Parametric quantification of myocardial ischaemia using real-time perfusion adenosine stress echocardiography images, with SPECT as reference method

Abstract

Background: Real-time perfusion (RTP) adenosine stress echocardiography (ASE) can be used to visually evaluate myocardial ischaemia. The RTP power modulation technique, provides images for off-line parametric perfusion quantification using Qontrast® software. From replenishment curves, this generates parametric images of peak signal intensity (A), myocardial blood flow velocity (β) and myocardial blood flow (Axβ) at rest and stress. This may be a tool for objective myocardial ischaemia evaluation. We assessed myocardial ischaemia by RTP-ASE Qontrast®-generated images, using 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) as reference. Methods: Sixty-seven patients admitted to SPECT underwent RTP-ASE (SONOS 5500) during Sonovue® infusion, before and throughout adenosine stress, also used for SPECT. Quantitative off-line analyses of myocardial perfusion by RTP-ASE Qontrast®-generated A, β and Axβ images, at different time points during rest and stress, were blindly compared to SPECT. Results: We analysed 201 coronary territories [corresponding to the left anterior descendent (LAD), left circumflex (LCx) and right coronary (RCA) arteries] from 67 patients. SPECT showed ischaemia in 18 patients. Receiver operator characteristics and kappa values showed that A, β and Axβ image interpretation significantly identified ischaemia in all territories (area under the curve 0·66–0·80, P = 0·001–0·05). Combined A, β and Axβ image interpretation gave the best results and the closest agreement was seen in the LAD territory: 89% accuracy; kappa 0·63; P<0·001. Conclusion: Myocardial isachemia can be evaluated in the LAD territory using RTP-ASE Qontrast®-generated images, especially by combined A, β and Axβ image interpretation. However, the technique needs improvements regarding the LCx and RCA territories.