Normal gadolinium-enhanced MR images of the developing appendicular skeleton: Part 2. Epiphyseal and metaphyseal marrow.
OBJECTIVE
We have studied how gadolinium enhancement of T1-weighted MR images affects the expected normal differences in signal intensity between metaphyseal hematopoietic and epiphyseal fatty marrow. We have also analyzed how enhancement affects the expected normal changes in the MR images of the marrow due to fatty conversion.


METHODS
We analyzed gadolinium-enhanced MR images of normal distal femurs in 18 immature rabbits that were 5-11 weeks old and of normal proximal femurs in 18 infants, children, and young adults who were 2 months to 21 years old. In all subjects, we studied the change with age in signal intensity and enhancement ratio of the epiphyseal and metaphyseal marrow. In the rabbits, marrow composition and transformation were histologically verified.


RESULTS
On unenhanced T1-weighted MR images of the rabbits and of the infants, children, and young adults, epiphyseal signal intensity always exceeded metaphyseal signal intensity; however, the enhancement ratio was always greater in the metaphysis. The signal intensity in metaphyseal and epiphyseal marrow on unenhanced MR images increased with age. However, enhancement ratios decreased with age in both areas. In the rabbits, histologic studies showed more fatty marrow in the epiphysis than in the corresponding metaphysis and an age-related increase in marrow fat at both sites.


CONCLUSIONS
In the marrow of the extremities, gadolinium enhancement is greater in the (hematopoietic) metaphysis than in the (fatty) epiphysis. In both areas, enhancement decreases as the marrow becomes more fatty. On T1-weighted images, administration of a gadolinium-containing contrast agent reduces the normal contrast between hematopoietic and fatty marrow and obscures the changes in marrow signal intensity due to fatty conversion.
Dwek
J R
JR
Department of Radiology, Children's Hospital, Boston, MA 02115, USA.
Shapiro
F
F
Laor
T
T
Barnewolt
C E
CE
Jaramillo
D
D
D000293:Adolescent; D000328:Adult; D000375:Aging; D000818:Animals; D001846:Bone Development; D001853:Bone Marrow / Q000033:anatomy & histology*; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D004838:Epiphyses / Q000033:anatomy & histology*; D005269:Femur / Q000033:anatomy & histology / Q000254:growth & development*; D005682:Gadolinium; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D010012:Osteogenesis; D011817:Rabbits; D012016:Reference Values
D003287:Contrast Media; D005682:Gadolinium