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Updated: Apr 14, 2026
In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging
Published on: February 25, 2022
Quantification of Retrograde Blood Flow in the Descending Aorta Using Transesophageal Echocardiography in Comparison
Thomas Wehrum1, Miriam Kams, Felix Günther
1Department of Neurology, University Medical Center Freiburg, Freiburg, Germany.
Insights
Routine 2D transesophageal echocardiography (TEE) can estimate retrograde flow length in the descending aorta (DAo), a potential source of brain embolism. While TEE offers a cost-effective screening method, 4D flow MRI remains essential for precise embolization pathway assessment.
Area of Science:
- Cardiovascular Imaging
- Neurology
- Medical Technology
Background:
- Retrograde diastolic blood flow in the proximal descending aorta (DAo) is a potential source of brain embolism.
- Plaques ≥4 mm thick in the DAo can connect with brain-supplying arteries.
- Currently, only 4D flow MRI can visualize and quantify these embolization pathways in vivo.
Purpose of the Study:
- To determine if routine 2D transesophageal echocardiography (TEE) can estimate the extent of retrograde flow in the DAo.
- To correlate TEE-derived velocity-time-integral ratio (VTIratio) with retrograde pathline length visualized by 4D flow MRI.
Main Methods:
- Prospective study of 48 acute stroke patients undergoing routine TEE.
- Doppler examinations at the aortic arch-DAo transition zone using a 20 mm sample volume.
- Calculation of VTIratio and correlation with 4D flow MRI-derived retrograde pathline length.
Main Results:
- Mean VTIratio was 0.53 ± 0.16, with a mean retrograde pathline length of 3.1 ± 1.4 cm.
- VTIratio independently predicted retrograde pathline length (r = 0.44; p = 0.002).
- A VTIratio threshold of 0.6012 differentiated large (≥3 cm) from small (<3 cm) retrograde flow with 92% specificity.
Conclusions:
- TEE can predict retrograde pathline length in the DAo.
- TEE may serve as a cost-effective tool for large-scale studies on DAo flow reversal predictors.
- TEE has limited value as a screening tool; 4D flow MRI is indispensable for precise individual embolization pathway assessment.
Background:
Retrograde diastolic blood flow in the proximal descending aorta (DAo), which connects plaques ≥4 mm thickness with brain-supplying arteries, has previously been identified as a possible source of brain embolism. Currently, only 4D flow MRI is able to visualize and quantify potential retrograde embolization pathways in the DAo in-vivo. Hence, it was our aim to test if the extent of retrograde flow could be estimated by routine 2D transesophageal echocardiography (TEE).
Methods:
Forty-eight acute stroke patients were prospectively included and they underwent Doppler examinations of the transition zone between the aortic arch and the DAo using a 20 mm 2D sample volume in longitudinal section at 90-140° Doppler angle during routine TEE. Velocity-time-integrals (VTI) were studied for antegrade and retrograde velocities and the ratio (VTIratio) was calculated and correlated with the length of retrograde pathlines at that site, which were visualized using 4D flow MRI at 3-Tesla. A receiver operating characteristic (ROC) curve was used to evaluate a threshold value of VTIratio in differentiating large (≥3 cm) from small (<3 cm) retrograde flow extent.
Results:
At the TEE measurement site, the mean VTIratio was 0.53 ± 0.16 and the mean length of retrograde pathlines reaching back into the aortic arch was 3.1 ± 1.4 cm. VTIratio was an independent predictor of retrograde pathline length (r = 0.44; p = 0.002). ROC analysis identified a VTIratio threshold value of 0.6012 with a sensitivity of 0.5, a specificity of 0.92, and positive and negative predictive values of 0.84 and 0.68, respectively. Accordingly, 11 (22.91%) patients had a VTIratio cutoff value ≥0.6012 and corresponding retrograde pathline length ≥3 cm in 4D flow MRI.
Conclusions:
TEE allows predicting the length of retrograde pathlines. Hence, it may offer a cost-effective way to investigate independent predictors of DAo flow reversal in large-scale studies. However, TEE is only of limited value as a screening tool for high retrograde flow in a clinical setting, as only ∼23% of patients can be spared 4D flow MRI, which remains indispensable for the exact assessment of individual embolization pathways from plaques of the DAo in-vivo.
