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Phantom studies simulating the impact of trabecular structure on marrow relaxation time, T 2 ′
Author(s) -
Engelke Klaus,
Majumdar S.,
Genant H. K.
Publication year - 1994
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.1910310406
Subject(s) - imaging phantom , relaxation (psychology) , constant (computer programming) , materials science , biomedical engineering , nuclear magnetic resonance , string (physics) , signal (programming language) , bone density , molecular physics , physics , optics , pathology , biology , medicine , computer science , quantum mechanics , neuroscience , programming language , osteoporosis
Phantom studies were conducted to investigate the impact of trabecular structure on the T 2 ′ signal measured by MRI. For a separation of density from structural effects, several phantoms were built. They consisted of parallel polyethylene strings arranged in a variety of different patterns to simulate (a) a constant uniform trabecular distribution with increasing trabecular thickness and (b) different structures with identical overall trabecular density. An asymmetric spin echo sequence was used to determine the apparent relaxation time T 2 ′. Changes in T 2 ′ are induced by susceptibility differences between the polyethylene strings simulating trabeculae and Gd‐TPA doped saline simulating bone marrow. The results showed an increasing T 2 ′ decay rate with (a) decreasing spacing while the string density was constant and (b) with increasing string density while the string arrangement was constant. The results demonstrate that the T 2 ′ signal is affected not only by density but also by spatial distribution. However, the results also indicate that a separation of the two effects is not possible from a T 2 ′ measurement alone, but that e.g., a matching CT slice that would provide purely density information is additionally needed. Theoretical simulations confirmed these results.