Cortical Bone Mechanical Assessment via Free Water Relaxometry at 3 T

Abstract

Background: Investigation of cortical bone using magnetic resonance imaging is a developing field, which uses short/ultrashort echo time (TE) pulse sequences to quantify bone water content and to obtain indirect information about bone microstructure. Purpose: To improve the accuracy of the previously proposed technique of free water T 1 quantification and to seek the relationship between cortical bone free water T 1 and its mechanical competence. Study Type: Prospective. Subjects: Twenty samples of bovine tibia bone. Field Strength/Sequences: 3.0 T; ultra-fast two-dimensional gradient echo, Radio frequency-spoiled three-dimensional gradient echo. Assessment: Cortical bone free water T 1 was quantified via three different methods: inversion recovery (IR), variable flip angle (VFA), and variable repetition time (VTR). Signal-to-noise ratio was measured by dividing the signal of each segmented sample to background noise. Segmentation was done manually. The effect of noise on T 1 quantification was evaluated. Then, the samples were subjected to mechanical compression test to measure the toughness, yield stress, ultimate stress, and Young modulus. Statistical Tests: All the statistical analysis (Shapiro-Wilk, way analysis of variance, paired t test, Pearson correlation, and Bland-Altman plot) were done using SPSS. Results: Significant difference was found between T 1 quantification groups (P < 0.05). Average T 1 of each quantification method differed significantly after adding noise (P < 0.05). VFA-T 1 values significantly correlated with toughness (r = À0.68, P < 0.05), ultimate stress (r = À0.71, P < 0.05), and yield stress (r = À0.62, P < 0.05). No significant correlation was found between VTR-T 1 values and toughness (P = 0.07), ultimate stress (P = 0.47), yield stress (P = 0.30), and Young modulus (P = 0.39). Data Conclusion: Pore water T 1 value is associated with bone mechanical competence, and VFA method employing short-TE pulse sequence seems a superior technique to VTR method for this quantification. Level of Evidence: 2 Technical Efficacy: 1

Editorial for “Cortical Bone Mechanical Assessment via Free Water Relaxometry at 3 T”

“…Because the T2* is less than 400 μs for BW and more than 1 ms for PW in 3 T MRI, it is reasonable that the T1 value measured by STE (TE, 1.3 ms) in this study is attributed to the PW rather than BW because of the rapid decay of BW signal. The diverse results between Jerban's study 7 and the current study 8 might be due to the difference of T1 values between BW and PW. It is worth for further studies to clarify the relationship between the T1 value of the water (TW, BW, and PW) and the mechanical properties in the cortical bone.…”

“…In the article entitled “Cortical Bone Mechanical Assessment via Free Water Relaxometry at 3T”, the authors quantified free water (or PW as mentioned) content of cortical bone in 20 tibiae of freshly slaughtered cows using STE (TE, 1.3 ms) pulse sequences, including inversion recovery (IR), variable flip angle (VFA), and variable repetition time (VTR) methods, to quantify T1 values of tibial cortical bone and obtained indirect information about bone microstructure and mechanical properties. 8 They also investigated the contribution of the T1 value for the PW in the cortical bone to the mechanical properties of the cortical bone via mechanical compression test. In T1 measurements, their results showed that the T1 values measured by the VTR and VFA methods (VTR‐T1 and VFA‐T1, respectively) did not differ from that measured by the IR method (IR‐T1).…”

The Impact of Major and Trace Elements in Serum and Bone on Dual-Energy X-Ray Absorptiometry-Derived Hip Strength

“…Fourthly, due to limitations in the methods used in this study, we did not assess the water content of the bone, which is an integral constituent that influences the mechanical properties of bone. Approximately 20% of the cortical bone consists of water, which is bound to the collagenous structure, embedded in the crystal lattice and freely residing in the network of pores, playing an important role in matrix mineralization and overall bone resistance [ 40 , 41 ]. Finally, bone samples were obtained from patients with hip OA, and hence, our findings may not apply to healthy individuals or patients with other bone disorders, as hip OA is associated with chronic inflammatory state that involves auricular cartilage, subchondral cortical and trabecular bone, and synovium, leading to articular cartilage stress distribution changes with subchondral bone expansion.…”

Study of Ultrasonic Guided Wave Propagation in Bone Composite Structures for Revealing Osteoporosis Diagnostic Indicators

“…Ultrasonometry has advantages over the widely used X-ray densitometry, such as the absence of ionizing radiation, compactness, and lower costs. There are also other methods for bone inspection based on various physical phenomena and principles, such as magnetic resonance imaging [ 19 , 20 ], pulse-echo measurements [ 21 ], and ultrasound back scattering [ 22 ]. They aim to assess bone porosity and thickness by measuring the free water content in the bone volume or the reflected and scattered waves.…”