RT Journal Article
SR Electronic
T1 Direct comparison of the tau PET tracers [18F]flortaucipir and [18F]MK-6240 in human subjects
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.120.254961
DO 10.2967/jnumed.120.254961
A1 Alexandra Gogola
A1 Davneet Singh Minhas
A1 Victor L Villemagne
A1 Ann D Cohen
A1 James M. Mountz
A1 Tharick Ali Pascoal
A1 Charles M Laymon
A1 N. Scott Mason
A1 Milos D. Ikonomovic
A1 Chester A Mathis
A1 Beth E. Snitz
A1 Oscar L. Lopez
A1 William E Klunk
A1 Brian J Lopresti
YR 2021
UL http://jnm.snmjournals.org/content/early/2021/04/15/jnumed.120.254961.abstract
AB Tau PET tracers exhibit varying levels of specific signal and distinct off-target binding patterns that are more diverse than amyloid PET tracers. This study compares two frequently used tau PET tracers, [18F]flortaucipir (FTP) and [18F]MK-6240, in the same subjects. METHODS: [18F]flortaucipir and [18F]MK-6240 scans were collected within two months in 15 elderly subjects varying in terms of clinical diagnosis and cognition. FreeSurfer v5.3 was applied to 3T MR images to segment Braak pathologic regions (I-VI) for PET analyses. Off-target binding was assessed in choroid plexus, meninges, and striatum. SUVR outcomes were determined over 80-100 min ([18F]flortaucipir) or 70-90 min ([18F]MK-6240) normalized to cerebellar grey matter. Blinded visual interpretation of images was performed by five raters for both medial temporal lobe (MTL) and neocortex (NEO) and an overall (majority) rating determined. RESULTS: Overall visual ratings showed complete concordance between radiotracers for both MTL and NEO. SUVR outcomes were highly correlated (r2>0.92; P << 0.001) for all Braak regions except Braak II. The dynamic range of SUVR values in target regions was approximately two-fold higher for [18F]MK-6240 compared to [18F]flortaucipir. Cerebellar SUV values were similar for [18F]MK-6240 and [18F]flortaucipir, suggesting that differences in SUVR values are driven by specific signal. Apparent off-target binding in striatum and choroid plexus was often observed with [18F]flortaucipir, and most often in meninges with [18F]MK-6240. CONCLUSION: Both [18F]MK-6240 and [18F]flortaucipir are capable of quantifying signal in a common set of brain regions that develop tau pathology in AD and perform equally well in visual interpretations. Each also shows distinct patterns of apparent off-target binding. [18F]MK-6240 showed greater dynamic range in SUVR estimates, which may be an advantage for detecting very early signal or in longitudinal studies designed to detect small interval changes.