CARDIAC IMAGING
Noninvasive Etiologic Diagnosis of Cardiac Amyloidosis Using 99mTc-3,3-Diphosphono-1,2-Propanodicarboxylic Acid Scintigraphy
Enrica Perugini, MD*,
Pier Luigi Guidalotti, MD ,
Fabrizio Salvi, MD ,
Robin M.T. Cooke, MA*,
Cinzia Pettinato, MD ,
Letizia Riva, MD*,
Ornella Leone, MD ,
Mohsen Farsad, MD ,
Paolo Ciliberti, MD*,
Letizia Bacchi-Reggiani, MSc, MBiostat*,
Francesco Fallani, MD*,
Angelo Branzi, MD* and
Claudio Rapezzi, MD*,*
* Institute of Cardiology
Nuclear Medicine Unit
Department of Pathology, University of Bologna and S. Orsola-Malpighi Hospital, Bologna, Italy
Department of Neurology, Ospedale Bellaria, Bologna, Italy
Manuscript received March 4, 2005;
revised manuscript received May 18, 2005,
accepted May 24, 2005.
* Reprint requests and correspondence: Prof. Claudio Rapezzi, Istituto di Cardiologia, Policlinico S. Orsola-Malpighi, via Massarenti 9, 40138 Bologna, Italy
(Email: crapezzi{at}aosp.bo.it).
OBJECTIVES: 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 causein addition to type of organ-involved (soft-tissue/heart) and tracer typeof 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.
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Abbreviations and Acronyms
| | AL = monoclonal immunoglobulin light-chain | | CA = cardiac amyloidosis | | LV = left ventricle/ventricular | | OLT = orthotopic liver transplantation | | ROI = region of interest | | SPECT = single-photon emission computed tomography | | 99mTc-DPD = 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid | | 99mTc-MDP = 99mTc-methylene diphosphonate | | TTR = transthyretin |
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