Assessment of anterior cruciate ligament reconstruction using 3D ultrashort echo‐time MR imaging

Abstract

This work demonstrates the potential of ultrashort TE (UTE) imaging for visualizing graft material and fixation elements after surgical repair of soft tissue trauma such as ligament or meniscal injury. Three asymptomatic patients with anterior cruciate ligament (ACL) reconstruction using different graft fixation methods were imaged at 1.5T using a 3D UTE sequence. Conventional multislice turbo spinecho (TSE) measurements were performed for comparison. 3D UTE imaging yields high signal from tendon graft material at isotropic spatial resolution, thus facilitating direct positive contrast graft visualization. Furthermore, metal and biopolymer graft fixation elements are clearly depicted due to the high contrast between the signal-void implants and the graft material. Thus, the ability of UTE MRI to visualize short-T 2 tissues such as tendons, ligaments, or tendon grafts can provide additional information about the status of the graft and its fixation in the situation after cruciate ligament repair. UTE MRI can therefore potentially support diagnosis when problems occur or persist after surgical procedures involving short-T 2 tissues and implants.

Metal-Induced Artifacts in MRI

“…As with other methods, for a high readout bandwidth these artifacts can be reduced [33], but have not been compared directly with MAVRIC or SEMAC. Furthermore, the very short echo times may allow visualization of the polyethylene spacer, which could have diagnostic value [34]. The non-Cartesian methods add additional implementational complexity, which also has limited their use for routine scanning.…”

Ultrashort echo time and zero echo time MRI at 7T

“…Zero echo time (ZTE) and ultrashort echo time (UTE) pulse sequences use specialized acquisition and reconstruction techniques to enable detection of ultrashort-T2 components in vivo. These sequences allow for direct visualization of tendons ( $T_2^{\ast }\approx 1\text{ms}$) (1–7), cortical bone ( $T_2^{\ast }\approx 0.4\text{ms}$) (8–16), and lung parenchyma ( $T_2^{\ast }\approx 0.5-3\text{ms}$) (17–22), as well as components in myelin ( $T_2^{\ast }\approx 0.1-0.4\text{ms}$ (23–25)) and ligaments (26) (up to 80% fraction of $T_2^{\ast }\approx 1\text{ms}$ (27)).…”

Application of Nanoparticles on Diagnosis and Therapy in Gliomas

“…Ultrashort echo time (UTE) imaging is able to track materials with extremely short T(2)*-weighted and very fast signal decay [54, 55]. With very short echo time (TE), typically below 0.1 milliseconds, UTE imaging allows signal acquisition with little T(2)*-weighted influence.…”