Background Right ventricular (RV) dysfunction ensues due to rheumatic mitral stenosis (RMS).The evaluation of RV function is clinically important for the diagnosis,treatment,and follow-up for patients with different degrees of RMS.Thepurpose of this study was to determine whether the 64-slice multi-detector row computed tomography (64-slice MDCT)can assess the RV function in RMS with high accuracy and reproducibility when compared to MR imaging (MRI).Methods Right ventricular end-diastolic and end-systolic volumes (RV-EDV and RV-ESV),stroke volume (RV-SV),ejection fraction (RV-EF),cardiac output (RV-CO),and wall mass (RV-Mass) were measured with dedicated cardiac analysis software on 64-slice MDCT and compared with values measured with MRI in 43 consecutive patients with RMS.Agreement between MRI and 64-MDCT results were compared with Bland and Altman analysis and linear regression analysis.Repeated measurements were performed to determine intraobserver and interobserver variability.Results No significant differences were revealed in calculated RV function parameters between the two methods.RV-EDV,RV-ESV,RV-SV,RV-EF,RV-CO,and RV-Mass by 64-slice MDCT were similar to those by MRI (P＞0.05).There were good correlations (r=0.98,0.97,0.96,0.96,0.95 and 0.77,respectively) and close agreement (bias=-0.2 ml,-1.0ml,0.8 ml,0.5％,26.1 ml,and 0.5 g,respectively,P＞0.05).The variability in 64-slice MDCT measurements was similar to that in MRI values.Conclusion ECG-gated 64-slice MDCT could assess the RV function in RMS with high accuracy and reproducibility when compared to MRI.