Real-time monitoring of inertial cavitation effects of microbubbles by using MRI: In vitro experiments

Hsu Hsia Peng*, Chen Hua Wu, Shih Tsung Kang, Jia Wei Zhang, Hao Li Liu, Wen Shiang Chen, Chung Hsin Wang, Chih Kuang Yeh

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

5 Scopus citations

Abstract

Purpose: To investigate the feasibility of half-Fourier acquisition single-shot turbo spin-echo (HASTE) for real-time monitoring of signal changes because of water flow induced by inertial cavitation (IC) during microbubbles (MBs)-present focused ultrasound (FUS) exposure. Theory and Methods: Strong turbulence produced in MB solution at the onset of IC results in the difficulty to refocus signal echoes and thus the decrease in signal intensity (SI). Fundamental investigations were conducted using an agar phantom containing MB dilutions exposed to 1.85-MHz FUS. The effects of various experimental conditions including MB concentrations, imaging slice thicknesses, chamber diameters, acoustic pressures, duty cycles, and pulse repetition frequencies (PRFs) were discussed. Results: Continuous 2.8 MPa FUS exposure resulted in SI changed from 11% to 55% when MBs concentrations increased from 0.025% to 0.1%. When slice thickness increased from 3 mm to 6 or 8 mm, smaller SI changes were observed (84%, 59%, and 46%). Images acquired with chamber diameter of 6 and 3 mm showed SI changes of 84% and 35%, respectively. In burst modes, higher duty cycles exhibited higher SI changes, and lower PRFs exhibited smaller and longer SI decrease. Conclusion: Under various conditions, substantial signal changes were observable, suggesting the feasibility of applying HASTE to real-time monitor IC effect under FUS exposure. Magn Reson Med 77:102–111, 2017.

Original languageEnglish
Pages (from-to)102-111
Number of pages10
JournalMagnetic Resonance in Medicine
Volume77
Issue number1
DOIs
StatePublished - 01 01 2017

Bibliographical note

Publisher Copyright:
© 2015 Wiley Periodicals, Inc.

Keywords

  • focused ultrasound
  • half-Fourier acquisition single-shot turbo spin-echo (HASTE)
  • inertial cavitation
  • microbubble
  • real-time monitoring

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