Bone pathologic correlation of multimodality imaging in Paget's disease.

The pagetic bones in the active phase of the disease with brisk lysis and sclerosis manifest intense tracer uptake on planar bone and SPECT images. Intense tracer uptake, however, can occur also in infections, dysplasias and metastases. Pinhole bone scintigraphy has been shown to portray specific diagnostic signs in a number of skeletal diseases. In an effort to identify useful bone scan signs, we prospectively carried out 99mTc-oxidronate pinhole bone scintigraphy of the skull, vertebrae, ribs, humerus, sacrum and ilium in two patients with Paget's disease of the bone. The pinhole bone scintigraphy findings correlated with radiographic, CT and MRI findings and in the vertebra with the pathological study. Interestingly enough, pinhole bone scintigraphy revealed intense tracer uptake preferentially in the bone cortex and the rim of the affected bones. Thus, the cranial inner table, humeral cortex and vertebral endplates and rims were the seats of characteristic tracer uptake, respectively creating a scintigraphic version of the radiographic "cotton wool" sign, "casket" sign and "picture frame" sign. The pagetic lesions in the sacrum and ilium also showed intense cortical and rim uptake. Correlation of pinhole bone scintigraphy with radiography, CT and MRI indicated that such cortical or rim uptake is characteristic of Paget's disease.