Noninvasive etiologic diagnosis of cardiac amyloidosis using 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy.
OBJECTIVE
We investigated the diagnostic accuracy of 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) scintigraphy for differentiation of monoclonal immunoglobulin light-chain (AL) and transthyretin (TTR)-related cardiac amyloidosis.


BACKGROUND
Differential diagnosis between TTR-related and AL amyloidosis is often complex and time-consuming.


METHODS
Patients under routine observation with TTR-related/AL systemic amyloidosis and echocardiographic evidence of cardiac involvement were studied with 99mTc-DPD scintigraphy.


RESULTS
Patients with cardiac involvement of TTR-related (group A; n = 15) and AL (group B; n = 10) etiology were comparable for left ventricular mass and renal function. Heart and heart/whole-body tracer retention were significantly higher (p < 0.05) in group A as compared with group B and with 10 unaffected controls. At visual scoring, cardiac 99mTc-DPD uptake was present in all group A patients and absent in all group B patients; thus, using genotyping/immunohistochemistry as the reference technique, the accuracy of 99mTc-DPD scintigraphy for distinction of TTR-related and AL etiology was 100%. Cardiac 99mTc-DPD uptake was also absent among unaffected controls. Using echocardiography as the reference standard for recognition of cardiac involvement, sensitivity and specificity of scintigraphy were both 100% for group A patients; in group B, sensitivity was 0% and specificity was 100% (accuracy, 50%). Eleven patients with myocardial 99mTc-DPD uptake underwent 99mTc-methylene diphosphonate (99mTc-MDP) scintigraphy; all patients showed a 99mTc-MDP myocardial visual score of 0.


CONCLUSIONS
Etiology is a third major cause--in addition to type of organ-involved (soft-tissue/heart) and tracer type--of scintigraphic variability in cardiac amyloidosis. This is a highly relevant consideration for future studies. We conclude that 99mTc-DPD scintigraphy is a useful step in the workup of the differential diagnosis of TTR versus AL etiology in patients with documented cardiac amyloidosis.
Perugini
Enrica
E
Institute of Cardiology, University of Bologna and S. Orsola-Malpighi Hospital, Bologna, Italy.
Guidalotti
Pier Luigi
PL
Salvi
Fabrizio
F
Cooke
Robin M T
RM
Pettinato
Cinzia
C
Riva
Letizia
L
Leone
Ornella
O
Farsad
Mohsen
M
Ciliberti
Paolo
P
Bacchi-Reggiani
Letizia
L
Fallani
Francesco
F
Branzi
Angelo
A
Rapezzi
Claudio
C
D000368:Aged; D000686:Amyloidosis / Q000000981:diagnostic imaging* / Q000209:etiology*; D003937:Diagnosis, Differential; D004164:Diphosphonates; D005260:Female; D006331:Heart Diseases / Q000000981:diagnostic imaging* / Q000209:etiology*; D006801:Humans; D007147:Immunoglobulin Light Chains; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D011228:Prealbumin; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results
D004164:Diphosphonates; D007147:Immunoglobulin Light Chains; D015609:Organotechnetium Compounds; D011228:Prealbumin; D019275:Radiopharmaceuticals; C033905:technetium Tc 99m 1,1-diphosphonopropane-2,3-dicarboxylic acid