P15.11.A 18F-Fluciclovine PET/CT to distinguish radiation necrosis from tumour progression in brain metastases treated with stereotactic radiosurgery: results of a prospective pilot study

Abstract Background Amino acid PET radiopharmaceutical, 18F-fluciclovine, shows increased uptake in brain tumors relative to normal tissue and may be a useful tool for detecting recurrent metastases. Here, we report results from prospective pilot study evaluating the use of 18F-fluciclovine PET/CT distinguish radiation necrosis tumour progression among patients with metastases treated stereotactic radiosurgery (SRS). Material Methods The primary objective was estimate accuracy distinguishing progression. trial included adults who underwent SRS presented follow up MRI (with DSC MR perfusion) which equivocal versus Within 30 days brain, an (Siemens mCT) acquired 5-15 min post-injection images generated by PSF reconstruction. Quantitative metrics each lesion were documented SUVmean ratios calculated. reference standard diagnosis vs clinical every 2-4 months until multidisciplinary consensus or confirmation. Results Of 16 enrolled between 7/2019-11/2020, 1 patient died prior diagnosis, allowing 15 evaluable subjects 20 lesions. Primary histology NSCLC 9 (45%) lesions, breast 7 (35%), melanoma 3 (15%), endometrial (5%). final (80%) lesions 4 (20%). SUVmax statistically significant predictor (P = 0.011), higher values indicative area under ROC curve 0.833 (95% CI: 0.590, 1.0). A cutoff 4.3 provided sensitivity identify 1.0 (4/4) specificity rule out 0.63 (10/16). 0.018), SUVpeak 0.007), SUVpeak/normal 0.002) also reached statistical significance as predictors progression, SUVmax/normal 0.1) SUVmean/normal 0.5) not significant. AUC significantly than AUCs other quantitative variables (P-values > 0.2). Conclusion In this study, 18F Fluciclovine demonstrated promising previously SRS. Using SUVmax, cutpoint 0.63. Confirmatory phase II III studies are ongoing.