Abbreviated quantitative UTE imaging in anterior cruciate ligament reconstruction

Abstract

Background Existing ultrashort echo time magnetic resonance imaging (UTE MRI) methods require prohibitively long acquisition times (~ 20–40 min) to quantitatively assess the clinically relevant fast decay T2* component in ligaments and tendons. The purpose of this study was to evaluate the feasibility and clinical translatability of a novel abbreviated quantitative UTE MRI paradigm for monitoring graft remodeling after anterior cruciate ligament (ACL) reconstruction. Methods Eight patients who had Graftlink™ hamstring autograft reconstruction were recruited for this prospective study. A 3D double-echo UTE sequence at 3.0 Tesla was performed at 3- and 6-months post-surgery. An abbreviated UTE MRI paradigm was established based on numerical simulations and in vivo validation from healthy knees. This proposed approach was used to assess the T2* for fast decay component ($$ {T}_{2s}^{\ast } $$ T 2 s ∗ ) and bound water signal fraction (fbw) of ACL graft in regions of interest drawn by a radiologist. Results Compared to the conventional bi-exponential model, the abbreviated UTE MRI paradigm achieved low relative estimation bias for $$ {T}_{2s}^{\ast } $$ T 2 s ∗ and fbw over a range of clinically relevant values for ACL grafts. A decrease in $$ {T}_{2s}^{\ast } $$ T 2 s ∗ of the intra-articular graft was observed in 7 of the 8 ACL reconstruction patients from 3- to 6-months (− 0.11 ± 0.16 ms, P = 0.10). Increases in $$ {T}_{2s}^{\ast } $$ T 2 s ∗ and fbw from 3- to 6-months were observed in the tibial intra-bone graft ($$ {\varDelta T}_{2s}^{\ast } $$ ΔT 2 s ∗ : 0.19 ± 0.18 ms, P < 0.05; Δfbw: 4% ± 4%, P < 0.05). Lower $$ {T}_{2s}^{\ast } $$ T 2 s ∗ (− 0.09 ± 0.11 ms, P < 0.05) was observed at 3-months when comparing the intra-bone graft to the graft/bone interface in the femoral tunnel. The same comparisons at the 6-months also yielded relatively lower $$ {T}_{2s}^{\ast } $$ T 2 s ∗ (− 0.09 ± 0.12 ms, P < 0.05). Conclusion The proposed abbreviated 3D UTE MRI paradigm is capable of assessing the ACL graft remodeling process in a clinically translatable acquisition time. Longitudinal changes in $$ {T}_{2s}^{\ast } $$ T 2 s ∗ and fbw of the ACL graft were observed.

Association Between T2* Relaxation Times Derived From Ultrashort Echo Time MRI and Symptoms During Exercise Therapy for Patellar Tendinopathy: A Large Prospective Study

“… 19 The capability of UTE‐MRI to detect longitudinal changes had already been demonstrated by others, specifically in healing tendon grafts following anterior cruciate ligament reconstruction, in human cadaveric tendons that were subjected to tensile static loading, and in Achilles tendons of long distance runners. 32 , 33 , 34 …”

“…For this project, this scanning protocol was acceptable, because we did not intend to develop an image protocol that could be used in clinical imaging. For clinical applications, we recommend an abbreviated protocol, for example, as implemented by Fukuda et al 32 With only six echo times in the short TE range, they managed to observe a decreased T 2 * in a remodeling anterior cruciate ligament graft 6 months post‐surgery. Forth, a change in the MR acquisition protocol during the trial was required to optimize SNR for better fitting of T 2 * data, which unfortunately lead to exclusion of 11 patients in the final analyses.…”

Myelin Imaging Using Dual-echo 3D Ultra-short Echo Time MRI with Rosette k-Space Pattern

“…An MPRAGE sequence was performed before the UTE sequence for the anatomical reference. The parameters used in the 3D dual-echo UTE sequence with rosette k-space sampling were: field of view (FOV)=240x240x240 mm 3…”

“…However, depending on the surrounding chemical environment, some protons in specific tissues in the human body have an ultra-short T 2 , which conventional MRI can hardly detect due to the relatively long echo time (TE) in the order of milliseconds (ms). For example, the myelin bilayer in cerebral white matter (WM) (1), cortical and trabecular bones (2), ligaments (3), tissues with high iron concentration (4), etc. On the other hand, ultra-short echo time (UTE) MRI (5) sequences are capable of acquiring data with TE in the order of microseconds (μs), which can provide images of tissues with ultra-short T 2 directly.…”

Three-Dimensional Reconstruction Algorithm-Based Magnetic Resonance Imaging Evaluation of Biomechanical Changes in Articular Cartilage in Patients after Anterior Cruciate Ligament Reconstruction

“…Hu et al [ 16 ] applied 1000 N axial pressure to the knee joint of cadavers and found that MRI images based on the 3D finite element model were convenient for measuring the articular cartilage contact stress of medial and lateral compartments when the knee joint was almost straightened during single-beam ACL reconstruction. Wan et al's [ 17 ] experimental study in vivo indicates that ACL reconstruction will lead to cartilage degeneration; Fukuda et al [ 18 ] reported that ACL reconstruction can improve the stability of knee joint, and MRI images based on the 3D finite element model can measure the graft tension and cartilage contact stress. The operation of cadaver experiment is complicated, and the biomechanics (kinematics, graft tension, and cartilage contact stress) of knee joint under different load conditions cannot be fully measured after ACL reconstruction.…”