The low signal-to-noise ratio (SNR) found in ultralow field magnetic resonance imaging (MRI) may be increased using the Overhauser effect ( 1 Leunbach I. European Patent 0409292 A2 1994 Google Scholar , 2 Overhauser AW Polarization of nuclei in metals. Phys Rev. 1953; 92: 411-412 Crossref Scopus (1120) Google Scholar ) or other dynamic nuclear polarization (DNP) techniques ( 3 Planinšic G Grucker D Stepišnik J New method for contrast manipulation in DNP-enhanced MRI. Magn Reson Med. 1996; 35: 379-383 Crossref PubMed Scopus (1) Google Scholar ). The spin polarization, from an unpaired electron present in a contrast medium molecule, can be transferred to the protons of water and result in an enhanced nuclear magnetic resonance (NMR) water signal. The theoretical maximum available enhancement, if the electron spin transition in the contrast medium molecule is fully saturated, may be as high as 329. The theory for signal enhancement using this technique is described elsewhere ( 4 Ardenkjær-Larsen J-H EPR and DNP properties of certain novel single electron contrast agents intended for oximetrical imaging. J Magn Reson. 1998; 133: 1-12 Crossref PubMed Scopus (290) Google Scholar ).