Magnetomotive optical coherence elastography for biomedical applications

This thesis presents a new non-invasive optical method for assessing biomechanical properties of tissues and cells in real time and with micron scale resolution, magnetomotive optical coherence elastography (MM-OCE). Biomechanical properties are important because they relate to the tissues’ state of health and they can be utilized for monitoring changes due to pathological processes or therapeutic treatments. In optical coherence tomography (OCT), the imaging technique that MM-OCE is based on, near infrared light penetrates a few millimeters into highly scattering biological tissues and the backscattered light is detected in real time with interferometry. Post-processing of the optical signal renders structural images and displacement maps of dynamic processes within the specimens, which contain information about the mechanical signature of the tissues or cells. MM-OCE utilizes magnetic nanoparticles or microspheres that are embedded in the samples of interest, and which induce motion in the samples in the presence of an external magnetic field produced by a custom built solenoid coil. Three studies are presented: the first one introduces the MM-OCE technology and demonstrates its feasibility and versatility on a set of tissue-mimicking silicone phantoms, the second one applies MM-OCE to excised rabbit tissues and reveals their intricate biomechanical behavior, and the third one explores the possibility of extending the technique to the study of cells. Finally, I discuss aspects of this work that can be further advanced by future modeling of the biomechanical properties of different types of soft tissue