Best investigation for the detection of bone metastases1

Best investigation for the detection of bone metastases is?

A. X-ray
B. CT Scan
C. MRI
D. Bone scan

Correct answer : D. Bone scan
Best investigation for the detection of bone metastases

Radioisotope bone scan is the preferred method for the detection of bone metastases
It is more sensitive than radiography for the detection of most metastases
Technetium-99m is the commonly used radioisotope
It accumulates in reactive new bone that is formed in the metastases resulting in a ‘hot spot‘ in the scan
The amount of accumulation depends on the level of blood flow
In some cases, ‘cold spots‘ are also noted due to the absence of bone formation within the lesion
The results from a bone scan are not specific as the tracer can accumulate in other areas with increased bone formation such as sites of fracture healing / infection
So a bone scan should be followed by other radiological modalities such as CT scan to confirm the lesion

Ref: Radiological imaging for the diagnosis of bone metastases, L. D. Rybak, D. I. Rosenthal, The Quarterly Journal of Nuclear Medicine and Molecular Imaging, 2001;45:53-64