What is the gold standard investigation for ATTR cardiac amyloidosis?
Endomyocardial biopsy.
Why is a delayed 3-hour acquisition performed?
Increased soft tissue uptake at 1- hour can artificially increase the counts when measuring the region of interest of the contralateral lung. Waiting till 3 hours to acquire the image allows the clearance of the soft tissue uptake to allow a more accurate assessment of counts.
Increased activity within the myocardium of the left ventricle on the 1-hour delayed planar image. This persists on the 3-hour delayed image.
Perugini score = 3
Heart to contralateral lung ratio (HCL ratio) = 1.76
Focal uptake in the left 6th and 10th rib from rib fractures of indeterminate age was localised on SPECT-CT (not shown).
Moderate uptake in the right innominate bone is suggestive of Paget's disease.