Researchers developed a simple tool for detecting cases of transthyretin amyloid cardiomyopathy (ATTR-CM) using single-photon emission computerized tomography/computed tomography (SPECT/CT) scans. Their findings were recently published in the European Journal of Nuclear Medicine and Molecular Imaging.
SPECT/CT scans help show how well an organ is working. They can be used to obtain detailed anatomical images of the heart. With the help of radioactive tracers (small, safe amounts of radioactive substance) injected into the bloodstream, they can also visualize amyloid deposits. Typically, the tracer technetium-99m pyrophosphate (Tc-99m PYP) is used to detect ATTR-CM.
Although several methods exist to screen for ATTR-CM, they are often invasive, susceptible to false positives or are computationally intensive, the authors explained. “We aimed to develop a simple quantitative metric that ensures reproducibility and interchangeability across different institutions and camera systems,” they wrote.
The study included 52 patients who underwent Tc-99m PYP SPECT/CT scans between April 2021 and September 2024 at four hospitals in Japan. Of these individuals, 11 were diagnosed with ATTR-CM via myocardial biopsy.
Read more about ATTR-CM testing and diagnosis
The authors then calculated the lateral wall to aorta (LW/Ao) ratio, which measures the amount of radiotracer taken up in the side wall of the heart relative to that of the aorta. The reliability of this measurement was compared to that of the conventional methods of measuring tracer uptake.
This metric had a sensitivity of 100%, meaning all of the patients with ATTR-CM screened positive for the disease using this measurement. The LW/Ao ratio also had a specificity of 97.6%, meaning that 97.6% of the patients without ATTR-CM screened negative for the disease.
These findings confirm the ability of the LW/Ao ratio to avoid both false positives and false negatives within this study population. Not only does this demonstrate that patients with ATTR-CM are accurately being identified, but it also indicates that patients without the disease are unlikely to be incorrectly diagnosed with ATTR-CM.
“In the future, a prospective, multi-center study would further improve the generalizability of our findings,” the study concluded.
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