18F-florbetaben had high sensitivity for Alzheimer’s disease (AD), clearly distinguished patients with frontotemporal lobar degeneration (FTLD) from AD and provided results comparable to those reported with 11C-Pittsburgh Compound B in a variety of neurodegenerative diseases, according to a study in the August issue of the Journal of Nuclear Medicine.
Amyloid imaging with 18F-labeled radiotracers will allow widespread use—facilitating research, diagnosis and therapeutic development for AD, the researchers noted. The purpose of the study was to compare cortical amyloid deposition using 18F-florbetaben and PET in controls and subjects with mild cognitive impairment (MCI), FTLD, dementia with Lewy bodies, vascular dementia, Parkinson’s disease and AD.
After injecting subjects with 300 MBq of 18F-florbetaben and completing PET exams, Victor L. Villemagne, MD, of the department of nuclear medicine and the PET center at Austin Health in Victoria, Australia, and colleagues reviewed 109 subjects in three clinical studies at Austin Health:
- 32 controls;
- 20 subjects with MCI;
- 30 patients with AD;
- 11 with FTLD;
- Seven with dementia with Lewy bodies;
- Five with Parkinson’s disease; and
- Four with vascular dementia.
The researchers also calculated the standardized uptake value (SUV) ratios using the cerebellar cortex as a reference region between 90 and 110 minutes after injection. When compared with the other groups, the researchers reported that the AD patients demonstrated significantly higher SUV ratios in neocortical areas.
Ninety-six percent and 60 percent of MCI subjects showed diffuse cortical 18F-florbetaben retention, Villemagne and colleagues wrote. In contrast, only 9 percent of FTLD, 25 percent of vascular dementia, 29 percent of dementia with Lewy bodies, and no Parkinson’s patients and 16 percent of controls showed cortical binding. Although there was a correlation between Mini Mental State Examination and beta -amyloid burden in the MCI group, no correlation was observed in controls, FTLD or Alzheimer’s patients.
“This is the first report, to our knowledge, in which 109 participants encompassing a wide range of dementing and nondementing neurodegenerative diseases were evaluated with an 18F-labeled A-imaging radiotracer,” the authors wrote.
In contrast with previous reports using 11C-PiB, the relationship between age and neocortical SUV ratios in controls did not reach significance, most likely attributable to the low number of controls with elevated 18F-florbetaben binding.
“The distribution of 18F-florbetaben binding matched the postmortem distribution of neuritic plaques in AD, providing a robust separation of AD patients from controls and from patients with FTLD or Parkinson’s,” Villemagne and colleagues concluded. “This separation was achieved either with visual image inspection or a simple semiquantitative measure derived from a short scan at 90 minutes after injection of the tracer. These findings suggest that 18F-florbetaben PET can be used in clinical practice, with a short scan easily tolerated by elderly patients while allowing economical use of a PET camera.”