Measurement of bound and pore water T1 relaxation times in cortical bone using three-dimensional ultrashort echo time cones sequences

Abstract

Purpose: We present three-dimensional ultrashort echo time Cones (3D UTE Cones) techniques for quantification of total water T₁ ( T1TW), bound water T₁ ( T1BW), and pore water T₁ ( T1PW) in vitro and in vivo using a 3 Tesla (T) scanner.

Methods: T1TW, T1BW, and T1PW 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 T1TW, T1BW, and T1PW in the tibial midshaft of healthy volunteers (n = 8).

Results: Comparable T₁ 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 T1TW of 208 ± 22 ms, a mean T1PW of 545 ± 28 ms, and a mean T1BW of 131 ± 12 ms for bovine cortical bone; and a mean T1TW of 246 ± 32 ms, a mean T1PW of 524 ± 46 ms, and a mean T1BW of 134 ± 11 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 T₁ images in vitro and in vivo. Magn Reson Med 77:2136-2145, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Keywords: Cones; T1 measurement; UTE; bound water; cortical bone; pore water.