Precision-guided sampling schedules for efficient T1ρ mapping

Casey P. Johnson, Daniel R. Thedens, Vincent A. Magnotta

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Purpose: To describe, assess, and implement a simple precision estimation framework for optimization of spinlock time (TSL) sampling schedules for quantitative T1r mapping using a mono-exponential signal model.

Materials and Methods: A method is described for estimating T1r 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 T1r 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 T1r 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 T1r 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.

Original languageEnglish (US)
Pages (from-to)242-250
Number of pages9
JournalJournal of Magnetic Resonance Imaging
Issue number1
StatePublished - Jan 1 2015


  • Precision
  • Quantitative mapping
  • Relaxometry
  • SNR
  • Spin lock
  • T1rho


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