Tracer kinetic models yield similar results in cardiac testing

When estimating myocardial blood flow (MBF) using four tracer kinetic analysis models, researchers have found no significant difference in diagnostic ability between methods, according to a study published online Dec. 18 in Radiology.

Estimating MBF plays an important role in diagnosing coronary artery disease by increasing objectivity and improving diagnostic sensitivity in the presence of multi-vessel disease, according to study authors, including lead writer John D. Biglands, PhD, of Leeds Institute of Cardiovascular and Metabolic Medicine.

Published perfusion estimates vary, likely thanks to differing patient populations, contrast injection procedures, imaging pulse sequence and tracer kinetic analysis models.

“Investigations into differences between tracer kinetic methods have been performed previously,” Biglands and colleagues wrote. “However, the effect of these differences on the diagnosis of ischemic heart disease has not been studied.”

For this study, researchers selected four tracer kinetic analysis models and measured their performance in the quantification of coronary artery disease. The selected models represent the most commonly used methods for use in the heart and include:

  • Fermi-constrained deconvolution
  • Model-independent deconvolution
  • A one-compartment model
  • An uptake model

For the study, 50 patients suspected of coronary artery disease had MBF estimated using rest and adenosine stress MR imaging using the four tracer kinetic analysis.

The results show that the MBF and the myocardial perfusion reserve (MPR), the outcome measures for the four models, were:

  • 0.86 and 0.92 for the Fermi model
  • 0.85 and 0.87 for the uptake model
  • 0.85 and 0.80 for the one-compartment model
  • 0.87 and 0.87 for the model-independent deconvolution

The researchers found that the only major difference in results was that Fermi model outperformed the one-compartment model if MPR was the outcome measure.

“The finding that all of the assessed methods perform equally well is important because the methods differ in complexity of implementation, in speed of computation, and in the amount of data required to quantify MBF,” the authors concluded. “Simpler or quicker methods may be selected in the future without loss of diagnostic performance in quantitative studies. The practical implications of not performing a rest examination for quantitative studies has the potential to significantly reduce patient imaging time.”

This study was a sub-cohort from a larger study, the cardiovascular magnetic resonance and single-photon emission computed tomography for diagnosis of coronary heart disease (CE-MARC) trial. The CE-MARC research sought to establish the diagnostic accuracy of multiparametric cardiovascular magnetic resonance protocol with x-ray coronary angiography as the reference standard and to compare it with single-photon emission computed tomography in patients suspected of having coronary heart disease.