Estudio del ventrículo derecho mediante resonancia magnética

Evaluation of a Semi-automatic Right Ventricle Segmentation Method on Short-Axis MR Images

The purpose of this study was to evaluate a semi-automatic right ventricle segmentation method on short-axis cardiac cine MR images which segment all right ventricle contours in a cardiac phase using one seed contour. Twenty-eight consecutive short-axis, four-chamber, and tricuspid valve view cardiac cine MRI examinations of healthy volunteers were used. Two independent observers performed the manual and automatic segmentations of the right ventricles. Analyses were based on the ventricular volume and ejection fraction of the right heart chamber. Reproducibility of the manual and semi-automatic segmentations was assessed using intra- and inter-observer variability. Validity of the semi-automatic segmentations was analyzed with reference to the manual segmentations. The inter- and intra-observer variability of manual segmentations were between 0.8 and 3.2%. The semi-automatic segmentations were highly correlated with the manual segmentations (R² 0.79-0.98), with median difference of 0.9-4.8% and of 3.3% for volume and ejection fraction parameters, respectively. In comparison to the manual segmentation, the semi-automatic segmentation produced contours with median dice metrics of 0.95 and 0.87 and median Hausdorff distance of 5.05 and 7.35 mm for contours at end-diastolic and end-systolic phases, respectively. The inter- and intra-observer variability of the semi-automatic segmentations were lower than observed in the manual segmentations. Both manual and semi-automatic segmentations performed better at the end-diastolic phase than at the end-systolic phase. The investigated semi-automatic segmentation method managed to produce a valid and reproducible alternative to manual right ventricle segmentation.

Three-Dimensional Tricuspid Annular Motion Analysis from Cardiac Magnetic Resonance Feature-Tracking

Right ventricular (RV) dysfunction is known to be highly correlated with mortality and morbidity; nevertheless, imaging-based assessment of RV anatomy and physiology lags far behind that of the left ventricle. In this study, we advance RV imaging using cardiac magnetic resonance (CMR) to accomplish the following aims: (i) track the motion of six tricuspid annular (TA) sites using a semi-automatic tracking system; (ii) extract clinically important TA measurements-systolic velocity (Sm), early diastolic velocity (Em), late diastolic velocity (Am), and TA plane systolic excursion (TAPSE)-for each TA site and compare these CMR-derived measurements in healthy subjects vs. patients with heart failure, repaired tetralogy of Fallot, pulmonary hypertension, and hypertrophic cardiomyopathy; (iii) investigate how the TA motion related measurements compare with information provided by invasive right heart catheterization (RHC); (iv) evaluate the rate of change in surface area swept out by the reconstructed tricuspid annulus over time and (v) assess the reproducibility of this CMR-based technique. Results indicate that TA motion parameter data obtained in three dimensions using the proposed CMR-based systematic methodology achieve superior diagnostic performance (Sm: AUC = 0.957; TAPSE: AUC = 0.981) compared to two-dimensional CMR imaging. Both Sm and TAPSE from CMR correlated positively with dP/dt _max/IP from RHC (Sm: r = 0.621, p < 0.01; TAPSE: r = 0.648, p < 0.01). Our highly reproducible and robust methodology holds potential for extending CMR imaging to characterization of TA morphology and dynamic behaviour, eventually leading to deeper understanding of RV function and improved diagnostic capability.