4D Flow MRI Applications for Aortic Disease

Burris, Nicholas S.; Hope, Michael D.

doi:10.1016/j.mric.2014.08.006

Cited by 67 publications

(50 citation statements)

References 48 publications

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“…The results of the present study illustrate how flow is displaced from the centerline of the aorta in the ascending aorta. The normal TAV cusp opens at an ~75° angle and flow is located in the centerline of the AA . In aortic valvular stenosis, the cusp opening angle and the orientation of the heart influence the angle at which the jet flow leaves the heart.…”

Section: Discussionmentioning

confidence: 56%

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Aortic dilatation associates with flow displacement and increased circumferential wall shear stress in patients without aortic stenosis: A prospective clinical study

Kauhanen

Hedman

Kariniemi

et al. 2019

Magnetic Resonance Imaging

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Background The relationship between blood flow characteristics and ascending aortic (AA) dilatation has not been studied in patients with a tricuspid aortic valve (TAV) without aortic stenosis. Purpose To evaluate whether 4D flow characteristics determined in MRI are related to AA dilatation by comparing dilated AA and nondilated AA subjects with TAV. Study Type Prospective. Population Twenty patients with dilated AA and 20 age‐matched patients with nondilated AA. Field Strength/Sequence 1.5T/4D flow, 2D flow, and anatomic images. Assessment Altogether, 16 different 4D flow parameters were assessed in 10 planes in the thoracic aorta. Intra‐ and interobserver reproducibility were analyzed. Statistical Tests Independent t‐test for normally distributed and the Mann–Whitney test for skewed distributed parameters were used. A paired‐samples t‐test was used to compare 2D and 4D flow parameters. Intraclass correlation coefficient (ICC) was used in intra‐ and interobserver reproducibility analysis. Results Aortic flow was displaced from the centerline of the aorta in the proximal and tubular planes. Flow displacement (FD) was greatest in the proximal plane of AA and was higher in dilated AA (4.5%, range 3.0–5.8%) than in nondilated AA (2.0%, 1.0–3.0%, P < 0.001). Total wall shear stress (WSS) values were 1.3 ± 0.4 times higher on the displaced side than on the opposite side of the aorta (P < 0.01). The circumferential WSS (WSSC) ratio to total WSS was greater in dilated AA, being 0.48 ± 0.11 vs. 0.32 ± 0.09 in the inner curvature of the proximal AA (P < 0.001) and 0.37 ± 0.11 vs. 0.26 ± 0.07 in the whole aortic ring in the distal AA (P < 0.001). Depending on 4D flow parameters, reproducibility varied from excellent (ICC = 0.923) to very low (ICC = 0.204). Data Conclusion The present study demonstrates that 4D flow measurements help to visualize the pathological flow patterns related to aortic dilatation. Flow displacement and an increased WSSc/WSS ratio are significantly associated with AA dilatation. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:136–145.

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Section: Discussionmentioning

confidence: 56%

“…In addition, total WSS values were lower in the dilated AA group . Alterations in WSS have also been shown to cause changes in endothelial metabolism, which could further lead to vessel wall stiffness and vessel wall remodeling …”

Section: Discussionmentioning

confidence: 94%

Aortic dilatation associates with flow displacement and increased circumferential wall shear stress in patients without aortic stenosis: A prospective clinical study

Kauhanen

Hedman

Kariniemi

et al. 2019

Magnetic Resonance Imaging

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“…Studies in patients with bicuspid aortic valve (BAV) have shown that disorganized outflow patterns due to abnormal valve opening can result in markedly altered regional WSS [11, 12, 17]. In addition, there is evidence that changes in WSS influence endothelial cell function and thus, promote vascular remodeling and vessel dilatation [18, 19].…”

Section: Introductionmentioning

confidence: 99%

Longitudinal Evaluation of Aortic Hemodynamics in Marfan Syndrome: New Insights from a 4D Flow Cardiovascular Magnetic Resonance Multi-Year Follow-Up Study

