Feasibility of Doppler variance imaging for red blood cell aggregation characterization.

An abnormal level of red blood cell (RBC) aggregation is a clinical condition associated with many pathologies. Our purpose is to investigate the feasibility of spectral domain phase-resolved optical Doppler tomography incorporated with Doppler variance imaging to characterize RBC aggregation in flowing blood. Variance/standard deviation (SD) of the Doppler frequency spectrum of porcine blood flowing through a glass tube (diameter 300 microm) at 4.7 mms is measured. For nonaggregating RBCs with hematocrits of 20, 40, and 60%, the mean centerline SD values were 34.2+/-1.2, 47.8+/-1.0, and 47.2+/-0.5, respectively. After dextran 500 induction, the SD value decreased significantly to 29.9+/-0.7, 37.9+/-3.0, and 40.1+/-0.6 (P<0.01) in the aggregated blood, respectively. The results demonstrate that Doppler variance imaging using the SD value is capable of differentiating normal and aggregated blood.