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PHYSICS (573 journals)

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Journal Cover Ultrasound in Medicine & Biology
  [SJR: 0.885]   [H-I: 106]   [8 followers]  Follow
    
   Full-text available via subscription Subscription journal
   ISSN (Print) 0301-5629
   Published by Elsevier Homepage  [3043 journals]
  • Small Bowel Ultrasound beyond Inflammatory Bowel Disease: An Updated
           Review of the Recent Literature
    • Authors: Federica Cavalcoli; Alessandra Zilli; Mirella Fraquelli; Dario Conte; Sara Massironi
      Pages: 1741 - 1752
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Federica Cavalcoli, Alessandra Zilli, Mirella Fraquelli, Dario Conte, Sara Massironi
      The use of bowel ultrasonography (US) for the evaluation of gut diseases has increased in recent years and has been proven to provide a widely available, non-invasive and inexpensive method for the initial work-up and follow-up of different intestinal diseases, limited mostly by technical challenges posed by the patient's anatomy. The present review aims to provide an extensive overview of the main pathologic features at US examination of intestinal diseases other than inflammatory bowel disease, both acute (e.g., acute appendicitis, colonic diverticulitis, infectious diseases and ischemic conditions) and chronic (e.g., celiac disease, cystic fibrosis and other enterocolites). The identification of typical US features may help in the diagnostic process and guide the treatment approach. Therefore, the application of knowledge of the US appearance of gastrointestinal diseases is of relevance in enabling greater diagnostic performance and better patient management.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.028
       
  • Ultrasound Assessment of Human Meniscus
    • Authors: Tuomas Viren; Juuso T. Honkanen; Elvis K. Danso; Lassi Rieppo; Rami K. Korhonen; Juha Töyräs
      Pages: 1753 - 1763
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Tuomas Viren, Juuso T. Honkanen, Elvis K. Danso, Lassi Rieppo, Rami K. Korhonen, Juha Töyräs
      The aim of the present study was to evaluate the applicability of ultrasound imaging to quantitative assessment of human meniscus in vitro. Meniscus samples (n = 26) were harvested from 13 knee joints of non-arthritic human cadavers. Subsequently, three locations (anterior, center and posterior) from each meniscus were imaged with two ultrasound transducers (frequencies 9 and 40 MHz), and quantitative ultrasound parameters were determined. Furthermore, partial-least-squares regression analysis was applied for ultrasound signal to determine the relations between ultrasound scattering and meniscus integrity. Significant correlations between measured and predicted meniscus compositions and mechanical properties were obtained (R 2 = 0.38–0.69, p < 0.05). The relationship between conventional ultrasound parameters and integrity of the meniscus was weaker. To conclude, ultrasound imaging exhibited a potential for evaluation of meniscus integrity. Higher ultrasound frequency combined with multivariate analysis of ultrasound backscattering was found to be the most sensitive for evaluation of meniscus integrity.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.01.020
       
  • Ultrasound Findings on Hands and Wrists of Patients with Systemic Lupus
           Erythematosus: Relationship with Physical Examination
    • Authors: Carolina Freitas Lins; Daniel Lima de Sá Ribeiro; Willer Gonçalves Dourado Santos; Genevievi Rosa; Viviane Machicado; Ana Luisa Pedreira; Emanuela Pimenta da Fonseca; Anna Paula Mota Duque Sousa; Carla Baleeiro Rodrigues Silva; Marcos Antonio Almeida Matos; Mittermayer Barreto Santiago
      Pages: 1764 - 1768
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Carolina Freitas Lins, Daniel Lima de Sá Ribeiro, Willer Gonçalves Dourado Santos, Genevievi Rosa, Viviane Machicado, Ana Luisa Pedreira, Emanuela Pimenta da Fonseca, Anna Paula Mota Duque Sousa, Carla Baleeiro Rodrigues Silva, Marcos Antonio Almeida Matos, Mittermayer Barreto Santiago
      Diagnosis of synovitis/tenosynovitis by physical examination can be difficult. Ultrasound (US) can be an effective tool for the evaluation of joint involvement in systemic lupus erythematosus (SLE). This study will describe musculoskeletal findings by US in SLE patients and the evaluation of their correlation with physical examination. SLE patients underwent clinical/sonographic evaluation of hand/wrists. In total, 896 joints were evaluated: at least 1 change on physical examination was found in 136 joints and at least 1 US abnormality was found in 65 of 896 joints. Out of the 65 joints with US changes, only 13 had findings on physical examination. Conversely, 111 joints had tenderness on physical examination with no sonographic abnormalities. Tenosynovitis was statistically significant more frequently with joint edema (41%) (p = 0.0003). US can detect musculoskeletal changes in only a minority of symptomatic SLE patients. Clinical findings may be related to some reasons that cannot be explained using US.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.016
       
  • Reliability of Sonographic Assessment of Biceps Femoris Distal Tendon
           Strain during Passive Stretching
    • Authors: Eleftherios Kellis; Athanasios Ellinoudis; Konstantina Intziegianni
      Pages: 1769 - 1779
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Eleftherios Kellis, Athanasios Ellinoudis, Konstantina Intziegianni
      The purpose of this study was to determine the intra-rater, inter-examiner and inter-observer reliability of biceps femoris long head (BFlh) tendon strain using ultrasound imaging. Nineteen patients (age: 20.4 ± 0.35 y) were tested twice with a 1-wk interval. Each session included passive stretching from three different hip positions. Tests were performed independently by two examiners while BFlh tendon displacement (mm) and strain (%) were manually extracted from ultrasound video footages by two observers. Intra-rater comparisons revealed an intra-class correlation coefficient (ICC2,1) range of 0.87 to 0.98 and a variability less than 4.74%. Inter-examiner comparisons revealed an ICC2,1 range of 0.83 to 0.99 and less than 4.69% variability. Inter-observer ICCs ranged from 0.93 to 0.97 with variability less than 4.89%. Using a well-defined scanning protocol, two experienced examiners attained high levels of intra-rater agreement, with similarly excellent results for inter-rater and inter-observer reliability for BFlh tendon displacement and strain.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.018
       
  • Revisiting the Cramér Rao Lower Bound for Elastography: Predicting the
           Performance of Axial, Lateral and Polar Strain Elastograms
    • Authors: Prashant Verma; Marvin M. Doyley
      Pages: 1780 - 1796
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Prashant Verma, Marvin M. Doyley
      We derived the Cramér Rao lower bound for 2-D estimators employed in quasi-static elastography. To illustrate the theory, we modeled the 2-D point spread function as a sinc-modulated sine pulse in the axial direction and as a sinc function in the lateral direction. We compared theoretical predictions of the variance incurred in displacements and strains when quasi-static elastography was performed under varying conditions (different scanning methods, different configuration of conventional linear array imaging and different-size kernels) with those measured from simulated or experimentally acquired data. We performed studies to illustrate the application of the derived expressions when performing vascular elastography with plane wave and compounded plane wave imaging. Standard deviations in lateral displacements were an order higher than those in axial. Additionally, the derived expressions predicted that peak performance should occur when 2% strain is applied, the same order of magnitude as observed in simulations (1%) and experiments (1%–2%). We assessed how different configurations of conventional linear array imaging (number of active reception and transmission elements) influenced the quality of axial and lateral strain elastograms. The theoretical expressions predicted that 2-D echo tracking should be performed with wide kernels, but the length of the kernels should be selected using knowledge of the magnitude of the applied strain: specifically, longer kernels for small strains (<5%) and shorter kernels for larger strains. Although the general trends of theoretical predictions and experimental observations were similar, biases incurred during beamforming and subsample displacement estimation produced noticeable differences.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.019
       
