The novel tracer improved both sensitivity and specificity in the study group, of which more than 50 percent were obese and typically more difficult to obtain high-quality imaging.
A novel tracer used in positron emission tomography (PET) perfusion imaging may help improve the diagnosis of coronary artery disease (CAD), especially in patients who are obese.
The research, presented at the 2023 Society of Nuclear Medicine & Molecular Imaging (SNMMI) Annual Meeting, taking place June 24-27, 2023 in Chicago, could help fill a gap in care for patients with obesity who are at a greater risk for CAD but for whom imaging is often difficult to attain.
“Due to their body shape, it’s often hard to image obese individuals,” said study author Krishna Patel, MD, assistant professor of medicine and cardiology at the Icahn School of Medicine At Mount Sinai, in a statement. “This can result in inferior image quality and diagnostic performance despite requiring a higher dose of radiation.”
Researchers led by Patel compared data using the investigational 18F-flurpiridaz PET radiotracer (GE, Lantheus) to single photon emission computed tomography (SPECT) myocardial perfusion imaging, which is the current diagnostic standard, among a subgroup of participants in the phase 3 multicenter clinical trial of 18F-flurpiridaz.
The subgroup analysis included 298 individuals who were classified as obese, with a mean body mass index of 35.8 kg/m2 (mean age, 62.1 years; 81.8% male). Patients underwent one-day rest-stress 18F-flurpiridaz PET MPI or one- or two-day rest-stress 99mTC-SPECT MPI prior to coronary angiography. MPI images were then read by 3 blinded experts, with sensitivity and specificity results compared between PET and SPECT MPI among participants who were obese and those who were not (n=280).
The primary end point was defined as sensitivity and specificity by 2 expert readers for diagnosis of CAD, which was defined as at least a 50% stenosis in at least 1 majoy coronary artery or majoy branch vessel via assessment of one-sided z-test with significance level of 0.025.
Ultimately, results from the angiography showed that 39.3% of all patients in the subgroup had CAD. Overall, sensitivity and specificity data demonstrated that 18F-flurpiridaz met the primary end point (sensitivity: 76.9%; 95% CI, 69.3-84.6; P =.0001; specificity: 66.9%; 95% CI, 60.0-73.7; P =.03). Among those who were obese, sensitivity (76.9% vs 69.2%, difference: 7.7% [-3.6%, 19.0%], P =.064) and specificity (66.9% vs 61.9%, difference: 5.0% [-4.6%, 14.6%] P =.001) of 18F-flurpiridaz was greater than 99mTC-SPECT MPI. Sensitivity, specificity, and accuracy of 18F-flurpiridaz were similar among participants who were obese and those who were not; an analysis showing diagnostic accuracy of 18F-flurpiridaz was also similar between the two groups, but higher than what was observed using 99mTC-SPECT MPI.
Notably, 18F-flurpiridaz PET had significantly lower radiaton exposure compared with 99mTC-SPECT MPI, including in participants who were obese.
In addition to the above benefits, Dr. Patel also pointed out that the novel PET tracer could help boost access to this key perfusion imaging, as centers who use PET for oncology can perfect stress perfusion studies using 18F-flurpiridaz.