ABSTRACT
High-resolution nuclear magnetic resonance (NMR) techniques are powerful tools to study biosystems both in vivo and ex vivo using static samples or rotated ones at appropriate speed of magic angle spinning (Schick 1996, García-Martín et al. 2001, Lindon et al. 2001, 2009, Gun’ko et al. 2005d, 2009d, Barker and Lin 2006, Wind and Hu 2006, Grivet and Delort 2009, Gröger et al. 2009, Michaelis et al. 2009, Muja and Bulte 2009, Courtier-Murias et al. 2012, Duarte and Gil 2012). Water as an essential component of bio-objects plays a very important role in intracellular (Figure 7.1) and extracellular processes which can be studied using the NMR techniques (Finch and Schneider 1975, García-Martín et al. 2001, Turov and Gorbyk 2003, Gun’ko et al. 2005d, 2009d, Tompa et al. 2009, 2010). In bio-objects, many metabolic compounds are mobile enough to be observed with standard high-resolution NMR, and although the metabolite concentrations are low (typically in the micromolar range) many metabolites can be detected by the NMR methods. Therefore in addition to MRI, non-or minimally invasive magnetic resonance spectroscopy (MRS) and spectroscopic or chemical shift imaging (CSI) are increasingly used for biochemical and biomedical research. With MRS that has been employed both in vivo, ex vivo (i.e., using intact excised lesions and tissues), and in vitro (using, e.g., urine, plasma, and tissue and cell extracts), the resonance lines of several key metabolites are measured, and several metabolites have been used as biomarkers as their presence and concentrations could be linked to, e.g., drug response, toxic effects, specic metabolic pathways, tumor phenotype, tumorigenesis, tumor size, tumor diagnosis, increased cell proliferation, cell apoptosis and necrosis, and brain disorders. Hence, MRS provides important complementary information to MRI, and it has been shown that in several cases the combination of MRI and MRS improves the diagnosis of diseases and lesions such as brain, breast, and prostate lesions, sometimes even to the extent that biopsies may no longer be necessary (Wind and Hu 2006).
