer History'
    • Authors: Jai Kyung You; Mi Kyung Song; Min Jung Kim; Eun-Kyung Kim; Hee Jung Moon; Ji Hyun Youk; Jung Hyun Yoon; Vivian Youngjean Park; Seho Park; Seung Il Kim; Byeong-Woo Park
      Abstract: Publication date: Available online 10 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Jai Kyung You, Mi Kyung Song, Min Jung Kim, Eun-Kyung Kim, Hee Jung Moon, Ji Hyun Youk, Jung Hyun Yoon, Vivian Youngjean Park, Seho Park, Seung Il Kim, Byeong-Woo Park
      The aim of the work described here was to evaluate whether surveillance with biannual ultrasound (US) plus annual mammography (biannual group) for women with a history of breast cancer surgery results in earlier detection or in the detection of smaller second cancers than annual US plus mammography (annual group). Additionally, we compared the prevalence of distant metastases or palpable second cancers between the biannual and annual groups. The institutional review board of our institution approved this retrospective study, and patient consent was waived. Between January 2011 and December 2012, we retrospectively reviewed the clinical and imaging follow-up of 3023 patients with mammographic and US surveillance after breast cancer surgery to assess second cancers detected by local surveillance (locoregional recurrence, contralateral breast cancer or distant metastasis). The biannual and annual groups were divided with respect to the mean surveillance interval and compared with respect to clinicopathologic findings. Multivariable logistic regression with propensity score methods was used to examine the effect of the type of surveillance on outcomes. As for the size of the second cancer, no difference was seen between the biannual and annual groups (12.8 ± 6.6 mm vs. 14.1 ± 7.1 mm, p = 0.461); neither was there a significant difference between the groups in the presence of symptoms at the time of diagnosis of the second cancer (17.0% [8/47] vs. 10% [2/20], p = 0.711). Regardless of detection by local surveillance, the prevalence of distant metastases did not differ between the two groups (1.1% [27/2370] vs. 1.0% [7/653], p = 0.88) on univariate or multivariate analysis. The results of our retrospective study indicate that second cancers detected by biannual US surveillance in patients with a history of breast cancer surgery are not smaller and do not occur earlier than those detected by annual US surveillance. However, a randomized controlled study is required to verify these results before they can be generalized to clinical practice.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.019
       
  • Virtual Touch Tissue Quantification for Assessing Renal Pathology in
           Idiopathic Nephrotic Syndrome
    • Authors: Xue Yang; Ning Yu; Jing Yu; Hongqiao Wang; Xiumei Li
      Abstract: Publication date: Available online 9 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Xue Yang, Ning Yu, Jing Yu, Hongqiao Wang, Xiumei Li
      The aim of this study was to evaluate Virtual Touch tissue quantification in assessing renal interstitial fibrosis in patients with idiopathic nephrotic syndrome. Ninety patients with idiopathic nephrotic syndrome were assigned to mild, moderate and severe groups depending on the degree of renal interstitial fibrosis on histopathologic examination of renal biopsy specimens. Thirty healthy patients were also selected as the control group. Virtual Touch tissue quantification was performed to measure the shear wave velocity of the renal parenchyma. There was no statistically significant difference in shear wave velocity between the mild and control groups (p > 0.05); however, the moderate and severe groups did significantly differ compared with the control (p < 0.001). The area under the receiver operating characteristic curve value for the shear wave velocity of renal interstitial fibrosis in the moderate group versus the control and mild groups together was 0.869 (95% confidence interval: 0.791–0.947) and that in the severe group versus the control, mild and moderate groups together was 0.954 (95% confidence interval: 0.917–0.998). The corresponding best cutoff points were 2.41 and 2.77 m/s, with sensitivities of 91.7% and 86.8%, specificities of 78.0% and 92.0%, negative predictive values 0.907 and 0.907, positive predictive values 0.800 and 0.971 and Youden index values of 0.697 and 0.788, respectively. Virtual Touch tissue quantification may non-invasively and quantitatively estimate the degree of renal interstitial fibrosis in patients with idiopathic nephrotic syndrome as a baseline for monitoring progression and treatment response.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.012
       
  • Contrast-Enhanced Ultrasound-Guided Fine-Needle Aspiration for Sentinel
           Lymph Node Biopsy in Early-Stage Breast Cancer
    • Authors: Jieyu Zhong; De-sheng Sun; Wei Wei; Xiaoling Liu; Jun Liu; Xiaoqin Wu; Yusen Zhang; Haiyu Luo; Yongbin Li
      Abstract: Publication date: Available online 6 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Jieyu Zhong, De-sheng Sun, Wei Wei, Xiaoling Liu, Jun Liu, Xiaoqin Wu, Yusen Zhang, Haiyu Luo, Yongbin Li
      The purpose of this study was to assess whether translymphatic contrast-enhanced ultrasound (CEUS) combined with fine-needle aspiration (FNA) can be used pre-operatively to assess the status of axillary lymph nodes in early-stage breast cancer patients. Furthermore, we wanted to determine whether this less invasive method could potentially be a pre-operative surgical strategy. One hundred sixty-four sentinel lymph nodes (SLNs) were detected by CEUS after intradermal injection of microbubbles in 126 cases. One hundred twenty of 126 cases (95.24%) were accurately diagnosed with the SLN-FNA method. All 6 false-negative cases were due to micrometastasis or macrometastasis. There were no false-positive results after CEUS-guided FNA biopsy based on post-operative histopathological results. In conclusion, translymphatic CEUS combined with SLN-FNA is a less traumatic approach that has high accuracy in the pre-operative evaluation of axillary lymph node status. It might have the potential to be as reliable an indicator for axillary lymph node dissection as SLN biopsy.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.005
       
