A new method to assess the kinetics of rouleaux formation in human subcutaneous veins using high frequency parametric imaging: preliminary results

Abstract

Laser erythroaggregameter is considered as the gold standard method for in vitro red blood cell (RBC) aggregation characterization. With this method, a high shear rate is first applied on the blood sample to disrupt the aggregates and to provide a common reference level prior to the aggregation phases. In vivo, it is very difficult to have a standard protocol that would allow studying the kinetics of rouleaux formation following prior disruption of the aggregates. We propose a new approach using low frequency shear waves to initially disrupt the aggregates, followed by the measurement of the kinetics of aggregation with high-frequency ultrasound in a peripheral subcutaneous vein following flow stoppage. Radio frequency (RF) data was recorded and absolute backscatter coefficient (BSC) and spectral slope (SS) were calculated on video sequences of 25 s for two normal individuals. BSC and SS varied over time (p < 0.001) and differed between subjects (p < 0.001), due to the different aggregability of RBCs between the two individuals. This later result was corroborated by the laser aggregameter method. Immediately after the transmission of shear waves, no significant differences between groups were found for BSC and SS, suggesting that this approach effectively provides a common reference level of disaggregation. In conclusion, it is shown that shear wave propagation in the subcutaneous vein allows disaggregation of RBCs and the obtaining of a common reference level to allow reproducible measurements of BSC and SS during the kinetic of rouleaux formation. It is believed that this method could be of clinical significance for in vivo measurements in pathologies associated with hyper-aggregation of erythrocytes.