Marker for diff types o petspect awful resolution

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Unformatted text preview: onal o What is tissue doing in that area o fMRI o SPECt, PET – metabolism o Ultrasound – faster flow = brighter o Photoacoustic – can see oxygenation of blood §༊ Tumors = more deoxygenated Molecular o Need contrast agent (to sense molecular interactions) o MRI – super paramagnetic nanoparticles (get dark spot where nanoparticles are) • • • • • • • • o Photoacoustic – yellow = gold o Ultrasound – can use microbubbles (targeted to p- selectin, imp. Marker for ______) Diff Types o PET/Spect §༊ Awful resolution o US – non- ionizing radiation Ultrasound Contrast Agents o Contrast due to differences in acoustic impedance o If gas bubble, strong diff. in impedance between bubble and surrounding material o Perfuorocarbon gas inside o Targeting Antibodies on outside o Restricted to vasculature (otherwise use nanoparticle…1- 200 nm???) (see Aziz’s notes) o Acoustic pressure goes up and down and microbubble size expands/contracts proportionally o Able to expand easier than contract à༎ generates 2nd and 3rd harmonic o Transmit at resonant frequency - à༎ receive at double frequency Use tricks o Send positive and negative pressure pulse o Then send negative and positive pressure pulses o What you receive will look like what you transmit (although attenuated) o When have microbubbles, doesn’t look like sinusoid anymore Sample applications – molecular imaging o Normal b- mode ultrasound image (arrows to tumors?) o Insert microbubbles à༎ vasculature lights up …tells you how perfused tissue is §༊ Physician concluded that these were small tumors w/o good vasculature o Non- targeted bubbles on top o 2nd ones targeted to...
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