  • A Machine-Learning Algorithm Toward Color Analysis for Chronic Liver
           Disease Classification, Employing Ultrasound Shear Wave Elastography
    • Authors: Ilias Gatos; Stavros Tsantis; Stavros Spiliopoulos; Dimitris Karnabatidis; Ioannis Theotokas; Pavlos Zoumpoulis; Thanasis Loupas; John D. Hazle; George C. Kagadis
      Pages: 1797 - 1810
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Ilias Gatos, Stavros Tsantis, Stavros Spiliopoulos, Dimitris Karnabatidis, Ioannis Theotokas, Pavlos Zoumpoulis, Thanasis Loupas, John D. Hazle, George C. Kagadis
      The purpose of the present study was to employ a computer-aided diagnosis system that classifies chronic liver disease (CLD) using ultrasound shear wave elastography (SWE) imaging, with a stiffness value-clustering and machine-learning algorithm. A clinical data set of 126 patients (56 healthy controls, 70 with CLD) was analyzed. First, an RGB-to-stiffness inverse mapping technique was employed. A five-cluster segmentation was then performed associating corresponding different-color regions with certain stiffness value ranges acquired from the SWE manufacturer-provided color bar. Subsequently, 35 features (7 for each cluster), indicative of physical characteristics existing within the SWE image, were extracted. A stepwise regression analysis toward feature reduction was used to derive a reduced feature subset that was fed into the support vector machine classification algorithm to classify CLD from healthy cases. The highest accuracy in classification of healthy to CLD subject discrimination from the support vector machine model was 87.3% with sensitivity and specificity values of 93.5% and 81.2%, respectively. Receiver operating characteristic curve analysis gave an area under the curve value of 0.87 (confidence interval: 0.77–0.92). A machine-learning algorithm that quantifies color information in terms of stiffness values from SWE images and discriminates CLD from healthy cases is introduced. New objective parameters and criteria for CLD diagnosis employing SWE images provided by the present study can be considered an important step toward color-based interpretation, and could assist radiologists' diagnostic performance on a daily basis after being installed in a PC and employed retrospectively, immediately after the examination.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.002
       
  • Peritoneal Carcinomatosis in Primary Ovarian Cancer: Ultrasound Detection
           and Comparison with Computed Tomography
    • Authors: Zhenhong Qi; Yixiu Zhang; Qing Dai; Yu Xia; Yuxin Jiang
      Pages: 1811 - 1819
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Zhenhong Qi, Yixiu Zhang, Qing Dai, Yu Xia, Yuxin Jiang
      We retrospectively compared detection rates and consistency for diagnosis of peritoneal carcinomatosis (PC) of primary ovarian cancer (OC) between ultrasound (US) and computed tomography (CT) scans in 41 patients whose PC of OC (stages IIC–IV) had been diagnosed by histopathology findings. Compared with CT detection rates, those for US were significantly higher for metastases to the pelvic area (92.3% vs. 43.6%, p < 0.001) and bowel surface (64.0% vs. 16.0%, p = 0.002); however, they did not significantly differ for other sites: omentum, diaphragm, lateral peritoneum, mesenteric, hepatic and splenic surfaces. Diagnostic consistency between US and CT scans were fair to moderate for splenic (κ = 0.806), hepatic (κ = 0.485), lateral peritoneum (κ = 0.450) and diaphragm (κ = 0.338) surfaces, but poorly consistent for other parts (κ = 0.144–0.229). In summary, US can complement CT scans, especially for detecting PC of primary OC metastases in pelvic and bowel surfaces.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.02.016
       
  • Irregular Defects in Hepatocellular Carcinomas During the Kupffer Phase of
           Contrast-Enhanced Ultrasonography with Perfluorobutane Microbubbles:
           Pathological Features and Metastatic Recurrence After Surgical Resection
    • Authors: Junya Nuta; Naoki Shingaki; Yoshiyuki Ida; Ryo Shimizu; Shinya Hayami; Masaki Ueno; Kazuhiro Fukatsu; Masahiro Itonaga; Takeichi Yoshida; Yoshimasa Maeda; Kosaku Moribata; Hisanobu Deguchi; Takao Maekita; Mikitaka Iguchi; Jun Kato; Hiroki Yamaue; Hideyuki Tamai
      Pages: 1829 - 1836
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Junya Nuta, Naoki Shingaki, Yoshiyuki Ida, Ryo Shimizu, Shinya Hayami, Masaki Ueno, Kazuhiro Fukatsu, Masahiro Itonaga, Takeichi Yoshida, Yoshimasa Maeda, Kosaku Moribata, Hisanobu Deguchi, Takao Maekita, Mikitaka Iguchi, Jun Kato, Hiroki Yamaue, Hideyuki Tamai
      The present study aimed to elucidate the association between post-vascular–phase (Kupffer-phase) images from contrast-enhanced ultrasonography (CEUS) with perfluorobutane microbubbles and metastatic recurrences after the resection of hepatocellular carcinoma (HCC). The study examined 73 patients with solitary HCC ≤5 cm in diameter who underwent CEUS before resection. HCC was defined as irregular type (including an irregular defect on Kupffer-phase images) or non-irregular type. Intrahepatic metastatic recurrence was defined as >3 intrahepatic recurrences. Metastatic recurrence included both extrahepatic and intrahepatic recurrences. Frequencies of microscopic portal invasion and intrahepatic metastasis were significantly higher in the irregular group than in the non-irregular group. Cumulative 5-y metastatic recurrence rates in the irregular and non-irregular groups were 43% and 7% (p = 0.028), respectively. Multivariate analyses identified Kupffer-phase findings as a factor significantly related to metastatic recurrence. In conclusion, HCCs with an irregular defect during Kupffer-phase CEUS are characterized by more frequent microscopic vascular invasion and intrahepatic metastasis and are significantly associated with metastatic recurrence after resection.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.023
       
  • Axillary Lymph Node Sonographic Features and Breast Tumor Characteristics
           as Predictors of Malignancy: A Nomogram to Predict Risk
    • Authors: Patricia Akissue de Camargo Teixeira; Luciano F. Chala; Carlos Shimizu; José R. Filassi; Jonathan Y. Maesaka; Nestor de Barros
      Pages: 1837 - 1845
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Patricia Akissue de Camargo Teixeira, Luciano F. Chala, Carlos Shimizu, José R. Filassi, Jonathan Y. Maesaka, Nestor de Barros
      The purpose of this study was to build a mathematical model to predict the probability of axillary lymph node metastasis based on the ultrasonographic features of axillary lymph nodes and the tumor characteristics. We included 74 patients (75 axillae) with invasive breast cancer who underwent axillary ultrasonography ipsilateral to the tumor and fine-needle aspiration of one selected lymph node. Lymph node pathology results from sentinel lymph node biopsy or surgical dissection were correlated with lymph node ultrasonographic data and with the cytologic findings of fine-needle aspiration. Our mathematical model of prediction risk of lymph node metastasis included only pre-surgical data from logistic regression analysis: lymph node cortical thickness (p = 0.005), pre-surgical tumor size (p = 0.030), menopausal status (p = 0.017), histologic type (p = 0.034) and tumor location (p = 0.011). The area under the receiver operating characteristic curve of the model was 0.848, reflecting an excellent discrimination of the model. This nomogram may assist in the choice of the optimal axillary approach.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.003
       
  • Accuracy of Lung Ultrasound in Patients with Acute Dyspnea: The Influence
           of Age, Multimorbidity and Cognitive and Motor Impairment
    • Authors: Luca Vizioli; Paola Forti; Elena Bartoli; Marco Giovagnoli; Guerino Recinella; Davide Bernucci; Marco Masetti; Elena Martino; Gian Luca Pirazzoli; Marco Zoli; Giampaolo Bianchi
      Pages: 1846 - 1852
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Luca Vizioli, Paola Forti, Elena Bartoli, Marco Giovagnoli, Guerino Recinella, Davide Bernucci, Marco Masetti, Elena Martino, Gian Luca Pirazzoli, Marco Zoli, Giampaolo Bianchi
      Discriminating between causes of dyspnea may be difficult, particularly in the elderly. The aim of this retrospective study of 83 inpatients with acute dyspnea was to assess the influence of age, multimorbidity and cognitive or motor impairment on the diagnostic accuracy of lung ultrasound (LUS) in discriminating acute heart failure (AHF) from noncardiogenic dyspnea (NCD). Univariate analysis indicates that LUS misdiagnosis was associated with the following parameters: history of stroke (p = 0.037), lower activity of daily living (p = 0.039), higher modified-Rankin scale (mRS) (p = 0.027) and need of two operators to complete LUS because of reduced patient compliance (p = 0.030). Regression analysis identified only history of stroke (p = 0.048) as an independent predictor of LUS misdiagnosis. This study supports LUS usefulness to differentiate AHF from NCD. Our data suggest that diagnostic accuracy of LUS is affected by history of stroke as a proxy for severe motor impairment but not by age, cognitive impairment and multimorbidity.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.017
       
