TY - JOUR
T1 - Quantitation of T2' anisotropic effects on magnetic resonance bone mineral density measurement
AU - Yablonskiy, Dmitriy A.
AU - Reinus, William R.
AU - Stark, Helmut
AU - Haacke, E. Mark
PY - 1997/2
Y1 - 1997/2
N2 - In this paper, the authors quantitate the anisotropy of susceptibility effects in an uniaxial trabecular bone model and show its relevance to clinical MR bone mineral density measurements. A physical model is described that quantitates the anisotropic MR behavior of uniaxial trabecular bone. To test the model, a phantom of parallel polyethylene filaments was scanned every 15°between 0°and 90°with respect to the system's main magnetic field (B̄0). The distal radial metaphysis of a healthy female volunteer was scanned in orthogonal projections. The signal from each phantom image and each radial image was separated in a pixel-wise fashion into R2 and R2' maps. AS predicted, R2' relaxation showed anisotropic behavior and changed according to sin2 (θ), confirming that columnar structures parallel with B̄0 will cause no MR susceptibility effects. Scans of the distal radius showed that R2' relaxation was twice as great with the forearm perpendicular to B̄0 as when it was parallel to it, demonstrating different contributions from struts and columns. For both phantom and radial bone scans, R2 relaxation was isotropic and did not change with object orientation.
AB - In this paper, the authors quantitate the anisotropy of susceptibility effects in an uniaxial trabecular bone model and show its relevance to clinical MR bone mineral density measurements. A physical model is described that quantitates the anisotropic MR behavior of uniaxial trabecular bone. To test the model, a phantom of parallel polyethylene filaments was scanned every 15°between 0°and 90°with respect to the system's main magnetic field (B̄0). The distal radial metaphysis of a healthy female volunteer was scanned in orthogonal projections. The signal from each phantom image and each radial image was separated in a pixel-wise fashion into R2 and R2' maps. AS predicted, R2' relaxation showed anisotropic behavior and changed according to sin2 (θ), confirming that columnar structures parallel with B̄0 will cause no MR susceptibility effects. Scans of the distal radius showed that R2' relaxation was twice as great with the forearm perpendicular to B̄0 as when it was parallel to it, demonstrating different contributions from struts and columns. For both phantom and radial bone scans, R2 relaxation was isotropic and did not change with object orientation.
KW - MR susceptibility effects
KW - bone mineral density
KW - osteoporosis
UR - http://www.scopus.com/inward/record.url?scp=0030614541&partnerID=8YFLogxK
U2 - 10.1002/mrm.1910370213
DO - 10.1002/mrm.1910370213
M3 - Article
C2 - 9001145
AN - SCOPUS:0030614541
SN - 0740-3194
VL - 37
SP - 214
EP - 221
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 2
ER -