Analysis of cross-correlation coefficients for subcutaneous blood signal detection by ARFI Imaging

ARFI subcutaneous blood detection is relevant for monitoring femoral puncture post cardiac catheterization as well as numerous other clinical applications. Blood signal isolation by conventional means is challenged by overlapping frequency spectra and low blood to surrounding tissue signal amplitude ratios. ARFI Imaging was performed ex vivo on a porcine muscle injected with a blood mimicking fluid. Fluid signal isolation was attempted by performing thresholding based on (1) variance of displacement, (2) mean cross-correlation, (3) variance of cross-correlation, (4) variance of first derivative of cross-correlation, and (5) variance of second derivative of cross-correlation. Using the results of the thresholding, an algorithm was developed which exploits both the second derivative of cross-correlation and the mean cross-correlation to extract blood signal.