  • Feasibility of Combined Doppler–ECG Assessment of Internal Jugular
           Veins
    • Authors: Inge Dierickx; Simon Van Hooland; Kathleen Tomsin; Daniel Vanhercke; Wilfried Cools; Hendrik Fransen; Wilfried Gyselaers
      Pages: 1853 - 1860
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Inge Dierickx, Simon Van Hooland, Kathleen Tomsin, Daniel Vanhercke, Wilfried Cools, Hendrik Fransen, Wilfried Gyselaers
      A standardized combined Doppler–electrocardiography technique was developed for measurement of the triphasic waveform characteristics in the internal jugular vein. Flow velocities at the A, X, V and Y peaks, the RR interval and the PA and RX times were measured. From these the venous impedance index ([X−A]/X) and the ratios PA/RR and RX/RR were calculated. Six measurements were performed at three different locations by two ultrasonographers in 21 randomly selected pregnant and non-pregnant women. Statistical models proved the feasibility and reproducibility of this technique, with the highest concordance correlation coefficients in the right distal internal vein. Bootstrapping revealed that repeating the measurements more than four times would not significantly enhance the precision of the estimated mean. Concordance correlation coefficients for the venous impedance index, PA time and PA/RR ratio were >0.63 for all three locations, proving their possible use in ongoing and future studies, analogous to previous studies in kidney and liver.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.001
       
  • Transcranial Doppler and Microemboli Detection: Relationships to
           Symptomatic Status and Histopathology Findings
    • Authors: Carol C. Mitchell; Stephanie M. Wilbrand; Bornali Kundu; Catherine N. Steffel; Tomy Varghese; Nirvedh H. Meshram; Geng Li; Thomas D. Cook; M. Shahriar Salamat; Robert J. Dempsey
      Pages: 1861 - 1867
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Carol C. Mitchell, Stephanie M. Wilbrand, Bornali Kundu, Catherine N. Steffel, Tomy Varghese, Nirvedh H. Meshram, Geng Li, Thomas D. Cook, M. Shahriar Salamat, Robert J. Dempsey
      The purpose of this study was to determine the relationship between symptomatic status, transcranial Doppler (TCD) microemboli presence and plaque histopathology findings. TCD was performed on 60 patients (37 symptomatic, 23 asymptomatic) before undergoing clinically indicated carotid endarterectomy. The frequency of microemboli signals was not significantly different between symptomatic and asymptomatic subject groups (p = 0.88) and there were no differences observed in the macroscopic or histopathology scoring of these plaques (p-values all > 0.05). The presence of microemboli was associated with an ulceration score (regardless of symptomatic or asymptomatic status, p = 0.034), with a one-level increase in ulceration rating associated with an odds ratio of 5.86 (95% [CI] 1.55, 43.4). These findings suggest that both symptomatic and asymptomatic patients may have plaque with similar features of instability and ability to create emboli. Thus, identifying new ways to measure plaque instability may provide important information for optimizing treatment to prevent future stroke.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.025
       
  • High-Frame-Rate Power Doppler Ultrasound Is More Sensitive than
           Conventional Power Doppler in Detecting Rheumatic Vascularisation
    • Authors: Myrthe van der Ven; Jolanda J. Luime; Levinia L. van der Velden; Johan G. Bosch; Johanna M.W. Hazes; Hendrik J. Vos
      Pages: 1868 - 1879
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Myrthe van der Ven, Jolanda J. Luime, Levinia L. van der Velden, Johan G. Bosch, Johanna M.W. Hazes, Hendrik J. Vos
      Early recognition of joint inflammation will increase treatment efficacy in rheumatoid arthritis (RA). Yet, conventional power Doppler (PD) ultrasound might not be sufficiently sensitive to detect minor inflammation. We investigated the sensitivity of high-frame rate Doppler, combined with singular value decomposition technique, to suppress tissue signals, for microvascular flow in a flow phantom setup and in a proof-of-principle study in healthy controls and in RA patients with different disease activities. In the flow phantom, minimal detectable flow velocity was a factor 3 lower with high-frame-rate PD than with conventional PD ultrasound. In the proof-of-principle study we detected a positive PD signal in all volunteers, diseased or healthy, with high-frame-rate PD ultrasound. We saw a gradual increase in PD signal in RA patients depending on disease activity. In conclusion, high-frame rate Doppler is more sensitive in detecting vascularisation than conventional PD ultrasound.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.027
       
  • Advanced Power Doppler Technique Increases Synovial Vascularity Detection
           in Patients with Rheumatoid Arthritis
    • Authors: Davide Orlandi; Salvatore Gitto; Silvia Perugin Bernardi; Angelo Corazza; Luca De Flaviis; Enzo Silvestri; Marco Amedeo Cimmino; Luca Maria Sconfienza
      Pages: 1880 - 1887
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Davide Orlandi, Salvatore Gitto, Silvia Perugin Bernardi, Angelo Corazza, Luca De Flaviis, Enzo Silvestri, Marco Amedeo Cimmino, Luca Maria Sconfienza
      We compared the diagnostic performance of an advanced power Doppler technique (superb microvascular imaging [SMI]) with that of power Doppler Imaging (PDI) and B-mode ultrasound (US) in patients with early rheumatoid arthritis (RA) and RA under treatment with rituximab. Thirty patients (21 women aged 45 ± 11 y) affected by RA with remission to moderate disease activity were examined. Both hand joints were evaluated using US, PDI and SMI. Two radiologists reviewed all video clips and evaluated synovial vascularity intensity using a semi-quantitative scoring system. SMI revealed the presence of synovial vascularity in a significantly larger number of patients than PDI (p = 0.02). Inter-observer agreement for US, PDI and SMI was moderate (κ = 0.59), very good (κ = 0.87) and very good (κ = 0.82), respectively. We conclude that SMI detects more vessels than PDI in RA patients. This may allow increased sensitivity for early diagnosis of synovial inflammation, monitoring of its dynamic changes under therapy and evaluation of true imaging remission.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.004
       
  • Acoustically Active Catheter for Intracardiac Navigation by Color Doppler
           Ultrasonography
    • Authors: Minako Katayama; David Zarbatany; Stephen S. Cha; Mostafa Fatemi; Marek Belohlavek
      Pages: 1888 - 1896
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Minako Katayama, David Zarbatany, Stephen S. Cha, Mostafa Fatemi, Marek Belohlavek
      Navigation of intracardiac catheters by echocardiography is challenging because of the fundamental limitations of B-mode ultrasonography. We describe a catheter fitted with a piezoelectric crystal, which vibrates and produces an instantaneous marker in color flow Doppler scans. The navigation learning curve was explored first in six pigs. Accuracy and precision of targeting with the navigation marker “off” (i.e., B-mode imaging) and “on” were assessed in another six pigs. Paired comparisons confirmed significantly (p = 0.04) shorter mean distances achieved in each pig with the color Doppler marker. Pooled (mean ± standard deviation) distance of the catheter tip from the target crystal was 5.27 ± 1.62 mm by B-mode guidance and 3.66 ± 1.45 mm by color Doppler marker navigation. Dye injection targeted into the ischemic border zone was successful in 8 of 10 pigs. Intracardiac catheter navigation with color Doppler ultrasonography is more accurate compared with conventional guidance by B-mode imaging.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.014
       
  • Left Atrial Mechanics and Integrated Calibrated Backscatter in
           Anthracycline-Treated Long-Term Survivors of Childhood Cancers
    • Authors: Vivian Wing-yi Li; Clare Tik-man Lai; Anthony Pak-yin Liu; Daniel Ka-leung Cheuk; Yiu-fai Cheung
      Pages: 1897 - 1905
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Vivian Wing-yi Li, Clare Tik-man Lai, Anthony Pak-yin Liu, Daniel Ka-leung Cheuk, Yiu-fai Cheung
      We tested the hypothesis that left atrial (LA) mechanics and myocardial calibrated integrated backscatter (cIB) are altered in anthracycline-treated long-term survivors of childhood cancers. Forty-nine survivors and 25 controls were studied. Survivors had significantly smaller maximal (p = 0.009) and minimal (p = 0.017) LA volumes and lower peak negative LA strains (p = 0.011). For left ventricular (LV) indices, survivors had significantly lower shortening fraction (p < 0.001), ejection fraction (p < 0.001) and mitral annular late diastolic velocity (p = 0.003). Myocardial cIB of the LA posterior wall, ventricular septum and LV posterior wall was significantly greater in survivors than controls (all p values <0.05). Peak negative LA strain was related to late diastolic mitral annular velocity (r = 0.27, p = 0.018), whereas LA cIB was related to the average of septal and LV posterior wall cIB (r = 0.54, p < 0.001). In conclusion, LA remodeling as characterized by contractile dysfunction and increased cIB suggestive of fibrosis occurs in adult survivors of childhood cancers.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.017
       
