Review on Acoustic Droplet Vaporization in Ultrasound Diagnostics and Therapeutics

Table 1

Droplet fabrication method, significances and specifications used in bubble activation.

Study	Core material	Shell	Fabrication method	Size before ADV	Size after ADV	Significance	Future potential
Li et al. [37]	Perfluoropentane	Albumin	Mixing Saline containing PBS albumin and perfluoropentane	Various sizes of micrometer scale	36 μm	A model that describes the location of initial nucleation site in liquid PFC droplets depending on droplet size and acoustic characteristics	The initial nucleation site always occurs within the droplet and not at the bubble-surface interface
Miles et al. [38]	Perfluoropentane	Lipids	NA	3-30 μm	NA	Possible to predict ADV initiation pressure threshold by combining classical nucleation theory with superharmonic focusing	Customize droplet size and/or pressure in advance depending on the application
Strohm et al. [22]	Perfluorohexane	Fluorosurfactant (Zonyl FSO)	Coarse emulsification by vortexing, followed by membrane emulsification	2.45-13.6 μm	NA	Only the physical properties of the PFH liquid determines the droplet photoacoustic spectrum features	Proof of concept
Doinikov et al. [39]	Octafluoropropane and decafluorobutane	1,2-distearyl-sn-glycero-3-phosphocholine, DSPE-PEG2000	Condensation	2.2-6.7 μm	Up to 40 μm	A new model that describes the dynamic behavior of highly volatile perfluorocarbon emulsions, which was in good agreement with experimental results	Predict the behavior of highly volatile perfluorocarbon emulsions at various acoustic parameter values
Lin et al. [40]	Decafluorobutane	DPPC, 16:0 PEG2000 PE	Condensation	243 nm	1.22 μm	PCCAs in microchannel will have a lower vaporization efficiency than PCCAs in free environment at the same acoustic conditions	Higher validity in conclusions drawn from images with microvasculature
Sheeran et al. [41]	Perfluoropropane or perfluorobutane	1,2-distearoyl-sn-glycero-3-phosphocholine, DSPE-PEG2000	Condensation	192 nm	1.2 μm (DFB), 1.6 μm (OFP)	Unique acoustic signals are generated by vaporizing phase-change droplets that can be detected and isolated from other acoustic sources	Combine different imaging modalities for optimal diagnostics
Puett et al. [42]	Decafluorobutane or octafluoropropane	DSPC, DSPE-PEG2000	Condensation	240 nm	NA	A new pulse sequence design that enables fast image-activation-image process	Fast and easy study of ADV activated droplets in research
Li et al. [43] (method developed by Paul S. Sheeran et al. [18])	Decafluorobutane	Lipids	Condensation	230-350 nm	5-6.5 μm	Linear relationship between droplet concentration and activation; at room temperature, the bubbles were fewer and larger compared to body temperature	Control of droplet concentrations in applications that use inertial cavitation
Reznik et al. [44]	Perfluoropentane	Fluorosurfactant (Zonyl FSO)	Tip-sinocation approach	400 nm	500 nm - 5 μm	The coating material highly influence the acoustic behavior of vaporized PFC droplets	Fluorosurfactant-coated droplets has potential as contrast agents in ultrasound imaging