Measurement of Bound and Pore Water T1 Relaxation Times in Cortical Bone Using Three-Dimensional Ultrashort Echo Time Cones Sequences

Purpose: We present three-dimensional ultrashort echo time Cones (3D UTE Cones) techniques for quantification of total water T-1 (T-1(TW)), bound water T-1 (T-1(BW)), and pore water T-1 (T-1(PW)) in vitro and in vivo using a 3 Tesla (T) scanner. Methods: T-1(TW), T-1(BW), and T-1(PW) were measured with three-dimensional (3D) Cones and adiabatic inversion recovery Cone (IR-Cone) sequences. Two-dimensional (2D) nonselective ultrashort echo time (UTE) techniques, including saturation recovery, variable repetition times (TRs), and inversion recovery (IR) preparation approaches were compared with 3D-Cones techniques on bovine cortical bone samples (n = 8). The 3D Cones sequences were used to measure T-1(TW), T-1(BW), and T-1(PW) in the tibial midshaft of healthy volunteers (n = 8). Results: Comparable T-1 images were achieved for cortical bone between 3D Cones and 2D UTE techniques as well as those published in the literature. The 3D Cones sequences showed a mean T-1(TW) of 208622 ms, a mean T-1(PW) of 545628 ms, and a mean T-1(BW) of 131612 ms for bovine cortical bone; and a mean T-1(TW) of 246632 ms, a mean T-1(PW) of 524646 ms, and a mean T-1(BW) of 134611 ms for the tibial midshaft of healthy volunteers. Conclusions: The 3D Cones sequences can be used for fast volumetric assessment of bound and pore water T-1 images in vitro and in vivo. (C) 2016 International Society for Magnetic Resonance in Medicine