Mapping absolute myocardial perfusion with MRI: Methods and results.

Ultra-rapid dynamic MRI (one image per heart beat) can follow the progressi on of the intra-myocardial signal during the first passage of diffusable ga dolinium chelates injected as a bolus through a peripheral vein. A quantita tive evaluation of myocardial perfusion is possible using a compartmental m odel of analysis. Absolute myocardial flow can be measured at rest and during hyperaemia indu ced by dipyridamole. It is possible to associate functional mapping, corres ponding to parametric images of the flow indices, to the global evaluation. The ratio between the values obtained during hyperaemia and under basal co nditions correspond to the myocardial reserve. The principles, results and limitations of this method are discussed in the light of published results, underlining the advantages of absolute flow me asurement and of the differences between the results of MRI and myocardial scintigraphy.