Ultrashort echo time magnetization transfer (UTE-MT) imaging of cortical bone

Magnetization transfer (MT) imaging is one way to indirectly assess pools of protons with fast transverse relaxation. However, conventional MT imaging sequences are not applicable to short T2 tissues such as cortical bone. Ultrashort echo time (UTE) sequences with TE values as low as 8 µs can detect...

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Bibliographic Details
Published in:NMR in biomedicine 2015-07, Vol.28 (7), p.873-880
Main Authors: Chang, Eric Y., Bae, Won C., Shao, Hongda, Biswas, Reni, Li, Shihong, Chen, Jun, Patil, Shantanu, Healey, Robert, D'Lima, Darryl D., Chung, Christine B., Du, Jiang
Format: Article
Language:English
Subjects:
Adult
Aged
Aged, 80 and over
Algorithms
Bone and Bones - anatomy & histology
Bone and Bones - physiology
Cadaver
Compressive Strength - physiology
Computer Simulation
cortical bone
Elastic Modulus - physiology
Elasticity Imaging Techniques - methods
Female
Humans
Image Enhancement - methods
Image Interpretation, Computer-Assisted - methods
magnetization transfer
Male
Middle Aged
Models, Biological
off-resonance saturation ratio
Porosity
Reproducibility of Results
Sensitivity and Specificity
Signal Processing, Computer-Assisted
Stress, Mechanical
Tensile Strength - physiology
UTE
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Summary:Magnetization transfer (MT) imaging is one way to indirectly assess pools of protons with fast transverse relaxation. However, conventional MT imaging sequences are not applicable to short T2 tissues such as cortical bone. Ultrashort echo time (UTE) sequences with TE values as low as 8 µs can detect signals from different water components in cortical bone. In this study we aim to evaluate two‐dimensional UTE‐MT imaging of cortical bone and its application in assessing cortical bone porosity as measured by micro‐computed tomography (μCT) and biomechanical properties. In total, 38 human cadaveric distal femur and proximal tibia bones were sectioned to produce 122 rectangular pieces of cortical bone for quantitative UTE‐MT MR imaging, μCT, and biomechanical testing. Off‐resonance saturation ratios (OSRs) with a series of MT pulse frequency offsets (Δf) were calculated and compared with porosity assessed with μCT, as well as elastic (modulus, yield stress, and strain) and failure (ultimate stress, failure strain, and energy) properties, using Pearson correlation and linear regression. A moderately strong negative correlation was observed between OSR and μCT porosity (R2 = 0.46–0.51), while a moderate positive correlation was observed between OSR and yield stress (R2 = 0.25–0.30) and failure stress (R2 = 0.31–0.35), and a weak positive correlation (R2 = 0.09–0.12) between OSR and Young's modulus at all off‐resonance saturation frequencies. OSR determined with the UTE‐MT sequence provides quantitative information on cortical bone and is sensitive to μCT porosity and biomechanical function. Copyright © 2015 John Wiley & Sons, Ltd. UTE‐MT imaging of 122 human cortical bone samples: correlation between OSR (at 1.5 kHz) and μCT cortical porosity (A), Young's modulus (B) and yield stress (C). OSR is negatively correlated with porosity, and positively correlated with Young's modulus and yield stress.
ISSN:0952-3480
1099-1492
DOI:10.1002/nbm.3316