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. (C) 2004 by the American College of Cardiology Foundation.