DOI: 10.1002/alz.075969 ISSN: 1552-5260

Biomarker interplay between CSF p‐tau and 18F‐PI‐2620 PET in Alzheimer’s disease and 4R‐tauopathy

Roxane Dilcher, Stephan Wall, Nicolai Franzmeier, Sabrina Katzdobler, Henryk Barthel, Olivia Wagemann, Carla Palleis, Endy Weidinger, Urban Fietzek, Carolin Isabella Kurz, Chrsitian Ferschmann, Maximilian Scheifele, Florian Eckenweber, Mirlind Zaganjori, Johannes Gnörich, Adrian Danek, Katharina Bürger, Daniel Janowitz, Boris‐Stephan Rauchmann, Sophia Stöcklein, Robert Perneczky, Florian Schoeberl, Andreas Zwergal, Günter Höglinger, Peter Bartenstein, Victor L Villemagne, John Seibyl, Osama Sabri, Johannes Levin, Matthias Brendel
  • Psychiatry and Mental health
  • Cellular and Molecular Neuroscience
  • Geriatrics and Gerontology
  • Neurology (clinical)
  • Developmental Neuroscience
  • Health Policy
  • Epidemiology



Reliable biomarkers for detecting different abnormal tau protein isoforms between neurodegenerative diseases are currently missing. Phosphorylated tau (p‐tau) in the cerebrospinal fluid (CSF) is acknowledged as a 3/4R tau biomarker in AD but not in other tauopathies. The positron emission tomography (PET) radiotracer 18F‐PI‐2620 has the potential to detect abnormal 3/4R‐tau in patients with Alzheimer’s disease (AD) and 4R‐tau in Progressive Supranuclear Palsy (PSP) or Corticobasal Syndrome (CBS). This study investigates the interplay between tau‐PET and CSF p‐tau in AD and 4R‐tauopathies.


In this cross‐sectional analysis, 52 patients with AD, 54 patients with PSP/CBS, and 11 controls underwent lumbar puncture and 0‐60 min dynamic 18F‐PI‐2620 PET scanning. Independent t‐tests assessed group differences in standardized uptake value ratios for the 20‐40min time window (SUVr20‐40) and p‐Tau. Quantitative and voxel‐wise multiple regression analyses tested the association between SUVr20‐40 and p‐tau and group interactions, using R and SPM and controlling for age and sex. ROC analyses were performed to evaluate biomarker performance in differentiating patient groups.


Patients with AD showed elevated CSF p‐tau levels (p<0.05; >61 pg/ml) and SUVr20‐40 in temporal, parietal, occipital, frontal, cingulate‐insula, striatum, and amygdala (p<0.05). In patients with AD the two biomarkers correlated positively (p<0.05). Patients with clinically suspected 4R‐tauopathies did not show elevated p‐tau levels but demonstrated high tau‐PET uptake in the lentiform nucleus (p<0.05), compared to controls and AD. ROC analyses showed that temporal SUVr20‐40 (87.3%) and p‐tau levels (80.8%) were able to differentiate AD from 4R‐tauopathies, while the lentiform nucleus tau‐PET showed moderate performance at discriminated patients with 4R‐tau from those with AD (56.7%) and healthy controls (66.3%). Interestingly, the AUC increased to 70%, when excluding patients with CBS.


The specific combination of CSF p‐tau levels and 18F‐PI‐2620 PET SUVR in disease‐specific regions facilitates biomarker‐guided stratification of AD and clinically suspected 4R‐tauopathies.

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