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Evaluation of quantitative parameters such as regional myocardial blood flow (rMBF), blood volume (rMBV), and mean transit time (rMTT) by MRI is gaining acceptance for clinical applications, but still lacks robust postprocessing methods for map generation. Moreover, robustness should be preserved over the full range of myocardial flows and volumes. Using experimental data from an isolated pig heart preparation, synthetic MR kinetics were generated and four deconvolution approaches were evaluated. These methods were then applied to the first-pass T(1) images of the isolated pig heart using an intravascular contrast agent and rMBF, rMBV and rMTT maps were generated. In both synthetic and experimental data, the fit between calculated and original data reached equally good results with the four techniques. rMBV was the only parameter estimated correctly in numerical experiments. Moreover, using the algebraic method ARMA, abnormal regions were well delineated on rMBV maps. At high flows, rMBF was underestimated at the experimental noise level. Finally, rMTT maps appeared noisy and highly unreliable, especially at high flows. In conclusion, over the myocardial flow range, i.e., 0-400 ml/min/100g, rMBF identification was biased in presence of noise, whereas rMBV was correctly identified. Thus, rMBV mapping could be a fast and robust way to detect abnormal myocardial regions., (Copyright 2002 Wiley-Liss, Inc.)

Recent developments in magnetic resonance imaging (MRI) using specific contrast media allow the assessment of myocardial perfusion. The purpose of this study was to characterize the intravascular properties of a new macromolecular contrast agent, CMD-A2-Gd-DOTA, to evaluate myocardial perfusion. Two groups of isolated pig hearts perfused at various controlled flows were used. To demonstrate the intravascular properties of CMD-A2-Gd-DOTA, the agent was simultaneously injected with 99mTc-labeled red blood cells in five hearts (group 1). Tracer kinetics of both compounds were assessed by coronary sinus effluent sampling, radioactivity counting and concentration determination in samples for first-pass time curves measurements. Five other hearts (group 2) were studied using a two-slice turboFLASH sequence on a 1.5-T whole-body MRI in order to evaluate first-pass CMD-A2-Gd-DOTA signal intensity (SI) versus time curves. In group 1, for the studied flows ranging from 0.8 to 3.1 ml/min(-1) x g(-1), CMD-A2-Gd-DOTA showed first-pass concentration curves typical of an intravascular contrast agent. In group 2, MRI parameters, i.e., upslope and mean transit time of SI time curves correlated strongly with myocardial perfusion. Within the physiologic range of flows, CMD-A2-Gd-DOTA was able to demonstrate tracer kinetics for in vivo assessment of myocardial perfusion using MRI.