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Title: Ultrasound contrast agent imaging: Real-time imaging of the superharmonics

Currently, in medical ultrasound contrast agent (UCA) imaging the second harmonic scattering of the microbubbles is regularly used. This scattering is in competition with the signal that is caused by nonlinear wave propagation in tissue. It was reported that UCA imaging based on the third or higher harmonics, i.e. “superharmonic” imaging, shows better contrast. However, the superharmonic scattering has a lower signal level compared to e.g. second harmonic signals. This study investigates the contrast-to-tissue ratio (CTR) and signal to noise ratio (SNR) of superharmonic UCA scattering in a tissue/vessel mimicking phantom using a real-time clinical scanner. Numerical simulations were performed to estimate the level of harmonics generated by the microbubbles. Data were acquired with a custom built dual-frequency cardiac phased array probe. Fundamental real-time images were produced while beam formed radiofrequency (RF) data was stored for further offline processing. The phantom consisted of a cavity filled with UCA surrounded by tissue mimicking material. The acoustic pressure in the cavity of the phantom was 110 kPa (MI = 0.11) ensuring non-destructivity of UCA. After processing of the acquired data from the phantom, the UCA-filled cavity could be clearly observed in the images, while tissue signals were suppressed at or below the noisemore » floor. The measured CTR values were 36 dB, >38 dB, and >32 dB, for the second, third, and fourth harmonic respectively, which were in agreement with those reported earlier for preliminary contrast superharmonic imaging. The single frame SNR values (in which ‘signal’ denotes the signal level from the UCA area) were 23 dB, 18 dB, and 11 dB, respectively. This indicates that noise, and not the tissue signal, is the limiting factor for the UCA detection when using the superharmonics in nondestructive mode.« less
Authors:
;  [1] ;  [2] ;  [1] ;  [3] ; ;  [4] ;  [2]
  1. MSD lab, Department of Information Engineering, Univ of Florence, Via S.Marta, 3, 50139 Firenze (Italy)
  2. (Netherlands)
  3. Acoustical Wavefield Imaging, ImPhys, Delft Univ Technology, van der Waalsweg 8, 2628 CH Delft (Netherlands)
  4. Erasmus MC, ’s-Gravendijkwal 230, Faculty Building, Ee 2302, 3015 CE Rotterdam (Netherlands)
Publication Date:
OSTI Identifier:
22492635
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1685; Journal Issue: 1; Conference: 20. international symposium on nonlinear acoustics, Ecully (France), 29 Jun - 3 Jul 2015, 2. international sonic boom forum, Ecully (France), 29 Jun - 3 Jul 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ANIMAL TISSUES; BIOMEDICAL RADIOGRAPHY; CAVITIES; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; CONTRAST MEDIA; DETECTION; HARMONICS; IMAGES; NOISE; NONLINEAR PROBLEMS; PHANTOMS; RADIOWAVE RADIATION; REAL TIME SYSTEMS; SCATTERING; SIGNALS; SIGNAL-TO-NOISE RATIO; ULTRASONOGRAPHY; WAVE PROPAGATION