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Mattana et al. Vessel Plus 2022;6:13 https://dx.doi.org/10.20517/2574-1209.2021.87 Page 3 of 11

Figure 1. Technetium-99m 3,3-diphosphono-1,2-propanodicarboxylic acid bone scan shows a carrier patient with Ala36Pro, visual score
3 with spleen uptake in 2014. After five years, the patient developed cardiac amyloidosis (hATTR CA).

Figure 2. Technetium-99m pyrophosphate bone scan at 1 h: (A) visual score 0; (B) visual score 1; (C) visual score 2; and (D) visual score
3.

uptake to the bone tracer uptake on the 3 h planar images (0: absent cardiac uptake; 1: mild cardiac uptake
less than bone; 2: moderate cardiac uptake equal to bone; 3: high cardiac uptake greater than bone): a
positive planar scan is considered when there is Grade 2 or 3 uptake. The mechanism of myocardial uptake
in CA is still unclear, but some authors reported that it is possibly related to the binding of the radiotracer to
micro-calcifications, in correlation with the different calcium concentration in the amyloid fibrils (Subtype
A showed higher uptake than Subtype B) .
[10]

The diagnostic accuracy of bone tracer scintigraphy has been widely described for both Tc-DPD [9,11-15] and
99m
99m Tc-PYP [16-19] . Nevertheless, not all bone tracers have been shown to be useful for the diagnosis of ATTR
99m
cardiomyopathy (ATTR-CM): Tc-methylene diphosphonate ( Tc-MDP), also commonly used for bone
99m
scintigraphy, showed low sensitivity for diagnosis of ATTR-CM and is not recommended for this aim .
[9]