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Journal Cover Ultrasonic Imaging
   [3 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  [753 journals]   [SJR: 0.651]   [H-I: 33]
  • Corrigendum
    • Pages: NP1 - NP1
      Abstract: Choi H, Kim MG, Cumins TM, Hwang JY, Shung KK. Power MOSFET–diode–based limiter for high-frequency ultrasound systems. Ultrason Imaging. 2014;36:317-330. Original
      DOI : 10.1177/0161734614524180 In this article, published in the October 2014 issue, the affiliation of the corresponding author Hojong Choi has been changed. Following is his revised affiliation: Hojong Choi, Department of Medical IT Convergence Engineering, Kumoh National Institute of Technology, Gumi, Gyeongbuk, South Korea Email: hojongch@kumoh.ac.kr
      PubDate: 2014-11-28T04:11:02-08:00
      Issue No: Vol. 37, No. 1 (2014)
       
  • Effective Scatterer Diameter Estimates for Broad Scatterer Size
           Distributions
    • Authors: Nordberg, E. P; Hall, T. J.
      Pages: 3 - 21
      Abstract: Acoustic form factors have been used to model the frequency dependence of acoustic scattering in phantoms and tissues. This work demonstrates that a broad range of scatterer sizes, individually well represented by Faran theory or a Gaussian form factor, is not accurately described by a single effective scatterer from either of these models. Contributions from a distribution of discrete scatterer sizes for two different form factor functions (Gaussian form factors and scattering functions from Faran’s theory) were calculated and linearly combined. Composite form factors created from Gaussian distributions of scatterer sizes centered at 50 µm with standard deviations of up to = 40 µm were fit to each scattering model between 2 and 12 MHz. Scatterer distributions were generated using one of two assumptions: the number density of the scatterer diameter distribution was Gaussian distributed, or the volume fraction of each scatterer diameter in the distribution was Gaussian distributed. Each simulated form factor was fit to a single-diameter form factor model for Gaussian and exponential form factors. The mean-squared error (MSE) between the composite simulated data and the best-fit single-diameter model was smaller with an exponential form factor model, compared with a Gaussian model, for distributions with standard deviations larger than 30% of the centroid value. In addition, exponential models were shown to have better ability to distinguish between Faran scattering model-based distributions with varying center diameters than the Gaussian form factor model. The evidence suggests that when little is known about the scattering medium, an exponential scattering model provides a better first approximation to the scattering correlation function for a broad distribution of spherically symmetric scatterers than when a Gaussian form factor model is assumed.
      PubDate: 2014-11-28T04:11:01-08:00
      DOI: 10.1177/0161734614534399|hwp:master-id:spuix;0161734614534399
      Issue No: Vol. 37, No. 1 (2014)
       
