Magnetomotive Optical Coherence Tomography for the Assessment of Atherosclerotic Lesions Using αvβ3 Integrin-Targeted Microspheres

Abstract

Purpose We investigated the early-stage fatty streaks/plaques detection using magnetomotive optical coherence tomography (MM-OCT) in conjunction with αvβ3 integrin-targeted magnetic microspheres (MSs). The targeting of functionalized MSs was investigated by perfusing ex vivo aortas from an atherosclerotic rabbit model in a custom-designed flow chamber at physiologically relevant pulsatile flow rates and pressures. Procedures Aortas were extracted and placed in a flow chamber. Magnetic MS contrast agents were perfused through the aortas and MM-OCT, fluorescence confocal, and bright field microscopy were performed on the ex vivo aorta specimens for localizing the MSs. Results The results showed a statistically significant and stronger MM-OCT signal (3.30±1.73 dB) from the aorta segment perfused with targeted MSs, compared with the nontargeted MSs (1.18±0.94 dB) and control (0.78±0.41 dB) aortas. In addition, there was a good co-registration of MM-OCT signals with confocal microscopy. Conclusions Early-stage fatty streaks/plaques have been successfully detected using MM-OCT in conjunction with αvβ3 integrin-targeted magnetic MSs.

Optical coherence elastography – OCT at work in tissue biomechanics [Invited]

“…Since biological tissues are inherently conductive, this method makes possible a wide range of investigations using biocurrent and tissue conductivity to study not only biomechanical properties, but also electrophysiological properties. A related alternative, extensively investigated by the Boppart group, is the use of magnetic nanoparticles, incorporated into tissues placed in an external magnetic field, as internal transducers for magnetomotive vibration [125][126][127][128][129][130][131][132][133][134][135][136][137][138][139]. Thus, loading is highly localized, to individual or aggregations of nanoparticles, but distributed throughout the tissue, and dynamic, in the alternating-current magnetic field.…”

“…Thus, loading is highly localized, to individual or aggregations of nanoparticles, but distributed throughout the tissue, and dynamic, in the alternating-current magnetic field. Nanoparticles can be functionalized to selectively target tissues of interest [127,136,138]. The particles can be used to induce elastic waves [133] or spectroscopic analysis can be performed by sweeping the excitation frequency and finding resonance modes for micro-rheological analysis [125,131].…”

Molecular Imaging in Optical Coherence Tomography

“…Finally, the control lesion, Fig. 7(c, f, I, l, o) demonstrates that the presence of nanoparticles had minimal impact of the morphology seen in the OCT image, and that there is no innate signal from MMOCT((76). The same surface modification can be utilized to target cancerous tissues.…”

Volumetric full-range magnetomotive optical coherence tomography

“…Titanium dioxide scattering particles (size < 5 μm, 0.5 mg∕ml) were added to the mixture to increase the optical scattering and the solution was sonicated for 1 h. A small amount of microspheres (25 μL∕ml) that contained magnetic nanoparticles (Fe 3 O 4 , size 50 to 100 nm) 4 were then added, and subsequently, the mixture was left in the oven for 8 h at 80°C for curing.…”

“…1,2 These magnetic particles can be engineered to target specific molecules that can enable the generation of molecular specific contrast and aid in the identification of diseased sites or organs in conjunction with MM-OCT. 3,4 The goal of MM-OCT imaging is to spatially localize the presence of magnetic particles within a tissue or organ. The underlying principle is based on the displacement of the magnetic particles under the influence of an externally applied magnetic field.…”