  • Diastolic Carotid Artery Longitudinal Wall Motion Is Sensitive to Both
           Aging and Coronary Artery Disease Status Independent of Arterial Stiffness
           
    • Authors: Jason S. Au; Sydney E. Valentino; Patrick G. McPhee; Maureen J. MacDonald
      Pages: 1906 - 1918
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Jason S. Au, Sydney E. Valentino, Patrick G. McPhee, Maureen J. MacDonald
      We investigated the ability of systolic and diastolic carotid artery longitudinal wall motion (CALM) to delineate expected differences in arterial health in individuals representing a range of both age and health status. We recruited 161 younger healthy adults (aged 24 ± 5 y), 51 older healthy adults (aged 70 ± 5 y) and 14 adults with coronary artery disease (aged 67 ± 8 y) for resting assessment of CALM and arterial stiffness. All CALM parameters were reduced in the old healthy adults and adults with coronary artery disease compared with the young healthy adults (p < 0.01), with diastolic velocity and maximum diastolic acceleration being further reduced in the adults with coronary artery disease than in the older healthy adults (p < 0.01). Diastolic CALM parameters were more strongly related to age (β range: −0.46 to −0.53) than systolic CALM parameters (β range: −0.24 to −0.44). In contrast to previous examinations of a variety of CALM parameters, diastolic CALM may provide superior promise in terms of characterizing arterial wall properties, with additional sensitivity to cardiovascular disease status.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.026
       
  • Myocardial Strain Rate by Anatomic Doppler Spectrum: First Clinical
           Experience Using Retrospective Spectral Tissue Doppler from Ultra-High
           Frame Rate Imaging
    • Authors: Lars Christian Naterstad Lervik; Birger Brekke; Svein Arne Aase; Mai Tone Lønnebakken; Dordi Stensvåg; Brage H. Amundsen; Hans Torp; Asbjorn Støylen
      Pages: 1919 - 1929
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Lars Christian Naterstad Lervik, Birger Brekke, Svein Arne Aase, Mai Tone Lønnebakken, Dordi Stensvåg, Brage H. Amundsen, Hans Torp, Asbjorn Støylen
      Strain rate imaging by tissue Doppler (TDI) is vulnerable to stationary reverberations and noise (clutter). Anatomic Doppler spectrum (ADS) presents retrospective spectral Doppler from ultra-high frame rate imaging (UFR-TDI) data for a region of interest, that is, ventricular wall or segment, at one time instance. This enables spectral assessment of strain rate (SR) without the influence of clutter. In this study, we assessed SR with ADS and conventional TDI in 20 patients with a recent myocardial infarction and 10 healthy volunteers. ADS-based SR correlated with fraction of scarred myocardium of the left ventricle (r = 0.68, p < 0.001), whereas SR by conventional TDI did not (r = 0.23, p = 0.30). ADS identified scarred myocardium and ADS Visual was the only method that differentiated transmural from non-transmural distribution of myocardial scar on a segmental level (p = 0.002). Finally, analysis of SR by ADS was feasible in a larger number of segments compared with SR by conventional TDI (p < 0.001).

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.016
       
  • Routine Ultrasound Quality Assurance in a Multi-Unit Radiology Department:
           A Retrospective Evaluation of Transducer Failures
    • Authors: Anne-Mari Vitikainen; Juha I. Peltonen; Eija Vartiainen
      Pages: 1930 - 1937
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Anne-Mari Vitikainen, Juha I. Peltonen, Eija Vartiainen
      The importance of quality assurance (QA) in medical ultrasound (US) has been widely recognized and recommendations concerning technical QA have been published over the years. However, the demonstrated impact of a properly working QA protocol on clinical routine has been scarce. We investigated the transducer write-off causes for a 5-y period in a multi-unit radiology department with an annual average of 230 transducers in demanding diagnostic use. The transducer faults and the initial observers of the faults leading to transducer write-offs were traced and categorized. The most common cause of transducer write-off was an image uniformity problem or element failure. Mechanical faults or excessive leakage current and defects in the lens constituted smaller yet substantial shares. Our results suggest that a properly working routine QA program can detect majority of the faults before they are reported by users.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.009
       
  • Non-invasive Estimation of Temperature during Physiotherapeutic Ultrasound
           Application Using the Average Gray-Level Content of B-Mode Images: A
           Metrological Approach
    • Authors: André V. Alvarenga; Volker Wilkens; Olga Georg; Rodrigo P.B. Costa-Félix
      Pages: 1938 - 1952
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): André V. Alvarenga, Volker Wilkens, Olga Georg, Rodrigo P.B. Costa-Félix
      Healing therapies that make use of ultrasound are based on raising the temperature in biological tissue. However, it is not possible to heal impaired tissue by applying a high dose of ultrasound. The temperature of the tissue is ultimately the physical quantity that has to be assessed to minimize the risk of undesired injury. Invasive temperature measurement techniques are easy to use, despite the fact that they are detrimental to human well being. Another approach to assessing a rise in tissue temperature is to derive the material's general response to temperature variations from ultrasonic parameters. In this article, a method for evaluating temperature variations is described. The method is based on the analytical study of an ultrasonic image, in which gray-level variations are correlated to the temperature variations in a tissue-mimicking material. The physical assumption is that temperature variations induce wave propagation changes modifying the backscattered ultrasound signal, which are expressed in the ultrasonographic images. For a temperature variation of about 15°C, the expanded uncertainty for a coverage probability of 0.95 was found to be 2.5°C in the heating regime and 1.9°C in the cooling regime. It is possible to use the model proposed in this article in a straightforward manner to monitor temperature variation during a physiotherapeutic ultrasound application, provided the tissue-mimicking material approach is transferred to actual biological tissue. The novelty of such approach resides in the metrology-based investigation outlined here, as well as in its ease of reproducibility.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.008
       
  • Delineation of Post-Procedure Ablation Regions with Electrode Displacement
           Elastography with a Comparison to Acoustic Radiation Force Impulse Imaging
           
    • Authors: Wenjun Yang; Tomy Varghese; Timothy Ziemlewicz; Marci Alexander; Meghan Lubner; James Louis Hinshaw; Shane Wells; Fred T. Lee
      Pages: 1953 - 1962
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Wenjun Yang, Tomy Varghese, Timothy Ziemlewicz, Marci Alexander, Meghan Lubner, James Louis Hinshaw, Shane Wells, Fred T. Lee
      We compared a quasi-static ultrasound elastography technique, referred to as electrode displacement elastography (EDE), with acoustic radiation force impulse imaging (ARFI) for monitoring microwave ablation (MWA) procedures on patients diagnosed with liver neoplasms. Forty-nine patients recruited to this study underwent EDE and ARFI with a Siemens Acuson S2000 system after an MWA procedure. On the basis of visualization results from two observers, the ablated region in ARFI images was recognizable on 20 patients on average in conjunction with B-mode imaging, whereas delineable ablation boundaries could be generated on 4 patients on average. With EDE, the ablated region was delineable on 40 patients on average, with less imaging depth dependence. Study of tissue-mimicking phantoms revealed that the ablation region dimensions measured on EDE and ARFI images were within 8%, whereas the image contrast and contrast-to-noise ratio with EDE was two to three times higher than that obtained with ARFI. This study indicated that EDE provided improved monitoring results for minimally invasive MWA in clinical procedures for liver cancer and metastases.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.021
       
