Table 1.

Nuclear medicine modalities to image PTO

Imaging test	Major advantages	Major disadvantages	Relative costs (€)	Sensitivity/specificity	When to order	Other comments
Bone scan + SPECT/CT	Widely available Cheap Negative bone scan excludes infection	Low specificity: increased uptake at all sites of increased bone metabolism irrespective of the underlying disease No role in acute PTO Probably positive for 1–2 years after ORIF	300-400	Sensitivity 80–90 % Specificity 50–70 %	Viable bone Suspected peripheral PTO, osteosynthesis in situ, placement >2 years ago	Positive bone scan must be interpreted with caution and other imaging methods are necessary to differentiate between an infection and other causes of increased osteoblastic activity
WBC scan + SPECT/CT	Specific for leukocytic infiltration Accurately detects both acute and chronic infections High diagnostic accuracy	Laborious preparation Dual time point imaging necessary	800–1000	Sensitivity 80–100 % Specificity 80–100 %	Suspected infected non-union Suspected peripheral PTO, osteosynthesis materials in situ, placement <2 years ago; or when bone scan is positive >2 years	Correct acquisition, analysis and interpretation protocol has to be followed With SPECT-CT differentiation between osteomyelitis and soft tissue infection possible
FDG-PET/CT	Short acquisition time High image resolution No need for blood manipulation	Not possible to differentiate between infection and inflammation No existing criteria for positivity	1000–1200	Sensitivity 40–100 %* Specificity 60–90 %* *depending on which criteria for positivity are used	Suspected peripheral PTO, no surgery or surgery >6 months ago and no osteosyn-thesis in situ Suspected PTO in the axial skeleton Suspicion for dissemination	Consensus criteria for positivity necessary

Right: PET-CT camera (Siemens Biograph mCT 64-slice)

Image courtesy: Siemens Medical Systems, Knoxville, TN, USA