Soft tissue uptake of [99mTc]-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) bone scinticraphy can help identify patients with hereditary cardiac transthyretin-related (ATTR) amyloidosis

Background With the emergence of new therapeutic options that slow the progression of transthyretin-related amyloidosis (ATTR), [99mTc]-3,3-Diphosphono-1,2-Propanodicarboxylic Acid (DPD) bone scintigraphy, is commonly used to diagnose cardiac ATTR (cATTR). ATTR exists in two forms: wild-type (wtATTR), caused by misaggregation of normal transthyretin, and hereditary (hATTR), resulting from gene mutations that lead to protein misfolding. Soft tissue uptake (ST) may help diagnosis or predict patients with polyneuropoathy Methods Patients with suspected cardiac or extracardiac amyloidosis underwent Tc-99m DPD myocardial scintigraphy. More than 900 patients were assessed, with additional diagnostic steps—including laboratory tests and invasive procedures such as biopsies—performed based on clinical and imaging findings. Results Among 180 patients with positive myocardial scintigraphy using Tc-99m DPD scintigraphy (Perugini Grade 2 or 3), 5 were ultimately diagnosed with hATTR . All of these patients showed increased soft tissue uptake in the DPD scintigraphy and complained about having polyneuropathy. Conclusion The findings indicate that Tc-99 DPD scintigraphy may serve as a valuable non-invasive method for identifying patients with cATTR. When increased ST uptake is presented in hATTR can be suspected. Further testing is needed such as gene sequencing test. This is very significant as hATTR usually presents earlier and often includes neurological symptoms (e.g., polyneuropathy, autonomic dysfunction), depending on the mutation and usually has worst prognosis compared to wtATTR.