Phase-resolved spectral-domain magnetomotive optical coherence tomography

We advance the magnetomotive-optical coherence tomography (MM-OCT) technique for detecting displacements of magnetic nanoparticles embedded in tissue-like phantoms by using apmplitude and phase-resolved methods with spectral-domain optical coherence tomography (SD-OCT). The magnetomotion is triggered by the external, noninvasive application of a magnetic field. We show that both amplitude and phase data are indicative of the presence and motion of light scatterers, and could potentially be used for studying the dynamics of magnetomotion. The magnetic field modulation is synchronized with data acquisition in a controlled, integrated system that includes a console for monitoring and initiating data acquisition, scanning devices, an electromagnet power supply, and the detection system. Using Fourier analysis, we show that the amplitude and phase modulations in the samples that contain magnetic contrast agents match the frequency of the applied magnetic field, while control samples do not respond to magnetic field activity. We vary the strength of the magnetic field and show that the amplitude and phase steps between regions of zero-magnetic field and regions with non-zero magnetic field change accordingly. The phase is shown to be more sensitive.