Accelerating 3D-T1? mapping of cartilage using compressed sensing with different sparse and low rank models.
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ABSTRACT: PURPOSE:To evaluate the feasibility of using compressed sensing (CS) to accelerate 3D-T1? mapping of cartilage and to reduce total scan times without degrading the estimation of T1? relaxation times. METHODS:Fully sampled 3D-T1? datasets were retrospectively undersampled by factors 2-10. CS reconstruction using 12 different sparsifying transforms were compared, including finite differences, temporal and spatial wavelets, learned transforms using principal component analysis (PCA) and K-means singular value decomposition (K-SVD), explicit exponential models, low rank and low rank plus sparse models. Spatial filtering prior to T1? parameter estimation was also tested. Synthetic phantom (n?=?6) and in vivo human knee cartilage datasets (n?=?7) were included. RESULTS:Most CS methods performed satisfactorily for an acceleration factor (AF) of 2, with relative T1? error lower than 4.5%. Some sparsifying transforms, such as spatiotemporal finite difference (STFD), exponential dictionaries (EXP) and low rank combined with spatial finite difference (L+S SFD) significantly improved this performance, reaching average relative T1? error below 6.5% on T1? relaxation times with AF up to 10, when spatial filtering was used before T1? fitting, at the expense of smoothing the T1? maps. The STFD achieved 5.1% error at AF?=?10 with spatial filtering prior to T1? fitting. CONCLUSION:Accelerating 3D-T1? mapping of cartilage with CS is feasible up to AF of 10 when using STFD, EXP or L+S SFD regularizers. These three best CS methods performed satisfactorily on synthetic phantom and in vivo knee cartilage for AFs up to 10, with T1? error of 6.5%.
SUBMITTER: Zibetti MVW
PROVIDER: S-EPMC6097944 | biostudies-literature | 2018 Oct
REPOSITORIES: biostudies-literature
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