Geiger¹,

Hirtler²,

Gottfried³

et al. 2016

Journal of Cardiovascular Magnetic Resonance

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BackgroundThe aim of this 4D flow cardiovascular magnetic resonance (CMR) follow-up study was to investigate longitudinal changes in aortic hemodynamics in adolescent patients with Marfan syndrome (MFS).Methods4D flow CMR for the assessment of in-vivo 3D blood flow with full coverage of the thoracic aorta was performed twice (baseline scan t1/follow-up scan t2) in 19 adolescent MFS patients (age at t1: 12.7 ± 3.6 years, t2: 16.2 ± 4.3 years) with a mean follow-up duration of 3.5 ± 1.2 years. Ten healthy volunteers (24 ± 3.8 years) served as a control group. Data analysis included aortic blood flow visualization by color-coded 3D pathlines, and grading of flow patterns (helices/vortices) on a 3-point scale (none, moderate, severe; blinded reading, 2 observers). Regional aortic peak systolic velocities and systolic 3D wall shear stress (WSS) along the entire aortic wall were quantified. Z-Scores of the aortic root and proximal descending aorta (DAo) were assessed.ResultsRegional systolic WSS was stable over the follow-up duration, except for a significant decrease in the proximal inner DAo segment (p = 0.02) between t1 and t2. MFS patients revealed significant lower mean systolic WSS in the proximal inner DAo compared with volunteers (0.78 ± 0.15 N/m2) at baseline t1 (0.60 ± 0.18 N/m2; p = 0.01) and follow-up t2 (0.55 ± 0.16 N/m2; p = 0.001). There were significant relationships (p < 0.01) between the segmental WSS in the proximal inner DAo, DAo Z-scores (r = −0.64) and helix/vortex pattern grading (r = −0.55) at both t1 and t2. The interobserver agreement for secondary flow patterns assessment was excellent (Cohen’s k = 0.71).ConclusionsMFS patients have lower segmental WSS in the inner proximal DAo segment which correlates with increased localized aberrant vortex/helix flow patterns and an enlarged diameter at one of the most critical sites for aortic dissection. General aortic hemodynamics are stable but these subtle localized DAo changes are already present at young age and tend to be more pronounced in the course of time.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-017-0347-5) contains supplementary material, which is available to authorized users.

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“…The ascending aorta is a prediliction site for atherosclerosis and a major source of strokes, thus, understanding the blood flow in the ascending aorta is important for prognosis and timing for intervention [3]. Magnetic resonance (MR) and ultrasound (US) are the main modalities for imaging of aortic flow.…”

Section: Introductionmentioning

confidence: 99%

Vector flow imaging of the ascending aorta

Hansen

Møller‐Sørensen

Kjærgaard

et al. 2015

2015 IEEE International Ultrasonics Symposium (IUS)

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Abstract-In the ascending aorta, atherosclerotic plaque formation, which is a risk factor for cerebrovascular events, most often occurs along the inner curvature. Atherosclerosis is a multifactorial disease, but the predilection site for the aortic vessel degradation is probably flow dependent. To better understand the aortic flow and especially the complex flow patterns, the ascending aorta was scanned intraoperatively in patients undergoing heart surgery using the angle-independent vector velocity ultrasound method Transverse Oscillation (TO). The primary aim of the study was to analyze systolic backflow in relation to atherosclerosis. Thirteen patients with normal aortic valves were included in to the study. TO implemented on a conventional US scanner (ProFocus 2202 UltraView, BK Medical, Herlev, Denmark) with a linear array transducer (8670, BK Medical, Herlev, Denmark) was used intraoperatively on the ascending aorta in long axis view. The presence of systolic backflow, visualized with TO, was correlated to aortic atherosclerosis, to systolic velocities obtained with transesophageal echocardiography and cardiac output obtained with pulmonary artery catheter thermodilution, to gender, age, aortic diameter, left ventricular ejection fraction (LVEF) and previous myocardial infarctions (MI). Systolic backflow in the ascending aorta was present for 38% (n=5) of the patients. The location of the backflow was strongly associated to the location of the plaques (p<0.005), and backflow was associated to high systolic velocities (p<0.05). The other obtained parameters were not associated to systolic backflow. It was shown that systolic backflow is a common flow feature in the ascending aorta, and that backflow is associated to atherosclerotic plaques and systolic velocities. The study indicates that vector flow imaging using TO can provide important blood flow information in the assessment of atherosclerosis.

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4D Flow MRI Applications for Aortic Disease

Cited by 67 publications

References 48 publications

Aortic dilatation associates with flow displacement and increased circumferential wall shear stress in patients without aortic stenosis: A prospective clinical study

Aortic dilatation associates with flow displacement and increased circumferential wall shear stress in patients without aortic stenosis: A prospective clinical study

Longitudinal Evaluation of Aortic Hemodynamics in Marfan Syndrome: New Insights from a 4D Flow Cardiovascular Magnetic Resonance Multi-Year Follow-Up Study

Vector flow imaging of the ascending aorta

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