MRI ROAD-MAP OF NORMAL AGE-RELATED BONE-MARROW .2. THORAX, PELVIS ANDEXTREMITIES

We retrospectively reviewed T1-weighted MR images of 381 patients aged from 7 days to 24 years to evaluate the bone marrow change in thoraci c wall and shoulder, pelvis and proximal femur and upper and lower ext remities. The patients included in the study were without history of b one marrow disease, A grade of from 1 to 4 was assigned to the marrow signal intensity of the examined anatomic segments, The signal intensi ty of all anatomic segments was as low as or lower than that of muscle in all patients younger than 2 months, reflecting underlying hematopo ietic marrow, The first segments to become hyperintense were the epiph yseal/round bone ossification centers, followed by the phalanges, diap hysis, flat bones and metaphysis. Marrow signal intensity increased in all regions with age, While in the epiphyseal/round bones and diaphys is bone marrow shows a diffuse and homogeneous increased signal intens ity with age, in the sternum, ribs, scapulae, posterior ilium and meta physis varying percentages of intermediate signal intensity are mainta ined. An orderly progression of red to yellow marrow was established.