Clinical implementation of accelerated T${}_2$ mapping. Quantitative magnetic resonance imaging as a biomarker for annular tear and lumbar disc herniation

This study evaluates GRAPPATINI, an accelerated T${}_2$ mapping sequence combining undersampling and model-based reconstruction to facilitate the clinical implementation of T${}_2$ mapping of the lumbar intervertebral disc. Fifty-eight individuals (26 females, 32 males, age 23.3 ± 8.0 years) were prospectively examined at 3 T. This cohort study consisted of 19 patients, 20 rowers, and 19 volunteers. GRAPPATINI was conducted with the same parameters as a conventional 2D multi-echo spin-echo (MESE) sequence in 02:27 min instead of 13:18 min. Additional T${}_2$ maps were calculated after discarding the first echo (T${}_{2-WO1ST}$) and only using even echoes (T${}_{2-EVEN}$). Segmentation was done on the four most central slices. The resulting T${}_2$ values were compared for all four measurements. T${}_{2-GRAPPATINI}$, T${}_{2-MESE}$, T${}_{2-EVEN}$, and T${}_{2-WO1ST}$ of the nucleus pulposus of normal discs differed significantly from those of bulging discs or herniated discs (all p < 0.001). For the posterior annular region, only T${}_{2-GRAPPATINI}$ showed a significant difference (p = 0.011) between normal and herniated discs. There was a significant difference between T${}_{2-GRAPPATINI}$, T${}_{2-MESE}$, T${}_{2-EVEN}$, and T${}_{2-WO1ST}$ of discs with and without an annular tear for the nucleus pulposus (all p < 0.001). The nucleus pulposus' T${}_2$ at different degeneration states showed significant differences between all group comparisons of Pfirrmann grades for T${}_{2-GRAPPATINI}$ (p = 0.000-0.018), T${}_{2-MESE}$ (p = 0.000-0.015), T${}_{2-EVEN}$ (p = 0.000-0.019), and T${}_{2-WO1ST}$ (p = 0.000-0.015). GRAPPATINI facilitates the use of T${}_2$ values as quantitative imaging biomarkers to detect disc pathologies such as degeneration, lumbar disc herniation, and annular tears while simultaneously shortening the acquisition time from 13:18 to 2:27 min.