Simultaneous Quantitative Susceptibility Mapping of Articular Cartilage and Cortical Bone of Human Knee Joint Using Ultrashort Echo Time Sequences.

Ming Zhang,Hanqi Wang,Hongjiang Wei,Yong Lu,Fuhua Yan,Zhihui Li,Yuyao Zhang,Tongtong Chen

doi:10.3389/fendo.2022.844351

Abstract

BackgroundIt is of great clinical importance to assess the microstructure of the articular cartilage and cortical bone of the human knee joint. While quantitative susceptibility mapping (QSM) is a promising tool for investigating the knee joint, however, previous QSM studies using conventional gradient recalled echo sequences or ultrashort echo time (UTE) sequences only focused on mapping the magnetic susceptibility of the articular cartilage or cortical bone, respectively. Simultaneously mapping the underlying susceptibilities of the articular cartilage and cortical bone of human in vivo has not been explored and reported.MethodThree-dimensional multi-echo radial UTE sequences with the shortest TE of 0.07 msec and computed tomography (CT) were performed on the bilateral knee joints of five healthy volunteers for this prospective study. UTE-QSM was reconstructed from the local field map after water-fat separation and background field removal. Spearman’s correlation analysis was used to explore the relationship between the magnetic susceptibility and CT values in 158 representative regions of interest of cortical bone.ResultThe susceptibility properties of the articular cartilage and cortical bone were successfully quantified by UTE-QSM. The laminar structure of articular cartilage was characterized by the difference of susceptibility value in each layer. Susceptibility was mostly diamagnetic in cortical bone. A significant negative correlation (r=−0.43, p<0.001) between the susceptibility value and CT value in cortical bone was observed.ConclusionUTE-QSM enables simultaneous susceptibility mapping of the articular cartilage and cortical bone of human in vivo. Good association between susceptibility and CT values in cortical bone suggests the potential of UTE-QSM for bone mapping for further clinical application.

Highlights

Cartilage and bone, providing stiffness and strength, are two fundamental knee joint structures
The Regions of Interest (ROIs) could finely match the anatomical structures of cortical bone, both on ultrashort echo time (UTE) and Computed tomography (CT) images
We described the feasibility of UTE-quantitative susceptibility mapping (QSM) for simultaneous susceptibility mapping of the articular cartilage and cortical bone of the human knee joint in vivo

Summary

Introduction

Cartilage and bone, providing stiffness and strength, are two fundamental knee joint structures. A useful tool to noninvasively investigate the microstructure of the articular cartilage and cortical bone is of great importance for clinical evaluation. The MRIbased ultrashort echo time (UTE) sequences, which collect signals immediately after pulse excitation resulting in a very short TE (typically less than 0.1 msec), provide the feasibility for direct cortical bone imaging [7–9]. It is of great clinical importance to assess the microstructure of the articular cartilage and cortical bone of the human knee joint. While quantitative susceptibility mapping (QSM) is a promising tool for investigating the knee joint, previous QSM studies using conventional gradient recalled echo sequences or ultrashort echo time (UTE) sequences only focused on mapping the magnetic susceptibility of the articular cartilage or cortical bone, respectively. Mapping the underlying susceptibilities of the articular cartilage and cortical bone of human in vivo has not been explored and reported

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