The Bone Scan in Metabolic Bone Disease

Abstract

Skeletal uptake of 99mTc-labelled diphosphonate depends primarily upon osteoblastic activity and, to a lesser extent, skeletal vascularity (Fogelman 1980). A bone scan image therefore presents a functional display of total skeletal metabolism and as such has a potentially valuable role to play in the assessment of patients with metabolic bone disorders. However, the bone scan appearances in metabolic bone disease are often non-specific, and their recognition depends upon a subjective impression of increased tracer uptake throughout the whole skeleton (Fogelman and Citrin 1981). This may be particularly difficult to detect when dealing with mild disease. It is the presence of focal lesions, as in metastatic disease, that makes a bone scan appear obviously abnormal. While focal lesions are easily identified, slightly increased tracer uptake throughout the whole skeleton may be virtually impossible to detect by visual inspection alone.