Transthyretin amyloid cardiomyopathy (ATTR-CM), is a heart muscle disease that's stops the heart muscle working properly. With an ageing population, it is increasingly common but untreated, it has a poor prognosis. Several novel expensive treatments have become available, although we do not understand exactly how they work and why some patients respond, and others do not. The challenge is to develop better methods for monitoring the effects of these treatments, maximizing their benefits and cost-effectiveness. In I-CARE we aim to bring a new imaging technique, named 18F-fluoride PET, to the clinic and thereby improve the care of patients with ATTR-CM. Hypotheses: 1. A delayed imaging protocol and state-of-the-art PET motion correction will optimise 18F-fluoride imaging in ATTR-CM and provide a clear threshold in myocardial TBR values for the diagnosis of ATTR-CM. 2. Optimised 18F-fluoride PET will provide a quantitative marker of the ATTR-CM burden that will allow disease progression and treatment response to be tracked. 3. Myocardial 18F-fluoride TBR values will reduce in patients responding to tafamidis treatment and increase in non-responders and patients not receiving therapy