Quantification of mitral regurgitation is still a controversial issue. Because quantitative analysis using the volumetric method is time-consuming, semi-quantitative analysis based on the characteristics of the regurgitant jet in the left atrium is the method used in daily clinical practice, despite its recognized limitations. In the last ten years various papers have proposed the PISA method as an alternative to the volumetric one, as the same quantitative parameters--regurgitant volume (RV) and effective regurgitant orifice (ERO)--can be obtained with a small number of measurements. The aim of the present study was to determine the degree of correlation and agreement between the two quantitative methods and to what extent the semi-quantitative analysis parameters correlated with the quantitative ones. We also compared the performance of the PISA method and semi-quantitative analysis in grading mitral regurgitation severity, using the volumetric method as gold standard. The study enrolled 77 patients (pts) aged 62 +/- 13 years (43 M and 34 F) with at least moderate mitral regurgitation determined by standard two-dimensional Doppler echo color flow imaging. The etiology of mitral valve regurgitation was: degenerative prolapse--40 pts (52%), ischemic--24 (31%), dilated cardiomyopathy--4 (5%), other pathologies-9 (12%). A sonographer performed the examinations under the supervision of one of two senior cardiologists. All quantitative Doppler measurements and calculations were performed on-line and the examinations recorded on videotape. Good correlations were found between RV (r = 0.81, p < 0.001, SE +/- 25) and ERO (r = 0.85, p < 0.001, SE +/- 17) measurements obtained by the two quantitative methods. However, the agreement was weakened by significant individual differences, particularly in the patients with degenerative prolapse. A satisfactory correlation was found between the jet area (JA) evaluated by semi-quantitative analysis and the RV and ERO calculated by both quantitative methods, with JA showing a tendency to underestimate the degree of mitral regurgitation in eccentric jets and to overestimate it in jets with central orientation. ROC curve analysis was used to evaluate the accuracy of ERO calculated by PISA and the JA by color Doppler in identifying different grades of mitral regurgitation defined by the values of ERO in the volumetric method. The calculated values of the area under the curve for the PISA ERO were higher than those for JA in the identification of patients with mild 0.93 (0.84-0.97) vs. 0.80 (0.70-0.89) p = 0.005 as well as severe mitral regurgitation 0.95 (0.87-0.98) vs. 0.81 (0.71-0.90) p = 0.006).