Question

The distant metastasis to bone can be best detected by:

• A. MRI
• B. Bone scan
• C. CT
• D. Intravenous venogram

Hint:

Which test surveys the entire skeleton in one sitting and shows lesions before plain x-rays do?

Answer 1

The Correct Option is B

Step 1: Define the clinical need.
The aim is to screen the whole skeleton for distant metastatic deposits, so the ideal investigation surveys the entire body in one study and is highly sensitive to early bony involvement.

Step 2: Recall the radionuclide bone scan.
A bone scan uses technetium-99m labelled methylene diphosphonate (Tc-99m MDP), which is taken up at sites of increased osteoblastic activity and bone turnover. Metastatic deposits stimulate reactive bone formation and therefore appear as areas of increased tracer uptake (hot spots).

Step 3: Why the bone scan is preferred.
It images the whole skeleton in a single examination and detects lesions earlier than plain radiographs, which require substantial bone loss before a lesion is visible. This makes it the standard screening test for skeletal metastases.

Step 4: Exclude the others.
MRI and CT give excellent local anatomical detail but are not practical whole-body screening tools for distant skeletal disease in routine practice. An intravenous venogram images veins and has no role in detecting bone metastasis.

Step 5: Conclusion.
Correct answer: Bone scan.