The indication for valve replacement depends on symptoms as well as functional and haemodynamic variables such as aortic valve area (AVA) and pressure gradients through the narrowed valve.
The purpose of the study is to investigate Cardiovascular MR (CMR) imaging with steady state free precession (SSFP) and routine velocity-encoded MRI techniques as a non-invasive approach for direct AVA planimetry. In addition, to define the reliability of this CMR technique as a routine method for quantifying cross valvular pressure gradient compared to echocardiographic and the invasive cardiac catheterization measurements, which serve as the gold standard.
Due to technical reasons, we started our project only towards the end of the year:
Methods and results:
| CVMR- Left Ventricular Ejection Fraction | CVMR- gradient estimation (mmHg) | Echo estimation (mmHg)- gradient | CVMR - Aortic valve area Planimetry (cm2) | Echo Aortic valve area evaluation (cm2) | 18 | NA | 25 | 1.5-(mild AS) | 1.6 (mild AS) |
| 16 | 36 | 35 | 0.5 (severe AS) | 0.8 (severe AS) |
| 23 | 59 | 60 | 0.93 (moderate AS) | 1.0(moderate AS) |
We evaluated 3 patients with aortic stenosis using cardio-vascular MRI (1.5-T General Electric MRI scanner with a 8-element, phased-array coil). Quantitative images were obtained through the aortic valve plane by using a breathold retrospectively gated velocity encoding technique. For planimetry of the aortic valve two views of the left ventricular outflow tract were obtained using SSFP CMR. Imaging planes for planimetry were laid out perpendicular to the aortic annulus in both series starting at the tips of the valvar leaflets during cardiac systole. Manual planimetry was obtained two times in each series and values were averaged.
The table summarizes the results and the correlation with echo-cardiographic measurements. Although the number of measurements is very limited, similar AS severity was found for the 3 categories of patients using Echo and CMR. Those preliminary results suggest that CMR may prove to be a reliable non-invasive modality for AS evaluation.
