Role of cardiac scintigraphy with 99mTc-DPD in the differentiation of cardiac amyloidosis subtype.

INTRODUCTION AND OBJECTIVES: We investigated the diagnostic accuracy of (99m)Tc-3,3-diphosphono-1,2 propanodicarboxylic acid ((99m)Tc-DPD) scintigraphy in differentiating between monoclonal immunoglobulin light chain and transthyretin-related cardiac amyloidosis. METHODS: Nineteen patients with documented cardiac amyloidosis were included: 8 with transthyretin-related amyloidosis (group A) and 11 with light chain amyloidosis (group B). All the patients underwent scintigraphy with (99m)Tc-DPD and (99m)Tc-methylene diphosphonate ((99m)Tc-MDP). RESULTS: On visual scoring, cardiac (99m)Tc-DPD uptake could be characterized as moderate to severe (scores of 2-3), with ventricular or biventricular distribution, in all group A patients (transthyretin-related cardiac amyloidosis), and was absent or mild (scores of 0-1) and diffusely distributed in all group B patients (monoclonal immunoglobulin light chain cardiac amyloidosis). (99m)Tc-DPD uptake was also absent (score of 0) among unaffected controls and in 2 unaffected relatives of patients with hereditary transthyretin-related amyloidosis who harbor a mutation in the TTR gene. With (99m)Tc-MDP, all the patients had a myocardial uptake score of 0-1. In our series, selective myocardial uptake of (99m)Tc-DPD provided 100% accuracy (95% confidence interval, 97.37%-100%) for the differentiation between transthyretin-related and monoclonal immunoglobulin light chain cardiac amyloidosis. CONCLUSIONS: We conclude that (99m)Tc-DPD scintigraphy is a useful test for the differential diagnosis of transthyretin vs monoclonal immunoglobulin light chain etiology in patients with cardiac amyloidosis.

Papel de la gammagrafía cardiaca con 99mTc-DPD en la discriminación del subtipo de amiloidosis cardiaca / Role of cardiac scintigraphy with 99mTc-DPD in the differentiation of cardiac amyloidosis subtype

Introducción y objetivos. Hemos estudiado la exactitud diagnóstica de la gammagrafía cardiaca con 99mTc-ácido 3,3-difosfono-1,2-propanodicarboxílico (99mTc-DPD) para la diferenciación de la amiloidosis cardiaca por depósito de cadenas ligeras de inmunoglobulina monoclonal y la relacionada con el depósito de transtiretina. Métodos. Se incluyó en el estudio a 19 pacientes con amiloidosis cardiaca demostrada: 8 con amiloidosis cardiaca relacionada con la transtiretina (grupo A) y 11 con amiloidosis cardiaca por depósito de cadenas ligeras de inmunoglobulina monoclonal (grupo B). A todos los pacientes se les realizó gammagrafía cardiaca con 99mTc-DPD y con 99mTc-metilendifosfonato (99mTc-MDP). Resultados. En la valoración visual, la captación cardiaca de 99mTc-DPD tenía intensidad moderada o intensa (grados 2-3) y distribución biventricular o ventricular en todos los pacientes del grupo A y era de nula a ligera (grados 0-1) y de distribución difusa en todos los del grupo B. La captación de 99mTc-DPD también estaba ausente (grado 0) en los controles normales y en 2 familiares sanos de pacientes con amiloidosis hereditaria relacionada con la transtiretina que eran portadores de una mutación patogénica en el gen TTR. Todos los pacientes mostraron ausencia de captación miocárdica en la gammagrafía con 99mTc-MDP (grado 0-1). En nuestro estudio, la captación selectiva de 99mTc-DPD proporcionó una exactitud del 100% (intervalo de confianza del 95%, 97,37-100%) para la diferenciación de la etiología relacionada con la transtiretina frente a amiloidosis cardiaca por depósito de cadenas ligeras de inmunoglobulina monoclonal. Conclusiones. La gammagrafía cardiaca con 99mTc-DPD es una herramienta para el diagnóstico diferencial entre la amiloidosis relacionada con la transtiretina y la amiloidosis cardiaca por depósito de cadenas ligeras de inmunoglobulina monoclonal en pacientes con amiloidosis cardiaca (AU)

Introduction and objectives. We investigated the diagnostic accuracy of technetium-99m-3,3-diphosphono-1,2 propanodicarboxylic acid (99mTc-DPD) scintigraphy in differentiating between monoclonal immunoglobulin light chain and transthyretin-related cardiac amyloidosis. Methods. Nineteen patients with documented cardiac amyloidosis were included: 8 with transthyretin-related amyloidosis (group A) and 11 with light chain amyloidosis (group B). All the patients underwent scintigraphy with 99mTc-DPD and technetium-99m-methylene diphosphonate (99mTc-MDP). Results. On visual scoring, cardiac 99mTc-DPD uptake could be characterized as moderate to severe (scores of 2-3), with ventricular or biventricular distribution, in all group A patients (transthyretin-related cardiac amyloidosis), and was absent or mild (scores of 0-1) and diffusely distributed in all group B patients (monoclonal immunoglobulin light chain cardiac amyloidosis). 99mTc-DPD uptake was also absent (score of 0) among unaffected controls and in 2 unaffected relatives of patients with hereditary transthyretin-related amyloidosis who harbor a mutation in the transthyretin gene. With 99mTc-MDP, all the patients had a myocardial uptake score of 0-1. In our series, selective myocardial uptake of 99mTc-DPD provided 100% accuracy (95% CI, 97.37%-100%) for the differentiation between transthyretin-related and light chain cardiac amyloidosis. Conclusions. We conclude that 99mTc-DPD scintigraphy is a useful test for the differential diagnosis of transthyretin versus light chain etiology in patients with cardiac amyloidosis (AU)