Accelerated T(2)Mapping of the Lumbar Intervertebral Disc Highly Undersampled K-Space Data for Robust T(2)Relaxation Time Measurement in Clinically Feasible Acquisition Times

Objectives T(2)mapping of the intervertebral disc (IVD) can depict quantitative changes reflecting biochemical change due to loss of glycosaminoglycan content. Conventional T(2)mapping is usually performed using a 2-dimensional multi-echo-spin echo sequence (2D-MESE) with long acquisition times that are generally not compatible with clinical routine. This study investigates the applicability of GRAPPATINI, a T(2)mapping sequence combining undersampling, model-based reconstruction, and parallel imaging, to offer clinically feasible acquisition times in T(2)mapping of the lumbar IVD. Materials and Methods Fifty-eight individuals (26 female; mean age, 23.3 +/- 8.1 years) were prospectively studied at 3 T. GRAPPATINI was conducted with the same parameters as the 2D-MESE while shortening the acquisition time from 13:18 to 2:27 minutes. The setup was also validated in a phantom experiment using a 6.48-hour-long single echo-spin echo sequence as reference. The IVDs were manually segmented on 4 central slices. Results The median nucleus pulposus showed a strong Pearson correlation coefficient between T(2GRAPPATINI)and T-2MESE(r(p)= 0.919;P< 0.001). There was also a significant correlation for the ventral (r(p)= 0.241;P< 0.001) and posterior (r(p)= 0.418;P< 0.001) annular regions. In the single spin-echo phantom experiment, the most accurate T(2)estimation was achieved using T(2GRAPPATINI)with a median absolute deviation of 15.3 milliseconds as compared with T(2MESE)with 26.5 milliseconds. Conclusions GRAPPATINI facilitates precise T(2)mapping at 3 T in accordance with clinical standards and reference methods using the same parameters while shortening acquisition times from 13:18 to 2:27 minutes with the same parameters.