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Dynamic and steady‐state oxygen‐dependent lung relaxometry using inversion recovery ultra‐fast steady‐state free precession imaging at 1.5 T
Author(s) -
Bauman Grzegorz,
Pusterla Orso,
Santini Francesco,
Bieri Oliver
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.26739
Subject(s) - relaxometry , voxel , steady state (chemistry) , magnetic resonance imaging , nuclear magnetic resonance , nuclear medicine , oxygen , chemistry , human lung , lung , physics , medicine , radiology , spin echo , organic chemistry
Purpose To demonstrate the feasibility of oxygen‐dependent relaxometry in human lung using an inversion recovery ultra‐fast steady‐state free precession (IR‐ufSSFP) technique. Methods Electrocardiogram‐triggered pulmonary relaxometry with IR‐ufSSFP was performed in 7 healthy human subjects at 1.5 T. The data were acquired under both normoxic and hyperoxic conditions. In a single breath‐hold of less than 9 seconds, 30 transient state IR‐ufSSFP images were acquired, yielding longitudinal (T1) and transversal (T2) relaxometry parameter maps using voxel‐wise nonlinear fitting. Possible spatial misalignments between consecutive IR‐ufSSFP parameter maps were corrected using elastic image registration. Furthermore, dynamic relaxometry oxygen wash‐in and wash‐out scans were performed in one volunteer. From this, T 1 ‐related wash‐in and wash‐out time constants ( τ wi , τ wo ) were calculated voxel‐wise on registered maps using an exponential fitting model. Results For healthy lung, observed T1 values were 1399 ± 77 and 1290 ± 76 ms under normoxic and hyperoxic conditions, respectively. Oxygen‐related reduction of T1 was statistically significant in every volunteer. No statistically significant change, however, was observed in T2, with normoxic and hyperoxic T2 values of 55 ± 16 and 56 ± 17 ms, respectively. The observed average τ wi was 87.0 ± 28.7 seconds, whereas the average τ wo was 73.5 ± 21.6 seconds. Conclusion IR‐ufSSFP allows fast, steady‐state, and dynamic oxygen‐dependent relaxometry of the human lung. Magn Reson Med 79:839–845, 2018. © 2017 International Society for Magnetic Resonance in Medicine.