Dynamic Gadolinium-enhanced MRI of the Proximal Femur: Preliminary Experience in Healthy Children

Objective: The purpose of this study is to use dynamic contrast-enhanced MRI to evaluate the perfusion characteristics of the proximal femur in the growing skeleton.

Materials And Methods: We evaluated 159 subjects (mean age, 5.67 years) who underwent a well-controlled protocol of contrast-enhanced MRI of the abdomen and hips. Perfusion and permeability parameters (enhancement ratio peak, AUC, time to peak, and rate of extraction) for six regions of the proximal femur were calculated.

Results: A decrease with age was found for all contrast kinetics parameters in all regions (p < 0.001). Perfusion parameters differed between the regions (p < 0.001). The highest perfusion and permeability parameters were found in the metaphyseal spongiosa, metaphyseal marrow, and periosteum. The metaphyseal spongiosa had a highly vascular pattern of enhancement and showed the highest enhancement ratio peak, AUC, and rate of extraction and the lowest time to peak. The metaphyseal marrow showed a vascular pattern of enhancement with a lower peak compared with the metaphyseal spongiosa. The periosteum showed prompt nonvascular contrast enhancement that reached a plateau that remained elevated.

Conclusion: The highest enhancement was seen in areas involved with growth: the metaphyseal spongiosa, which is related to endochondral ossification, and the periosteal cambium, which is related to membranous ossification. The enhancement characteristics are radically different: in the spongiosa; enhancement is brisk and declines, with a vascular pattern, whereas contrast uptake increases with time in the periosteum. Recognition of normal enhancement patterns of the proximal femur is important for distinguishing normal development from pathologic processes.