Estimating Motion in Ultrasound Images of the Small Bowel: Optical Flow without Image Structure

Measurement of motion in transabdominal ultrasound sequences of the small bowel is hampered by the unstructured, textured appearance of the images. We investigate a method of measuring Optical Flow in the sequences, based on an analysis of the spatio-temporal frequency spectrum. The method requires no unrealistic assumptions about the distribution of energy in the frequency spectrum and extends readily to deal with the aperture problem. Evaluation on synthetic image sequences indicates it has advantages in accuracy and precision of velocity estimates. Qualitative evaluation on real ultrasound sequences indicate encouraging performance, provided occurrence of the aperture problem is identified and appropriate processing applied.