  • Ultrasound Enhances Dentoalveolar Remodeling in an Ex Vivo Orthodontic,
           Ovariectomy-Induced Osteoporotic Model
    • Authors: Khuloud S. Alhazmi; Tarek El-Bialy; Ahmed R. Afify; Leena A. Merdad; Ali H. Hassan
      Pages: 1963 - 1974
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Khuloud S. Alhazmi, Tarek El-Bialy, Ahmed R. Afify, Leena A. Merdad, Ali H. Hassan
      The aim of the study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on dentoalveolar structures during application of force to a cultured mandible slice taken from an ovariectomized rat model of osteoporosis. Rats were divided based on whether they had ovariectomy and/or LIPUS application into four groups: control osteoporosis group, control normal group, ultrasound-treated osteoporosis group and ultrasound-treated normal group. The mandibles were dissected, sliced and cultured before application of a 0.5-N force. Tissue specimens from five rats per group received LIPUS; the remaining rats served as untreated controls. Tissue sections were evaluated histologically and histomorphometrically. Osteoporosis significantly affected the alveolar bone without any effect on the dentin–pulp complex. LIPUS enhanced osteoporotic alveolar bone remodeling and increased cementum and predentin thickness. Furthermore, LIPUS application significantly increased odontoblast and periodontal ligament cell counts (p < 0.05) in both groups. Therefore, LIPUS enhances alveolar bone remolding and increases cementum and predentin formation in osteoporotic rat mandible slice organ cultures.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.009
       
  • Dependence of Boiling Histotripsy Treatment Efficiency on HIFU Frequency
           and Focal Pressure Levels
    • Authors: Tatiana D. Khokhlova; Yasser A. Haider; Adam D. Maxwell; Wayne Kreider; Michael R. Bailey; Vera A. Khokhlova
      Pages: 1975 - 1985
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Tatiana D. Khokhlova, Yasser A. Haider, Adam D. Maxwell, Wayne Kreider, Michael R. Bailey, Vera A. Khokhlova
      Boiling histotripsy (BH) is a high-intensity focused ultrasound (HIFU)–based method of mechanical tissue fractionation that utilizes millisecond-long bursts of HIFU shock waves to cause boiling at the focus in milliseconds. The subsequent interaction of the incoming shocks with the vapor bubble mechanically lyses surrounding tissue and cells. The acoustic parameter space for BH has been investigated previously and an inverse dependence between the HIFU frequency and the dimensions of a BH lesion has been observed. The primary goal of the present study was to investigate in more detail the ablation rate and reliability of BH in the frequency range relevant to treatment of deep abdominal tissue targets (1–2 MHz). The second goal was to investigate the effect of focal peak pressure levels and shock amplitude on BH lesion formation, given a constant duty factor, a constant ratio of the pulse duration to the time to reach boiling and a constant number of BH pulses. A custom-built 12-element sector array HIFU transducer with F-number = 1.05 was used in all experiments. BH pulses at 5 different frequencies (1, 1.2, 1.5, 1.7 and 1.9 MHz) were delivered to optically transparent polyacrylamide gel phantoms and ex vivo bovine liver and myocardium tissue to observe cavitation and boiling bubble activity with high-speed photography and B-mode ultrasound imaging, correspondingly. In gel phantoms, a cavitation bubble cloud was shown to form prefocally and to shield the focus in all exposures at 1 and 1.2 MHz and in the highest amplitude exposures at 1.5–1.7 MHz; shielding was not observed at 1.9 MHz. In ex vivo tissue, this shielding effect was observed in 25% of exposures when peak negative in situ pressure exceeded 10.2 MPa at 1 MHz and 14.5 MPa at 1.5 MHz. When shielding occurred, the exposures resulted in mild tissue disruption in the prefocal region, but not liquefaction. The dimensions of liquefied lesions followed the inverse proportionality trend with frequency; consequently, the frequency range of 1.2–1.5 MHz appeared to be preferable for BH exposures in terms of the compromise between the ablation rate and reliability. The lesion size was independent of the duration of the BH pulses (or the total “HIFU on” time), provided that the number of pulses was constant and boiling was induced within each pulse. Thus, the use of shorter (1 ms vs. 10 ms), higher amplitude BH pulses allowed up to 10-fold reduction in treatment time for a given duty factor.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.030
       
  • Neuroprotective Effect of Low-Intensity Pulsed Ultrasound Against
           MPP+-Induced Neurotoxicity in PC12 Cells: Involvement of K2P Channels and
           Stretch-Activated Ion Channels
    • Authors: Lu Zhao; Yi Feng; Aiwei Shi; Lei Zhang; Shifang Guo; Mingxi Wan
      Pages: 1986 - 1999
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Lu Zhao, Yi Feng, Aiwei Shi, Lei Zhang, Shifang Guo, Mingxi Wan
      Parkinson's disease is the second most common neurodegenerative disease. It is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta. 1-Methyl-4-phenylpyridinium (MPP+) is a dopaminergic neuronal toxin that is widely used in constructing Parkinson's disease models in vitro. Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapeutic approach that has neuromodulation and neuroprotective effects in the central neural system; however, whether LIPUS can provide protection for dopaminergic neurons against MPP+-induced neurocytotoxicity remains unknown. In this study, we found that pre-treatment with LIPUS (1 MHz, 50 mW/cm2, 20% duty cycle and 100-Hz pulse repetition frequency, 10 min) inhibited MPP+-induced neurotoxicity and mitochondrial dysfunction in PC12 cells. LIPUS decreased MPP+-induced oxidative stress by modulating antioxidant proteins, including thioredoxin-1 and heme oxygenase-1, and prevented neurocytotoxicity via the phosphoinositide 3-kinase (PI3K)-Akt and ERK1/2 pathways. Furthermore, these beneficial effects were attributed to the activation of K2P channels and stretch-activated ion channels by LIPUS. These data indicate that LIPUS protects neuronal cells from MPP+-induced cell death through the K2P channel- and stretch-activated ion channel-mediated downstream pathways. The data also suggest that LIPUS could be a promising therapeutic method in halting or retarding the degeneration of dopaminergic neurons in Parkinson's disease in a non-invasive manner.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.020
       
  • In Vivo Multiparametric Ultrasound Imaging of Structural and Functional
           Tumor Modifications during Therapy
    • Authors: Alexandre Dizeux; Thomas Payen; Delphine Le Guillou-Buffello; Eva Comperat; Jean-Luc Gennisson; Mickael Tanter; Michael Oelze; S. Lori Bridal
      Pages: 2000 - 2012
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Alexandre Dizeux, Thomas Payen, Delphine Le Guillou-Buffello, Eva Comperat, Jean-Luc Gennisson, Mickael Tanter, Michael Oelze, S. Lori Bridal
      Longitudinal imaging techniques are needed that can meaningfully probe the tumor microenvironment and its spatial heterogeneity. Contrast-enhanced ultrasound, shear wave elastography and quantitative ultrasound are ultrasound-based techniques that provide information on the vascular function and micro-/macroscopic tissue structure. Modifications of the tumor microenvironment induced by cytotoxic and anti-angiogenic molecules in ectopic murine Lewis lung carcinoma tumors were monitored. The most heterogenous structures were found in tumors treated with anti-angiogenic drug that simultaneously accumulated the highest levels of necrosis and fibrosis. The anti-angiogenic group presented the highest number of correlations between parameters related to vascular function and those related to the micro-/macrostructure of the tumor microenvironment. Results suggest how patterns of multiparametric ultrasound modifications can be related to provide a more insightful marker of changes occurring within tumors during therapy.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.03.021
       
  • Determination of Skeletal Muscle Microvascular Flowmotion with
           Contrast-Enhanced Ultrasound
    • Authors: Sarah J. Blackwood; Renee M. Dwyer; Eloise A. Bradley; Michelle A. Keske; Stephen M. Richards; Stephen Rattigan
      Pages: 2013 - 2023
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Sarah J. Blackwood, Renee M. Dwyer, Eloise A. Bradley, Michelle A. Keske, Stephen M. Richards, Stephen Rattigan
      Most methods of assessing flowmotion (rhythmic oscillation of blood flow through tissue) are limited to small sections of tissue and are invasive in tissues other than skin. To overcome these limitations, we adapted the contrast-enhanced ultrasound (CEUS) technique to assess microvascular flowmotion throughout a large region of tissue, in a non-invasive manner and in real time. Skeletal muscle flowmotion was assessed in anaesthetised Sprague Dawley rats, using CEUS and laser Doppler flowmetry (LDF) for comparison. Wavelet transformation of CEUS and LDF data was used to quantify flowmotion. The α-adrenoceptor antagonist phentolamine was infused to predictably blunt the neurogenic component of flowmotion. Both techniques identified similar flowmotion patterns, validating the use of CEUS to assess flowmotion. This study demonstrates for the first time that the novel technique of CEUS can be adapted for determination of skeletal muscle flowmotion in large regions of skeletal muscle.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.012
       
