MAGNETIC-RESONANCE-IMAGING OF NORMAL BONE-MARROW

The appearance in magnetic resonance imaging (MRI) of the bones depend s, to a large extent on the unmineralized content of the bone cavities . Because yellow marrow contains a large number of fat protons and red marrow a significant number of water protons, MRI offers the opportun ity to map the distribution of red and yellow marrow. In addition, red marrow MR appearance varies according to the relative proportion of f at and nonfat cells. Variations in the composition of red marrow and i ts distribution among normal subjects, mainly in relation to age and s ex, contribute to creating a wide spectrum in bone MR appearance, whic h must be known in order to avoid confusion with bone marrow abnormali ties.