High Resolution Optical Doppler Tomography for in vivo Blood Flow Dynamics with Pharmacological Intervention
High spatial resolution noninvasive techniques for in vivo blood flow imaging are currently not available as a diagnostic tool in clinical medicine. Such techniques could have a significant impact for biomedical research and clinical diagnosis. The rationale for using Optical Doppler Tomography (ODT) to characterize the underlying microvasculature is that the technique will be able to probe user-specified discrete spatial locations with high spatial resolution. The objective of our research is to use a noninvasive tomographic imaging technique with high spatial resolution (2-15μm) to characterize and monitor fluid flow and microvasculature in highly scattered biological tissues at user-specified discrete locations. ODT combines Laser Doppler Flowmetry (LDF) with optical coherence tomography (OCT) to obtain high-resolution tomographic velocity and structural images of static and moving constituents biological tissue with high light scattering properties. ODT demonstrates the ability to simultaneously record structure and velocity in images. We present ODT images of structure and velocity using in vivo blood flow in the Chick Chorioallantoic Membrane (CAM). ODT images were also recorded before and after topical application of nitroglycerin. ODT images of in vivo CAM blood flow demonstrate that the magnitude of blood flow velocity at the center of the vein is maximal and that it decreases monotonically towards the peripheral wall. The arterial wall can be clearly identified by its dilatation after the application of nitroglycerin. Peak blood flow velocity at the center of the artery increased from 3000 to 4000μm/s after nitroglycerine application. Dilatation of the vein due to nitroglycerine is observed in both the structure and velocity at the center of the vein. It decreased from 2000 to 1000 μm/s after nitroglycerin application. In conclusion, in our in vivo studies on CAM model vasculatures, the application of ODT to characterize and image blood flow with high spatial resolution at discrete user-specified locations in biological tissues with high light scattering properties is feasible.