Evaluation of aortic stenosis by cardiovascular magnetic resonance imaging: comparison with established routine clinical techniques

Abstract

Objective: To evaluate whether direct planimetry of aortic valve area (AVA) by cardiac magnetic resonance (CMR) imaging is a reliable tool for determining the severity of aortic stenosis compared with transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE), and cardiac catheterisation. Methods: 44 symptomatic patients with severe aortic stenosis were studied. By cardiac catheterisation AVA was calculated by the Gorlin equation. AVA was measured with CMR from steady state free precession (true fast imaging with steady state precession) by planimetry. AVA was also determined from TOE images by planimetry and from TTE images by the continuity equation. Results: Bland-Altman analysis evaluating intraobserver and interobserver variability showed a very small bias for both (20.016 and 0.019, respectively; n = 20). Bias and limits of agreement between CMR and TTE were 0.05 (20.35, 0.44) cm 2 (n = 37), between CMR and TOE 0.02 (20.39, 0.42) cm 2 (n = 32), and between CMR and cardiac catheterisation 0.09 (20.30, 0.47) cm 2 (n = 36). The sensitivity and specificity of CMR to detect AVA ( 0.80 cm 2 measured by cardiac catheterisation was 78% and 89%, of TOE 70% and 70%, and of TTE 74% and 67%, respectively. Conclusion: CMR planimetry is highly reliable and reproducible. Further, CMR planimetry had the best sensitivity and specificity of all non-invasive methods for detecting severe aortic stenosis in comparison with cardiac catheterisation. Therefore, CMR planimetry of AVA with steady state free precession is a new powerful diagnostic tool, particularly for patients with uncertain or discrepant findings by other modalities.

Planimetric and continuity equation assessment of aortic valve area: Head to head comparison between cardiac magnetic resonance and echocardiography

“…Several recent studies have compared the measurements of AVA obtained by this planimetric approach with those obtained by TEE or during cardiac catheterization. All demonstrated good agreement between cMR and either TTE or hemodynamic measurements of AVA (3)(4)(5)(6). Potential limitations of planimetry consist of difficulties of precise visualization of the aortic leaflets due to partial volume effects, presence of calcification, or flow artifacts.…”

“…With the introduction of SSFP, this technique indeed permits high quality cine short-axis images of the aortic valve to be obtained and therefore its maximal opening area to be directly planimetered (3)(4)(5)(6). Several recent studies have compared the measurements of AVA obtained by this planimetric approach with those obtained by TEE or during cardiac catheterization.…”

“…SIMILAR TO ECHOCARDIOGRAPHY, cardiac MRI (cMR) allows for the assessment of aortic stenosis (AS) severity by use of two different approaches, i.e., the direct planimetry of the maximal anatomical orifice using cine MR imaging at the valve tips (1)(2)(3)(4)(5)(6) and the calculation of the functional orifice area using the continuity equation and velocity time integrals (VTIs) obtained at the valve tips and the left ventricular outflow tract with phase-contrast imaging (7,8). Although aortic valve areas (AVAs) obtained with both techniques have been shown to correlate well with echocardiography and the Gorlin formula, there has been no direct comparison of these two approaches in the same population.…”

Comparison of Magnetic Resonance Imaging and Cardiac Catheterization in Patients with Suspected Severe Aortic Stenosis

“…MRI assessment of AVA correlates well with transesophageal echocardiography. However, the published comparisons with cardiac catheterization are equivocal (4,5,8,10).…”

The emerging clinical role of cardiovascular magnetic resonance imaging

“…Aortic valve stenosis can be accurately quantified by planimetry of the aortic valve (96,97) (Figure 4), a method that does not depend on pressure gradient measurement-derived calculations, and that therefore may be less susceptible to pre-and afterload variations. Another established way to assess the aortic valve area is by flow measurements using phase-contrast CMR imaging, analogous to Doppler echocardiography.…”