Zdrav Vestn | Imaging of Brain Prion Protein Amyloid in Patients with Gertstmann-Sträussler-Scheinker Disease 969 KOMENTAR/COMMENTARY Imaging of Brain Prion Protein Amyloid in Patients with Gertstmann-Sträussler- Scheinker Disease Slikanje prionskega proteina možganov beta-amiloida pri bolnikih z Gerstmann-Sträussler-Scheinkerjevim sindromom Thuy A. Tran, 1,2 Deniz Kirik 1,3 1 Lund University Bioimaging Center, Faculty of Medicine, SE- 221 84 Lund, Sweden 2 Department of Medical Radiation Physics, Lund University and Lund University Hospital, Lund, Sweden 3 Brain Repair and Imaging in Neural Systems, Department of Experimental Medical Science, Lund University, SE-221 84, Lund, Sweden Korespondenca/ Correspondence: Deniz Kirik, PhD, Prof, Brain Repair and Imaging in Neural Systems, Lund University, BMC D11, SE-221 84 Lund, email: deniz.kirik@med.lu.se Ključne besede: diagnostika, FDDNP, konformacijske bolezni, PET, slikanje možganov Key words: brain-imaging, diagnostics, FDDNP, conformational diseases, PET Gerstmann–Straussler– Scheinker (GSS) disease is a transmissible spongiform en- cephalopathy, which is a rare but fatal ne- urodegenerative disease, characterized by accumulation of an abnormal, protease-re- sistant form of the prion protein (PrP) in the brain.1 Although it typically afects patients from age of 35 to 55, the disease onset could occur in persons as young as 25 years of age.2 While the defnitive diagnosis can be made at neuropathological examination of post- -mortem tissue, clinical progression is ac- companied with changes in the brain that can be followed by either immunoassays for a number of diferent wet biomarkers or by imaging techniques based on CT and MRI scanning or [18F]-FDG PET.3 However, the- se imaging methods provide low sensitivity and specifcity, indecisive in diagnosing pri- on diseases or giving sensitive readouts of disease progression. PET imaging using the radiofuorina- ted 2-(1-{6-[(2-[F-18]fuoroethyl)(methyl) amino]-2-naphthyl}ethylidene)malononi- trile, [18F]-FDDNP has been evaluated in a number of diseases, targeted Amyloid- -beta peptide and tangles tau protein in Alzheimer’s disease (AD),4,5 depression and anxiety.6 Te potential use of FDDNP for detec- ting the target prion amyloid in GSS [18F]- -FDDNP had previously been shown to be feasible in at least in vitro tissue specimens.7,8 However, its application for in vivo PET ima- ging had not been investigated in humans. Kepe and coworkers took this approach for- ward and were the frst to demonstrate the feasibility of detecting prion accumulation in living patients with GSS using ([18F]-FD- DNP PET and published their exciting re- sults recently in Brain Pathology.9 Kepe et al performed [18F]-FDDNP PET imaging in 6 GSS subjects with known point mutations of the prion protein (PRNP) gene. Tese data were later compared with [18F]- -FDG PET as well as with structural MRI brain scans. Te results showed an increased [18F]-FDDNP binding in the cerebellum, neocortex and subcortical areas of all symp- tomatic gene carriers, which are in agree- ment with the clinical symptoms while the two asymptomatic gene carriers showed no cortical [18F]-FDDNP binding. Te authors examined further the distribution of [18F]- -FDDNP in these patients by comparing it with the in vitro results from brain tissue specimens from deceased GSS subjects. Te in vivo accumulation of [18F]-FDDNP was very closely related to the distribution of prion protein pathology. Another strength in this study is the follow-up examinations in 2 patients afer 12–28 months, where the