Incremental value of parametric quantitative assessment of myocardial perfusion by triggered Low-Power myocardial contrast echocardiography.

OBJECTIVES: The purpose of this study was to compare the assessment of myocardial perfusion by myocardial parametric quantification (MPQ) with technetium-99m sestamibi single-photon emission computed tomographic (SPECT) imaging in humans.
BACKGROUND: Accurate visual interpretation of myocardial contrast echocardiographic (MCE) images is qualitative and requires considerable experience. Current computer-assisted quantitative perfusion protocols are tedious and lack spatial resolution. Myocardial parametric quantification is a novel method that quantifies, color encodes, and displays perfusion data as a set of myocardial parametric images according to the relative degree of perfusion.
METHODS: Forty-six consecutive patients underwent prospective stress/rest technetium-99m sestamibi gated-SPECT imaging and MCE using intravenous Optison or Definity. Apical two- and four-chamber cine loops at rest and after dipyridamole (0.56 mg/kg) stress were acquired. For each patient, the following assessments of myocardial perfusion were performed: 1). visual cine-loop assessment (VIS); 2). MPQ assessment; and 3). combined VIS + MPQ assessment.
RESULTS: The segmental rates of agreement for myocardial perfusion with SPECT were 83%, 89%, and 92% (kappa = 0.46, 0.58, and 0.68) for VIS, MPQ, and VIS + MPQ, respectively. Similar trends were seen for the classification of the presence or absence of a moderate to severe perfusion defect, with the agreement for VIS, MPQ, and VIS + MPQ being 92%, 97%, and 97%, respectively.
CONCLUSIONS: Myocardial parametric quantification demonstrates good agreement with SPECT and incremental agreement with VIS. Analysis strategies that incorporate MPQ demonstrate better agreement with SPECT than visual analysis alone.