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

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.

Articular Cartilage Assessment Using Ultrashort Echo Time MRI: A Review

“…There is only one study currently published in the literature that investigated the feasibility of simultaneous susceptibility mapping of the articular cartilage and cortical bone in knee ( 23 ). In this work, susceptibility variations were found in different layers of cartilage, which was in agreement with previous GRE-QSM studies ( 84 , 85 ).…”

“…By using UTE MRI, rapidly decaying signals that would typically be lost in conventional MRI can be acquired after short radiofrequency (RF) excitation, as quickly as is possible by the hardware (TE < 100μs), before any major T 2 / decay ( 10 ). Basic UTE, dual echo UTE with echo subtraction ( 11 ), inversion recovery UTE (IR-UTE) ( 12 ), dual-inversion recovery UTE (Dual-IR-UTE) ( 13 , 14 ), UTE ( 15 ), UTE-T1ρ ( 16 , 17 ), UTE with magnetization transfer (MT) ( 18 – 20 ), UTE with double echo steady state (DESS) ( 21 , 22 ), and UTE with quantitative susceptibility mapping (QSM) ( 23 ) are among the primary UTE MRI techniques which have been developed for qualitative and quantitative imaging of articular cartilage.…”

QSM Throughout the Body

“…Due to its sensitivity to magnetic tissue composition and structure, QSM has been successfully applied to study cartilage tissue in in animal models, ex vivo samples, as well as healthy and osteoarthritic subjects at different field strengths. 54,55,[179][180][181][182][183][184][185][186] The collagen fiber is a major source of contrast in cartilage to assess microstructural pathologies within the collagen matrix (Fig. 8a).…”