Mahsa Talebi1,2, Shahrokh Abbasi-Rad2, Malakeh Malekzadeh2,3, Mohamad Shahgholi2,4, Ali A Ardakani5, Kimia Foudeh4, Hamidreza S Rad1,2,6,7. 1. Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran. 2. The Quantitative MR Imaging and Spectroscopy Group, Research Center for Cellular and Molecular Imaging, Tehran University of Medical Sciences, Tehran, Iran. 3. Medical Physics Department, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. 4. Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran. 5. Department of Radiology Technology, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 6. Osteoporosis Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran. 7. Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
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 T1 quantification and to seek the relationship between cortical bone free water T1 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 T1 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 T1 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 T1 quantification groups (P < 0.05). Average T1 of each quantification method differed significantly after adding noise (P < 0.05). VFA-T1 values significantly correlated with toughness (r = -0.68, P < 0.05), ultimate stress (r = -0.71, P < 0.05), and yield stress (r = -0.62, P < 0.05). No significant correlation was found between VTR-T1 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 T1 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.
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 T1 quantification and to seek the relationship between cortical bone free water T1 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 T1 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 T1 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 T1 quantification groups (P < 0.05). Average T1 of each quantification method differed significantly after adding noise (P < 0.05). VFA-T1 values significantly correlated with toughness (r = -0.68, P < 0.05), ultimate stress (r = -0.71, P < 0.05), and yield stress (r = -0.62, P < 0.05). No significant correlation was found between VTR-T1 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 T1 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.