Slow flow or no flow? Color and power Doppler US pitfalls in the abdomen and pelvis.

Color and power Doppler ultrasonography allow rapid assessment of tissue vascularity. Motion sensitivity to phenomena such as flow along the edge of gallstones, urinary jets, and placentation abnormalities can result in artifactual flow patterns that require corroboration with spectral analysis. Similar artifacts have also been noted at the edge of bone and along the bowel wall secondary to bowel motion. These artifacts fall into four categories: (a) twinkle artifacts, which occur behind reflectors; (b) edge artifacts, which occur along strongly reflective interfaces; (c) flash artifacts, which occur due to tissue or fluid motion; and (d) pseudoflow, which occurs due to nonvascular flow of other fluids such as urine or ascites. Knowledge of the most common sites of color and power Doppler artifacts, familiarity with the typical appearances of these artifacts, and liberal use of spectral analysis will help prevent misinterpretation of these findings and may lead to improved diagnostic accuracy.