  • B-Mode and Acoustic Radiation Force Impulse (ARFI) Imaging of Prostate
           Zonal Anatomy: Comparison with 3T T2-Weighted MR Imaging
    • Authors: Palmeri, M. L; Miller, Z. A, Glass, T. J, Garcia-Reyes, K, Gupta, R. T, Rosenzweig, S. J, Kauffman, C, Polascik, T. J, Buck, A, Kulbacki, E, Madden, J, Lipman, S. L, Rouze, N. C, Nightingale, K. R.
      Pages: 22 - 41
      Abstract: Prostate cancer (PCa) is the most common non-cutaneous malignancy among men in the United States and the second leading cause of cancer-related death. Multi-parametric magnetic resonance imaging (mpMRI) has gained recent popularity to characterize PCa. Acoustic Radiation Force Impulse (ARFI) imaging has the potential to aid PCa diagnosis and management by using tissue stiffness to evaluate prostate zonal anatomy and lesions. MR and B-mode/ARFI in vivo imaging datasets were compared with one another and with gross pathology measurements made immediately after radical prostatectomy. Images were manually segmented in 3D Slicer to delineate the central gland (CG) and prostate capsule, and 3D models were rendered to evaluate zonal anatomy dimensions and volumes. Both imaging modalities showed good correlation between estimated organ volume and gross pathologic weights. Ultrasound and MR total prostate volumes were well correlated (R 2 = 0.77), but B-mode images yielded prostate volumes that were larger (16.82% ± 22.45%) than MR images, due to overestimation of the lateral dimension (18.4% ± 13.9%), with less significant differences in the other dimensions (7.4% ± 17.6%, anterior-to-posterior, and –10.8% ± 13.9%, apex-to-base). ARFI and MR CG volumes were also well correlated (R 2 = 0.85). CG volume differences were attributed to ARFI underestimation of the apex-to-base axis (–28.8% ± 9.4%) and ARFI overestimation of the lateral dimension (21.5% ± 14.3%). B-mode/ARFI imaging yielded prostate volumes and dimensions that were well correlated with MR T2-weighted image (T2WI) estimates, with biases in the lateral dimension due to poor contrast caused by extraprostatic fat. B-mode combined with ARFI imaging is a promising low-cost, portable, real-time modality that can complement mpMRI for PCa diagnosis, treatment planning, and management.
      PubDate: 2014-11-28T04:11:02-08:00
      DOI: 10.1177/0161734614542177|hwp:master-id:spuix;0161734614542177
      Issue No: Vol. 37, No. 1 (2014)
       
  • Comparison of Photoacoustically Derived Hemoglobin and Oxygenation
           Measurements with Contrast-Enhanced Ultrasound Estimated Vascularity and
           Immunohistochemical Staining in a Breast Cancer Model
    • Authors: Eisenbrey, J. R; Merton, D. A, Marshall, A, Liu, J.-B, Fox, T. B, Sridharan, A, Forsberg, F.
      Pages: 42 - 52
      Abstract: In this preliminary study, we compared two noninvasive techniques for imaging intratumoral physiological conditions to immunohistochemical staining in a murine breast cancer model. MDA-MB-231 tumors were implanted in the mammary pad of 11 nude rats. Ultrasound and photoacoustic (PA) scanning were performed using a Vevo 2100 scanner (Visualsonics, Toronto, Canada). Contrast-enhanced ultrasound (CEUS) was used to create maximum intensity projections as a measure of tumor vascularity. PAs were used to determine total hemoglobin signal (HbT), oxygenation levels in detected blood (SO2 Avg), and oxygenation levels over the entire tumor area (SO2 Tot). Tumors were then stained for vascular endothelial growth factor (VEGF), cyclooxygenase-2 (Cox-2), and the platelet endothelial cell adhesion molecule CD31. Correlations between findings were analyzed using Pearson’s coefficient. Significant correlation was observed between CEUS-derived vascularity measurements and both PA indicators of blood volume (r = 0.49 for HbT, r = 0.50 for SO2 Tot). Cox-2 showed significant negative correlation with SO2 Avg (r = –0.49, p = 0.020) and SO2 Tot (r = –0.43, p = 0.047), while CD31 showed significant negative correlation with CEUS-derived vascularity (r = –0.47, p = 0.036). However, no significant correlation was observed between VEGF expression and any imaging modality (p > 0.08). Photoacoustically derived HbT and SO2 Tot may be a good indicator of tumor fractional vascularity. While CEUS correlates with CD31 expression, photoacoustically derived SO2 Avg appears to be a better predictor of Cox-2 expression.
      PubDate: 2014-11-28T04:11:02-08:00
      DOI: 10.1177/0161734614527435|hwp:master-id:spuix;0161734614527435
      Issue No: Vol. 37, No. 1 (2014)
       
