Clinical implementation of accelerated T2 mapping: Quantitative magnetic resonance imaging as a biomarker for annular tear and lumbar disc herniation

Abstract

Abstract Objectives 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. Methods 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. Results 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). Conclusions 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. Key Points • 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 discs with bulging or herniation (all p < 0.001). • The investigated T 2 mapping techniques differed significantly in discs with and without annular tearing (all p < 0.001). • The nucleus pulposus’ T 2 showed significant differences between different stages of degeneration in all group comparisons 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).

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