Mr extended work space 2

After coronary artery occlusion, pigs were moved to the MDCT suite. In all cases, pigs were back in the catheterization laboratory within 15 min of ischemia onset. Arterial phase MDCT studies were performed in a 64-slice CT scanner (Brilliance CT 64; Philips Healthcare, Cleveland, OH) after intravenous administration of iodinated contrast medium. MDCT images were evaluated with dedicated software (MR Extended Work Space 2.6; Philips Healthcare, Best, The Netherlands) by two observers blinded to ischemia duration protocol and treatment allocation. Short-axis orientation images were obtained from volumetric CT images by multiplanar reconstruction. The region negative for contrast enhancement corresponds to the territory supplied by the occluded vessel (AAR) and was identified based on contrast enhancement differences vs the remote myocardium. The AAR was manually delineated and expressed as a percentage of LV area.

CMR images were analyzed using dedicated software (MR Extended Work Space 2.6, Philips Healthcare, The Netherlands). T2-maps were automatically generated on the acquisition scanner by fitting the SI of all echo times to a monoexponential decay curve at each pixel with a maximum likelihood expectation maximization algorithm. T2 relaxation maps were quantitatively analyzed by placing a wide transmural region of interest (ROI) at the ischemic and remote areas of the corresponding slice in all studies. The masking was defined in the first echo image to improve the contrast between the cardiac muscle and the cavity. Higher T2 values in this interface can be found due to slow flow artifact; therefore, ROIs were carefully placed avoiding those areas from the analysis to minimize contamination on the reported T2 values. Hypointense areas suggestive of microvascular obstruction or hemorrhage were included in the ROI for T2 quantification purposes.

All CMR studies were performed with patients under anesthesia, maintained by continuous intravenous infusion of midazolam, in a 3‐T Achieva Tx whole‐body scanner (Philips Healthcare, Best, The Netherlands) equipped with a 32‐element phased‐array cardiac coil. The protocol included (1) a standard segmented cine steady‐state free‐precession sequence to provide high‐quality anatomical references and to determine left ventricular end‐diastolic wall thickness (EDWT), left ventricular end‐diastolic volume (LVEDV), left ventricular end‐systolic volume (LVESV), and left ventricular ejection fraction (LVEF); (2) a late gadolinium‐enhanced sequence to assess infarct size; and (3) a dynamic acquisition with dual‐saturation technique during gadolinium‐based contrast administration to determine absolute myocardial perfusion.23, 24 CMR images were processed with a commercial analysis software (QMass MR 7.5 Medis, Leiden, the Netherlands and MR Extended Work Space 2.6, Philips Healthcare) and were analyzed by 2 independent blinded experienced investigators as previously described.23, 24, 25