Continuous-Wave Magnetic Resonance Imaging of Short T2 Materials

There is growing interest in the use of magnetic resonance imaging (MRI) to examine solid materials where the restricted motion of the probed spins leads to broad lines and short T₂ values, rendering many interesting systems invisible to conventional 2DFT pulsed imaging methods. In EPR T₂ seldom exceeds 0.1 μs and continuous-wave methods are adopted for spectroscopy and imaging. In this paper we demonstrate the use of continuous-wave MRI to obtain 2-dimensional images of short T₂ samples. The prototype system can image samples up to 50 mm in diameter by 60 mm long and has been used to image polymers and water penetration in porous media. Typical acquisition times range between 10 and 40 min. Resolution of 1 to 2 mm has been achieved for samples with T₂ values ranging from 38 to 750 μs. There is the possibility of producing image contrast that is determined by the material properties of the sample.