Magnetic resonance appearance of bone marrow in the mandible at different ages.

To differentiate pathologic states of bone marrow from normal age-related marrow conversion, magnetic resonance appearances of the mandible were analyzed cross-sectionally according to age in 73 normal volunteers. Low signal intensities of red marrow first changed to high signal intensities in the anterior region of the mandibular body. With increase in age, marrow conversion was observed in the premolar/molar region, angle, ramus, and condyle regions in that order. No red marrow was recognized in the body of the mandible of subjects more than 30 years old. After the age of 30, the majority of the subjects showed high signal intensities in the entire bone marrow of the mandible. However, one subject over 30 years of age showed some portions of red marrow in the ramus and condyle. This knowledge about age-related marrow conversion of the mandible on magnetic resonance imaging will be useful in the visual differentiation from abnormal bone marrow, such as anemias, inflammatory diseases, infiltrative neoplastic disorders, and metastatic diseases.