TriTone: a radiofrequency field (B1)-insensitive T1 estimator for MRI at high magnetic fields

Roman Fleysher, Lazar Fleysher, Songtao Liu, Oded Gonen

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Fast, high-resolution, longitudinal relaxation time (T1) mapping is invaluable in clinical and research applications. It has been shown that two spoiled gradient recalled echo (SPGR) images acquired in steady state with variable flip angles is an attractive alternative to the multi-image sets previously acquired with inversion or saturation recovery. The known sensitivity of the two-point method to transmit radiofrequency field (B1) inhomogeneity exacerbated at 3 T and above, however, mandates its combination with an additional, time-consuming and possibly specific-absorption-rate-intensive B1 measurement, preventing direct migration of the method to these fields. To address this, we introduce a method designed to be free of systematic errors caused by B1 inhomogeneity in which the value of T1 is extracted from three SPGR images acquired with echo planar imaging (EPI) readout. The precision of the T1 maps produced is found to be comparable to the two-point method, while the accuracy is greatly improved in the same time and spatial resolution. A welcome byproduct of the method is a map of B1 that can be used to correct other acquisitions in the same session. Tables of the optimal acquisition protocols are provided for several total imaging times.

Original languageEnglish (US)
Pages (from-to)781-789
Number of pages9
JournalMagnetic Resonance Imaging
Issue number6
StatePublished - Jul 2008
Externally publishedYes


  • Fast volumetric imaging
  • High-field MRI
  • Optimization methods
  • Quantitative MRI
  • RF inhomogeneity
  • T mapping

ASJC Scopus subject areas

  • Biophysics
  • Biomedical Engineering
  • Radiology Nuclear Medicine and imaging


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