  • High-Dynamic-Range Ultrasound: Application for Imaging Tendon Pathology
    • Authors: Yiming Xiao; Mathieu Boily; Hoda Sadat Hashemi; Hassan Rivaz
      Abstract: Publication date: Available online 5 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Yiming Xiao, Mathieu Boily, Hoda Sadat Hashemi, Hassan Rivaz
      Raw ultrasound (US) signal has a very high dynamic range (HDR) and, as such, is compressed in B-mode US using a logarithmic function to fit within the dynamic range of digital displays. However, in some cases, hyper-echogenic tissue can be overexposed at high gain levels with the loss of hypo-echogenic detail at low gain levels. This can cause the loss of anatomic detail and tissue texture and frequent and inconvenient gain adjustments, potentially affecting the diagnosis. To mitigate these drawbacks, we employed tone mapping operators (TMOs) in HDR photography to create HDR US. We compared HDR US produced from three different popular TMOs (Reinhard, Drago and Durand) against conventional US using a simulated US phantom and in vivo images of patellar tendon pathologies. Based on visual inspection and assessments of structural fidelity, image entropy and contrast-to-noise ratio metrics, Reinhard and Drago TMOs substantially improved image detail and texture.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.004
       
  • One-Lung Flooding Enables Ultrasound-Guided Transthoracic Needle Biopsy of
           Pulmonary Nodules with High Sensitivity
    • Authors: Thomas Günter Lesser; Iver Petersen; Frank Pölzing; Frank Wolfram
      Abstract: Publication date: Available online 4 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Thomas Günter Lesser, Iver Petersen, Frank Pölzing, Frank Wolfram
      Ultrasound-guided transthoracic needle biopsy (USgTTNB) can only be used for peripheral tumours that contact the pleura. Sonographic accessibility of the entire lung can be achieved using one-lung flooding. In this study, feasibility, sensitivity and complication rate of USgTTNB of lung nodules after one-lung flooding in an ex vivo and in vivo lung tumour model were assessed. USgTTNB was performed ex vivo after one-lung flooding in 10 resected human lung lobes containing carcinoma or metastasis. USgTTNB after one-lung flooding and simulation of a lung nodule was conducted in vivo in 5 animals. Transthoracic sonography and chest X-ray were obtained 30 min after reventilation. The lungs were examined macroscopically and histopathologically. The pathologic diagnosis was confirmed in 85.7% and 100% of tumours after first and second puncture attempts, respectively. The successful puncture rate in vivo was 90%. Neither pneumothorax nor bleeding was observed. One-lung flooding enables USgTTNB of lung nodules with a high sensitivity and minimal risk of complications in a pre-clinical model.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.003
       
  • High-Frequency Quantitative Ultrasound for Imaging Prostate Cancer Using a
           Novel Micro-Ultrasound Scanner
    • Authors: Daniel Rohrbach; Brian Wodlinger; Jerrold Wen; Jonathan Mamou; Ernest Feleppa
      Abstract: Publication date: Available online 4 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Daniel Rohrbach, Brian Wodlinger, Jerrold Wen, Jonathan Mamou, Ernest Feleppa
      Currently, biopsies guided by transrectal ultrasound (TRUS) are the only method for definitive diagnosis of prostate cancer. Studies by our group suggest that quantitative ultrasound (QUS) could provide a more sensitive means of targeting biopsies and directing focal treatments to cancer-suspicious regions in the prostate. Previous studies have utilized ultrasound signals at typical clinical frequencies, i.e., in the 6-MHz range. In the present study, a 29-MHz, TRUS, micro-ultrasound system and transducer (ExactVu micro-ultrasound, Exact Imaging, Markham, Canada) was used to acquire radio frequency data from 163 patients immediately before 12-core biopsy procedures, comprising 1956 cores. These retrospective data are a subset of data acquired in an ongoing, multisite, 2000-patient, randomized, clinical trial (clinicaltrials.gov NCT02079025). Spectrum-based QUS estimates of effective scatter diameter (ESD), effective acoustic concentration (EAC), midband (M), intercept (I) and slope (S) as well as envelope statistics employing a Nakagami distribution were used to train linear discriminant classifiers (LDCs) and support vector machines (SVMs). Classifier performance was assessed using area-under-the-curve (AUC) values obtained from receiver operating characteristic (ROC) analyses with 10-fold cross validation. A combination of ESD and EAC parameters resulted in an AUC value of 0.77 using a LDC. When Nakagami-µ or prostate-specific antigen (PSA) values were added as features, the AUC value increased to 0.79. SVM produced an AUC value of 0.77, using a combination of envelope and spectral QUS estimates. The best classification produced an AUC value of 0.81 using an LDC when combining envelope statistics, PSA, ESD and EAC. In a previous study, B-mode-based scoring and evaluation using the PRI-MUS protocol produced a maximal AUC value of 0.74 for higher Gleason-score values (GS >7) when read by an expert. Our initial results with AUC values of 0.81 are very encouraging for developing a new, predominantly user-independent, prostate-cancer, risk-assessing tool.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.014
       
