Fig. 4

Example of each limiting issue causing partial flow quantification. Filtered contrast-enhanced US images with velocity streamlines superimposed. The vessel wall is presented in black in all examples. The presence of a stent is indicated in white. a Loss of correlation due to high velocities or complex flow phenomena, here observed distal to a stenotic lesion, indicated with the orange arrow (supplementary video 4). b Only a small part of the vessel is captured within the field of view due to the geometry of the arteries (supplementary video 5). c Loss of contrast due to microbubble destruction. During systole (top), constant replenishment of microbubbles permits sufficient bubble signal, whereas severe bubble destruction occurs during diastole (bottom) due to the prolonged insonation period in the case of lower blood flow velocities (supplementary video 6). d A shadow region possibly caused by a calcified lesion at the anterior side of the lumen, resulting in an interruption of the vector velocity field (top) and bubble intensity (bottom) (supplementary video 7)