ST. LOUIS—Novel PET imaging of the hallmark neurofibrillary tangles in Alzheimer’s disease using F-18 THK5117 has nabbed the Society of Nuclear Medicine and Molecular Imaging’s 2014 Image of the Year award, presented to the researchers with the most spectacular visual demonstration of their work. The study involved was one of many presented today during the 2014 annual meeting press conference. This one in particular is groundbreaking because it exemplifies how longitudinal tau PET imaging tracks the progression of Alzheimer’s pathology compared to amyloid imaging.
The image was made possible by a team of researchers including Nobuyuki Okamura, MD, PhD, from the department of Tohoku University School of Medicine in Sendai, Japan. The objective of their study was the evaluation of this still investigational radiopharmaceutical as an in-vivo biomarker for Alzheimer’s pathology, specifically hyperphosphorylated tau deposits in the brain.
"In this study, the selective binding ability of F-18 THK5117 to tau was confirmed by the direct comparison with the amyloid PET tracer PiB," stated Okamura in an official statement. "I hope that this technique will contribute to the development of new anti-dementia drugs."
Results of the study showed how eight patients with Alzheimer’s disease and another six healthy controls were imaged for 90 minutes with both F-18 THK5117 PET and C-11 Pittsburgh Compound B (PiB). Scans were then interpreted to see how effective tau imaging with F-18 THK5117 PET was using C-11 PiB as a reference. Standard uptake value ratios were documented 60-80 minutes after injection of THK5117 and 40-70 minutes following PiB with the cerebellar cortex used as the region of interest.
Findings showed THK5117 retention in the lateral and medial temporal cortices of Alzheimer’s brains. Regional distribution of THK5117 contrasted significantly from C-11 PiB in subjects with the neurodegenerative disease and retention of THK5117 in the temporal cortex was positively linked to dementia severity. THK5117 retention in the hippocampus was also associated with hippocampal tau volume in Alzheimer’s patients. THK5117 retention in the right temporal lobe in healthy controls seemed to indicate areas of right temporal lobe atrophy, which was unexpected.
“Dr. Okamura’s work is in the forefront of such research,” said Satoshi Minoshima, MD, PhD, chair of the SNMMI Scientific Program Committee in the press release. “His group has successfully developed an F-18 labeled tracer, F-18 THK5117, that binds to tau/neurofibrillary tangles seen in Alzheimer's disease. Owing to its longer half-life, F-18 labeled tracers can potentially be distributed widely to many imaging centers. They demonstrated differential distributions of amyloid tracer versus tau/neurofibrillary tangle tracer in Alzheimer patients. Such observations shed critical light into pathogenesis and pathophysiology of Alzheimer's disease and will help develop better diagnostic methods and effective treatments.”