A method of electron spin resonance enhanced magnetic resonance imaging of a human or non-human animal body comprises administering to said body a physiologically tolerable ionic or ionizable paramagnetic substance capable of associating with a cell membrane lipid, said substance particularly being a triarylmethyl free radical. The diagnostic MRI composition may comprise a free radical together with a paramagnetic metal chelate complex and particularly a hydrophilic free radical together with a charged chelate or charged amphiphilic radical with an uncharged chelate. The ESREMRI apparatus includes means for manipulating the detected FID signals to generate an image representative of temporal and spatial variations in FID signal enhancement and may be used in brain activity imaging. <IMAGE>
Improvements in and relating to magnetic resonance imaging