One and Two-dimensional NMR to evaluate the performance of consolidants in porous media with a wide range of pore sizes: Applications to cultural heritage

The bone volume fraction, defined as the Bone-Volume-To-Total-Volume ratio (BV/TV), is an important parameter in the assessment of the bone's micro-structure, and is related to the fracture risk in osteoporosis. Although Magnetic Resonance Imaging (MRI) can assess bone micro-architecture parameters invivo, high-field whole body MRI scanners are hardly suitable for wide-scale screening campaigns. Recently, a new NMR application to assess in laboratory the BV/TV of trabecular bone (TB) has been proposed using low-field single-sided NMR. This paper presents an improvement of this technique that allows detection of only the signal from the marrow in the TB suppressing signals from other tissues, which may be present in the sensitive volume of single-sided scanners in a real scenario. The improvement was achieved by filtering signal acquisition by molecular diffusion. Experiments based on an ad-hoc designed Diffusion Weighted T1-T2 pulse sequence have demonstrated that muscle and cartilage signals can be suppressed by using diffusion weighting. On the basis of those experiments, a 1D measurement was established to allow correct estimation of the BV/TV of a TB sample also in the presence of muscle tissue in the sensitive volume of the NMR-scanner. The experiments presented, carried out with the NMR-MOUSE PM10 and the NMR-MOLE, exploiting diffusion-weighted pulse sequences, may pave the way for the in-vivo BV/TV evaluation using single-sided scanners.