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Journal Cover   Ultrasonic Imaging
  [SJR: 0.818]   [H-I: 34]   [1 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0161-7346 - ISSN (Online) 1096-0910
   Published by Sage Publications Homepage  [814 journals]
  • Back-Propagation Beamformer Design for Motion Estimation in
           Echocardiography
    • Authors: Guo, X; Liebgott, H, Friboulet, D.
      Pages: 179 - 204
      Abstract: Transverse oscillation (TO) techniques have shown their potential for improving the accuracy of local motion estimation in the transverse direction (i.e., the direction perpendicular to the beam axis). The conventional design of TOs in linear geometry, which is based on the Fraunhofer approximation, relates point spread function (PSF) and apodization function through a Fourier transform. Motivated by the adaptation of TOs in echocardiography, we propose a specific beamforming approach based on back-propagation (BP) to build TOs in sector-shaped geometry. Numerical simulations and experimental data give a comparison between proposed and conventional beamforming for TOs. The accuracy is first quantified by comparing the generated and theoretical PSF using the root mean square error (RMSE) and shows that BP-based beamforming approximates the desired TOs more closely than the conventional approach. Motion estimation is then evaluated. The axial and lateral displacements are within the range [0-0.6] mm and [0°-6.4°], respectively, which correspond to 0.8 times the axial (0.73 mm) and lateral (8°) wavelengths. The result shows that the proposed method yields a clear improvement for lateral displacements, by reducing the error by 28.6% compared with Fourier transform–based beamforming, while maintaining the same error for axial motion estimation. Experimental measurements are discussed to complete this study and confirm that BP-based beamforming leads to better controlled TO images than conventional Fourier-based beamforming.
      PubDate: 2015-06-03T04:50:05-07:00
      DOI: 10.1177/0161734614550659
      Issue No: Vol. 37, No. 3 (2015)
       
  • The Benefits of Compression Methods in Acoustic Coherence Tomography
    • Authors: Rouyer, J; Mensah, S, Vasseur, C, Lasaygues, P.
      Pages: 205 - 223
      Abstract: Pulse compression methods improve the quality of ultrasonic medical images. In comparison with standard broadband pulse techniques, these methods enhance the contrast-to-noise ratio (CNR) and increase the probing depth without any perceptible loss of spatial resolution. The Golay compression technique is analyzed here in the context of ultrasonic computed tomography, first on a one-dimensional target and second on a very low-contrast phantom probed using a half-ring array tomograph. The imaging performances were assessed based on the image CNR. The improvement obtained (up to 40%) depends, however, on the number of coherently associated diffraction projections. Beyond a certain number, few advantages were observed. Advances in ultrasound computed tomography suggest that pulse compression methods should provide a useful means of optimizing the trade-off between the image quality and the probing sampling density.
      PubDate: 2015-06-03T04:50:05-07:00
      DOI: 10.1177/0161734614553310
      Issue No: Vol. 37, No. 3 (2015)
       
  • VEGFR2-Targeted Ultrasound Imaging Agent Enhances the Detection of Ovarian
           Tumors at Early Stage in Laying Hens, a Preclinical Model of Spontaneous
           Ovarian Cancer
    • Authors: Barua, A; Yellapa, A, Bahr, J. M, Machado, S. A, Bitterman, P, Basu, S, Sharma, S, Abramowicz, J. S.
      Pages: 224 - 237
      Abstract: Tumor-associated neoangiogenesis (TAN) is an early event in ovarian cancer (OVCA) development. Increased expression of vascular endothelial growth factor receptor 2 (VEGFR2) by TAN vessels presents a potential target for early detection by ultrasound imaging. The goal of this study was to examine the suitability of VEGFR2-targeted ultrasound contrast agents in detecting spontaneous OVCA in laying hens. Effects of VEGFR2-targeted contrast agents in enhancing the intensity of ultrasound imaging from spontaneous ovarian tumors in hens were examined in a cross-sectional study. Enhancement in the intensity of ultrasound imaging was determined before and after injection of VEGFR2-targeted contrast agents. All ultrasound images were digitally stored and analyzed off-line. Following scanning, ovarian tissues were collected and processed for histology and detection of VEGFR2-expressing microvessels. Enhancement in visualization of ovarian morphology was detected by gray-scale imaging following injection of VEGFR2-targeted contrast agents. Compared with pre-contrast, contrast imaging enhanced the intensities of ultrasound imaging significantly (p < 0.0001) irrespective of the pathological status of ovaries. In contrast to normal hens, the intensity of ultrasound imaging was significantly (p < 0.0001) higher in hens with early stage OVCA and increased further in hens with late stage OVCA. Higher intensities of ultrasound imaging in hens with OVCA were positively correlated with increased (p < 0.0001) frequencies of VEGFR2-expressing microvessels. The results of this study suggest that VEGFR2-targeted contrast agents enhance the visualization of spontaneous ovarian tumors in hens at early and late stages of OVCA. The laying hen may be a suitable model to test new imaging agents and develop targeted therapeutics.
      PubDate: 2015-06-03T04:50:05-07:00
      DOI: 10.1177/0161734614553603
      Issue No: Vol. 37, No. 3 (2015)
       
