The International Dementia Conference Series, hosted by the McGill Centre for Studies in Aging resumed its biweekly events beginning September 15, 2021, with the Prion Hypothesis and Protein Aggregate Series.
Please join us on November 10, 2021, for a presentation by Victor Villemagne, MD, entitled "Amyloid and Tau imaging: Applications, quantification, and harmonization strategies."
Meeting ID: 835 5880 5980
Amyloid and Tau imaging: Applications, quantification, and harmonization strategies
Neuroimaging markers of misfolded and aggregated proteins associated with neurodegenerative conditions are being increasingly used for the diagnosis, prognosis, as well as recruitment and outcome measures in disease-specific therapeutic trials. The new proposed classification framework combines measures of Aβ (A), tau (T), and neurodegeneration/neuronal injury (N). This will require harmonization of semiquantitative measures across tracers. In the case of Aβ imaging a new approach allows the presentation tracer retention as assessed by different Aβ tracers using a single universal scale, named Centiloids. In the case of tau, and in order to capture the degree of regional tau deposition in the brain across tracers, the approach will require the use of a universal tau mask common to all tracers as well as the same standardization in sampling and normalization (target and reference regions). Given that tau imaging is a technique with high specificity for AD, it might be necessary to increase the sensitivity to allow detection of early tau deposition. The use of young Ab negative controls might allow to generate lower, more sensitive thresholds to discriminate between low and high tau. These measures of pathological protein aggregates can be used to assess longitudinal changes in protein deposition. It is important to remember that these measurements over time are affected by progressive cortical brain atrophy and changes in cerebral blood flow, so careful implementation of these measures as well as partial volume correction is recommended in the assessment of changes over time. In therapeutic trials, in particular, where the treatment drug could affect tracer central or peripheral binding, tracer metabolism or cerebral blood flow, all potentially affecting the input function of the tracer, a more quantitative approach, balancing accurate quantification and patient comfort, should be adopted.