Effect of trabecular bone on the appearance of marrow in gradient-echo imaging of the appendicular skeleton.
This prospective study evaluated the effect of trabecular bone on the appearance of marrow in gradient-echo (GRE) images of the appendicular skeleton in vivo at high magnetic field strength. Magnetic resonance (MR) imaging of 10 normal extremities in five patients was performed with spin-echo (SE) and GRE sequences. The latter were obtained with gradient recalled acquisition in a steady state. SE and GRE sequences had identical spacing and planes of imaging. Cortical bone appeared as a signal void regardless of the pulse sequences and parameters. Marrow in contact with trabecular bone exhibited a shortened effective transverse relaxation time (T2*) and resultant signal loss because of local field inhomogeneities where mineralized matrix interfaced with it. This T2* effect was increased in regions with more trabecular bone (epiphysis) than regions with little trabecular bone (diaphysis). A low signal intensity on GRE images may represent fatty marrow with a high content of trabecular bone and should not be interpreted only as hematopoietic marrow.
Sebag
G H
GH
Department of Diagnostic Radiology, Stanford University Medical Center, CA 94305-5105.
Moore
S G
SG
D001853:Bone Marrow / Q000033:anatomy & histology*; D001842:Bone and Bones / Q000033:anatomy & histology*; D005121:Extremities / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male