Feasibility of Ultrashort Echo Time T2* Mapping in Comparison With T2 Mapping for Quantitative Evaluation of Meniscal Degeneration

Abstract

Purpose: This study aimed to assess the feasibility of ultrashort echo time (UTE)-T2* mapping in comparison with T2 mapping for quantitative evaluation of meniscal degeneration. Materials and Methods: This study included 208 menisci of 99 patients (59 women and 40 men, median age 52 years old [16–80 years]) who underwent knee MRI with both standard T2 mapping and UTE-T2* mapping sequences. A radiologist reviewed the images and graded meniscal degeneration according to the morphologic criteria on T2-weighted and proton density-weighted sequences. Manually drawn regions of interest were placed along the outline and hyperintensity subregion within the meniscus, and in the same location on midsagittal images of each T2 and UTE-T2* sequence. Meniscal T2 and T2* values (T2m and T2*m) as well as T2 and T2* values of hyperintensity subregions (T2h, T2*h) were calculated. Results: There was a strong correlation between T2m, T2*m, T2h, and T2*h, and morphological grades (correlation coefficient 0.793–0.943, 95% CI). On morphologic analysis, 50, 52, 50, and 56 menisci were graded as 0, 1, 2, and 3, respectively. T2m, T2*m, T2h, and T2*h were found to be significantly different in all the grades and tended to be higher in the more degraded meniscus (p < 0.001 for both). Mean T2m was 10.78 ± 2.91 ms, 15.81 ± 2.99 ms, 20.26 ± 3.19 ms, and 30.80 ± 7.38 ms and mean T2*m was 7.10 ± 1.12 ms, 9.64 ± 1.27 ms, 12.01 ± 1.58 ms, and 18.98 ± 4.67 ms for grades 0, 1, 2, and 3, respectively. Mean T2h was 20.05 ± 3.67 ms, 24.39 ± 4.73 ms, and 38.92 ± 9.49 ms and mean T2*h was 10.94 ± 1.65 ms, 13.67 ± 2.41 ms, and 22.36 ± 5.20 ms for grades 1, 2, and 3, respectively. Conclusion: UTE-T2* mapping was feasible for quantitative evaluation of meniscal degeneration in patients. With a few improvements UTE-T2* mapping is a potential substitute for the standard T2 mapping, with improved efficacy.