Quantitative magnetic resonance micro-imaging methods for pharmaceutical research

This is a set of images acquired at 3.5 h after the start of dissolution of a swelling matrix tablet. The images give quantitative maps of the water concentration, water mobility and diffusion, and water movement around tablet. All four images are acquired in only 5 min, and they give a story of all these events happening cocurrently during the dissolution process. The use of magnetic resonance imaging (MRI) as a tool in pharmaceutical research is now well established and the current literature covers a multitude of different pharmaceutically relevant research areas. This review focuses on the use of quantitative magnetic resonance micro-imaging techniques and how they have been exploited to extract information that is of direct relevance to the pharmaceutical industry. The article is divided into two main areas. The first half outlines the theoretical aspects of magnetic resonance and deals with basic magnetic resonance theory, the effects of nuclear spin–lattice ( T 1), spin–spin ( T 2) relaxation and molecular diffusion upon image quantitation, and discusses the applications of rapid magnetic resonance imaging techniques. In addition to the theory, the review aims to provide some practical guidelines for the pharmaceutical researcher with an interest in MRI as to which MRI pulse sequences/protocols should be used and when. The second half of the article reviews the recent advances and developments that have appeared in the literature concerning the use of quantitative micro-imaging methods to pharmaceutically relevant research.