Individuals with obesity often suffer from medical conditions such as diabetes, high cholesterol, and high blood pressure, predisposing them to coronary artery disease (CAD). Therefore, imaging obese patients for CAD is crucial. However, the body shape of obese individuals often complicates the imaging process, resulting in subpar image quality and diagnostic performance, despite requiring a higher radiation dose. Now, new research reveals that a novel PET perfusion radiotracer, 18F-flurpiridaz, can diagnose CAD in obese patients with superior sensitivity and specificity compared to 99mTc-SPECT myocardial perfusion imaging (MPI). In the study, 18F-flurpiridaz PET MPI generated images at a lower radiation dose than 99mTc-SPECT MPI and demonstrated similar performance in both obese and non-obese patients.

The research findings presented by investigators at the Icahn School of Medicine at Mount Sinai (New York, NY, USA) report on a pre-specified subgroup of a phase III multicenter trial of 18F-flurpiridaz. The study enrolled a total of 604 patients with suspected CAD from 48 sites in the United States, Canada, and Europe. Patients underwent either one-day rest-stress 18F-flurpiridaz PET MPI or one- or two-day rest-stress 99mTc-SPECT MPI, followed by invasive coronary angiography. Three experts, blinded to clinical and invasive coronary angiography data, read the MPI images. Sensitivity and specificity for 18F-flurpiridaz PET MPI and 99mTc-SPECT MPI were calculated and then compared between PET and SPECT MPI among both obese and non-obese groups.

Out of the 578 patients with evaluable studies, 298 (51.6%) were classified as obese. 18F-flurpiridaz PET MPI demonstrated a sensitivity of 77% and a specificity of 67% in diagnosing significant CAD, whereas 99mTc-SPECT MPI yielded a sensitivity of 69.2% and specificity of 61.9%. The sensitivity, specificity, and accuracy of 18F-flurpiridaz PET MPI remained similar across both non-obese and obese sub-groups. The researchers also highlighted that 18F-flurpiridaz could substantially increase the availability and accessibility of PET myocardial perfusion imaging worldwide.

“We know that PET perfusion is the best noninvasive imaging modality for CAD; however, thus far, the availability of stress cardiac PET myocardial perfusion imaging is limited across the world, as both significant investment for the generator and large patient volume are required for it to make economic sense,” said Krishna Patel, MD, assistant professor of medicine and cardiology at the Icahn School of Medicine at Mount Sinai. “With availability as a unit dose, 18F-flurpiridaz can disrupt this space, as suddenly now most—if not all—centers that offer PET for oncology can now perform stress perfusion studies.” 

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