Serum amyloid P component is a normal
plasma protein and a universal non-fibrillar constituent of
amyloid deposits. Radiolabelled
serum amyloid P component scintigraphy is a non-invasive and quantitative method for imaging
amyloid deposits, which produces diagnostic images in most patients with systemic
amyloidosis, and can be used repeatedly to monitor the course of the disease. The scintigraphy technique and biopsy histology are complementary, providing a detailed microscopic analysis and a quantitative whole body survey respectively. Clinically useful observations provided by the imaging method include different organ distributions of
amyloid in different types of the disease, demonstration of
amyloid in anatomic sites not available for biopsy, and evidence for rapid progression and sometimes regression of
amyloid deposits with different rates in different organs. Labelled
serum amyloid P component studies thus make a unique contribution to the diagnosis and management of individual patients with systemic
amyloidosis, and to systematic studies of existing and novel
therapies. The technique is available routinely for all known or suspected cases of
amyloidosis in the NHS National
Amyloidosis Centre at the Royal Free Hospital, but it has not been developed commercially.