Right ventricular volumes and ejection fraction by MR imaging and stereology: comparison with standard image analysis...

The purpose of this study was to examine the accuracy of the stereological method for estimating right ventricular parameters on cine MR images. The end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were estimated in 19 consecutive patients with suspected or known coronary artery disease employing the stereological point counting method. Stereological measurements were performed with different grids of test points. The RV parameters were also derived by the standard method based on the manual adjustment of automatically obtained endocardial contours. The statistical difference and agreement between the two methods was found. Measurement reproducibility of both methods was determined. The counting of about 100 test points on all MR images provided EDV and ESV with a mean coefficient of error of 7.0 ± 1.3% and 7.4 ± 2.1%, respectively. The volume estimation precision was not significantly improved by counting more points (EDV: P = 0.058; ESV:P = 0.333). Stereological estimations were not significantly different from those by the standard method (EDV: P = 0.093; ESV: P = 0.072; SV: P = 0.291; EF: P = 0.300). The 95% limits of agreement between the two methods were clinically acceptable (EDV: -12.1 cm(3) , 18.9 cm(3) ; ESV: -6.4 cm(3) , 10.4 cm(3) ; SV: -10.5 cm(3) , 13.5 cm(3) ; EF: -7.5%, 6.3%). The repeatability of stereological estimations was better than that of the standard method (coefficient of variability: 3.4-5.3% versus 4.0-7.1%). The measurement time with stereolgy was less than 4 min. The stereological method may be considered as an improvement over the standard method due to its accuracy and repeatability.