A recent paper on diagnostic performance of RO948 F 18 tau PET in the differentiation of Alzheimer disease from other neurodegenerative disorders has been published. [18F]RO948 tau PET was compared with established MRI and CSF markers. In a subset of patients with semantic variant of primary progressive aphasia (svPPA) [18F]RO948 and [18F] flortaucipir was also compared. Participants were divided into either individuals without cognitive impairment, patients with mild cognitive impairment (MCI), AD dementia, and non-AD neurodegenerative disorders. [18F]RO948 did not bind significantly in the included non-AD disorders. In contrast, higher specificity was found for [18F]RO948 than for CSF Aβ42/Aβ40, when distinguishing AD dementia from no cognitive impairment and non-AD diseases. In differentiation Aβ-positive MCI from other conditions compared with AD dementia diagnostic performance of [18F]RO948 was lower. Irrespective of clinical diagnosis, tau PET positivity was almost exclusively observed in Aβ-positive individuals with exceptions for MAPT R406W mutation carriers. Compared with [18F]RO948, MRI and CSF measures performed less well in distinguishing AD dementia from non-AD disorders. In participants with svPPA lower binding of [18F]RO948 suggests a more favourable specificity profile compared with [18F] flortaucipir. The authors conclude that [18F]RO948 PET was superior to CSF p-tau181, Aβ42/Aβ40, Aβ42/p-tau181, and MRI measures in differentiation AD dementia from other neurodegenerative diseases and that has high specificity for AD-type PHF tau pathology outside the medial temporal lobe that is seen only in the context of Aβ positivity and certain MAPT mutations.
Antoine Leuzy, PhD; Ruben Smith, MD, PhD; Rik Ossenkoppele, PhD; Alexander Santillo,MD, PhD; Edilio Borroni, PhD; Gregory Klein, PhD; Tomas Ohlsson, PhD; Jonas Jögi, MD, PhD; Sebastian Palmqvist, MD, PhD; Niklas Mattsson-Carlgren, MD, PhD; Olof Strandberg, PhD; Erik Stomrud, MD, PhD; Oskar Hansson, MD, PhD. Diagnostic Performance of RO948 F 18 Tau Positron Emission Tomography in the Differentiation of Alzheimer Disease From Other Neurodegenerative Disorders. JAMA Neurol. 2020 May 11;e200989. doi: 10.1001/jamaneurol.2020.0989. https://pubmed.ncbi.nlm.nih.gov/32391858/