Magnetic resonance imaging in symptomatic Paget's disease.

Four patients with symptomatic Paget's disease of the appendicular skeleton were evaluated by magnetic resonance (MR) imaging. The plain film findings in each case were advanced but dissimilar. All patients had progressive symptoms of pain, and one presented with excruciating pain of short duration. The radiographic features included diffuse progressive osteolysis, cortical resorption, insufficiency fractures, bowing, and cortical and trabecular thickening. In three of the patients, MRI was performed to exclude sarcoma, revealing preservation of fatty marrow signal in all phases of Paget's disease except in patients with an acute fracture (demonstrated by MRI) and sarcoma. Small, focal, linear or oval areas of low signal seen against a background of normal marrow signal on short or long TR/TE do not mimic tumor. These findings suggest that fatty marrow signal is preserved in advanced Paget's disease unless an acute fracture or tumor is present.