title: Noninvasive etiologic diagnosis of cardiac amyloidosis using 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy.
abstract: 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.
authors.affiliation: Institute of Cardiology, University of Bologna and S. Orsola-Malpighi Hospital, Bologna, Italy.
authors.forename: Enrica
authors.initials: E
authors.lastname: Perugini
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Guidalotti
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Salvi
authors.forename: Robin M T
authors.initials: RM
authors.lastname: Cooke
authors.forename: Cinzia
authors.initials: C
authors.lastname: Pettinato
authors.forename: Letizia
authors.initials: L
authors.lastname: Riva
authors.forename: Ornella
authors.initials: O
authors.lastname: Leone
authors.forename: Mohsen
authors.initials: M
authors.lastname: Farsad
authors.forename: Paolo
authors.initials: P
authors.lastname: Ciliberti
authors.forename: Letizia
authors.initials: L
authors.lastname: Bacchi-Reggiani
authors.forename: Francesco
authors.initials: F
authors.lastname: Fallani
authors.forename: Angelo
authors.initials: A
authors.lastname: Branzi
authors.forename: Claudio
authors.initials: C
authors.lastname: Rapezzi
mesh_terms: 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
chemical_list: D004164:Diphosphonates; D007147:Immunoglobulin Light Chains; D015609:Organotechnetium Compounds; D011228:Prealbumin; D019275:Radiopharmaceuticals; C033905:technetium Tc 99m 1,1-diphosphonopropane-2,3-dicarboxylic acid