Tumor Recurrence versus Radiation Necrosis: ¹⁸F-FET and MRI Head-to-Head Comparison of Volumes on a Hybrid PET/MR System

¹⁸F-fluoro-ethyl-tyrosine (F¹⁸-FET), an amino acid radiotracer, is used in neuro-oncological imaging. The study aims at observing and comparing the volumes of the lesions detected on three dimensional (3D) fluid-attenuated inversion recovery (FLAIR), F¹⁸-FET PET, and gadolinium contrast-enhanced MRI (CE-MRI). Results on comparison of diffusion and perfusion weighted imaging with FET are underway. MRI sequences taken were 3D FLAIR and T1- MPRAGE. This study concluded that metabolic tumor volumes were more sensitive in detection of tumor volumes in the cases where no contrast enhancement was noted since the commencement or got resolved over time. Also, metabolic tumor volumes can be used for radiotherapy planning, considering they were more than contrast enhancing volumes in few cases.