Rapid whole brain 3D T2 mapping respiratory‐resolved Double‐Echo Steady State (DESS) sequence with improved repeatability

Abstract

AbstractPurposeTo propose a quantitative 3D double‐echo steady‐state (DESS) sequence that offers rapid and repeatable T2 mapping of the human brain using different encoding schemes that account for respiratory B0 variation.MethodsA retrospective self‐gating module was firstly implemented into the standard DESS sequence in order to suppress the respiratory artifact via data binning. A compressed‐sensing trajectory (CS‐DESS) was then optimized to accelerate the acquisition. Finally, a spiral Cartesian encoding (SPICCS‐DESS) was incorporated to further disrupt the coherent respiratory artifact. These different versions were compared to a standard DESS sequence (fully DESS) by assessing the T2 distribution and repeatability in different brain regions of eight volunteers at 3 T.ResultsThe respiratory artifact correction was determined to be optimal when the data was binned into seven respiratory phases. Compared to the fully DESS, T2 distribution was improved for the CS‐DESS and SPICCS‐DESS with interquartile ranges reduced significantly by a factor ranging from 2 to 12 in the caudate, putamen, and thalamus regions. In the gray and white matter areas, average absolute test–retest T2 differences across all volunteers were respectively 3.5 ± 2% and 3.1 ± 2.1% for the SPICCS‐DESS, 4.6 ± 4.6% and 4.9 ± 5.1% for the CS‐DESS, and 15% ± 13% and 7.3 ± 5.6% for the fully DESS. The SPICCS‐DESS sequence's acquisition time could be reduced by half (<4 min) while maintaining its efficient T2 mapping.ConclusionThe respiratory‐resolved SPICCS‐DESS sequence offers rapid, robust, and repeatable 3D T2 mapping of the human brain, which can be especially effective for longitudinal monitoring of cerebral pathologies.