Regadenoson stress PET/CT MPI trumps SPECT for CAD detection

Regadenoson stress Rb-82 PET/CT myocardial perfusion imaging (MPI) is highly sensitive, 92 percent, for the detection of obstructive CAD and beats SPECT MPI, according to a study published online Aug. 12 in the Journal of Nuclear Medicine.

Edward Hsiao, MD, from the Noninvasive Cardiovascular Imaging Program and departments of medicine and radiology at Brigham and Women’s Hospital in Boston, and colleagues evaluated the vasodilator regadenoson with Rb-82 PET/CT MPI for the detection of both single- and multi-vessel obstructive CAD. Researchers also calculated stress left ventricular ejection fraction (LVEF) minus rest LVEF to define LVEF reserve. An estimation of injured myocardium was made using the Duke score. Previous findings cited in the study presented regadenoson as a superior choice for stress MPI also due to the convenience of bolus injection and compatibility with PET.

“However, to the best of our knowledge, there are no published clinical studies illustrating the diagnostic accuracy of regadenoson stress with PET MPI for the detection of obstructive CAD,” wrote Hsiao et al. “Clinical diagnostic accuracy studies are paramount for supporting the continued use (or not) of regadenoson in clinical PET practice.”

The present study included 134 patients at a mean age of about 63 without suspicion of CAD who underwent Ru-82 PET/CT MPI with the stress agent regadenoson. Results showed that regadenoson Rb-82 PET/CT MPI correctly identified obstructive CAD in 59 of the 64 patients with very high sensitivity.

“Importantly, high diagnostic sensitivity was maintained irrespective of age, sex, and body mass index,” wrote the authors.

Substantially higher mean LVEF reserve was seen in patients with normal MPI scans, estimated at 6.5, than for those with reversible defects ranging from mild to severe, about 4.3 and -0.2, respectively. The mean LVEF reserve was significantly higher, approximately 7.2, for patients who were at low risk of CAD. Specificity was relatively low at 77 percent, but the authors attributed this to possible post-test referral bias.

“Regadenoson used as a vasodilator stress agent in conjunction with Rb-82 PET MPI offers rapid testing and high diagnostic accuracy for the detection of obstructive CAD at a low radiation dose,” the researchers wrote. “In patients with single-vessel CAD, the test sensitivity of regadenoson Rd-82 PET MPI is as good as in patients with multivessel CAD and higher than that reported with SPECT MPI.”