Potential for imaging cerebral amyloid deposits using I-123-labelled serum amyloid P component and SPET

The systemic and cerebral accumulation of I-123-labelled serum amyloid P component (I-123-SAP) was studied in patients with hereditary cerebral amyloid angiopathy-Dutch type (HCHWA-D) to determine the usefulness of I-123-SAP imaging in cerebral amyloidosis. Whole-body and SPET scintigraphic imaging was performed in two patients with HCHWA-D and four controls after the intraveous injection of I-123-SAP. Venous I-123-SAP clearance was also determined. Accumulation of the tracer was observed in the cerebral cortex of both patients, whereas no accumulation was seen in the controls. Blood clearance of radioactivity was similar in the patients and controls, suggesting that the amount of uptake of I-123-SAP in the cerebral amyloid deposits is relatively small. We believe this to be the first demonstration of cerebral amyloid deposits in vivo. Our findings indicate that I-123-SAP scintigraphy has possibilities for the diagnosis of patients with cerebral amyloid diseases, in addition to its use in patients with systemic amyloid deposition.