Correlation of global and regional quantitative 99mTc-3,3-diphosphono-1,2 propanodicarboxylicacid single-photon emission computed tomography with echocardiography in patients with suspected transthyretin-related cardiomyopathy.

AIM: Quantitative single-photon emission computed tomography (SPECT) with 99m Tc-3,3-diphosphono-1,2 propanodicarboxylicacid ([ 99m Tc]Tc-DPD) is a cornerstone in the noninvasive diagnostic workup of amyloid transthyretin-related cardiomyopathy (ATTR-CM). As diagnosis is often suspected after transthoracic echocardiography (TTE), this study aims to explore the correlations between global and regional quantitative [ 99m Tc]Tc-DPD SPECT results and TTE findings in patients with suspected ATTR-CM. METHODS: Patients with suspected ATTR-CM from a single-center registry (B-CARE) were retrospectively included. All underwent quantitative [ 99m Tc]Tc-DPD SPECT/CT at the baseline examination with calculation of standardized values [maximum standardized uptake value (SUV max ) and peak SUV (SUV peak )], also normalized to bone activity (nSUV max and nSUV peak ). Data on TTE, performed within 2 weeks from the DPD scintigraphy, were also collected. RESULTS: One hundred forty four patients were included. Of these, 99 patients were eventually diagnosed with ATTR-CM. There was a significant correlation between septal ( P ≤ 0.001) and lateral wall thickness ( P = 0.004) and their respective, regional SUVs ( P < 0.001 and P = 0.004, respectively), as well as global SUVs and maximum wall thickness ( P = 0.024). Also, the presence of severe diastolic dysfunction correlated with nSUVs ( P = 0.011). CONCLUSION: The robust correlation found between TTE-derived parameters and the corresponding [ 99m Tc]Tc-DPD SPECT SUVs supports the link between morphologic alterations and [ 99m Tc]Tc-DPD activity within the myocardium, also potentially highlighting a pathophysiological mechanism involved in the progression of ATTR-CM.