Dual isotope SPECT imaging of I-123 and I-125

Peripheral amyloidosis is a debilitating and often fatal disease. SPECT imaging of amyloid in mice has been established using
¹²⁵
I-SAP. Current efforts are aimed at using
¹²⁵
I-labeled synthetic peptides such as p5, which are easier to translate into the clinic in the US since SAP is of human origin. It needs to be shown that the new peptide biomarkers correlate well with the gold standard, SAP. As both materials can be radioiodinated using facile chemistry, the challenge then becomes to develop a protocol that supports dual isotope SPECT imaging of
¹²³
I-labeled SAP and the
¹²⁵
I-labeled peptide. We address this challenge by first quantifying the amount of cross-talk between the two radio nuclides. We subsequently suggest a correction method.