PET Imaging With [18F]Fluselenamyl in People With Cardiac Amyloidosis

This observational study will evaluate the imaging performance of the investigational positron emission tomography (PET) radiotracer\[18F\]Fluselenamyl (FSA) in individuals with cardiac amyloidosis. The study aims to determine whether \[18F\]Fluselenamyl PET imaging can detect and characterize amyloid deposits in the heart. Participants will undergo PET imaging following administration of \[18F\]Fluselenamyl, along with clinical assessments and other study procedures as needed. Imaging results will be used to assess tracer uptake in the heart and to evaluate the potential of \[18F\]Fluselenamyl as a noninvasive tool for detecting cardiac amyloidosis. The study will also collect safety information, including clinical assessments, laboratory testing, and monitoring for adverse events. This research may help establish \[18F\]Fluselenamyl as a novel imaging biomarker for cardiac amyloidosis.

Inclusion Criteria: * Male or Female, any race * Age ≥ 18 years * Confirmed CA, clinical suspicion for CA, or markers of potential CA (i.e. left ventricular hypertrophy and heart failure) * Willing and able to undergo \[F18\]-FSA PET scan, and cardiac MRI Exclusion Criteria: * Incapable of providing written informed consent or lacking a legally authorized representative (LAR) to provide informed consent * Unwilling or unable to undergo PET scan tracer injections * Participants with chronic liver diseases not related to amyloidosis * Participant has any condition that, in the investigator's opinion, could increase the risk to the participant, limit the participant's ability to tolerate the research procedures or interfere with the collection/analysis of the data (e.g., participants with severe chronic back pain might not be able to lie still for the duration of the scanning procedures) * Has hypersensitivity to \[F-18\]-Fluselenamyl or any of its excipients * Contraindications to MRI (e.g. electronic medical devices that are not compatible with MRI, inability to lie still for extended periods that make it unsafe for the individual to participate) * Contraindication to contrast (gadolinium) MRI given a glomerular filtration rate (GFR) of the kidney\