In vitro determination of cardiac ventricular volumes using MRI at 1.0 T in a porcine heart model

Usefulness of scoring right ventricular function for assessment of prognostic factors in patients with chronic thromboembolic pulmonary hypertension

Right ventricular (RV) function is associated with prognosis in chronic thromboembolic pulmonary hypertension (CTEPH). This study aimed to establish an RV dysfunction score using RV echocardiographic parameters to clarify the clinical characteristics in patients with CTEPH and to compare RV dysfunction score with parameters such as World Health Organization (WHO) functional class, hemodynamics, exercise capacity, and plasma BNP level. We enrolled 35 inpatients with CTEPH (mean age, 62 ± 15 years, 15 males). We constructed ‘an RV dysfunction score’ calculated as the summation of each point awarded for the presence of four parameters: tricuspid annular plane systolic excursion (TAPSE) < 16 mm, 1 point; tissue Doppler-derived tricuspid lateral annular systolic velocity (S′) < 10 cm/s, 1 point; right ventricular fractional area change (RVFAC) < 35%, 1 point; and right ventricular myocardial performance index (RV-MPI) > 0.4, 1 point. TAPSE, S′, RVFAC, and RV-MPI was 18.7 ± 4.8 mm, 11.9 ± 3.1 cm/s, 33.5 ± 13.9%, and 0.39 ± 0.2, respectively. The RV dysfunction score was associated with symptom [WHO functional class (p = 0.026)], hemodynamics [mean PAP (p = 0.01), cardiac index (p = 0.009), pulmonary vascular resistance (p = 0.001), and SvO₂ (p = 0.039)], exercise capacity [6-min walk distance (p = 0.046), peakVO₂ (p = 0.016), and VE/VCO₂ slope (p = 0.031)], and plasma BNP level (p = 0.005). This RV dysfunction score using the four RV echocardiographic parameters could be a simple and useful scoring system to evaluate prognostic factors in patients with CTEPH.

Assessment of the precision and reproducibility of ventricular volume, function, and mass measurements with ferumoxytol-enhanced 4D flow MRI

PURPOSE

To compare the precision and interobserver agreement of ventricular volume, function, and mass quantification by 3D time-resolved (4D) flow MRI relative to cine steady-state free precession (SSFP).

MATERIALS AND METHODS

With Institutional Research Board approval, informed consent, and HIPAA compliance, 22 consecutive patients with congenital heart disease (CHD) (10 males, 6.4 ± 4.8 years) referred for 3T ferumoxytol-enhanced cardiac MRI were prospectively recruited. Complete ventricular coverage with standard 2D short-axis cine SSFP and whole chest coverage with axial 4D flow were obtained. Two blinded radiologists independently segmented images for left ventricular (LV) and right ventricular (RV) myocardium at end systole (ES) and end diastole (ED). Statistical analysis included linear regression, analysis of variance (ANOVA), Bland-Altman (BA) analysis, and intraclass correlation (ICC).

RESULTS

Significant positive correlations were found between 4D flow and SSFP for ventricular volumes (r = 0.808-0.972, P < 0.001), ejection fraction (EF) (r = 0.900-928, P < 0.001), and mass (r = 0.884-0.934, P < 0.001). BA relative limits of agreement for both ventricles were between -52% to 34% for volumes, -29% to 27% for EF, and -41% to 48% for mass, with wider limits of agreement for the RV compared to the LV. There was no significant difference between techniques with respect to mean square difference of ED-ES mass for either LV (F = 2.05, P = 0.159) or RV (F = 0.625, P = 0.434). Interobserver agreement was moderate to good with both 4D flow (ICC 0.523-0.993) and SSFP (ICC 0.619-0.982), with overlapping confidence intervals.

CONCLUSION

Quantification of ventricular volume, function, and mass can be accomplished with 4D flow MRI with precision and interobserver agreement comparable to that of cine SSFP. J. Magn. Reson. Imaging 2016;44:383-392.