Figure 14d.

Artifacts that should be excluded from MR elastographic measurements of stiffness. (a) MR elastogram: For ROI placement, typically about 1 cm, or one-half of a wavelength, is excluded around the edge of the liver, including fissures and fossa, to account for partial volume effects (arrows), which may result in an artificially high stiffness calculation. (b) MR elastogram shows an artifactual “hot spot” (arrow) that is often found directly under the passive driver. (c, d) Axial diffusion-weighted MR image (c) and MR elastogram (d) show that large (>3-mm) vessels (arrows) do not reflect parenchymal stiffness. (e, f) A wave image (e) and MR elastogram (f) show that regions of wave interference (arrow) can be constructive or destructive, resulting in variable effects on the liver stiffness.