International Journal of Clinical and Medical Imaging

Tau and Pet/Mri Imaging Biomarkers for Detecting and Diagnosing Early Dementia

*Yongxia Zhou
Department Of Radiology, Center For Biomedical Imaging, NYU Langone Medical Center, New York, United States

*Corresponding Author:
Yongxia Zhou
Department Of Radiology, Center For Biomedical Imaging, NYU Langone Medical Center, New York, United States
Email:Yongxia.zhou@yahoo.com

Published on: 2018-09-09

Abstract

Specific objective of this project is to quantify the neuropathological tau depositions in brain regions and to investigate primary age-related tau pathology and associations with amyloid and glucose-metabolism, neurocognitive tests and MRI metrics. Preliminary results demonstrated higher temporal deposition especially in the hippocampus and the inferior temporal regions compared to mean cortical deposition. Quantitative Braak stage-based regional analyses found highest tau deposition in the Braak stage II in the preclinical samples. There was significant age related higher tau deposition in temporal cortex, while non-significant correlation in mean cortical region. Significant correlations were found between tau deposition and memory as well as executive function scores, especially from middle and inferior temporal cortex; and significant correlations between tau and MRI metrics including diffusion, perfusion, functional and structural connectivities. Our results confirm current notion of this new tau tracer for reliably and consistently labeling and quantifying in vivo human taupathy in early dementia.

Keywords

Alzheimer’s Disease; Mild Cognitive Impairment; Tau; Amyloid; Fdg; Memory Score; Executive Function; Diffusion; Perfusion; Functional Connectivity; Morphometry

Introduction

As illustrated in the hypothetical model, compared to other PET tracers including beta-amyloid (Aβ), [18-F] Fluoro-2-deoxyglucose (FDG) and MRI structural/functional biomarkers, the intracellular tau deposition had been assumed to be particularly sensitive in the prodromal stage, especially the preclinical and mild cognitive impairment (MCI) stages [1,2]. The difficulties of labeling intracellular tau neurofibrillary tangle (NFT) deposition include requirement of high specificity of the tracer over the other five tau isoforms and enough abundance of the binding of the tracer to the intracellular tau[3,4]. The tracer molecular size needs to be small enough and designed to be lipophilic to cross the blood brain barrier (BBB) and cell membrane, to bind to the paired-helical filaments (PHF)-tau selectively[5]. With the development of tracer labeling and imaging techniques, over the past two decades, there are quite a few recent studies reported that successfully imaged tau depositions, especially the intracellular PHF which are insoluble fibers composed of hyper-phosphorylated tau, in MCI and Alzheimer’s disease (AD); and correlated with several cognitive tests [6,7]. However, due to recent availability of the PET tracer, there are very limited numbers of participants studied and most of them were relatively elderly [8-12].