Improved precision in SASHA T1 mapping with a variable flip angle readout

Kelvin Chow,Joseph J Pagano,Richard B Thompson,Bruce S Spottiswoode

doi:10.1186/1532-429x-16-s1-m9

Abstract

Background The SAturation-recovery single-SHot Acquisition (SASHA) T1 mapping sequence has excellent accuracy independent of T1, T2, heart rate, and flip angle [1], which are known dependencies of the more commonly used MOdified Look-Locker Inversion-recovery (MOLLI) sequence. However, SASHA has a greater T1 variability (poorer precision) compared to MOLLI. A two-parameter fit, with assumed ideal saturation, has been shown to improve precision compared to the standard three-parameter fit used for SASHA, but at the expense of introducing systematic errors [2]. We propose that a variable flip angle (VFA) readout will reduce these systematic errors and thereby allow the improved precision of a two-parameter fit while maintaining the accuracy of the three-parameter fit.

Highlights

The SAturation-recovery single-SHot Acquisition (SASHA) T1 mapping sequence has excellent accuracy independent of T1, T2, heart rate, and flip angle [1], which are known dependencies of the more commonly used MOdified Look-Locker Inversion-recovery (MOLLI) sequence
Values are reported as mean ± standard deviation across subjects
Image artifacts from the bSSFP readout were consistently reduced with the SASHA-variable flip angle (VFA) sequence compared to the standard SASHA sequence, which may contribute to the improved variability performance (Figure 1)

Summary

Background

The SAturation-recovery single-SHot Acquisition (SASHA) T1 mapping sequence has excellent accuracy independent of T1, T2, heart rate, and flip angle [1], which are known dependencies of the more commonly used MOdified Look-Locker Inversion-recovery (MOLLI) sequence. SASHA has a greater T1 variability (poorer precision) compared to MOLLI. A two-parameter fit, with assumed ideal saturation, has been shown to improve precision compared to the standard three-parameter fit used for SASHA, but at the expense of introducing systematic errors [2]. We propose that a variable flip angle (VFA) readout will reduce these systematic errors and thereby allow the improved precision of a two-parameter fit while maintaining the accuracy of the three-parameter fit

Methods

Results

Conclusions