T1 correlates age: A short-TE MR relaxometry study in vivo on human cortical bone free water at 1.5 T.

Large pores of human cortical bone (> 30 μm) are filled with fluids, essentially consisting of water, suggesting that cortical bone free water can be considered as a reliable surrogate measure of cortical bone porosity and hence quality. Signal from such pores can be reliably captured using Short Echo Time (STE) pulse sequence with echo-time in the range of 1–1.5 msec (which should be judiciously selected correspond to T 2 ⁎ value of free water molecules). Furthermore, it is well-known that cortical bone T 1 -relaxivity is a function of its geometry, suggesting that cortical bone free water increases with age. In this work, we quantified cortical bone free water longitudinal relaxation time (T 1 ) by a Dual-TR technique using STE pulse sequence. In the sequel, we investigated relationship between STE-derived cortical bone free water T 1 -values and age in a group of healthy volunteers (thirty subjects covering the age range of 20–70 years) at 1.5 T. Preliminary results showed that cortical bone free water T 1 highly correlates with age ( r 2 = 0.73, p < 0.0001), representing cortical bone free water T 1 as a reliable indicator of cortical bone porosity and age-related deterioration. It can be concluded that STE-MRI can be utilized as proper alternative in quantifying cortical bone porosity parameters in-vivo , with the advantages of widespread clinical availability and being cost-effective. [ABSTRACT FROM AUTHOR]