Bone scintigraphy (bone scanning) is a valuable tool for evaluating the skeletal system. It is based on the fact that metabolically active bone will incorporate a radioactive tracer. A bone scan is a highly sensitive test for identifying tumors, infections, arthritis, and occult fractures because these conditions all result in high bone turnover.
Bone scintigraphy reveals changes in bone metabolism more than changes in bone structure. Therefore, bone scintigraphy generally complements rather than replaces routine radiography for evaluating bone lesions.
To perform bone scintigraphy, the radiopharmaceutical is administered intravenously, and multiple images are collected over the next few hours. Generally, bone scans are performed three in phases:
- 1) Immediately after the injection (vascular phase),
- 2) At 5 minutes (soft tissue phase), and
- 3) At 3-4 hours (bone phase). Evaluating the 3 phases of the scan provides information about blood flow, soft tissue (muscle, ligament, tendon), and bone metabolism.
To prepare an animal for bone scintigraphy, the owner should withhold food after midnight the night before and water after 6 AM the morning of the scan.
Figure 1. Multiple delayed images of a dog with a primary osteosarcoma (bone tumor) in the left skull with diffuse metastatic disease.