MRI Physics And Clinical Applications Practice Exam

Motion-related ghosting is the most common MRI artifact because patient movement during data acquisition introduces phase errors that do not cancel out between successive line acquisitions. MRI collects data over several seconds, so even small movements from breathing, swallowing, or restlessness create inconsistencies that manifest as duplicate, ghost-like copies of anatomy shifted along the phase-encode direction. This type of artifact routinely appears across many sequences and body regions, making it the most frequent issue seen in clinical practice. Chemical shift artifact, while common near fat–water interfaces, arises from separate resonance frequencies of fat and water and shows up as misregistration or a bright band at fat boundaries—not as universally encountered as motion ghosts. Aliasing occurs when the field of view is too small and wraps anatomy into the opposite side of the image; it’s sequence- and setup-dependent rather than universally pervasive. Zipper artifact results from hardware or external interference and tends to be localized and intermittent.