Contrast-enhanced imaging of SPIO-labeled platelets using magnetomotive ultrasound.
The ability to image platelets in vivo can provide insight into blood clotting processes and coagulopathies, and aid in identifying sites of vascular endothelial damage related to trauma or cardiovascular disease. Toward this end, we have developed a magnetomotive ultrasound (MMUS) system that provides contrast-enhanced imaging of superparamagnetic iron oxide (SPIO) labeled platelets via magnetically-induced vibration. Platelets are a promising platform for functional imaging contrast because they readily take up SPIOs and are easily harvested from blood. Here we report a novel MMUS system that accommodates an arbitrarily thick sample while maintaining portability. We employed a frequency- and phase-locked motion detection algorithm based on bandpass filtering of the differential RF phase, which allows for the detection of sub-resolution vibration amplitudes on the order of several nanometers. We then demonstrated MMUS in homogenous tissue phantoms at SPIO concentrations as low as 0.09 mg ml(-1) Fe (p < 0.0001, n = 6, t-test). Finally, we showed that our system is capable of three-dimensional imaging of a 185 µL simulated clot containing SPIO-platelets. This highlights the potential utility for non-invasive imaging of platelet-rich clots, which would constitute a fundamental advance in technology for the study of hemostasis and detection of clinically relevant thrombi.
Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-3255, USA.
Ava G
AG
Pope
Gongting
G
Wu
Frances Y
FY
McWhorter
Elizabeth P
EP
Merricks
Timothy C
TC
Nichols
Tomasz J
TJ
Czernuszewicz
Caterina M
CM
Gallippi
Amy L
AL
Oldenburg
D000818:Animals; D001692:Biological Transport; D001792:Blood Platelets / Q000000981:diagnostic imaging* / Q000378:metabolism; D003287:Contrast Media; D005290:Ferric Compounds / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D059346:Magnets; D019047:Phantoms, Imaging; D013194:Staining and Labeling; D014463:Ultrasonography / Q000379:methods*
D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide