A comparison of multi-echo spin-echo and triple-echo steady-state T2 mapping for in vivo evaluation of articular cartilage

Abstract

ObjectivesTo assess the clinical relevance of T2 relaxation times, measured by 3D triple-echo steady-state (3D-TESS), in knee articular cartilage compared to conventional multi-echo spin-echo T2-mapping.MethodsThirteen volunteers and ten patients with focal cartilage lesions were included in this prospective study. All subjects underwent 3-Tesla MRI consisting of a multi-echo multi-slice spin-echo sequence (CPMG) as a reference method for T2 mapping, and 3D TESS with the same geometry settings, but variable acquisition times: standard (TESSs 4:35min) and quick (TESSq 2:05min). T2 values were compared in six different regions in the femoral and tibial cartilage using a Wilcoxon signed ranks test and the Pearson correlation coefficient (r). The local ethics committee approved this study, and all participants gave written informed consent.ResultsThe mean quantitative T2 values measured by CPMG (mean: 46±9ms) in volunteers were significantly higher compared to those measured with TESS (mean: 31±5ms) in all regions. Both methods performed similarly in patients, but CPMG provided a slightly higher difference between lesions and native cartilage (CPMG: 90ms→61ms [31%],p=0.0125;TESS 32ms→24ms [24%],p=0.0839).Conclusions3D-TESS provides results similar to those of a conventional multi-echo spin-echo sequence with many benefits, such as shortening of total acquisition time and insensitivity to B1 and B0 changes.Key points• 3D-TESS T2mapping provides clinically comparable results to CPMG in shorter scan-time.• Clinical and investigational studies may benefit from high temporal resolution of 3D-TESS.• 3D-TESS T2values are able to differentiate between healthy and damaged cartilage.

Isotropic three‐dimensional T2 mapping of knee cartilage: Development and validation

“…In vitro, the Bland–Altman analysis resulted in a smaller bias for the Iso3DGRE than for the MSME technique, indicating that the Iso3DGRE technique might have slightly higher accuracy in T 2 determination, while the precision was the same for both techniques. However, the T 2 values in the range of interest were slightly underestimated for Iso3DGRE, while for MSME the T 2 values were overestimated, as established in several prior studies . Given the negligible intercept value that resulted from the linear regression between the SE reference standard and the Iso3DGRE‐derived T 2 values (0.2 msec), this underestimation can potentially be corrected simply by using a scaling factor, if desired.…”

Motion-insensitive rapid configuration relaxometry

“…To this end, TESS acquires the three lowest SSFP configuration modes within a single acquisition (or TR) yielding two independent ratios for simultaneous rapid quantification of both and using a golden section search. Quite remarkably, TESS achieves an almost completely ‐unbiased estimation of , and showed good prospects for rapid three‐dimensional (3D) mapping of articular cartilage imaging in the clinical setting . Generally, TESS is also insensitive to inhomogeneities but the nonbalanced gradient scheme introduces some motion sensitivity that can be softened with a single‐slice version of TESS providing high quality maps in the human brain even at ultra‐high fields .…”

Exploiting multicompartment effects in triple‐echo steady‐state T2 mapping for fat fraction quantification

“…[6] and [7]) was a multiple of the in-phase time, resulting in a constructive summation of their compartments (Eq. [9]). The highest frequency occurred for the F À1 state (ie, with a frequency of 1/ (3TE1 þ 2dTE)) (Eq.…”

“…[4][5][6][7][8]), whereas the amplitude of the modulations is dependent on ff. When using a more realistic fat model with more than one spectral fat peak, Equation [9] becomes…”