FIG 1. Images of a 15-year-old girl with a recurrent aneurysmal bone cyst involving T11–L1.

A, Axial T2-weighted MR image shows a large, expansile spinal lesion with multiple fluid-fluid levels (arrows), typical for an aneurysmal bone cyst. The dependent fluid layers in the cyst appear hypointense to the supernatant layers because of T2 shortening from intracellular deoxyhemoglobin in erythrocytes. This locally aggressive lesion has eroded the cortical allograft (arrowheads) placed during the T12 corpectomy for the original lesion. T1-weighted enhanced sequences obtained after the IV administration of gadolinium-based paramagnetic contrast material (not shown) showed no evidence of a solid component within this lesion.

B, Sagittal-view T2-weighted MR image, showing fluid-fluid level.

C, CT section obtained during the ablation shows a pigtail catheter in place within the lesion (arrow).

D, CT section obtained through the lesion at approximately the same level as that shown in panel A 1 hour after intralesional injection of iodinated contrast material shows opacification of its multiple cystic spaces (arrowheads), as well as an air bubble from the injection (open arrow). Note, again, the erosion of the cortical allograft (solid arrows).

E, Axial T2-weighted MR image obtained through the lesion 7 months after treatment shows replacement of the cystic spaces of the lesion with tissue of intermediate to high signal intensity.

F, CT section obtained through the lesion 22 months after radionuclide ablation shows ossification within the tumor, with incorporation of the cortical allograft.