Preliminary quantitative evaluation of ¹⁸F-FDDNP PET/CT in Alzheimer's disease, using different regions of reference

Introduction. - Alzheimer's disease (AD) is the leading cause of dementia in the world. His current treatment is symptomatic. New therapies, aimed at slowing the neurodegenerative process, are actually under study. Early detection of AD as also the evaluation of new generation of neuroprotectors drugs is essential. For this reason, markers of amyloid plaques and neurofibrillary lesions have been developed including ¹⁸F-FDDNP. Methods. - Two patients and two controls were included in this preliminary study. They were submitted to a PET/CT with ¹⁸F-FDDNP. Data acquisition was performed in a list mode during 90 minutes. We used a cerebral atlas to create ROI, after co registration with a perfusion PET template, and we estimated the distribution volume ratio (DVR) using two different reference regions: the cerebellum and the white matter. We calculated a simplified index of quantification (SUVr) using a single 10 minutes acquisition frame. Results. - We found an increased DVR in temporal lobes (amygdala) (1.23-1.40 in patients vs 1.06-1.31 in controls, with cerebellum as reference region) and fronto-basal regions (1.48-1.30 in patients vs 1.16-1.23 in controls with the same reference region and 1.25-1.18 in patients vs 1.13- 1.19 in controls with white matter as reference region). SUVr calculated between 50 and 60 minutes after injection was highly correlated to DVR values (correlation coefficient 0.93). The SUVr difference between patients and controls was more important with cerebellum rather than white matter as reference region (26% in amygdala). Conclusion. - This is a very preliminary study due to the low number of subjects included. However, the results obtained suggest the feasibility of brain ROI segmentation and the DVR-SUVr calculation using an anatomical atlas. (authors)