syngo WARP – Metal Artifact Reduction Techniques in Magnetic Resonance Imaging

■ Through-plane distortion: The local field offset leads to curved and frayed slices instead of the expected flat image plane (Fig. 1). Since both in-plane and through-plane distortions shift image pixels away from their real positions, image geometry appears to be distorted. In both cases, regions with severe field changes will lead to signal voids visible as black spots and signal pileups visible as bright spots. However, it makes sense to distinguish between inand through-plane artifacts, since different techniques are needed to reduce these types of artifacts.