Precision-guided sampling schedules for efficient T1ρ mapping

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Abstract

Purpose:

To describe, assess, and implement a simple precision estimation framework for optimization of spin-lock time (TSL) sampling schedules for quantitative T1ρ mapping using a mono-exponential signal model.

Materials and Methods:

A method is described for estimating T1ρ precision, and a cost function based on the precision estimates is evaluated to determine efficient TSL sampling schedules. The validity of the framework was tested by imaging a phantom with various sampling schedules and comparing theoretical and experimental precision values. The method utility was demonstrated with in vivo T1ρ mapping of brain tissue using a similar procedure as the phantom experiment. To assist investigators, optimal sampling schedules are tabulated for various tissue types and an online calculator is implemented.

Results:

Theoretical and experimental precision values followed similar trends for both the phantom and in vivo experiments. The mean absolute percentage error (MAPE) of theoretical estimates of T1ρ map signal-to-noise ratio (SNR) was typically 5% in the phantom experiment and 33% in the in vivo demonstration. In both experiments, optimal TSL schedules yielded greater T1ρ map SNR efficiency than typical schedules.

Conclusion:

The framework can be used to improve the imaging efficiency of T1ρ mapping protocols and to guide selection of imaging parameters. J. Magn. Reson. Imaging 2015;41:242–250. © 2014 Wiley Periodicals, Inc.

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