A – FDG-PET (Fluoro-2-deoxy-D-glucose Positron Emission Tomography) demonstrating asymmetric hypometabolism in thalami (left worse than right). B & C – Axial FLAIR (Fluid-Attenuated Inversion Recovery) sequences demonstrating an increased depth of sulci diffusely and ventricle size consistent with atrophy development over the course of 5 months.

A – H&E (hematoxylin and eosin) staining from entorhinal cortex demonstrating mild spongiform changes (vacuolization – black arrows). There were no spongiform changes present in other slides. B – H&E staining from left thalamus demonstrating neuronal loss and lack of spongiform changes. C – Immunohistochemistry against PrP in left thalamus demonstrating typical weak and patchy staining pattern seen in FFI. D – Western Blot against Proteinase Resistant Prion Protein (PrPsc) using proteinase K digestion protocol in frontal lobe tissue. The first lane (patient) demonstrates high levels of PrPsc resistant to proteinase K digestion as typically seen in FFI. Second and third lanes represent controls (type 1 PrPsc and type 2 PrPsc, respectively).