Clinical Utility of Radiation Medicine 99mTc-Methylene Di- phosphanate Bone Scintigraphy in the Early Diagnosis of Rheumatoid Arthritis

The value of 99mTc-Methylene diphosphanate (99mTc-MDP) bone scan in predicting development of bony destruction, swelling, new bone erosions and skeletal deformities in small joints and bones was studied by visual evaluation of bone scans. 99m Tc-MDP was injected intravenously. 3 hours after the 99mTc-MDP injection, they have been underwent spot views of entire skeletons with planar scintigraphy in the anterior and posterior positions. All patients were examined under the Electronics Corporation of India Limited (ECIL) single head gamma camera imaging machine, equipped with a low-energy high-resolution parallel-hole collimator. In 9 patients with newly diagnosed rheumatoid arthritis a total of 60 patients of 99mTc-MDP bone scan were examined clinically, scintigraphically, and radiographically. The follow up period was 2 years. Seven patients found increased radiopharmaceutical increased in small joints. Onset of the rheumatoid disease was found in three out of seven patients. 2/9 patients, the joints which were eroded scintigraphically, was active at all the checkups. Erosions were detected earlier in foot joints than in finger joints. New erosions were especially prone to appear in joints with persisting and high scintigraphic activity. On the contrary, inactive joints by radionuclide scanning never eroded. Scintigraphic and clinical activity and radiographic erosion correlated significantly with each other. The sensitivity and specificity of visual scintigraphic assessment and the relative pixel activity method proved to be superior to the region of interest methods and clinical evaluation for prediction of bony erosions in patients of rheumatoid arthritis.