In order to observe the feature of age-related marrow conversion and maturation of epiphyseal cartilage and analyze the distribution of red and yellow marrow in the proximal femur at STIR MR imaging, STIR and T(1) weighted MR imaging of the proximal femur in 52 subjects, aged 4 months to 25 years old, were retrospectively analyzed for the distribution and appearance of red and yellow marrow. The subjects with no known bone marrow abnormalities were divided into 6 age groups. The signal intensity of the marrow in the proximal epiphysis, proximal metaphysis, proximal diaphysis, distal diaphysis and greater trochanter was compared with the signal intensity and homogeneity of surrounding muscle and fat and graded by two observers. The results showed that the conversion of hematopoietic marrow in the proximal femur followed a well-defined sequence, occurring first in the proximal epiphysis, followed by the distal diaphysis, and then greater trochanter and metaphysis. STIR in combination with T(1)-weighted imaging could display clearly the origin of ossification center and the course of conversion from red to yellow marrow in proximal epiphysis and greater trochanter. STIR imaging showed that the marrow conversion in proximal metaphysic began below epiphyseal plate and intertrochanter. The site of red yellow was distributed in weight-bearing axis by 20 years of age. The marrow conversion of diaphysis was from distal end to proximal end, and the consequence of conversion was that distal diaphysis contained yellow marrow but proximal diaphysis partly red marrow connected with the red marrow of metaphysic. The epiphyseal cartilage had different characters of signal-intensity with age in STIR sequence. The distribution of red marrow in STIR imaging was more close to that of anatomy than T(1)-weighted imaging. It was concluded that STIR could dynamically display the feature of marrow conversion and the development of epiphyseal cartilage and accurately reveal the age-related distribution of red and yellow marrow on STIR imaging in the proximal femur.
Age Factors ; Bone Marrow/*anatomy & histology ; Bone Marrow/physiology ; Epiphyses/anatomy & histology ; Femur/*anatomy & histology ; Image Enhancement/*methods ; Magnetic Resonance Imaging/*methods ; Retrospective Studies ; Young Adult

The purpose of this study is to define the appearance of normal epiphyseal and metaphyseal marrow and normal changes of marrow due to fatty conversion on Gadolinium (Gd)-enhanced MR Imaging. Unenhanced and enhanced T1-weighted MR imaging were performed in proximal and distal femoral ends of 8 healthy piglets at the ages of 2, 4, 6 and 8 weeks, respectively. The changes with age in signal intensity and enhancement ratio of the epiphyseal and metaphyseal marrow with age were examined. The correlation of MRI characteristics with histological findings was studied. Our study showed that marrow of the metaphysis and of periphery of the 2nd ossification center were well vascularized hematopoietic marrow and had great enhancements. The enhancement ratio of metaphysis was greater than that of epiphyseal marrow and both enhancement ratios degraded gradually with age. The central regions of the epiphyseal ossification center and of the diaphysis were of fatty marrow and had little enhancement. It is concluded that on Gd-enhanced MR imaging the hematopoietic marrow of metaphysis and of periphery of the 2nd ossification center had greater enhancement than that of fatty marrow of central region of the 2nd ossification center. All of their enhancements decreased gradually with age.
Epiphyses/*anatomy & histology ; Femur/anatomy & histology ; Femur/*growth & development ; Gadolinium/*diagnostic use ; Growth Plate/*anatomy & histology ; Growth Plate/blood supply ; Growth Plate/growth & development ; Image Enhancement ; Magnetic Resonance Imaging ; Swine ; Swine, Miniature