MR-Guided PET Reconstruction

We report a case of a 33-year-old man with epilepsy and equivocal EEG, MRI signs of mesiotemporal sclerosis, and nondiagnostic standard FDG-PET imaging. The patient underwent repeat FDG-PET/MRI to clarify the sidedness of the epileptogenic focus and to confirm the suspected MTS. The standard PET reconstruction using block sequential regularized expectation maximization failed to provide evidence of a clear epileptogenic focus. However, using MR-guided PET reconstruction, circumscribed hypometabolism was observed in the right-sided entorhinal cortex, compatible with the epileptogenic focus. The MR-guided PET reconstruction provided significantly improved gray/white matter differentiation, enhancing confidence in imaging interpretation.