Abstract Details

PET with β-amyloid ligands is emerging as a molecular imaging technique targeting WM integrity. PiB seems to be a sensitive and reliable PET ligand in measuring WM integrity, however given its short half-life, it is not commercially available. An F18 ligand such as FMT with a longer half-life may be an alternative.

Investigate whether a similar variation in white matter (WM) binding exists between C11-Pittsburgh compound-B (PiB) and F18-Flutemetamol (FMT) PET ligands.

Cognitively unimpaired (CU) older and younger adults were included from volunteers responding to study advertisement for β-amyloid PET (N=61). Individuals prospectively underwent MRI, PiB and FMT PET. MRI-FLAIR images were segmented into WM hyperintensity (WMH) and normal appearing WM (NAWM) and registered to the T1-weighted image. PiB and FMT PET images were registered to the T1-weighted image. PiB and FMT standard uptake value ratios (SUVrs) from WMH and NAWM were calculated using cerebellar crus uptake as a reference.

Median age was 67 years (61-83 years) in older adults and 38 years (30-48 years) in younger adults. PiB and FMT SUVrs were higher in older compared to younger CU adults in WMH (p<0.001) and in NAWM (p<0.001). WMH and NAWM SUVrs were higher with FMT than PiB in older (p<0.001) and in younger (p<0.001) CU adults. PiB and FMT SUVrs were higher in NAWM compared to WMH in older (p<0.001) and younger (p<0.001) CU adults. There was no apparent difference between PiB versus FMT SUVrs in differentiating WMH from NAWM in older and younger adults.

PiB and FMT can successfully distinguish between WMH and NAWM. In WMH and NAWM, PiB and FMT show a similar topographical pattern of uptake in WM with a similar age association. However, given its longer half-life, commercial availability, and higher binding potential, FMT can be an alternative to PiB in PET, specifically targeting MS.