SAP scan

A SAP scan is a type of nuclear medicine imaging test which uses iodine-123 (¹²³I) and serum amyloid P component (SAP) to diagnose amyloidosis.^[1][2]

SAP scan images showing progression of AL amyloidosis kidney and liver involvement following chemotherapy

For the amyloid scan used in diagnosis of Alzheimer's disease, see Positron emission tomography § Neuroimaging.

In patients with amyloidosis, large deposits of SAP coat the affected organs, in addition to the low levels normally found in the blood stream.^[3] The injected ¹²³I-SAP localises specifically to amyloid deposits, showing up as hot spots in the image.^[4]

Procedure

The radiopharmaceutical is injected into the patient, with imaging taking place on a gamma camera 6-24 hours later.^[3] An early blood-pool image provides a baseline for comparison with the organ SAP uptake after 24 hours.^[4]

Availability

Europe

¹²³I-SAP was granted orphan designation by the European Medicines Agency in 2003, however this was withdrawn in 2016.^[5]

SAP scanning is only carried out at two European centres; in the United Kingdom from the National Amyloidosis Centre, based at the Royal Free Hospital,^[6] and in the Netherlands at University Medical Center Groningen.^[7]

North America

SAP scanning is not approved in the United States due to its use of human blood products.^[7]

See also

• DPD scan