Comparative analysis of peptide p5 and serum amyloid P component for imaging AA amyloid in mice using dual-isotope SPECT

Mol Imaging Biol. 2012 Aug;14(4):402-7. doi: 10.1007/s11307-011-0524-0.


Purpose: I-labeled human serum amyloid P component (SAP) is used clinically only in the UK for imaging visceral amyloidosis to assist with diagnosis, disease staging, and monitoring response to therapy. We compare a new amyloid-reactive probe, peptide p5, with SAP for imaging amyloidosis.

Procedures: Dual-energy SPECT/CT images were acquired of (125)I-labeled SAP and (99m)Tc-labeled p5 in mice with systemic AA amyloidosis (n = 3). Twelve organs and tissues were harvested for radiotracer biodistribution assessment and for micro-autoradiographic analysis.

Results: I-SAP and (99m)Tc-p5 localized equivalently in amyloid deposits in liver (∼10% injected dose (ID)/g) whereas (125)I-SAP was twofold higher in the spleen (∼20% ID/g; (99m)Tc-p5, ∼10% ID/g). In contrast, (99m)Tc-p5 was bound to pancreatic and intestinal amyloid approximately fivefold more efficiently as evidenced in biodistribution data.

Conclusions: Radiolabeled p5 is an effective amyloid-imaging radiotracer as compared to SAP in the murine model of amyloidosis and may be rapidly translated for imaging patients with visceral amyloidosis in the USA.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Amyloid / metabolism*
  • Amyloidosis / diagnostic imaging*
  • Animals
  • Humans
  • Iodine Radioisotopes
  • Mice
  • Mice, Inbred BALB C
  • Mice, Transgenic
  • Peptides*
  • Serum Amyloid P-Component*
  • Technetium*
  • Tissue Distribution
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, X-Ray Computed


  • Amyloid
  • Iodine Radioisotopes
  • Peptides
  • Serum Amyloid P-Component
  • Technetium