A test material for tissue characterisation and system calibration in MRI

Abstract

A tissue-equivalent test material for magnetic resonance imaging (MRI) has been produced from a polysaccharide gel, agarose, containing gadolinium chloride chelated to EDTA. By varying the amounts of each constituent, the T₁ and T₂ of the material can be varied independently. As a result, the entire range of in vivo tissue relaxation times can be covered. Through the mathematical modelling of the ¹H relaxation theories for both the gel and chelated paramagnetic ion, it has been possible to create a material with relaxation properties and behaviour predictable as functions of both the Larmor frequency and temperature. The similarity of the material to in vivo tissues, in terms of its biological and physical NMR characteristics, makes it an excellent tissue-equivalent substance, in addition to being an accurate calibration standard for routine MRI.