Quantitative analysis of amyloid β deposition in patients with Alzheimer's disease using positron emission tomography

Positron emission tomography (PET) is a sensitive technique for functional and molecular imaging. In Japan, the incidence of cognitive disorders is increasing at an accelerated pace, partly due to the increasing size of the elderly population. Basic and clinical studies on dementia have become very important. In vivo detection of amyloid beta (Aβ) deposits could be useful for early diagnosis of Alzheimer's disease (AD). "Aβ imaging" by PET has been recognized as one of the most important methods for the early diagnosis of AD. Clinical PET studies have been conducted using several probes, such as [¹⁸F]FDDNP, [¹¹C]SB-13 and [¹¹C]Pittsburgh compound-B ([¹¹C]PIB). [¹¹C]PIB is the most commonly used probe. In this chapter, a novel imaging probe, 2-[2-(2-dimethylaminothiazol-5-yl)-ethenyl]-6- [2-(fluoro)ethoxy] benzoxazole ([¹¹C]BF-227), is reported. To the authors' knowledge, [¹¹C]BF-227 is the first Aβ imaging probe to be used in Japan. The purpose of this chapter is to examine methods for quantitative analysis of Aβ deposition in the human brain using PET and [¹¹C]BF-227. Six AD patients and six healthy control subjects were used in the present study. Dynamic PET images were obtained over 60 min. Blood samples were obtained from the radial arteries. The results were analyzed using Logan graphical analysis and full kinetic analysis. A significantly higher distribution volume ratio (DVR) value was observed in AD patients in cortical regions, e.g., the cingulate, frontal, temporal, parietal and occipital regions, than in control subjects. Satisfactory correlation of these values to the semiquantitative standardized uptake values (SUV) was obtained. These findings suggest that [¹¹C]BF-227 is a promising PET probe for clinical evaluation of early Aβ deposition in AD patients.