FDG PET/CT is useful for the interim evaluation of response to therapy in pts affected by diskitis

2137 Objectives The antibiotic therapeutical approach in pts affected by diskitis is often empiric. Therfore, early evaluation of the response to therapy is important. In many pts inflammatory indexes are low during all the phases of the diseases or altered by concomitant diseases. Aim was to assess the possible role of FDG PET-CT for the early evaluation of the response to therapy in patients affected by infective diskitis, in comparison to CRP serum level. Methods 34 pts (18F, mean age 64) diagnosed with infective diskitis were enrolled. 6 had a proved tubercular infection, 1 fungal infection and 27 pyogenic diskitis. All the pts underwent a baseline FDG PET-CT+CRP and a second exam+CRP 2 to 4 weeks after the therapy beginning. PET results in terms of SUV max1, SUV max2 and deltaSUV max were compared to MR, inflammatory indexes and clinical status during therapy. Results Mean SUV max at diagnosis was 8,6±3,7. Mean CRP at diagnosis was 3,8±3,8. 26 pts showed a clinical progressive response while 8 pts were non responder. SUV1 was not correlated to CRP1 (p=0,7) as well as SUV2 to CRP2 (p=0,4). In responder pts, SUV2 and CRP2 were significantly lower than SUV1 and CRP1 (p 36%. ROC curves for SUV2 showed a sensitivity of 84,6% and specificity of 62,5% with a cut-off≤6,4. ROC curves for delta CRP showed a sensitivity of 82,6% and specificity of 71,4% with a cut-off≤ 96%. ROC curves for CRP2 showed a sensitivity of 73,1% and specificity of 85,7% with a cut-off Conclusions Our results indicate that delta SUV max provides the higher specificity for identifying responder pts. SUV max2 and CRP2 provide high and comparable sensitivities. This may help the clinician to guide the antibiotic therapy, especially in case of an empiric line