Diagnostic performance of 123I-labeled serum amyloid P component scintigraphy in patients with amyloidosis.
OBJECTIVE
To assess the diagnostic accuracy and additional information provided by 123I-labeled serum amyloid P component (SAP) scintigraphy in patients with systemic and localized amyloidosis.


METHODS
123I-labeled human SAP was injected intravenously into 20 controls and 189 consecutive patients with histologically proven amyloidosis: of AA type in 60 cases, AL type in 80, hereditary ATTR type in 27, and localized amyloidosis in 22 cases. SAP scintigrams were obtained 24 hours after tracer injection and were analyzed for abnormal patterns of uptake. Sensitivity and specificity were determined, and scintigraphic findings were compared with clinical data.


RESULTS
Diagnostic sensitivity of SAP scintigraphy for systemic AA, AL, and ATTR amyloidosis was 90%, 90%, and 48% respectively, and specificity was 93%. The distribution of amyloid was less diverse in AA than in AL type. Myocardial uptake was not visualized in any patient. Splenic amyloid was very frequent (80%) in AA and AL type but rarely detected clinically (14%). Abnormal tracer uptake in the liver and kidneys correlated with disturbed liver function and proteinuria, respectively. Bone marrow uptake was specific for AL (21%) and was more frequent in AL kappa than AL lambda. Localized amyloid deposits were not imaged.


CONCLUSIONS
SAP scintigraphy is diagnostic of amyloid in most patients with AA and AL type but fewer with hereditary ATTR type, relating to differing distributions and burdens of amyloid in these disorders. It usually reveals more widespread organ involvement than is identified clinically, and certain distributions of amyloid are characteristic of particular fibril types.
Department of Rheumatology, University Medical Centre, Groningen, The Netherlands. b.p.c.hazenberg@int.umcg.nl
Bouke P C
BP
Hazenberg
Martin H
MH
van Rijswijk
D Albertus
DA
Piers
Marjolijn N
MN
Lub-de Hooge
Edo
E
Vellenga
Elizabeth B
EB
Haagsma
Philip N
PN
Hawkins
Pieter L
PL
Jager
D000328:Adult; D000368:Aged; D000686:Amyloidosis / Q000000981:diagnostic imaging* / Q000235:genetics / Q000378:metabolism*; D028226:Amyloidosis, Familial / Q000000981:diagnostic imaging / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000378:metabolism; D007145:Immunoglobulin kappa-Chains / Q000378:metabolism; D007146:Immunoglobulin lambda-Chains / Q000378:metabolism; D007457:Iodine Radioisotopes; D007668:Kidney / Q000378:metabolism / Q000503:physiopathology; D008099:Liver / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011228:Prealbumin / Q000235:genetics / Q000378:metabolism; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D000685:Serum Amyloid A Protein / Q000378:metabolism; D000683:Serum Amyloid P-Component / Q000378:metabolism*
D007147:Immunoglobulin Light Chains; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D007457:Iodine Radioisotopes; D011228:Prealbumin; D000685:Serum Amyloid A Protein; D000683:Serum Amyloid P-Component