  • Image Fusion of Real-Time Ultrasonography with Computed Tomography:
           Factors Affecting the Registration Error and Motion of Focal Hepatic
           Lesions
    • Authors: Min Woo Lee; Hyun Jeong Park; Tae Wook Kang; Jiwon Ryu; Won-Chul Bang; Bora Lee; Eun Sun Lee; Byung Ihn Choi
      Pages: 2024 - 2032
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Min Woo Lee, Hyun Jeong Park, Tae Wook Kang, Jiwon Ryu, Won-Chul Bang, Bora Lee, Eun Sun Lee, Byung Ihn Choi
      Factors affecting the registration error (RE) and motion of focal hepatic lesions (FHLs) in image fusion of real-time ultrasonography (US) with computed tomography (CT) images were prospectively assessed by focusing on respiratory movement and FHL location. Real-time US and pre-acquired CT images at end-inspiration were fused with FHLs for 103 patients. Three-dimensional US data containing FHLs were obtained during end-inspiratory/expiratory phases. Multivariate analysis revealed that diaphragm motion (p < 0.001), chronic liver disease (p = 0.02) and the absolute difference in distance between the FHL and the central portal vein (CPV) during respiration (p = 0.03) were the independent factors that revealed the maximum effect on RE. In contrast, diaphragm motion (p < 0.001) and distance between the FHL and CPV at inspiration (p = 0.036) revealed the maximum effect on FHL motion. In conclusion, RE and FHL motion are affected by the degree of respiratory movement and the location of the FHL. Therefore, image fusion with CT images should be used with caution if the degree of respiratory motion is significant or if the FHL is located at the periphery of the liver.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.01.027
       
  • Three-Dimensional Model-Based Segmentation in Echocardiography Using High
           Temporal Tissue and Blood Flow Information
    • Authors: Inge H. Gerrits; Maartje M. Nillesen; Livia Kapusta; Johan M. Thijssen; Chris L. de Korte
      Pages: 2033 - 2044
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Inge H. Gerrits, Maartje M. Nillesen, Livia Kapusta, Johan M. Thijssen, Chris L. de Korte
      Accurate 3-D surface segmentation is a challenging task in echocardiography because of the relatively low image quality. We introduce a new method for 3-D segmentation of the endocardium involving temporal decorrelation of echo signals originating from tissue and blood using radiofrequency (RF) signals acquired in 3-D Doppler mode. Temporal features were extracted in 3-D Doppler mode, where a sequence of RF lines is recorded for each image line. Each set of RF lines is highly correlated because of the high pulse repetition frequency. However, for high blood flow, the RF signals will decorrelate over time in contrast to the endocardium, which will remain relatively highly correlated over time. These decorrelation features permit differentiation between myocardial tissue and blood flow. We describe an implementation of a 3-D segmentation model in which temporal information is used as external constraint. The model was validated in a phantom and in vivo in healthy volunteers (n = 5). The phantom study revealed that the model successfully segmented the artificial blood lumen even for low flow velocity and illustrated the sensitivity of the segmentations to flow rate. In healthy volunteers, high Dice similarity indices indicate that 3-D segmentation of the endocardial border in vivo is feasible.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.002
       
  • Studying Arterial Stiffness Using High-Frequency Ultrasound in Mice with
           Alzheimer Disease
    • Authors: Chin-Chia Huang; Hsiang-Fan Cheng; Ben-Peng Zhu; Pei-Yu Chen; Suet Theng Beh; Yu-Min Kuo; Chih-Chung Huang
      Pages: 2054 - 2064
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Chin-Chia Huang, Hsiang-Fan Cheng, Ben-Peng Zhu, Pei-Yu Chen, Suet Theng Beh, Yu-Min Kuo, Chih-Chung Huang
      Alzheimer disease (AD) is an irreversible, progressive brain disorder that causes slow loss of memory and thinking skills, normally leading to death in 3–9 y. The etiology of AD is not fully understood but is widely believed to be induced by the production and deposition of amyloid-β peptide in the brain. Recently, a correlation was discovered between amyloid-β deposition and atherosclerosis in the cerebral arteries of postmortem brains, indicating that amyloid-β promotes atherogenesis and that in turn atherosclerosis promotes brain amyloid-β accumulation. However, a direct measurement of arterial stiffness for AD is lacking. In the present study, the pulse wave velocity (PWV) of the carotid artery was measured non-invasively in young (3-mo-old) and middle-aged (9-mo-old) wild-type (WT) and modeled AD mice to obtain quantitative data of arterial stiffness by using a 35-MHz high-frequency dual-element transducer. Experimental results show that the PWVs were 1.6 ± 0.5 m/s for young and 2.4 ± 0.4 m/s for middle-aged WT mice and 1.7 ± 0.4 m/s for young and 3.2 ± 0.6 m/s for middle-aged AD mice. Middle-aged groups had higher PWVs (p < 0.0001), which were more pronounced in the AD mice (p < 0.001). The differences in PWVs were not caused by arterial lumen diameter, wall thickness or contents of elastin or collagen. These results imply that AD increases the stiffness of the carotid artery and introduce ultrasound as a potential tool for AD research and diagnosis.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.029
       
  • Ultrasound Image Despeckling Based on Statistical Similarity
    • Authors: Fabio Baselice
      Pages: 2065 - 2078
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Fabio Baselice
      Ultrasound images are affected by the speckle phenomenon, a multiplicative noise that degrades image quality. Several methods for denoising have been proposed in recent years, based on different approaches. The so-called non-local mean is considered the state-of-the-art method; the idea is to find similar patches across the image and exploit them to regularize the image. The method proposed here is in the non-local family, although instead of partitioning the target image in patches, it works pixelwise. The similarity between pixels is evaluated by analyzing their statistical behavior, in particular, by measuring the Kolmogorov–Smirnov distance between their distributions. To make this possible, a stack of acquired images is required. The proposed method has been tested on both simulated and real data sets and compared with other widely adopted techniques. Performance is interesting, with quality parameters and visual inspection confirming such findings.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.006
       
  • Preclinical Testing of Frequency-Tunable Capacitive Micromachined
           Ultrasonic Transducer Probe Prototypes
    • Authors: Martin Pekař; Alexander F. Kolen; Harm Belt; Frank van Heesch; Nenad Mihajlović; Imo E. Hoefer; Tamas Szili-Török; Hendrik J. Vos; Johan G. Bosch; Gijs van Soest; Antonius F.W. van der Steen
      Pages: 2079 - 2085
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Martin Pekař, Alexander F. Kolen, Harm Belt, Frank van Heesch, Nenad Mihajlović, Imo E. Hoefer, Tamas Szili-Török, Hendrik J. Vos, Johan G. Bosch, Gijs van Soest, Antonius F.W. van der Steen
      In intracardiac echocardiography (ICE) it may be beneficial to generate ultrasound images acquired at multiple frequencies, having the possibility of high penetration or high-resolution imaging in a single device. The objective of the presented work is to test two frequency-tunable probe prototypes in a preclinical setting: a rigid probe having a diameter of 11 mm and a new flexible and steerable 12-Fr ICE catheter. Both probes feature a forward-looking 32-element capacitive micromachined ultrasonic transducer array (aperture of 2 × 2 mm2) operated in collapse mode, which allows for frequency tuning in the 6-MHz–18-MHz range. The rigid probe prototype is tested ex vivo in a passive heart platform. Images of an aortic valve acquired in high-penetration (6 MHz), generic (12 MHz) and high-resolution (18 MHz) mode combine satisfying image quality and penetration depth between 2.5 cm and 10 cm. The ICE catheter prototype is tested in vivo using a porcine animal model. Images of an aortic valve are acquired in the 3 imaging modes with the ICE catheter placed in an ascending aorta at multiple depths. It was found that the combination of the forward-looking design and frequency-tuning capability allows visualizing intracardiac structures of various sizes at different distances relative to the catheter tip, providing both wide overviews and detailed close-ups.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.005
       
