Quantitative assessment of myocardial perfusion using real-time three-dimensional echocardiographic imaging

The new real-time three-dimensional (RT3D) echocardiographic technology offers an opportunity for myocardial perfusion imaging in the entire heart without the need for reconstruction from multiple slices and repeated contrast maneuvers. Our aims were to develop and validate a technique for quantitative volumetric assessment of myocardial perfusion. Studies were conducted in 5 isolated rabbit hearts and in 5 patients with ischemic heart disease. In rabbits, RT3D datasets were acquired over 30 sec, during which infusion of contrast agent definity was initiated and reached steady-state myocardial enhancement. Data were obtained at 3 different levels of coronary flow. At each level, myocardial videointensity (MVI) was measured over time in 3 LV short-axis slices of fixed thickness and peak contrast inflow rate (PCIR) was calculated. Administration of contrast resulted in clearly visible and measurable dynamic changes in MVI. PCIR followed the changes in coronary flow (p<0.0I). Feasibility in humans was tested by imaging the interventricular septum during initiation of infusion of definity at rest and during adenosine infusion. Dynamic changes in MVI were visible and suitable for quantitative analysis. In 2 patients, adenosine resulted in dark regions, reflecting lack of myocardial filling in stenosis-related territories. RT3D imaging and quantification of myocardial perfusion using our algorithm are feasible. This approach can potentially allow more accurate assessment of the extent of perfusion defects than 2D myocardial contrast echocardiography.