Dynamic T2 mapping by multi‐spin‐echo spatiotemporal encoding

Purpose To develop a pulse sequence for acquiring robust, quantitative T2 relaxation maps in real time. Methods The pulse scheme relies on fully refocused spatiotemporally encoded multi‐spin‐echo trains, which provide images that are significantly less distorted than spin‐echo echo planar imaging‐ba...

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Bibliographic Details
Published in:Magnetic resonance in medicine 2020-08, Vol.84 (2), p.895-907
Main Authors: Bao, Qingjia, Ma, Lingceng, Liberman, Gilad, Solomon, Eddy, Martinho, Ricardo P., Frydman, Lucio
Format: Article
Language:English
Subjects:
abdominal imaging
Breast
breast MRI
Inhomogeneity
Mapping
multi‐spin‐echo sequences
Neuroimaging
Organs
quantitative T2 mapping
Scanners
Shot
Spatial discrimination
Spatial resolution
spatiotemporal encoding
Spin dynamics
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Summary:Purpose To develop a pulse sequence for acquiring robust, quantitative T2 relaxation maps in real time. Methods The pulse scheme relies on fully refocused spatiotemporally encoded multi‐spin‐echo trains, which provide images that are significantly less distorted than spin‐echo echo planar imaging‐based counterparts. This enables single‐shot T2 mapping in inhomogeneity‐prone regions. Another advantage of these schemes stems from their ability to interleave multiple scans in a reference‐free manner, providing an option to increase sensitivity and spatial resolution with minimal motional artifacts. Results The method was implemented in preclinical and clinical scanners, where single‐shot acquisitions delivered reliable T2 maps in ≤200 ms with ≈250 µm and ≈3 mm resolutions, respectively. Ca. 4 times higher spatial resolutions were achieved for the motion‐compensated interleaved versions of these acquisitions, delivering T2 maps in ca. 10 s per slice. These maps were nearly indistinguishable from multi‐scan relaxometric maps requiring orders‐of‐magnitude longer acquisitions; this was confirmed by mice head and real‐time mice abdomen 7T scans performed following contrast‐agent injections, as well as by 3T human brain and breast scans. Conclusion This study introduced and demonstrated a new approach for acquiring rapid and quantitative T2 data, which is particularly reliable when operating at high fields and/or targeting heterogeneous organs or regions.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.28158