Which material would create the largest artifact in MRI?

The material that would create the largest artifact in MRI is a cobalt screw. This is primarily due to the ferromagnetic properties of cobalt, which can significantly affect the homogeneity of the magnetic field within the MRI system. When ferromagnetic materials like cobalt are placed within the magnetic field of an MRI scanner, they can become magnetized and cause distortions in the magnetic field.

These distortions lead to substantial signal loss in the MRI images, resulting in large artifacts that can obscure structures and complicate image interpretation. Ferromagnetic materials tend to have a strong influence on the imaging environment, not only creating artifacts but also posing potential safety risks due to their attraction to the MRI's strong magnetic field.

Conversely, materials such as aluminum and titanium are non-ferromagnetic and therefore do not generate large artifacts. While 316L stainless steel has some level of magnetic susceptibility, it is generally less significant than that of cobalt in terms of artifact creation. This understanding of metallic properties and their interaction with MRI technology is crucial for safety and image quality in Magnetic Resonance Imaging.