The winning entry, left, in a recent vendor-sponsored preclinical- imaging competition presented at the World Molecular Imaging Conference in Kyoto, Japan, compared the amyloid-binding efficacy of the imaging agent 125I- SAP (in use in Europe, but not approved for use in the United States) with a novel peptide tracer devised by the researchers, in a mouse model, using dual-energy SPECT/CT.
The team then compared the biodistribution of the two agents in the same animal with systemic amyloidosis. Regions of interest were segmented from the CT images and overlaid on the coregistered SPECT data (above, left), and quantitative measurements of biodistribution were performed in harvested tissue (above, right). The team demonstrated that the p31 peptide, compared with SAP protein, was comparable in its ability to bind with amyloid in the liver (and, to a lesser degree, in the spleen), but much more efficient at imaging pancreatic and intestinal amyloid.
Amyloidosis is a protein-folding pathology associated with Alzheimer disease, type 2 diabetes, chronic inflammation, and some plasma- cell cancers. No routine clinical means currently exist, in the United States, for imaging the noncerebral amyloid deposits associated with these disorders. A team of researchers at the University of Tennessee—Jonathan Wall, PhD; Tina Richey; Emily Martin; Alan Stuckey; and Stephen Kennel, PhD—developed a peptide tracer (99mTc-p31) to address this lack of imaging agent.