  • Acoustic and Elastic Properties of Glycerol in Oil-Based Gel Phantoms
    • Authors: Luciana C. Cabrelli; Felipe W. Grillo; Diego R.T. Sampaio; Antonio A.O. Carneiro; Theo Z. Pavan
      Pages: 2086 - 2094
      Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9
      Author(s): Luciana C. Cabrelli, Felipe W. Grillo, Diego R.T. Sampaio, Antonio A.O. Carneiro, Theo Z. Pavan
      Phantoms are important tools for image quality control and medical training. Many phantom materials have been proposed for ultrasound; most of them use water as the solvent, but these materials have disadvantages such as dehydration and low temporal stability if not properly stored. To overcome these difficulties, copolymer-in-oil gel was proposed as an inert and stable material; however, speed of sound for these materials is still lower than what is described for most biological tissues. Here, we propose the glycerol dispersion in oil-based gels to modify the acoustic and elastic properties of copolymer-in-oil phantoms. We manufactured copolymer-in-oil gels using styrene-ethylene/butylene-styrene (SEBS) in concentrations 8%–15%. We used 2 types of mineral oils with different viscosities. Glycerol was added in a volume fraction 0%–30% of the total amount of liquid. The acoustic (i.e., speed of sound, attenuation and backscattering) and the mechanical (i.e., density and Young's modulus) properties of the samples were within the range of values observed for soft tissues. The acoustic parameters of the samples were dependent on oil viscosity and glycerol concentration. The speed of sound ranged 1423 m/s – 1502 m/s, while the acoustic attenuation and the ultrasonic backscattering increased by adding glycerol. The density and the Young's moduli were less affected by the presence of glycerol. We conclude that glycerol can be used to control the acoustic parameters of copolymer-in-oil gels. Additionally, it opens the possibility of incorporating other oil-insoluble substances to control further properties of the phantom.

      PubDate: 2017-07-25T15:29:52Z
      DOI: 10.1016/j.ultrasmedbio.2017.05.010
       
  • Can the Contrast-Enhanced Ultrasound Washout Rate Be Used to Predict
           Microvascular Invasion in Hepatocellular Carcinoma'
    • Authors: Wei Zhu; Xiachuan Qing; Feng Yan; Yan Luo; Yongzhong Li; Xiang Zhou
      Pages: 1571 - 1580
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Wei Zhu, Xiachuan Qing, Feng Yan, Yan Luo, Yongzhong Li, Xiang Zhou
      The objective of this study was to investigate use of the washout rate of hepatocellular carcinoma on contrast-enhanced ultrasound (CEUS) for pre-operative determination of the presence of microvascular invasion. The study included 271 patients who underwent liver resection for hepatocellular carcinoma between April 2008 and December 2012, and were examined with contrast-enhanced ultrasound before surgery. Patients were followed up at 3-mo intervals for 3 y. Four washout patterns were classified according to the start time of washout: rapid, portal, delayed and slow. Rapid washout, presence of two or more tumors and tumor size ≥5 cm were identified as independent pre-operative predictors of microvascular invasion on multivariate analysis. Recurrence rates for patients with none, one, two or three predictors were 22.6%, 34.7%, 57.6% and 75.0%, respectively. In combination with tumor number and tumor size, contrast-enhanced ultrasound washout rate may have a role in identifying hepatocellular carcinoma patients with microvascular invasion.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.003
       
  • Pre-Operative Evaluation of Axillary Lymph Node Status in Patients with
           Suspected Breast Cancer Using Shear Wave Elastography
    • Authors: Ji Hyun Youk; Eun Ju Son; Jeong-Ah Kim; Hye Mi Gweon
      Pages: 1581 - 1586
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Ji Hyun Youk, Eun Ju Son, Jeong-Ah Kim, Hye Mi Gweon
      The aim of this study was to evaluate shear wave elastography (SWE) for pre-operative evaluation of axillary lymph node (LN) status in patients with suspected breast cancer. A total of 130 axillary LNs in 130 patients who underwent SWE before fine-needle aspiration, core biopsy or surgery were analyzed. On gray-scale images, long and short axes, shape (elliptical or round), border (sharp or unsharp) and cortical thickening (concentric, eccentric or no fatty hilum) of LNs were assessed. On SWE, mean, maximum, minimum, standard deviation and the lesion-to-fat ratio (E ratio) values of elasticity were collected. Gray-scale and SWE features were compared statistically between metastatic and benign LNs using the χ2-test and independent t-test. Diagnostic performance of each feature was evaluated using the area under the receiver operating characteristic curve (AUC). Logistic regression analysis was used to determine gray-scale or SWE features independently associated with metastatic LNs. Of the 130 LNs, 65 (50%) were metastatic and 65 (50%) were benign after surgery. Metastatic LNs were significantly larger (p = 0.018); had higher elasticity indexes at SWE (p < 0.0001); and had higher proportions of round shape (p = 0.033), unsharp border (p = 0.048) and eccentric cortical thickening or no fatty hilum (p = 0.005) compared with benign LNs. On multivariate analysis, E ratio was independently associated with metastatic LNs (odds ratio = 3.312, p = 0.008). E ratio had the highest AUC among gray-scale (0.582–0.719) and SWE (0.900–0.950) variables. SWE had good diagnostic performance in metastatic axillary LNs, and E ratio was independently associated with metastatic LNs.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.03.016
       
  • US Elastography Using Carotid Artery Pulsation May Increase the Diagnostic
           Accuracy for Thyroid Nodules with US-Pathology Discordance
    • Authors: Yoon Joo Cho; Eun Ju Ha; Miran Han; Jin Wook Choi
      Pages: 1587 - 1595
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Yoon Joo Cho, Eun Ju Ha, Miran Han, Jin Wook Choi
      This study evaluated the diagnostic performance of ultrasound elastography (USE) using carotid arterial pulsation and determined the reproducibility of USE for thyroid nodules. A total of 148 patients with 173 thyroid nodules participated. The mean elasticity contrast index (ECI) was significantly higher in malignant nodules (3.1 ± 1.5) than in benign nodules (1.7 ± 0.8) (p < 0.001). When a cut-off ECI value of 3.5 was used, the diagnostic accuracy (78.6%) of gray-scale ultrasound (US) + ECI was the highest compared with that of the gray-scale US (76.9%) and ECI (67.1%). In 16 of 43 nodules (37.2%) with US-pathology, discordance could be correctly reclassified as benign (8 of 11) or malignant (8 of 32). The intra-class correlation coefficient for inter-observer agreement was 0.96, and those for intra-observer agreement were 0.97 and 0.98. Thyroid nodules with ECI values of >3.5 may have an additional value to increase the diagnostic accuracy for nodules with US-pathology discordance with reproducible results.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.007
       
  • Cardiac Shear Wave Elastography Using a Clinical Ultrasound System
    • Authors: Mihai Strachinaru; Johan G. Bosch; Bas M. van Dalen; Lennart van Gils; Antonius F.W. van der Steen; Nico de Jong; Marcel L. Geleijnse; Hendrik J. Vos
      Pages: 1596 - 1606
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Mihai Strachinaru, Johan G. Bosch, Bas M. van Dalen, Lennart van Gils, Antonius F.W. van der Steen, Nico de Jong, Marcel L. Geleijnse, Hendrik J. Vos
      The propagation velocity of shear waves relates to tissue stiffness. We prove that a regular clinical cardiac ultrasound system can determine shear wave velocity with a conventional unmodified tissue Doppler imaging (TDI) application. The investigation was performed on five tissue phantoms with different stiffness using a research platform capable of inducing and tracking shear waves and a clinical cardiac system (Philips iE33, achieving frame rates of 400–700 Hz in TDI by tuning the normal system settings). We also tested the technique in vivo on a normal individual and on typical pathologies modifying the consistency of the left ventricular wall. The research platform scanner was used as reference. Shear wave velocities measured with TDI on the clinical cardiac system were very close to those measured by the research platform scanner. The mean difference between the clinical and research systems was 0.18 ± 0.22 m/s, and the limits of agreement, from −0.27 to +0.63 m/s. In vivo, the velocity of the wave induced by aortic valve closure in the interventricular septum increased in patients with expected increased wall stiffness.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.04.012
       
