More accurate trabecular bone imaging using UTE MRI at the resonance frequency of fat

Saeed Jerban; Dina Moazamian; Hamidreza Shaterian Mohammadi; Yajun Ma; Hyungseok Jang; Behnam Namiranian; Soo Hyun Shin; Salem Alenezi; Sameer B Shah; Christine B Chung; Eric Y Chang; Jiang Du

doi:10.1016/j.bone.2024.117096

More accurate trabecular bone imaging using UTE MRI at the resonance frequency of fat

Bone. 2024 Apr 15:184:117096. doi: 10.1016/j.bone.2024.117096. Online ahead of print.

Authors

Affiliations

¹ Department of Radiology, University of California, San Diego, La Jolla, CA, USA. Electronic address: sjerban@health.ucsd.edu.
² Department of Radiology, University of California, San Diego, La Jolla, CA, USA.
³ Research and Laboratories Sector, Saudi Food and Drug Authority, Riyadh, Saudi Arabia.
⁴ Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, La Jolla, CA, USA; Orthopaedic Research, University of California, San Diego, La Jolla, CA, USA.
⁵ Department of Radiology, University of California, San Diego, La Jolla, CA, USA; Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, La Jolla, CA, USA.
⁶ Department of Radiology, University of California, San Diego, La Jolla, CA, USA; Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, La Jolla, CA, USA. Electronic address: jiangdu@health.ucsd.edu.

PMID: 38631596
DOI: 10.1016/j.bone.2024.117096

Abstract

High-resolution magnetic resonance imaging (HR-MRI) has been increasingly used to assess the trabecular bone structure. High susceptibility at the marrow/bone interface may significantly reduce the marrow's apparent transverse relaxation time (T2*), overestimating trabecular bone thickness. Ultrashort echo time MRI (UTE-MRI) can minimize the signal loss caused by susceptibility-induced T2* shortening. However, UTE-MRI is sensitive to chemical shift artifacts, which manifest as spatial blurring and ringing artifacts partially due to non-Cartesian sampling. In this study, we proposed UTE-MRI at the resonance frequency of fat to minimize marrow-related chemical shift artifacts and the overestimation of trabecular thickness. Cubes of trabecular bone from six donors (75 ± 4 years old) were scanned using a 3 T clinical scanner at the resonance frequencies of fat and water, respectively, using 3D UTE sequences with five TEs (0.032, 1.1, 2.2, 3.3, and 4.4 ms) and a clinical 3D gradient echo (GRE) sequence at 0.2 × 0.2 × 0.4 mm³ voxel size. Trabecular bone thickness was measured in 30 regions of interest (ROIs) per sample. MRI results were compared with thicknesses obtained from micro-computed tomography (μCT) at 50 μm³ voxel size. Linear regression models were used to calculate the coefficient of determination between MRI- and μCT-based trabecular thickness. All MRI-based trabecular thicknesses showed significant correlations with μCT measurements. The correlations were higher (examined with paired Student's t-test, P < 0.01) for 3D UTE images performed at the fat frequency (R² = 0.59-0.74, P < 0.01) than those at the water frequency (R² = 0.18-0.52, P < 0.01) and clinical GRE images (R² = 0.39-0.47, P < 0.01). Significantly reduced correlations were observed with longer TEs. This study highlighted the feasibility of UTE-MRI at the fat frequency for a more accurate assessment of trabecular bone thickness.

Keywords: Fat peak frequency; MRI; Microstructure; Trabecular bone; UTE.