Motion artifacts are caused by which of the following?

Motion artifacts in magnetic resonance imaging (MRI) typically arise from patient movement during the scanning process. These artifacts occur when the spins of protons (hydrogen nuclei) in the body change location between different phase encoding steps. Each phase encoding step captures a slice of the data, and if there’s movement during this time, the encoding of the spins will be inconsistent across the dataset, leading to distorted images. This can manifest as blurring or ghosting of the structures in the image.

While other options like static magnetic fields, electrical interference, and image reconstruction errors can introduce artifacts in imaging, they do not directly correlate with the specific type of motion artifacts associated with patient movement. Static magnetic fields create the fundamental magnetic environment for the MRI but don’t relate to changes in spin location due to motion. Electrical interference typically leads to noise rather than motion-specific artifacts, and reconstruction errors pertain more to how the data is processed after acquisition rather than during the actual imaging phase itself. Thus, option B is the primary cause of motion artifacts in MRI, highlighting the importance of minimizing patient movement for optimal image quality.