In Vivo Imaging of Soft Tissue Infection

Example 4

Initial in vivo studies focused on soft tissue models of MSSA infection. This included a mouse thigh infection model and rat triceps model. FIG. 2 shows data for the accumulation of [¹⁸F]F-PABA in the triceps of an infected rat. Fifty μL of 10⁹ CFU of Newman S. aureus BHI culture was injected into the right triceps of a rat. After 10-15 hr the rats were imaged following iv administration of 0.8-1.2 mCi of [¹⁸F]F-PABA. The images clearly show the accumulation of radioactivity in the right but not the left triceps. In addition to monitoring the time course of [¹⁸F]F-PABA biodistribution, we also quantified tracer levels by postmortem ex vivo counting. While the [¹⁸F]F-PABA distributed to all tissues and organs with the exception of the brain, significant tracer accumulation was only observed in the right triceps, as well as the kidney, bladder and GI tracts due to tracer clearance. At 60 min tracer levels were 5.4× higher in the infected right triceps compared to the uninfected left triceps. This compares favorably with other tracers.