Abstract 1124 Positioning of the Image Plane in Phase Contrast MRI impacts Aortic Stenosis Assessment

Objectives. To determine the phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) level above aortic leaflet-attachment-plane (LAP) that generates the most valid measures of flow-velocity and -volume compared to cardiac catheterization in aortic stenosis (AS).

Methods. Fifty-five patients with moderate to severe AS underwent cardiac catheterization, transthoracic echocardiography (TTE) and CMR including cine-imaging and PC-CMR. A total of 171 image-planes parallel to LAP were measured via PC-CMR, at 22mm below to 24mm above LAP at end-diastole. Aortic valve area (AVA) via PC-CMR was calculated as flow-volume divided by peak-velocity during systole. Stroke volume (SV) and AVA were compared to volumetric SV and invasive AVA via the Gorlin-formula, respectively.

Results. Above LAP, SV by PC-CMR showed no significant differences depending on image-plane position and correlated strongly with volumetry (r: 0.647, p<0.001, bias: 1ml, p=0.540). AVA-assessment in layers from 0 10mm above LAP differed significantly from invasive measurement (0.85±0.30cm² vs. 0.71±0.24cm², bias: 0.14cm², p<0.001). In contrast, AVA-values by PC-CMR measured 10 20mm above LAP showed good agreement with invasive determination without significant bias (0.70±0.25cm² vs. 0.70±0.25cm², bias: 0.001cm², p=0.974). Within these measurements, 15mm above LAP displayed the lowest bias ( 0.05cm², p=0.516). SV and AVA via TTE correlated moderately (r: 0.492, p<0.001; bias: -14ml, p<0.001) and weakly (r: 0.356, p<0.001, bias: 0.17cm², p<0.001), respectively, with cardiac catheterization.

Conclusion. PC-CMR measurements at 0-10mm above LAP should be avoided due to significant AVA-overestimation compared to invasive determination. AVA-assessment by PC-CMR between 10-20mm above LAP did not differ from invasive measurements, with the lowest intermethodical bias measured 15mm above LAP.

Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5
Positioning of the Image Plane in Phase Contrast MRI impacts Aortic Stenosis Assessment
F. Troger¹, M. Reindl¹, I. Lechner¹, C. Tiller¹, M. Holzknecht¹, M. Pamminger², P. Poskaite², C. Kremser², S. J. Reinstadler¹, A. Bauer¹, B. Metzler¹, G. Klug¹, A. Mayr²
¹Universitätsklinik für Innere Medizin III, Medizinische Universität Innsbruck, Innsbruck, AT; ²Universitätsklinik für Radiologie, Medizinische Universität Innsbruck, Innsbruck, AT;
Objectives. To determine the phase-contrast cardiovascular magnetic resonance imaging (PC-CMR) level above aortic leaflet-attachment-plane (LAP) that generates the most valid measures of flow-velocity and -volume compared to cardiac catheterization in aortic stenosis (AS). Methods. Fifty-five patients with moderate to severe AS underwent cardiac catheterization, transthoracic echocardiography (TTE) and CMR including cine-imaging and PC-CMR. A total of 171 image-planes parallel to LAP were measured via PC-CMR, at 22mm below to 24mm above LAP at end-diastole. Aortic valve area (AVA) via PC-CMR was calculated as flow-volume divided by peak-velocity during systole. Stroke volume (SV) and AVA were compared to volumetric SV and invasive AVA via the Gorlin-formula, respectively. Results. Above LAP, SV by PC-CMR showed no significant differences depending on image-plane position and correlated strongly with volumetry (r: 0.647, p<0.001, bias: 1ml, p=0.540). AVA-assessment in layers from 0 10mm above LAP differed significantly from invasive measurement (0.85±0.30cm² vs. 0.71±0.24cm², bias: 0.14cm², p<0.001). In contrast, AVA-values by PC-CMR measured 10 20mm above LAP showed good agreement with invasive determination without significant bias (0.70±0.25cm² vs. 0.70±0.25cm², bias: 0.001cm², p=0.974). Within these measurements, 15mm above LAP displayed the lowest bias ( 0.05cm², p=0.516). SV and AVA via TTE correlated moderately (r: 0.492, p<0.001; bias: -14ml, p<0.001) and weakly (r: 0.356, p<0.001, bias: 0.17cm², p<0.001), respectively, with cardiac catheterization. Conclusion. PC-CMR measurements at 0-10mm above LAP should be avoided due to significant AVA-overestimation compared to invasive determination. AVA-assessment by PC-CMR between 10-20mm above LAP did not differ from invasive measurements, with the lowest intermethodical bias measured 15mm above LAP.
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