Technetium-99m-labeled antigranulocyte antibody bone marrow scintigraphy

Abstract

Although bone scintigraphy is a sensitive method for detecting skeletal metastases, it is often equivocal for metastases due to poor specificity. This study evaluates Tc-99m-antigranulocyte antibody (AGA) bone marrow scintigraphy in differentiating malignant from benign lesions, in 42 patients with skeletal tumors who had equivocal bone scans. Methods: AGA scans performed approximately 1 wk after Tc-99m-MDP bone imaging were visually assessed for the presence of concordant marrow defects. Final diagnoses were made from radiological results, follow-up bone scans or clinical evaluation for 12 mo or longer. Results: The final diagnoses were: skeletal metastasis (19 patients), no metastasis (20 patients) and unconfirmed (3 patients). AGA scans could not determine the presence of a concordant defect in three patients because of overlying liver activity or previous irradiation of the region. Seventeen patients had bone marrow defects concordant with bone scan lesions, whereas 15/19 patients without metastasis had normal AGA scans. The sensitivity and specificity of AGA for detecting skeletal metastases were 100% and 79%, respectively. Conclusion: AGA scans had a low incidence of skeletal metastases in patients who had equivocal bone scans. Although a concordant marrow defect increases the possibility of metastasis, further radiological investigation to exclude benign disease is warranted.