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Updated: Mar 12, 2026
Introduction to the Ultrasound Targeted Microbubble Destruction Technique
Published on: June 12, 2011
Inhalable Ultrasound Contrast Agent with Induced Microbubble Destruction and Associated Biological Effects on the
Andrew S Weitz1, Patrick R Sears2, Phillip W Clapp3
1Lampe Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC, USA.
Background:
Intentional destruction of ultrasound microbubble (MB) contrast agents by induced cavitation is a well-established technique in contrast imaging applications and may translate to pulmonary imaging. However, the safety of exposing human bronchial epithelial (hBE) cells to an inhalable contrast agent with intentional MB destruction is not known.
Methods:
We conducted an in vitro evaluation by exposing hBE cell cultures to a mucus-targeting, cationic MB contrast agent. A total of 12 hBE cell cultures, from 3 healthy donors (4 cultures each), were exposed to 4 experimental conditions: (i) No-contrast imaging with no MBs, using cadence contrast pulse sequencing followed by a MB destruction pulse exposure (mechanical index [MI] ramped from 0.14 to 1.90); (ii) contrast imaging using MBs with contrast pulse sequencing at low MI (MI maintained at 0.14); (iii) contrast imaging with intentional MB destruction by MB destruction pulse exposure; and (iv) Triton-X (positive control, inducing cellular death). Cell culture viability was evaluated pre- and 24 hours post-exposure by quantifying percent ciliated area and ciliary beat frequency.
Results:
The contrast signal was visible for all cultures administered MBs, with signal loss only apparent after the MB destruction pulse. Culture viability (percent ciliated area) was comparable at pre- and post-exposure, for all imaging conditions (coefficient of variation range, 3%-8%), with no decline in ciliary beat frequency. No ciliated area persisted after exposure to Triton-X.
Conclusions:
Intentional MB destruction induced by a high MI does not induce cellular death to the respiratory epithelium. These findings support further development of an inhaled MB contrast agent for pulmonary imaging applications.
