Premium
The robustness of T 2 value as a trabecular structural index at multiple spatial resolutions of 7 Tesla MRI
Author(s) -
Lee D.K.,
Song Y.K.,
Park B.W.,
Cho H.P.,
Yeom J.S.,
Cho G.,
Cho H.
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.27202
Subject(s) - image resolution , trabecular bone , multislice , nuclear magnetic resonance , gradient echo , chemistry , nuclear medicine , spin echo , materials science , biomedical engineering , magnetic resonance imaging , physics , medicine , optics , pathology , osteoporosis , radiology
Purpose To evaluate the robustness of MR transverse relaxation times of trabecular bone from spin‐echo and gradient‐echo acquisitions at multiple spatial resolutions of 7 T. Methods The effects of MRI resolutions to T 2 andT 2 *of trabecular bone were numerically evaluated by Monte Carlo simulations. T 2 ,T 2 * , and trabecular structural indices from multislice multi‐echo and UTE acquisitions were measured in defatted human distal femoral condyles on a 7 T scanner. Reference structural indices were extracted from high‐resolution microcomputed tomography images. For bovine knee trabecular samples with intact bone marrow, T 2 andT 2 *were measured by degrading spatial resolutions on a 7 T system. Results In the defatted trabecular experiment, both T 2 andT 2 *values showed strong ( | r | > 0.80) correlations with trabecular spacing and number, at a high spatial resolution of 125 µm 3 . The correlations for MR image‐segmentation‐derived structural indices were significantly degraded ( | r | < 0.50) at spatial resolutions of 250 and 500 µm 3 . The correlations forT 2 *rapidly dropped ( | r | < 0.50) at a spatial resolution of 500 µm 3 , whereas those for T 2 remained consistently high ( | r | > 0.85). In the bovine trabecular experiments with intact marrow, low‐resolution (approximately 1 mm 3 , 2 minutes) T 2 values did not shorten ( | r | > 0.95 with respect to approximately 0.4 mm 3 , 11 minutes) and maintained consistent correlations ( | r | > 0.70) with respect to trabecular spacing (turbo spin echo, 22.5 minutes). Conclusion T 2 measurements of trabeculae at 7 T are robust with degrading spatial resolution and may be preferable in assessing trabecular spacing index with reduced scan time, when high‐resolution 3D micro‐MRI is difficult to obtain.