4D Flow cardiovascular magnetic resonance consensus statement: 2023 update

4D Flow MRI; Hemodynamics; RecommendationsRessonància magnètica de flux 4D; Hemodinàmica; RecomanacionsResonancia magnética de flujo 4D; Hemodinámica; RecomendacionesHemodynamic assessment is an integral part of the diagnosis and management of cardiovascular disease. Four-dimensional cardiovascular magnetic resonance flow imaging (4D Flow CMR) allows comprehensive and accurate assessment of flow in a single acquisition. This consensus paper is an update from the 2015 ‘4D Flow CMR Consensus Statement’. We elaborate on 4D Flow CMR sequence options and imaging considerations. The document aims to assist centers starting out with 4D Flow CMR of the heart and great vessels with advice on acquisition parameters, post-processing workflows and integration into clinical practice. Furthermore, we define minimum quality assurance and validation standards for clinical centers. We also address the challenges faced in quality assurance and validation in the research setting. We also include a checklist for recommended publication standards, specifically for 4D Flow CMR. Finally, we discuss the current limitations and the future of 4D Flow CMR. This updated consensus paper will further facilitate widespread adoption of 4D Flow CMR in the clinical workflow across the globe and aid consistently high-quality publication standards.1R01HL149787-01A1 (S. Schnell, M. Markl), 1R21NS122511-01 (S. Schnell), 1R01CA233878-01 (J.Collins) J.Sotelo thanks to ANID–Millennium Science Initiative Program–ICN2021_004 and FONDECYT de iniciación en investigación #11200481. Dr. Oechtering receives funding from the German Research Foundation (OE 746/1-1)

Characterisation of haemodynamic and vascular dysfunction in bicuspid aortic valve disease using advanced cardiovascular magnetic resonance imaging techniques

Bicuspid aortic valve disease (BAV) is known to be heritable and often shows a concomitant aortopathy with increased risk of aortic dissection. This may also be present in family members. The underlying pathophysiology was largely believed to be an intrinsic aortopathy. However, recent advances in cardiovascular magnetic resonance imaging now allow in-depth haemodynamic and functional assessment of the aorta to further delineate the underlying pathophysiology. This thesis explored the association of haemodynamic and functional aortic changes with aortic dilation in BAV patients, first degree relatives and healthy volunteers. Patients with a bicuspid aortic valve were found to have an abnormal degree of helical flow in the ascending aorta with predominantly right-handed helical flow. Compared to healthy volunteers patients with a bicuspid aortic valve had larger ascending aortas, higher rotational (helical) flow, systolic flow angle and systolic wall shear stress. There were also differences between the cusp fusion patterns in BAV, with right-non coronary cusp fusion showing more severe flow and aortic abnormalities than those with a right-left coronary cusp fusion pattern: higher rotational flow, higher in-plane wall sheer stress and larger aortas respectively. BAV patients with normal flow patterns had similar aortic dimensions and wall shear stress to healthy volunteers and younger BAV patients showed abnormal flow patterns but no aortic dilation, both further supporting the importance of flow pattern in the aetiology of aortic dilation. However, aortic function measures (distensibility, aortic strain and pulse wave velocity) were similar between healthy volunteers, patients with a bicuspid aortic valve and first degree relatives with a tricuspid aortic valve. Aortic valve replacement (AVR) significantly changed the ascending aortic flow pattern in patients with a bicuspid aortic valve. The majority of patients with mechanical AVR or Ross procedure showed normal flow patterns with near normal rotational flow values post operatively and reduced in-plane wall shear stress. By contrast, all subjects with bioprosthetic AVR had residual abnormal helical flow patterns (mainly marked right-handed helical flow), with similar rotational flow values to native BAV. Wall shear stress post-bioprosthetic AVR showed a similar pattern. These findings point towards the importance of haemodynamic factors in the bicuspid aortic valve aortopathy rather than additional haemodynamic-independent mechanisms. Haemodynamic classification may allow better risk prediction and selection of patients for earlier surgical intervention. Changes in abnormal flow pattern after valve replacement could have important implications for future aortic growth, and may influence the future choice of prosthetic valves.</p

Characterisation of haemodynamic and vascular dysfunction in bicuspid aortic valve disease using advanced cardiovascular magnetic resonance imaging techniques

Bicuspid aortic valve disease (BAV) is known to be heritable and often shows a concomitant aortopathy with increased risk of aortic dissection. This may also be present in family members. The underlying pathophysiology was largely believed to be an intrinsic aortopathy. However, recent advances in cardiovascular magnetic resonance imaging now allow in-depth haemodynamic and functional assessment of the aorta to further delineate the underlying pathophysiology. This thesis explored the association of haemodynamic and functional aortic changes with aortic dilation in BAV patients, first degree relatives and healthy volunteers. Patients with a bicuspid aortic valve were found to have an abnormal degree of helical flow in the ascending aorta with predominantly right-handed helical flow. Compared to healthy volunteers patients with a bicuspid aortic valve had larger ascending aortas, higher rotational (helical) flow, systolic flow angle and systolic wall shear stress. There were also differences between the cusp fusion patterns in BAV, with right-non coronary cusp fusion showing more severe flow and aortic abnormalities than those with a right-left coronary cusp fusion pattern: higher rotational flow, higher in-plane wall sheer stress and larger aortas respectively. BAV patients with normal flow patterns had similar aortic dimensions and wall shear stress to healthy volunteers and younger BAV patients showed abnormal flow patterns but no aortic dilation, both further supporting the importance of flow pattern in the aetiology of aortic dilation. However, aortic function measures (distensibility, aortic strain and pulse wave velocity) were similar between healthy volunteers, patients with a bicuspid aortic valve and first degree relatives with a tricuspid aortic valve. Aortic valve replacement (AVR) significantly changed the ascending aortic flow pattern in patients with a bicuspid aortic valve. The majority of patients with mechanical AVR or Ross procedure showed normal flow patterns with near normal rotational flow values post operatively and reduced in-plane wall shear stress. By contrast, all subjects with bioprosthetic AVR had residual abnormal helical flow patterns (mainly marked right-handed helical flow), with similar rotational flow values to native BAV. Wall shear stress post-bioprosthetic AVR showed a similar pattern. These findings point towards the importance of haemodynamic factors in the bicuspid aortic valve aortopathy rather than additional haemodynamic-independent mechanisms. Haemodynamic classification may allow better risk prediction and selection of patients for earlier surgical intervention. Changes in abnormal flow pattern after valve replacement could have important implications for future aortic growth, and may influence the future choice of prosthetic valves.</p