  • Artifact Reduction of Ultrasound Nakagami Imaging by Combining Multifocus
           Image Reconstruction and the Noise-Assisted Correlation Algorithm
    • Authors: Tsui, P.-H; Tsai, Y.-W.
      Pages: 53 - 69
      Abstract: Several studies have investigated Nakagami imaging to complement the B-scan in tissue characterization. The noise-induced artifact and the parameter ambiguity effect can affect performance of Nakagami imaging in the detection of variations in scatterer concentration. This study combined multifocus image reconstruction and the noise-assisted correlation algorithm (NCA) into the algorithm of Nakagami imaging to suppress the artifacts. A single-element imaging system equipped with a 5 MHz transducer was used to perform the brightness/depth (B/D) scanning of agar phantoms with scatterer concentrations ranging from 2 to 32 scatterers/mm3. Experiments were also carried out on a mass with some strong point reflectors in a breast phantom using a commercial scanner with a 7.5 MHz linear array transducer operated at multifocus mode. The multifocus radiofrequency (RF) signals after the NCA process were used for Nakagami imaging. In the experiments on agar phantoms, an increasing scatterer concentration from 2 to 32 scatterers/mm3 led to backscattered statistics ranging from pre-Rayleigh to Rayleigh distributions, corresponding to the increase in the Nakagami parameter measured in the focal zone from 0.1 to 0.8. However, the artifacts in the far field resulted in the Nakagami parameters of various scatterer concentrations to be close to 1 (Rayleigh distribution), making Nakagami imaging difficult to characterize scatterers. In the same scatterer concentration range, multifocus Nakagami imaging with the NCA simultaneously suppressed two types of artifacts, making the Nakagami parameter increase from 0.1 to 0.8 in the focal zone and from 0.18 to 0.7 in the far field, respectively. In the breast phantom experiments, the backscattered statistics of the mass corresponded to a high degree of pre-Rayleigh distribution. The Nakagami parameter of the mass before and after artifact reduction was 0.7 and 0.37, respectively. The results demonstrated that the proposed method for artifact reduction allows a sensitive and effective scatterer characterization by Nakagami imaging.
      PubDate: 2014-11-28T04:11:02-08:00
      DOI: 10.1177/0161734614526379|hwp:master-id:spuix;0161734614526379
      Issue No: Vol. 37, No. 1 (2014)
       
  • Method to Estimate the Deviation from Ideal Uniaxial Compression during
           Freehand Elastography
    • Authors: Xia, R; Thittai, A. K.
      Pages: 70 - 82
      Abstract: Quasi-static ultrasound elastography was introduced in the early 1990s to provide a way to visualize the mechanical properties of target tissue. Most commonly, only the axial strain is imaged and referred to as an Axial Strain Elastogram (ASE) or elastogram for simplicity. It has been shown that one can image the axial-shear strain distributions as well in addition to ASE. The image of the axial-shear strain is referred to as an axial-shear strain elastogram (ASSE). It has also been shown that the presence or absence of non-zero axial-shear strain values inside the inclusion (referred to as fill-in) along with contrasting margin at its boundary may serve as a potential feature from ASSE that can aid in non-invasive breast lesion classification. However, during freehand elastography, deviations from uniaxial compression often occur typically appearing in several of the frames of a cine-loop obtained during compression. It was shown recently that accounting for such deviations would be important for reliable interpretation of the "fill-in" observed in ASSE. In this article, we describe a method to estimate the angle of iso-displacement contour at a given depth and use this as a measure to quantify the deviation from the desired uniaxial compression during freehand elastography. We validate the estimated angle obtained from the axial-displacement map against the designed values in simulation and tissue-mimicking phantom experiments. The potential of the angle estimate to detect unreliable ASSE frames among the freehand-acquired data cine-loop is demonstrated using example cases of in vivo breast lesion data. Based on the results, we conclude that the angle of the iso-displacement contour from the axial-displacement map can be used as a metric to qualify an ASSE frame as reliable to interpret or not. Importantly, this metric can be obtained in real time and thus can provide operator feedback to guide and improve in vivo freehand elastography data acquisition quality.
      PubDate: 2014-11-28T04:11:02-08:00
      DOI: 10.1177/0161734614537044|hwp:master-id:spuix;0161734614537044
      Issue No: Vol. 37, No. 1 (2014)
       
 
 
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