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Journal Cover Ultrasonic Imaging
  [SJR: 0.61]   [H-I: 38]   [2 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  [853 journals]
  • Segmental Analysis of Cardiac Short-Axis Views Using Lagrangian Radial and
           Circumferential Strain
    • Authors: Ma, C; Wang, X, Varghese, T.
      Pages: 363 - 383
      Abstract: Accurate description of myocardial deformation in the left ventricle is a three-dimensional problem, requiring three normal strain components along its natural axis, that is, longitudinal, radial, and circumferential strains. Although longitudinal strains are best estimated from long-axis views, radial and circumferential strains are best depicted in short-axis views. An algorithm that utilizes a polar grid for short-axis views previously developed in our laboratory for a Lagrangian description of tissue deformation is utilized for radial and circumferential displacement and strain estimation. Deformation of the myocardial wall, utilizing numerical simulations with ANSYS, and a finite-element analysis–based canine heart model were adapted as the input to a frequency-domain ultrasound simulation program to generate radiofrequency echo signals. Clinical in vivo data were also acquired from a healthy volunteer. Local displacements estimated along and perpendicular to the ultrasound beam propagation direction are then transformed into radial and circumferential displacements and strains using the polar grid based on a pre-determined centroid location. Lagrangian strain variations demonstrate good agreement with the ideal strain when compared with Eulerian results. Lagrangian radial and circumferential strain estimation results are also demonstrated for experimental data on a healthy volunteer. Lagrangian radial and circumferential strain tracking provide accurate results with the assistance of the polar grid, as demonstrated using both numerical simulations and in vivo study.
      PubDate: 2016-10-13T04:50:51-07:00
      DOI: 10.1177/0161734615613322
      Issue No: Vol. 38, No. 6 (2016)
       
  • Segmentation of Breast Lesions in Ultrasound Images through
           Multiresolution Analysis Using Undecimated Discrete Wavelet Transform
    • Authors: Prabusankarlal, K. M; Thirumoorthy, P, Manavalan, R.
      Pages: 384 - 402
      Abstract: Earliest detection and diagnosis of breast cancer reduces mortality rate of patients by increasing the treatment options. A novel method for the segmentation of breast ultrasound images is proposed in this work. The proposed method utilizes undecimated discrete wavelet transform to perform multiresolution analysis of the input ultrasound image. As the resolution level increases, although the effect of noise reduces, the details of the image also dilute. The appropriate resolution level, which contains essential details of the tumor, is automatically selected through mean structural similarity. The feature vector for each pixel is constructed by sampling intra-resolution and inter-resolution data of the image. The dimensionality of feature vectors is reduced by using principal components analysis. The reduced set of feature vectors is segmented into two disjoint clusters using spatial regularized fuzzy c-means algorithm. The proposed algorithm is evaluated by using four validation metrics on a breast ultrasound database of 150 images including 90 benign and 60 malignant cases. The algorithm produced significantly better segmentation results (Dice coef = 0.8595, boundary displacement error = 9.796, dvi = 1.744, and global consistency error = 0.1835) than the other three state of the art methods.
      PubDate: 2016-10-13T04:50:51-07:00
      DOI: 10.1177/0161734615615838
      Issue No: Vol. 38, No. 6 (2016)
       
  • Chirp-Coded Ultraharmonic Imaging with a Modified Clinical Intravascular
           Ultrasound System
    • Authors: Shekhar, H; Huntzicker, S, Awuor, I, Doyley, M. M.
      Pages: 403 - 419
      Abstract: Imaging plaque microvasculature with contrast-enhanced intravascular ultrasound (IVUS) could help clinicians evaluate atherosclerosis and guide therapeutic interventions. In this study, we evaluated the performance of chirp-coded ultraharmonic imaging using a modified IVUS system (iLab™, Boston Scientific/Scimed) equipped with clinically available peripheral and coronary imaging catheters. Flow phantoms perfused with a phospholipid-encapsulated contrast agent were visualized using ultraharmonic imaging at 12 MHz and 30 MHz transmit frequencies. Flow channels with diameters as small as 0.8 mm and 0.5 mm were visualized using the peripheral and coronary imaging catheters. Radio-frequency signals were acquired at standard IVUS rotation speed, which resulted in a frame rate of 30 frames/s. Contrast-to-tissue ratios up to 17.9 ± 1.11 dB and 10.7 ± 2.85 dB were attained by chirp-coded ultraharmonic imaging at 12 MHz and 30 MHz transmit frequencies, respectively. These results demonstrate the feasibility of performing ultraharmonic imaging at standard frame rates with clinically available IVUS catheters using chirp-coded excitation.
      PubDate: 2016-10-13T04:50:51-07:00
      DOI: 10.1177/0161734615618639
      Issue No: Vol. 38, No. 6 (2016)
       
 
 
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