Table 1.

Looking for the magic bullet: Desirable properties of an ideal bacteria-specific PET/SPECT imaging agent for DFIs. (Adapted from [14].)

Tissue Penetration	High tissue penetration in areas with reduced vascular supply and heterogeneous infection conditions.
Sensitive	High target-to-background signal ratio. Low limit of detection (≤105 colony-forming units (CFUs)) [7].
Specific	Bacterial accumulation in both susceptible and drug-resistant organisms in different growth phases. Capable of differentiating between bacterial infection and sterile inflammation.
Specific for Gram-positive bacteria	Selective accumulation within Gram-positive pathogens. Capable of differentiating between Gram-positive and Gram-negative infections and sterile inflammation.
Quantitative	Signal proportional to the bacterial burden.
Stable	Chemically stable in blood. Low degradation of the agent by the host.
Safe	Acceptable radiation dose and repeat injection feasible without toxicity.
Manufacturable	Good manufacturing practice (GMP) production line with available PET/SPECT radioisotopes at a reasonable expense.