Age-related changes of multi-parametric quantitative imaging across the adult lifespan in the lumbar vertebra.

Objective.To introduce a gradient recalled echo (GRE)-based method for multi-parametric imaging and investigate changes with age across the adult lifespan in the lumbar spine.Approach.Dual flip angles (FA) chemical shift-encoded multi-echo GRE (DFA-MEGRE) approach was proposed, which includes three repetitions of GRE acquisition. Six in-phase echoes from dual FAs were used for T1 and PD quantifications. Water, fat,R2*, proton-density fat fraction (PDFF), and quantitative susceptibility mapping (QSM) maps were obtained from six echoes with FA = 15°. The DFA-MEGRE approach was applied to a phantom and 41 healthy volunteers (18-71 yr old). Correlation analysis was applied to validate the accuracy of the proposed method for parameter quantification. Region-of-interest (ROI) analysis was performed on the vertebra for all volunteer data. Correlation analysis was performed on quantitative parameters and age.Main results.The DFA-MEGRE approach offers multiple sets of images, including qualitative T1W, PDW,T2*W, water, and fat maps as well as quantitative PD,T1,R2*, PDFF, and QSM maps. The scan times for whole lumber spine coverage with DFA-MEGRE were about 6.5 min. There are strong correlations between measured PD and true PD values and between measuredR2* and trueR2 values. Correlation analysis showed that there were age-related quadratic changes in all five quantitative parameters in the vertebra.Significance.The proposed DFA-MEGRE method creates multi-parametric quantitative imaging of the spine and can be extended to other parts of the body. The age-related changes of the multi-parametric quantitative imaging demonstrate that they have great potential for longitudinal study and disease assessment in the spine.