Flow of blood-saline mixtures studied by time-domain optical coherence tomography

In-vitro analysis of flowing blood-saline mixtures is performed by time-domain optical coherence tomography imaging. The mixtures contain blood in concentrations ranging from 100% to 20%. For each image, a corresponding compounded profile is obtained by adding one thousand adjacent A-scans. The compounded profiles are used for characterizing the optical coherence tomography signal as it propagates within the studied blood\u2013saline mixtures. The results obtained point toward the possibility of acquiring intra-vascular images of arterial tissue that is located behind slabs of flowing blood-saline. A threshold in the propagation distance beyond which the recorded signal becomes dominated by its multiple scattered components is established along the compounded profiles. The threshold location, at a depth of ~0.6 mm, is independent of blood concentration. Further investigation of the compounded profiles reveals that the region extending to a maximum depth of about 200 \u3bcm from the point where the probing beam enters blood-saline mixtures could reveal information about the flow regime. This opens the possibility of another application for time-domain optical coherence tomography in intravascular imaging: assessing the flow regime, i.e. laminar or turbulent.Peer reviewed: YesNRC publication: Ye