  • Ultrasound Image Edge Detection Based on a Novel Multiplicative Gradient
           and Canny Operator
    • Authors: Zheng, Y; Zhou, Y, Zhou, H, Gong, X.
      Pages: 238 - 250
      Abstract: To achieve the fast and accurate segmentation of ultrasound image, a novel edge detection method for speckle noised ultrasound images was proposed, which was based on the traditional Canny and a novel multiplicative gradient operator. The proposed technique combines a new multiplicative gradient operator of non-Newtonian type with the traditional Canny operator to generate the initial edge map, which is subsequently optimized by the following edge tracing step. To verify the proposed method, we compared it with several other edge detection methods that had good robustness to noise, with experiments on the simulated and in vivo medical ultrasound image. Experimental results showed that the proposed algorithm has higher speed for real-time processing, and the edge detection accuracy could be 75% or more. Thus, the proposed method is very suitable for fast and accurate edge detection of medical ultrasound images.
      PubDate: 2015-06-03T04:50:05-07:00
      DOI: 10.1177/0161734614554461
      Issue No: Vol. 37, No. 3 (2015)
       
  • Elastography in the Differential Diagnosis of Thyroid Nodules
    • Authors: Cakal, E; Şahin, M, Unsal, I. O, Gunguneş, A, Akkaymak, E, Ozkaya, E. C, Bozkurt, N. C, Ozbek, M, Delibaşı, T.
      Pages: 251 - 257
      Abstract: Despite the publication of a recent meta-analysis of elastography in thyroid nodules, further work is necessary on this issue in different populations. In this study, we aimed to evaluate the clinical value of elastography on nodular goiters in mild iodine-deficient regions without excluding patients according to nodule characteristics. This prospective study was conducted between April 2010 and December 2011 in Yıldırım Beyazıt Dıskapı Research Hospital Endocrinology outpatient clinic. Five hundred twenty-eight nodular goiter patients who underwent thyroid fine-needle aspiration biopsy were included in our study. Elastography scores and indexes were measured with real-time ultrasound elastography (Hitachi® EUB 7000 HV machine with 13 MHz linear transducer). There were 471 females and 57 males and their ages ranged from 45 years to 78 years. A total of 601 nodules were evaluated in these patients. The area under the curve (AUC) for the elasto score was 0.91 (p < 0.0001) and AUC for the strain index (SI) was 0.96 (p < 0.0001). We suggest that the SI reflects malignancy better than the elasto score. We conclude that elastography scores greater than 3 have 76% sensitivity and 96% specificity for diagnosing malignancy. For SI, we conclude that 3.75 (83% sensitivity and 95% specificity) is the cutoff point. Elasto score and SI measurements of thyroid nodules in our population are efficient and increase the diagnostic performance of the sonography.
      PubDate: 2015-06-03T04:50:05-07:00
      DOI: 10.1177/0161734614547542
      Issue No: Vol. 37, No. 3 (2015)
       
  • Doppler Assessment of Renal Hemodynamic Alterations in Homozygous Sickle
           Cell Disease and Sickle Beta-Thalassemia
    • Authors: Saif, A; Soliman, N, Abdelhamid, A.
      Pages: 258 - 264
      Abstract: We evaluated the renal vascular indices in children and adolescents with sickle cell disease (SCD) using Doppler ultrasonography. We also assessed the renal hemodynamics alterations in patients with homozygous SCD and sickle beta-thalassemia (sickle β-thalassemia). We studied 75 patients (age range = 3-20 years; M = 9.95 ± 4.15) with SCD: 42 patients suffering from homozygous SCD and 33 patients diagnosed with sickle β-thalassemia. Thirty, age- and sex-matched, normal subjects were also included as a control group. Both patients and control groups had Doppler assessment of pulsatility (PI) and resistivity (RI) indices of main renal, segmental, interlobar, and arcuate arteries. Both PIs and RIs were significantly higher in SCD patients, compared with the control group. Among patients, PIs and RIs in the main renal, segmental, interlobar, and arcuate arteries were significantly higher in patients with homozygous SCD as compared with those with sickle β-thalassemia (p values
      PubDate: 2015-06-03T04:50:05-07:00
      DOI: 10.1177/0161734614553831
      Issue No: Vol. 37, No. 3 (2015)
       
 
 
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