MRI vs Scintigraphy in the Detection of Vertebral Metastases: Preliminary Results

Since the introduction of 99mTc-MDP bone scintigraphy (Subramaniam and McAfee 1971), the use of this radiopharmaceutical is the method of choice in establishing the presence of bone metastases. The presence of bone metastases causes osteolytic and osteoblastic responses. The technetium-labeled MDP is taken up by chemisorption onto phosphorus groups of calcium hydroxyapatite, the basic crystal of bone (Gold and Basset 1986). Radionuclide bone sinctiscans are very sensitive for detecting the altered local metabolism in areas of skeletal remodeling associated with metastatic deposits. The radionuclide study requires as little as a 5%–10% change in the lesion-to-normal bone ratio for an abnormal focus to be appreciated on the scintiscan. However, it is well known that bone scintigraphy can be false negative in the case of very aggressive metastasis. Furthermore, false positive findings of bone scintigraphy are described in patients with nonmalignant disease like degeneration, healing fractures, and various metabolic disorders like osteoporosis and osteomalacia (Thrall and Ellis 1987). The potential of MRI for detecting bone metastases is considered to be very good (Daffner et al. 1986; Modic et al. 1986; Moon et al. 1983; Smoker et al. 1987; Zimmer et al. 1985). We compared in a retrospective manner the bone scintiscans and MRI examinations of 48 patients with malignant disease and suspected vertebral metastases.