Fig. 2.

UTE-MRI, μCT images, and MT-modeling results of three representative cortical bone strips harvested from different donors possessing three different levels of porosities. (a) UTE-MRI (TE = 0.032 ms) images of twenty cortical bone strips with approx. 4 × 2 mm cross-sections. Three of the cortical bone strips harvested from a 47-year-old male (I), a 57-year-old female (II), and a 91-year-old female (III) are indicated with yellow rectangles. A rubber reference was also scanned together with bone samples, showing with much brighter signal at the top of the syringe cross-section. (b), (c), and (d) Corresponding μCT images of cortical bone strips indicated as I, II, and III, respectively in Fig. 2(a). Average porosity was 5%, 33%, and 53% for specimens (b), (c), and (d), respectively. (e), (f), and (g) The two-pool MT modeling analyses for bone strips indicated in (a) as I, II, and III, respectively, using three pulse power levels (400° in blue, 600° in green, and 800° in red) and five frequency offsets (2, 5, 10, 20, 50 kHz). MMF and T2_MM refer to macromolecular fraction and macromolecular T2, respectively.