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Variable flip angle 3D ultrashort echo time (UTE) T 1 mapping of mouse lung: A repeatability assessment
Author(s) -
Alamidi Daniel F.,
Smailagic Amir,
Bidar Abdel W.,
Parker Nicole S.,
Olsson Marita,
Hockings Paul D.,
Lagerstrand Kerstin M.,
Olsson Lars E.
Publication year - 2018
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.25999
Subject(s) - repeatability , lung , coefficient of variation , nuclear medicine , flip angle , analysis of variance , medicine , repeated measures design , biomedical engineering , magnetic resonance imaging , chemistry , radiology , mathematics , chromatography , statistics
Background Lung T 1 is a potential translational biomarker of lung disease. The precision and repeatability of variable flip angle (VFA) T 1 mapping using modern 3D ultrashort echo time (UTE) imaging of the whole lung needs to be established before it can be used to assess response to disease and therapy. Purpose To evaluate the feasibility of regional lung T 1 quantification with VFA 3D‐UTE and to investigate long‐ and short‐term T 1 repeatability in the lungs of naive mice. Study type Prospective preclinical animal study. Population Eight naive mice and phantoms. Field strength/Sequence 3D free‐breathing radial UTE (8 μs) at 4.7T. Assessment VFA 3D‐UTE T 1 calculations were validated against T 1 values measured with inversion recovery (IR) in phantoms. Lung T 1 and proton density ( S 0 ) measurements of whole lung and muscle were repeated five times over 1 month in free‐breathing naive mice. Two consecutive T 1 measurements were performed during one of the imaging sessions. Statistical Tests Agreement in T 1 between VFA 3D‐UTE and IR in phantoms was assessed using Bland–Altman and Pearson 's correlation analysis. The T 1 repeatability in mice was evaluated using coefficient of variation (CV), repeated‐measures analysis of variance (ANOVA), and paired t ‐test. Results Good T 1 agreement between the VFA 3D‐UTE and IR methods was found in phantoms. T 1 in lung and muscle showed a 5% and 3% CV (1255 ± 63 msec and 1432 ± 42 msec, respectively, mean ± SD) with no changes in T 1 or S 0 over a month. Consecutive measurements resulted in an increase of 2% in both lung T 1 and S 0 . Data Conclusion VFA 3D‐UTE shows promise as a reliable T 1 mapping method that enables full lung coverage, high signal‐to‐noise ratio (∼25), and spatial resolution (300 μm) in freely breathing animals. The precision of the VFA 3D‐UTE method will enable better design and powering of studies. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:846–852.