Gradiometer Using Middle Loops as Sensing Elements in a Low-Field SQUID MRI System

A new gradiometer scheme uses middle loops as sensing elements in low-field superconducting quantum interference device (SQUID) magnetic resonance imaging (MRI). This design of a second order gradiometer increases its sensitivity and makes it more uniform, compared to the conventional side loop sensing scheme with a comparable matching SQUID. The space between the two middle loops becomes the imaging volume with the enclosing cryostat built accordingly.