MSR’s are necessary for medical processes that use highly sensitive sensors to detect and measure minute biomagnetic signals radiated from various parts of the human body. The MSR improves the strength of the useful signal by excluding the background magnetism and other spurious magnetic fields. An MSR is an enclosure with a shell comprising layers of high permeability metals that are also good electrical conductors. This attenuates (absorbs) the spurious magnetic and electrical fields emanating from numerous sources in buildings such as hospitals. Before designing an MSR, the electromagnetic ambient at the proposed site has to be determined. Depending on the results, alternative sites may need to be considered to make a solution technical feasible or financially acceptable.