Page 26 - Spring 2019
P. 26

'I'hera¢:uI.Ist:iI: Cavitation
Cavitation Nucleation Cavltatlon Detection Therageutlc Effect
500 M, E  wiui cuvltutlovi -
F”; 4 »-v v» ; mm.‘ - Wllh cavltatloh nuclei .
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 B-Mode Ullmsound with ‘
FUS I ,/,j,,, Cavitation Map Overlay
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in any rim Depth -unrus low! lmm) ‘~ 5
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Figurz 5. Naeleatiari and eavitatiari deteetiari strategies far a range af emerging theraeeastie upplimtiaris. Tap rim: passively mamtared
cuvitatinn—mei1iated thermal ublutiwi nucleated by ideally injected gas—smbilizingpurtic1es in liver tissue. Czntzr TIIW.’ daal—arra,v passively
mapped mvitutinmmeiiiuted fraetiariatieri af the intervertebral disc, nucleated by gas—stubilizirig salid palymerie particles. Botfitm TIIW.’
sing1e—mmy passively mapped cuvitutinmenhanced drag delivery ta tamars. fallawirig systemic admimstratiari nf1ipid—she11ed micmlzulzbles
and an aricalytic virus. see text far a fuller explanation.
This process is illustrated in Figure 5, top raw, using a sample monitoring of temperature remains extremely challenging,
of bovine liver exposed to FUS while monitoring the process exploiting acoustic cavitation to mediate tissue heating en-
with a single-element passive-cavitation detector (PCD). In ables the use of passive cavitation detection and mapping as
the absence of cavitation nuclei, the PCD signal is weak and a means of both monitoring (Iensen et al., 2013) and control-
the tissue is unaltered. However, when using these same FUS ling (Hockham et al., 2010) the treatment in real time.
settings in the presence of locally injected cavitation nuclei,
the PCD signal is elevated by an order of magnitude and dis- There are several emerging biomedical applications where
tinct regions of tissue ablation (in Figure 5, mp right, light the use of ultrasound-mediated heating is not appropriate
pink regions correspond to exposures at three locations) are due to the potential for damage to adjacent structures, and
observed (Hockham, 2013). Because the ultrasound-based tissue disruption must be achieved by mechanical means
24 l AI:|'.iuII:l:I Tbday 1 spring 2019















































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