High-signal T2 changes of the bone marrow of the foot and ankle in children: red marrow or traumatic changes?
BACKGROUND
High-signal T2-weighted bone marrow changes can be found in both bone marrow edema and hematopoietic marrow and are often seen on pediatric MR images of the feet and ankle.


OBJECTIVE
To evaluate whether high-signal T2 changes of the bone marrow seen on pediatric MRI of feet and ankles represent residual hematopoietic marrow.


METHODS
A total of 402 bones in 41 pediatric MRI studies of feet and ankles (34 children, 1-18 years) were reviewed by two observers who were blinded to the patients' ages. The studies were reviewed for the presence of high-signal changes of the bone marrow on sagittal fluid-sensitive images. The frequency and location of these foci were correlated with the patients' ages.


RESULTS
High-signal T2 changes of the bone marrow were seen in 45/402 bones (11%) and in 24/41 patients younger than 16 years (59%). The changes were most commonly located in the calcaneus (54%), followed by the talus (35%) and navicular bone (35%), invariably at the endosteal surface. In 16 ankles, such foci were seen in the feet but not in the distal tibia/fibula. Symmetric presence (two ankles) or absence (four ankles) of high-signal marrow were seen in six of seven patients with bilateral ankles.


CONCLUSIONS
High-signal T2 changes of the bone marrow in pediatric feet and ankle MRIs have a symmetric, fairly consistent pattern and disappear after the age of 15 years. We believe that these high-signal areas are normal and represent residual hematopoietic marrow.
Shabshin
Nogah
N
Department of Radiology, Thomas Jefferson Medical College, Philadelphia, PA, USA. shabshin@yahoo.com
Schweitzer
Mark E
ME
Morrison
William B
WB
Carrino
John A
JA
Keller
Marc S
MS
Grissom
Leslie E
LE
D000293:Adolescent; D000842:Ankle / Q000033:anatomy & histology*; D016512:Ankle Injuries / Q000175:diagnosis; D001853:Bone Marrow / Q000033:anatomy & histology*; D001855:Bone Marrow Diseases / Q000175:diagnosis; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D005528:Foot / Q000033:anatomy & histology*; D018409:Foot Injuries / Q000175:diagnosis; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012189:Retrospective Studies