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A novel approach for semi-quantitative estimation of global amyloid uptake utilizing 18F-florbetapir (florbetapir F 18) and positron emission tomography

¹ Avid Radiopharmaceuticals, Philadelphia, PA ² Gdanski Uniwersytet Medyczny, Gdansk, Poland

Abstract No. 53

Objectives: Quantitative measurement of florbetapir uptake may improve the in-vivo assessment of Aβ deposition. We validated the accuracy of an automatic algorithm, with no requirement for normalizing PET images in standard space, and minimal operator and software intervention, to estimate global cortical uptake of amyloid tracer.

Methods: Florbetapir PET images from 10 Aβ+ AD patients and 10 Aβ- controls (based on clinical diagnosis and visual reads) were reconstructed by iterative technique with 4i/16s and 5 mm FWHM post-reconstruction Gaussian filter then processed automatically to generate a 128 bin count frequency versus intensity histogram. The first order derivative Gaussian (FWHM= 3mm optimized based on separate group of 5 Aβ- and 5 Aβ+ images) convolved histogram curve was searched in the intensity direction to estimate the separation of high and low intensity areas of brain. The high/low affinity curve area ratio (CAR) was calculated to estimate specific amyloid binding. Accuracy of CAR was assessed by comparing with average visual reads (VR) in a 0-4 point scale (0: low amyloid rating, 4: high amyloid rating) by three independent observers and also with cortical standardized uptake value ratios (SUVr) in reference to cerebellum.

Results: The histogram technique differentiated (p<0.0001) between Aβ+ and Aβ- subjects with no inter-cohort overlap (see table 1). There was a strong correlation between CAR and both SUVr (r=0.93) and VR (r=0.91).

Conclusions: A histogram analysis technique has potential to precisely differentiate between Aβ+ and Aβ- subjects while not introducing error caused by fitting PET images to standard templates and ROI drawing

View larger version (12K): [in this window] [in a new window]   Table 1: Statistical results for visual reads, histogram analysis and SUVr

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Saha, K. Articles by Skovronsky, D. PubMed Articles by Saha, K. Articles by Skovronsky, D.