Discriminating radiation injury from recurrent tumor with [(18)F]PARPi and amino acid PET in mouse models

BACKGROUND: Radiation injury can be indistinguishable from recurrent tumor on standard imaging. Current protocols for this differential diagnosis require one or more follow-up imaging studies, long dynamic acquisitions, or complex image post-processing; despite much research, the inability to confidently distinguish between these two entities continues to pose a significant dilemma for the treating clinician. Using mouse models of both glioblastoma and radiation necrosis, we tested the potential of poly(ADP-ribose) polymerase (PARP)-targeted PET imaging with [(18)F]PARPi to better discriminate radiation injury from tumor. RESULTS: In mice with experimental radiation necrosis, lesion uptake on [(18)F]PARPi-PET was similar to contralateral uptake (1.02 ± 0.26 lesion/contralateral %IA/cc(max) ratio), while [(18)F]FET-PET clearly delineated the contrast-enhancing region on MR (2.12 ± 0.16 lesion/contralateral %IA/cc(max) ratio). In mice with focal intracranial U251 xenografts, tumor visualization on PARPi-PET was superior to FET-PET, and lesion-to-contralateral activity ratios (max/max, p = 0.034) were higher on PARPi-PET than on FET-PET. CONCLUSIONS: A murine model of radiation necrosis does not demonstrate [(18)F]PARPi avidity, and [(18)F]PARPi-PET is better than [(18)F]FET-PET in distinguishing radiation injury from brain tumor. [(18)F]PARPi-PET can be used for discrimination between recurrent tumor and radiation injury within a single, static imaging session, which may be of value to resolve a common dilemma in neuro-oncology. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13550-018-0399-z) contains supplementary material, which is available to authorized users.