  • Aortic Valve Stenosis Increases Helical Flow and Flow Complexity: A Study
           of Intra-Operative Cardiac Vector Flow Imaging
    • Authors: Kristoffer Lindskov Hansen; Hasse Møller-Sørensen; Jesper Kjaergaard; Maiken Brit Jensen; Jørgen Arendt Jensen; Michael Bachmann Nielsen
      Pages: 1607 - 1617
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Kristoffer Lindskov Hansen, Hasse Møller-Sørensen, Jesper Kjaergaard, Maiken Brit Jensen, Jørgen Arendt Jensen, Michael Bachmann Nielsen
      Aortic valve stenosis alters blood flow in the ascending aorta. Using intra-operative vector flow imaging on the ascending aorta, secondary helical flow during peak systole and diastole, as well as flow complexity of primary flow during systole, were investigated in patients with normal, stenotic and replaced aortic valves. Peak systolic helical flow, diastolic helical flow and flow complexity during systole differed between the groups (p < 0.0001), and correlated to peak systolic velocity (R = 0.94, 0.87 and 0.88, respectively). The study indicates that aortic valve stenosis increases helical flow and flow complexity, which are measurable with vector flow imaging. For assessment of aortic stenosis and optimization of valve surgery, vector flow imaging may be useful.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.03.018
       
  • Echo Particle Image Velocimetry for Estimation of Carotid Artery Wall
           Shear Stress: Repeatability, Reproducibility and Comparison with
           Phase-Contrast Magnetic Resonance Imaging
    • Authors: Arati Gurung; Phillip E. Gates; Luciano Mazzaro; Jonathan Fulford; Fuxing Zhang; Alex J. Barker; Jean Hertzberg; Kunihiko Aizawa; William D. Strain; Salim Elyas; Angela C. Shore; Robin Shandas
      Pages: 1618 - 1627
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Arati Gurung, Phillip E. Gates, Luciano Mazzaro, Jonathan Fulford, Fuxing Zhang, Alex J. Barker, Jean Hertzberg, Kunihiko Aizawa, William D. Strain, Salim Elyas, Angela C. Shore, Robin Shandas
      Measurement of hemodynamic wall shear stress (WSS) is important in investigating the role of WSS in the initiation and progression of atherosclerosis. Echo particle image velocimetry (echo PIV) is a novel ultrasound-based technique for measuring WSS in vivo that has previously been validated in vitro using the standard optical PIV technique. We evaluated the repeatability and reproducibility of echo PIV for measuring WSS in the human common carotid artery. We measured WSS in 28 healthy participants (18 males and 10 females, mean age: 56 ± 12 y). Echo PIV was highly repeatable, with an intra-observer variability of 1.0 ± 0.1 dyn/cm2 for peak systolic (maximum), 0.9 dyn/cm2 for mean and 0.5 dyn/cm2 for end-diastolic (minimum) WSS measurements. Likewise, echo PIV was reproducible, with a low inter-observer variability (max: 2.0 ± 0.2 dyn/cm2, mean: 1.3 ± 0.1 dyn/cm2, end-diastolic: 0.7 dyn/cm2) and more variable inter-scan (test–retest) variability (max: 7.1 ± 2.3 dyn/cm2, mean: 2.9 ± 0.4 dyn/cm2, min: 1.5 ± 0.1 dyn/cm2). We compared echo PIV with the reference method, phase-contrast magnetic resonance imaging (PC-MRI); echo PIV-based WSS measurements agreed qualitatively with PC-MRI measurements (r = 0.89, p < 0.05). Significant differences were observed in some WSS measurements (echo PIV vs. PC-MRI): WSS at peak systole: 21 ± 7.0 dyn/cm2 vs. 15 ± 5.0 dyn/cm2; time-averaged WSS: 8.9 ± 3.0 dyn/cm2 vs. 7.1 ± 3.0 dyn/cm2 (p < 0.05); WSS at end diastole: 3.8 ± 2.8 dyn/cm2 vs. 3.9 ± 2 dyn/cm2 (p > 0.05). For the first time, we report that echo PIV can measure WSS with good repeatability and reproducibility in adult humans with a broad age range. Echo PIV is feasible in humans and offers an easy-to-use, ultrasound-based, quantitative technique for measuring WSS in vivo in humans with good repeatability and reproducibility.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.03.020
       
  • Measuring Absolute Blood Perfusion in Mice Using Dynamic Contrast-Enhanced
           Ultrasound
    • Authors: Abbas Shirinifard; Suresh Thiagarajan; Melissa D. Johnson; Christopher Calabrese; András Sablauer
      Pages: 1628 - 1638
      Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8
      Author(s): Abbas Shirinifard, Suresh Thiagarajan, Melissa D. Johnson, Christopher Calabrese, András Sablauer
      We investigated the feasibility of estimating absolute tissue blood perfusion using dynamic contrast-enhanced ultrasound (CEUS) imaging in mice. We developed a novel method of microbubble administration and a model-free approach to estimate absolute kidney perfusion, and explored the kidney as a reference organ to estimate absolute perfusion of a neuroblastoma tumor. We performed CEUS on the kidneys of CD1 nude mice using the VisualSonics VEVO 2100 imaging system. We estimated individual kidney blood perfusion using the burst–replenishment (BR) technique. We repeated the kidney imaging on the mice after a week. We performed CEUS imaging of a neuroblastoma mouse xenograft tumor along with its right kidney using two sets of microbubble administration parameters to estimate absolute tumor blood perfusion. We performed statistical tests at a significance level of 0.05. Our estimated absolute kidney perfusion (425 ± 123 mL/min/100 g) was within the range of previously reported values. There was no statistical difference between the estimated absolute kidney blood perfusions from the 2 wk of imaging (paired t-test, p = 0.09). We estimated the absolute blood perfusion in the neuroblastoma tumor to be 16.49 and 16.9 mL/min/100 g for the two sets of microbubble administration parameters (Wilcoxon rank-sum test, p = 0.6). We have established the kidney as a reliable reference organ in which to estimate absolute perfusion of other tissues. Using a neuroblastoma tumor, we have determined the feasibility of estimating absolute blood perfusion in tissues using contrast-enhanced ultrasound imaging.

      PubDate: 2017-07-10T03:11:01Z
      DOI: 10.1016/j.ultrasmedbio.2017.02.004
       
  • Editorial Advisory Board
    • Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9


      PubDate: 2017-07-25T15:29:52Z
       
  • Calendar
    • Abstract: Publication date: September 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 9


      PubDate: 2017-07-25T15:29:52Z
       
  • Editorial Advisory Board
    • Abstract: Publication date: August 2017
      Source:Ultrasound in Medicine & Biology, Volume 43, Issue 8


      PubDate: 2017-07-10T03:11:01Z
       
  • Comparison of 2-D Shear Wave Elastography and Transient Elastography for
           Assessing Liver Fibrosis in Chronic Hepatitis B
    • Authors: Jie Zeng; Jian Zheng; Zeping Huang; Shigao Chen; Jing Liu; Tao Wu; Rongqin Zheng; Mingde Lu
      Abstract: Publication date: Available online 5 May 2017
      Source:Ultrasound in Medicine & Biology
      Author(s): Jie Zeng, Jian Zheng, Zeping Huang, Shigao Chen, Jing Liu, Tao Wu, Rongqin Zheng, Mingde Lu
      This study compared 2-D shear wave elastography (SWE) and transient elastography (TE) for liver fibrosis staging in patients with chronic hepatitis B (CHB) infection using liver biopsy as the reference standard. Patients with CHB infection who underwent liver biopsy were consecutively included. After exclusions, 257 patients were analyzed. Two-dimensional SWE resulted in a significantly higher rate of reliable measurements (98.1%, 252/257) than TE (93.0%, 239/257) (p = 0.011). Liver stiffness measurements of the two examinations exhibited a strong correlation (r = 0.835, p < 0.001). In patients given a confirmed histologic diagnosis, Spearman's rank coefficients were 0.520 in stage F0 (p < 0.001), 0.684 in stage F1 (p < 0.001), 0.777 in stage F2 (p < 0.001), 0.672 in stage F3 (p < 0.001) and 0.755 in stage F4 (p < 0.001). There were no significant differences between the areas under the receiver operating characteristic (ROC) curves of 2-D SWE and TE for liver fibrosis staging (all p values > 0.05). Two-dimensional SWE had diagnostic accuracy comparable to that of TE for liver fibrosis staging. The measurements that the two techniques provide are not interchangeable.

      PubDate: 2017-05-08T10:27:27Z
      DOI: 10.1016/j.ultrasmedbio.2017.03.014
       
 
 
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