Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Radiolabeled PET


Published on

Radiolabeled PET

Published in: Health & Medicine
  • Be the first to comment

  • Be the first to like this

Radiolabeled PET

  1. 1. Radiolabeled PET imaging tracers for in vivo detection of pre-symptomatic Alzheimer’s disease [EXCERPT] Copyright © by Lorena Tonarelli, M.Sc. 2014 Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by the formation, in the brain, of extracellu- lar β-amyloid deposits and intraneuronal τ- protein tangles, which correlate to cogni- tive decline. [1,2] Currently, the diagnosis of AD is based on clinical criteria. However, these have low sensitivity and specificity, and only allow making a diagnosis of probable or possible Alzheimer’s disease. Conventional mag- netic resonance (MR) and computed tomo- graphy (CT) imaging also have low sensitiv- ity and specificity. They are primarily used as adjuncts to clinical diagnosis to help ex- clude other types of dementia, and to as- sess the degree of brain atrophy. Conse- quently, a definite diagnosis of AD can be achieved only at autopsy. [3] Non-invasive radio-labeled positron emis- sion tomography (PET) imaging tracers have been developed in the past 20 years, which can detect, in vivo, β-amyloid and τ- protein deposits, well before AD symp- toms become apparent. The most widely studied of these tracers are the 11C- Pittsburgh Compound B (11C-PIB) and 18F-(2-(1-{6-[(2-[18F]fluoroethyl)(methyl)a mino]-2-naphthyl}ethylidene)malononitrile)( 18F-FDDNP). [4,5,6] Another 18F-labeled PET β-amyloid tracer under study is 18F- AV-45 (florbetapir F18). [7] Patients undergo PET imaging after receiv- ing an intravenous injection of the selected biomarker. This travels to the brain, where it binds uniquely to β-amyloid (11C-PIB and florbetapir F18) or to β-amyloid and τ (18F-FDDNP). [4,5,6,7] Amyloid aggre- gates become apparent in the scans within as little as 30 minutes. [8] Both qualitative and quantitive β-amyloid pathology data obtained with radio-labeled PET imaging correlate well with visual ob- servations at autopsy. [9] To date, no ad- verse events have been reported, in stud- ies, following the use of radiolabeled PET tracers. [8] Clinically relevant advantages An advantage of 18F-labeled PET amyloid- β imaging tracers over conventional diag- nostic methods is the possibility of reach- ing a diagnosis in vivo. Other benefits in- clude: 2