Determination of the volume of coronary microemboli needed for reproducible visualization of microinfarcts on contrast enhanced MDCT and MRI

Methods Under X-ray guidance, a 3F catheter was placed selectively in LAD coronary artery of pigs (n=18). The animals received either 16mm or 32mm volumes of 40120μm Embosphere, microemboli (Biosphere Med, Rockland, MA) were selectively delivered in the LAD coronary artery to produce microinfarcts. The microemboli used were in the same size as those that pass through the pores of distal filtration devices and the volumes found at autopsy. On day 3, both MDCT (64-slice) and MRI (1.5T) were performed using CT iohexol (350mg/ml x 2) and MR Gd-DTPA (0.1mmol/kg x 2) contrast media. The images were used for assessing LV function, perfusion and viability (visualization of speckled microinfarcts), respectively. A semi-automatic threshold method was used to measure enhanced speckled microinfarcts. Histology was used to confirm the presence of microvascular obstruction and microinfarcts.