Parameters related to pore-space structure of the trabeculae in cancellous bone are difficult to determine quantitatively, but they can be important to characterize changes induced in bone by diseases such as osteoporosis. We present two nuclear magnetic resonance (NMR) methods to measure the internal porosity φtrab of the trabeculae, based on two different measurements of the fraction of intratrabecular and intertrabecular pore-space in animal femur samples. These procedures have been developed within the more general framework of the NMR studies for fluids in porous media. In the first method we use the ratio between the amount of collagen (solid-like) H1 and that of the fluids in the samples. In the second, which can be applied only on defatted and water saturated samples, we use the distributions of longitudinal relaxation times. The φtrab values obtained are constant for porosity φ of the samples over the range 40%–70%, with each method giving φtrab=(29±4)%, which is consistent with the only data available, the porosity of related cortical bone. The traditional parameter bone volume fraction is simply given by (1−φ)/(1−φtrab).

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Articles you may be interested inComposition, microstructures, and magnetic properties of Bi-modified NiCuZn-ferrite for low temperature Co-fired ceramic application J. Appl. Phys. 115, 17A524 (2014); 10.1063/1.4867595Effects of time and temperature of firing on Fe-rich ceramics studied by Mössbauer spectroscopy and twodimensional 1H-nuclear magnetic resonance relaxometry Nuclear magnetic resonance ͑NMR͒ relaxation and imaging are shown to give information on the changes of the pore space structure in ceramics during the sintering process. On a set of ceramic samples held at fixed maximum firing temperature of 1280°C for different lengths of time, called ''soaking times'' in the ceramics industry, NMR methods were applied to quantify pore space properties such as connected porosity and pore size distributions. The longer the soaking time the lower the connected porosity, but no corresponding general statement can be made with regard to the pore size distribution. The homogeneous distribution of pores where the porosity is 17% for minimal soaking times becomes heterogeneous and with bigger pores but with porosity only about 5% after 10 min of soaking time. The results obtained are combined with those from traditional techniques such as scanning electron microscopy ͑SEM͒ and mercury intrusion porosimetry ͑MIP͒. The measured connected porosities and SEM analysis are in agreement with the NMR results. The ''pore size'' distributions obtained by magnetic resonance relaxation and MIP differ substantially and give complementary information, because in relaxation measurements ''size'' tends to correspond to pore dimensions, while in MIP ''size'' corresponds to the dimensions of the pore ''throats,'' the channels connecting the pores. The discrepancy between pore and pore-channel size increases with the soaking time and makes it clear that a higher level of sintering allows the formation of larger pores connected by smaller channels. For the longest soaking time sample, the SEM photos and the lack of a NMR signal make it clear that there is substantial isolated porosity and essentially no connected porosity.

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