Use of Tc-99m PYP Planar and SPECT Imaging to Diagnose TTR Type Cardiac Amyloidosis
Image Modality: Echocardiogram
PYP Planar SPECT Imaging to Detect TTR Type Cardiac Amyloidosis
A 70-year-old African-American male patient presented with decompensated diastolic heart failure (HF) with significant left ventricular hypertrophy on echocardiography and strain pattern suggestive of cardiac amyloidosis with "speckled" appearance of the myocardium with reduced global longitudinal strain in the basal and mid segments of the left ventricular walls and normal global longitudinal strain in the apex, the so-called "apical sparing" stain pattern typically seen in cardiac amyloidosis (Figure 1). The patient had technetium-99m pyrophosphate (Tc-99m PYP) imaging for transthyretin (TTR type) cardiac amyloidosis. Figure 2 shows Planar imaging with quantitative assessment with a heart to contralateral lung uptake ratio of 1.4. Semi-quantitative assessment of the 3-hour delay single-photon emission computed tomography (SPECT) imaging shows Grade 3 myocardial uptake (Figure 3). These findings suggested TTR type cardiac amyloidosis.1 The patient was referred to a center specialized in the management of cardiac amyloidosis, where he went on to have this diagnosis confirmed and treated.
Cardiac amyloidosis remains an underdiagnosed cause of HF. There are two forms of amyloidosis that may affect the heart, and these include myocardial amyloid deposits formed from misfolded light chain or TTR proteins. Differentiating these two forms of cardiac amyloid is vital in determining prognosis and treatment as well as genetic counselling. Tc-99m PYP has a distinct affinity for binding to the TTR proteins and can be utilized to noninvasively identify patients with TTR-type cardiac amyloid with a sensitivity and specificity of 97% and 100%, respectively.2 This allows for TTR-type cardiac amyloid to be diagnosed noninvasively with the use of Tc-99m PYP imaging. Every effort should be made to confirm the diagnosis with myocardial biopsy. However, there are some patients in whom myocardial biopsy may be associated with unacceptable risk; in these cases, Tc-99m PYP nuclear imaging may be useful in providing a diagnosis.
- Dorbala S, Bokhari S, Miller E, Bullock-Palmer RP, Soman P, Thompson R. ASNC Practice Points: 99mTechnetium-Pyrophosphate Imaging for Transthyretin Cardiac Amyloidosis (American Society of Nuclear Cardiology website). 2018. Available at: https://www.asnc.org/Files/Practice%20Resources/Practice%20Points/ASNC%20Practice%20Point-99mTechnetiumPyrophosphateImaging2016.pdf. Accessed 01/15/2018.
- Bokhari S, Castaño A, Pozniakoff T, Deslisle S, Latif F, Maurer MS. (99m)Tc-pyrophosphate scintigraphy for differentiating light-chain cardiac amyloidosis from the transthyretin-related familial and senile cardiac amyloidoses. Circ Cardiovasc Imaging 2013;6:195-201.
Date: January 15, 2018
Authors: Renee Bullock-Palmer, MBBS, FACC
Source: ACC Media File
Clinical Topics: Arrhythmias and Clinical EP, Geriatric Cardiology, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Genetic Arrhythmic Conditions, Acute Heart Failure, Chronic Heart Failure, Computed Tomography, Echocardiography/Ultrasound, Nuclear Imaging
Keywords: Geriatrics, Heart Failure, Diagnostic Imaging, Prealbumin, Technetium, Diphosphates, Hypertrophy, Left Ventricular, Heart Failure, Diastolic, Plaque, Amyloid, Genetic Counseling, Technetium Tc 99m Pyrophosphate, Amyloidosis, Myocardium, Echocardiography, Tomography, Emission-Computed, Single-Photon