  • Hepatic Steatosis Assessment with Ultrasound Small-Window Entropy Imaging
    • Authors: Zhuhuang Zhou; Dar-In Tai; Yung-Liang Wan; Jeng-Hwei Tseng; Yi-Ru Lin; Shuicai Wu; Kuen-Cheh Yang; Yin-Yin Liao; Chih-Kuang Yeh; Po-Hsiang Tsui
      Abstract: Publication date: Available online 2 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Zhuhuang Zhou, Dar-In Tai, Yung-Liang Wan, Jeng-Hwei Tseng, Yi-Ru Lin, Shuicai Wu, Kuen-Cheh Yang, Yin-Yin Liao, Chih-Kuang Yeh, Po-Hsiang Tsui
      Nonalcoholic fatty liver disease is a type of hepatic steatosis that is not only associated with critical metabolic risk factors but can also result in advanced liver diseases. Ultrasound parametric imaging, which is based on statistical models, assesses fatty liver changes, using quantitative visualization of hepatic-steatosis–caused variations in the statistical properties of backscattered signals. One constraint with using statistical models in ultrasound imaging is that ultrasound data must conform to the distribution employed. Small-window entropy imaging was recently proposed as a non–model-based parametric imaging technique with physical meanings of backscattered statistics. In this study, we explored the feasibility of using small-window entropy imaging in the assessment of fatty liver disease and evaluated its performance through comparisons with parametric imaging based on the Nakagami distribution model (currently the most frequently used statistical model). Liver donors (n = 53) and patients (n = 142) were recruited to evaluate hepatic fat fractions (HFFs), using magnetic resonance spectroscopy and to evaluate the stages of fatty liver disease (normal, mild, moderate and severe), using liver biopsy with histopathology. Livers were scanned using a 3-MHz ultrasound to construct B-mode, small-window entropy and Nakagami images to correlate with HFF analyses and fatty liver stages. The diagnostic values of the imaging methods were evaluated using receiver operating characteristic curves. The results demonstrated that the entropy value obtained using small-window entropy imaging correlated well with log10(HFF), with a correlation coefficient r = 0.74, which was higher than those obtained for the B-scan and Nakagami images. Moreover, small-window entropy imaging also resulted in the highest area under the receiver operating characteristic curve (0.80 for stages equal to or more severe than mild; 0.90 for equal to or more severe than moderate; 0.89 for severe), which indicated that non–model-based entropy imaging—using the small-window technique—performs more favorably than other techniques in fatty liver assessment.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.03.002
       
  • Max dD/Dt: A Novel Parameter to Assess Fetal Cardiac Contractility and a
           Substitute for Max dP/Dt
    • Authors: Yasuyuki Fujita; Ryo Kiyokoba; Yasuo Yumoto; Kiyoko Kato
      Abstract: Publication date: Available online 2 April 2018
      Source:Ultrasound in Medicine & Biology
      Author(s): Yasuyuki Fujita, Ryo Kiyokoba, Yasuo Yumoto, Kiyoko Kato
      Aortic pulse waveforms are composed of a forward wave from the heart and a reflection wave from the periphery. We focused on this forward wave and suggested a new parameter, the maximum slope of aortic pulse waveforms (max dD/dt), for fetal cardiac contractility. Max dD/dt was calculated from fetal aortic pulse waveforms recorded with an echo-tracking system. A normal range of max dD/dt was constructed in 105 healthy fetuses using linear regression analysis. Twenty-two fetuses with suspected fetal cardiac dysfunction were divided into normal and decreased max dD/dt groups, and their clinical parameters were compared. Max dD/dt of aortic pulse waveforms increased linearly with advancing gestational age (r = 0.93). The decreased max dD/dt was associated with abnormal cardiotocography findings and short- and long-term prognosis. In conclusion, max dD/dt calculated from the aortic pulse waveforms in fetuses can substitute for max dP/dt, an index of cardiac contractility in adults.

      PubDate: 2018-04-15T17:42:25Z
      DOI: 10.1016/j.ultrasmedbio.2018.02.001
       
 
 
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