Objective: The MR findings of two cases of subperiosteal hematoma of t
he orbit are described. Materials and Methods: We present two cases of
subperiosteal hematoma of the orbit following minor head trauma, the
first presenting with chronic progressive exophthalmos and the second
with acute proptosis. Results: Both cases showed a well-defined biconv
ex mass with a curvilinear hypointense band in the superior portion of
the orbit. In Case 1 chronic hematoma demonstrated high signal on bot
h T1- and T2-weighted imaging, and in Case 2 acute hematoma displayed
intermediate signal on T1-weighted imaging and high signal on T2-weigh
ted imaging. Follow-up MRI in Case 2 demonstrated the typical signal c
hanges from acute to subacute hematoma. Conclusion: Subperiosteal hema
toma has a characteristic appearance on MRI which is virtually diagnos
tic. In proper clinical settings MRI is the modality of choice for the
detection and characterization of this hematoma.