**Introduction/Hypothesis:**
18F-fluorodeoxyglycose (FDG)/13N-ammonia cardiac positron emission tomography/computed tomography (PET/CT) scan is routinely used for diagnostic evaluation and surveillance of inflammatory cardiomyopathies such as cardiac sarcoidosis. We report a case of wild-type transthyretin (TTR) cardiac amyloidosis (CA) with positive 18F-FDG/13N-ammonia cardiac PET/CT.

**Methods**
N/A

**Results**
85-year-old male with supraventricular tachycardia ablation, non-sustained ventricular tachycardia, non-obstructive coronary artery disease and presumed isolated cardiac sarcoidosis diagnosed 3 years ago (based on delayed gadolinium enhancement on cardiac magnetic resonance imaging and myocardial inflammation with perfusion abnormalities on 18F-FDG/13N-ammonia cardiac PET/CT [Figure A]) on methotrexate presented for evaluation of fatigue and dyspnea. Physical examination was unremarkable. High sensitivity troponin-T was 39 ng/L (25 ng/L 3 years ago) and NT-proBNP was 1279 pg/mL (268 pg/mL 3 years ago). Electrocardiogram (ECG) showed sinus rhythm with elevated artificial intelligence-enhanced ECG probability for amyloid (0.98 versus 0.34 three years ago; detection threshold >0.48). Repeat 18F-FDG/13N-ammonia cardiac PET/CT demonstrated resolution of myocardial inflammation (Figure B). Echocardiogram showed normal biventricular chamber size/function but increased concentric left ventricular (LV) wall thickness (18 mm)/mass and decreased LV global longitudinal strain of -16% compared to prior study. These findings raised suspicion for CA leading to a 99mTechnetium Pyrophosphate scan which was strongly suggestive of CA (Figures C-E). Screening for light chain CA and testing for TTR gene were negative. Methotrexate was discontinued and Tafamidis was started.

**Conclusion**
Reasons for a positive 18F-FDG/13N-ammonia cardiac PET/CT scan may include underlying inflammation related to pathophysiology of cardiac amyloidosis, difficulty suppressing physiological myocardial 18F-FDG uptake due to amyloid infiltration and/or co-existent inflammatory cardiomyopathy.



Wild-type Transthyretin Cardiac Amyloidosis with Positive 18F-FDG/13N-ammonia Cardiac Positron Emission Tomography

This course will explore basic and cutting-edge imaging techniques to improve patient care and hone individual skills in performance and interpretation of echocardiography, nuclear cardiology, cardiac computed tomography, and cardiovascular magnetic resonance imaging. Days will reinforce how cardiovascular imaging may improve comprehension in ischemic heart disease, structural heart disease, cardiomyopathies, and heart failure. Experts will utilize novel techniques to reinforce key topics including taped interventional cases and a strong emphasis on case presentations.