Single- and Bi-component T2* analysis of tendon before and during tensile loading, using UTE sequences

Abstract

No significant difference in single- or bi-component results was found after the application of tension to tendons. Results are similar regardless of UTE sequence used for acquisition.

Assessment of different fitting methods for in-vivo bi-component T2* analysis of human patellar tendon in magnetic resonance imaging

“…The UTE sequence used in our study utilized a center-out twisted 3D cone k-space trajectory which has been shown to increase sampling uniformity, decrease undersampling artifact, and provide better SNR performance when compared to traditional 2D and 3D radial UTE sequences 33 . The sequence has had successful applications in sodium imaging 42,43 and ex-vivo Achilles tendon imaging 24 . In our study, the 3D cone UTE sequence provided complete anatomic coverage of the patellar tendon in human subjects at 3.0T with clinically feasible spatial resolutions and scan times and with an SNR of 54.5, which has been shown to be adequate to accurately estimate bi-component T2* parameters from previous literature 28 and the results of our simulation study.…”

“…Chang et al detected short and long relaxing water components in histologically normal human cadaveric Achilles tendon with a T2* of 1.8ms and 9.2ms and a fraction of 79.2% and 20.8% respectively 23 . The Authors later reported that bi-component T2* parameters did not change with tensile loading of the Achilles tendon 24 . Jarus et al compared single-component and bi-component T2* analysis of the Achilles tendon in human subjects and found that the bi-component analysis provided greater diagnostic performance for distinguishing between normal and pathologic tendon 25 .…”

“…The same simulation was repeated with different levels of added noise at SNR = 20, 50 and 90. The set of model parameters used in the numerical simulations was chosen to mimic bi-component T2* parameters of tendon previously published in the literature 24 . Accordingly, parameters of the two water pools were chosen as follows: fs =80%, T*2,s = 1 ms, and T*2,l = 20 ms.…”

“…The UTE sequence utilized a k-space sampling scheme of a center-out twisted 3D cone trajectory which allowed a minimal echo time (TE) of 0. 24 . For each acquisition, the same repetition time (TR) was used, and four echoes were acquired.…”

“…The voxel-by-voxel curve fitting was performed using an in-house T2*, mapping software program developed based on the non-linear least square "fmincon" function implemented in Matlab. The initial parameter guess T*2,s = 1 ms, T*2,1 =20 ms and fs =80% based on previous published tendon studies was used in the iterative optimization 24 . The parameter searching space were [0ms, 20ms], [0ms, 100ms] and [0%, 100%] for T*2,s, and T*2,l, and fs respectively, reflecting a reasonable parameter range within the patellar tendon.…”