68Ga-Citrate PET/CT in patents with inflammatory/infectious disease

Objectives 67Ga-citrate has been used in the diagnostic of inflammatory-infectious diseases. Although accurate,67Ga-citrate scintigraphy presents some practical disadvantages.Ga68 is a positron emitting isotope for PET diagnostics with short half life, high-energy photons, high spatial resolution, low costs, low dosimetry and a short time procedure. To preliminary evaluate the accuracy of 68Ga-citrate PET/CT imaging in inflammatory-infectious diseases.

Methods This study was approved by our local Ethical Committee. 38 pts (mean age 50) were enrolled, for a total of 47 scans. 8 had a suspected discitis, 25 osteomyelitis, 3 IBD, 2 other diseases (1 FUO (fever of unknown origin) 1 myocardial sarcoidosis). 9pts underwent also a post therapy scan. Each pt underwent a 68Ga-citrate PET/CT(GE Discovery LS or STE). PET images were interpreted considering clinical data. Both visual and semi-quantitative (SUV max) assessment was performed. PET results were compared to WBC scintigraphy, MR and histopathology (when possible) within 2 weeks and clinical follow up.

Results The image quality was high for each pt. 17/47 scans were negative and 30/47 were positive with mean SUV max 4,4. Among the negative PET, 3pts had a discal degeneration, 10 were studied after an effective treatment, 1 had an eosinophilic granuloma, 1 a FUO and 1 a myocardial sarcoidosis (small lesions). Among the positive PET we found three false positive results represented by 2 bone lymphomas and an osteoblastoma, whose diagnosis was reached only after biopsy (MR was positive for OM as well). Overall, we found 27 TP, 15 TN, 3 FP and 2 FN scans, giving respectively: sensitivity 93%, specificity 83%, PPV 90%, NPV 88%, accuracy 89%.

Conclusions Although preliminary, these data confirm the possible 68Ga-citrate role for diagnosis of bone infections, especially in consideration of its very favourable characteristics. However, more studied are required, including a comparison population evaluated with the more standard FDG